Brain, Behavior, and Immunity 51 (2016) 240–251
Contents lists available at ScienceDirect
Brain, Behavior, and Immunity
journal homepage: www.elsevier.com/locate/ybrbi
Maturation- and sex-sensitive depression of hippocampal excitatory
transmission in a rat schizophrenia model
Eti Patrich a,b,c,1, Yael Piontkewitz d,1, Asher Peretz a, Ina Weiner b,c, Bernard Attali a,c,⇑
a
Department of Physiology & Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
Department of Psychology, Gordon Faculty of Social Sciences, Tel Aviv University, Tel Aviv 69978, Israel
c
Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 69978, Israel
d
Strauss Center for Computational Neuroimaging, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
b
a r t i c l e
i n f o
Article history:
Received 2 June 2015
Received in revised form 20 August 2015
Accepted 27 August 2015
Available online 29 August 2015
Keywords:
Schizophrenia
Maternal immune activation
Poly I:C
Hippocampus
Risperidone
Antipsychotic drugs
a b s t r a c t
Schizophrenia is associated with behavioral and brain structural abnormalities, of which the hippocampus appears to be one of the most consistent region affected. Previous studies performed on the poly I:C
model of schizophrenia suggest that alterations in hippocampal synaptic transmission and plasticity take
place in the offspring. However, these investigations yielded conflicting results and the neurophysiological alterations responsible for these deficits are still unclear. Here we performed for the first time a longitudinal study examining the impact of prenatal poly I:C treatment and of gender on hippocampal
excitatory neurotransmission. In addition, we examined the potential preventive/curative effects of
risperidone (RIS) treatment during the peri-adolescence period. Excitatory synaptic transmission was
determined by stimulating Schaffer collaterals and monitoring fiber volley amplitude and slope of
field-EPSP (fEPSP) in CA1 pyramidal neurons in male and female offspring hippocampal slices from postnatal days (PNDs) 18–20, 34, 70 and 90. Depression of hippocampal excitatory transmission appeared at
juvenile age in male offspring of the poly I:C group, while it expressed with a delay in female, manifesting
at adulthood. In addition, a reduced hippocampal size was found in both adult male and female offspring
of poly I:C treated dams. Treatment with RIS at the peri-adolescence period fully restored in males but
partly repaired in females these deficiencies. A maturation- and sex-dependent decrease in hippocampal
excitatory transmission occurs in the offspring of poly I:C treated pregnant mothers. Pharmacological
intervention with RIS during peri-adolescence can cure in a gender-sensitive fashion early occurring hippocampal synaptic deficits.
Ó 2015 Elsevier Inc. All rights reserved.
1. Introduction
Schizophrenia is a severe and chronic psychotic illness affecting
almost 1% of the population worldwide. In the hippocampus of
schizophrenic patients, anomalies like pyramidal neuron loss,
asymmetric alterations in hippocampal neuronal size and shape,
were described, possibly resulting in aberrant functional connectivity of hippocampal network (Benes et al., 1991; Boyer et al.,
2007; Harrison, 1999; Harrison and Eastwood, 2001; Jonsson
et al., 1999). Postmortem and magnetic resonance imaging (MRI)
studies showed altered hippocampal size and shape in first episode
subjects as well as in the prodromal stage, before expression of the
full clinical phenotype (Harrison, 1999, 2004; DeLisi, 2008; Lawrie
⇑ Corresponding author at: Department of Physiology & Pharmacology, Sackler
Faculty of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
E-mail address: [email protected] (B. Attali).
1
Equal contributors.
http://dx.doi.org/10.1016/j.bbi.2015.08.021
0889-1591/Ó 2015 Elsevier Inc. All rights reserved.
et al., 2008; Nelson et al., 1998). At the neurophysiological level,
many lines of evidence support dopaminergic and glutamatergic
dysregulations as a major pathogenic mechanism of schizophrenia
(Coyle, 2006; Javitt et al., 2011; Moghaddam and Javitt, 2012).
Converging evidence from epidemiological, brain imaging and
neuropathological studies suggest that schizophrenia is a neurodevelopmental disorder, whereby brain abnormalities occur early in
life and where genetic, epigenetic and environmental factors provide substantial triggers for the disease to manifest clinically at
early adulthood (Arnold, 1999; Beckmann, 1999; Murray et al.,
1992; Murray and Lewis, 1987; Weinberger, 1987; Bilbo and
Schwarz, 2012). One of the major environmental risk factors for
schizophrenia is maternal immune activation (MIA) subsequent
to maternal viral or bacterial infections during pregnancy (Brown
et al., 2000; Fatemi et al., 2012; Hultman et al., 1999; Mednick
et al., 1988; Yolken et al., 2000). Immune activation of pregnant
rodents by injection of a synthetic analog of double-stranded
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
RNA, polyriboinosinic polyribocytidilic acid (poly I:C), which mimics viral infection, leads to a broad range of schizophrenia-relevant
behavioral and neuroanatomical deficits that exhibit a characteristic emergence at adulthood (Meyer et al., 2005; Ozawa et al., 2006;
Shi et al., 2003; Zuckerman et al., 2003; Zuckerman and Weiner,
2003, 2005; Piontkewitz et al., 2012a).
Electrophysiological studies on the poly I:C model of
schizophrenia suggest that one of the consequences of MIA may
be an alteration of hippocampal synaptic transmission and longterm plasticity in the offspring (Boksa, 2010). However, these studies yielded conflicting results, with an increase or decrease of the
glutamatergic or GABAergic neurotransmission (Hellstrom et al.,
2005; Ducharme et al., 2012; Escobar et al., 2011; Lante et al.,
2007; Lowe et al., 2008; Oh-Nishi et al., 2010; Roumier et al., 2008).
It has been shown that anti-psychotic drugs (APDs) can treat
the behavioral abnormalities in the poly I:C model and in other
models of MIA (Shi et al., 2003; Zuckerman et al., 2003;
Zuckerman and Weiner, 2005; Piontkewitz et al., 2009, 2011a;
Romero et al., 2007). Furthermore, treatment with APDs during
peri-adolescence prior to the emergence of schizophrenia-like
abnormal behavior was shown to prevent the emergence of neuroanatomical and behavioral symptoms in adults of various animal
model of schizophrenia (Piontkewitz et al., 2009, 2011a, 2012b;
Meyer et al., 2010; Richtand et al., 2006, 2011).
In this study, we examined the impact of prenatal poly I:C treatment on hippocampal glutamatergic neurotransmission and volume at different periods of offspring postnatal development. Sex
differences are known to exist in schizophrenia (DeLisi, 1992;
DeLisi et al., 1989; Gattaz et al., 1994; Grigoriadis and Seeman,
2002; Hafner and an der Heiden, 1998; Rana et al., 2012;
Piontkewitz et al., 2011b). Thus, we explored whether differences
in nature or timing of the hippocampal neurophysiological defects
would be found between male and female offspring. Finally, based
on our previous studies (Piontkewitz et al., 2009a, 2011a, 2012a,b),
we investigated the potential preventive effects of risperidone
(RIS) administered during peri-adolescence (postnatal days [PNDs]
34–47) on hippocampal glutamatergic transmission defects in
male and female offspring. A maturation and sex dependent
decrease in hippocampal glutamatergic transmission was observed
in poly I:C offspring. At juvenile age (PNDs 18–20), a significant
reduction in the Schaffer collateral-CA1 pyramidal neuron
transmission was found exclusively in male offspring from poly I:
C-treated mothers. At adult stage, both male and female offspring
of poly I:C-treated mothers exhibited a depression in glutamatergic transmission and RIS treatment during peri-adolescence
corrected these deficits. MRI imaging data indicated that adult
male and female offspring of poly I:C treated dams exhibit reduced
hippocampal size that was restored by administration of RIS at
peri-adolescence.
241
Piontkewitz et al., 2009). At 3 months of age, Wistar rats were
mated and the first day after copulation was defined as day 1 of
pregnancy. On gestation day (GD) 15, pregnant dams were anesthetized with 3% isoflurane (Minrad, Bethlehem, PA) in 98% O2
and given a single intravenous injection at the tail vein of 4 mg/
kg poly I:C (Sigma, Rehovot, Israel; dissolved in saline), or an equivalent volume of saline. The volume of injection was 1 ml/kg. Poly I:
C caused weight loss for about 1 day without significantly increasing miscarriage rate. On PND 21 (except where mentioned), pups
were weaned and housed 2–4 to a cage by sex and litter, and maintained undisturbed until the experimental manipulation (drug
injection at PND 34, hippocampal slices preparation and MRI scanning). In all experiments, each experimental group consisted of
subjects derived from multiple independent litters, with no more
than 1–2 rats from the same litter in any of the experimental
groups. N = 6–7 offspring of poly I:C or saline- treated mothers that
were sacrificed at each PND. 1–3 slices were recorded from each
offspring.
2.3. Preventive treatment
Preventive treatment was given on PNDs 34–47. This time period is considered to represent adolescence or peri-adolescence
(Spear, 2000), in which poly I:C offspring are behaviorally and neuroanatomically asymptomatic (Piontkewitz et al., 2011a). Our previous work showed that preventive treatment during PNDs 34–47
with the APD RIS, successfully prevented the behavioral and neuroanatomical abnormalities in offspring of poly I:C treated mothers
(Piontkewitz et al., 2011a). Female and male offspring of poly I:C
and saline injected mothers were daily injected intraperitoneally
(i.p.) with 0.045 mg/kg RIS (Janssen, Beerse, Belgium) or vehicle
on PNDs 34–47 (Piontkewitz et al., 2011a). RIS was dissolved in
0.1 M tartaric acid (7.5 ll/mg) and diluted with saline. The volume
of injection was 1 ml/kg.
2.4. Hippocampal slice preparation
Brains were rapidly removed from both female and male offspring at PNDs 18–20, 34, 70 and 90. Coronal hippocampal slices
(400 lm thick) were prepared in a cold (4 °C) storage buffer containing (in mM): sucrose, 206; KCl, 2; MgSO4, 2; NaH2PO4, 1.25;
NaHCO3, 26; CaCl2, 1; MgCl2, 1; glucose, 10 using a Leica VT1200
vibratome. Slices were immediately transferred to a submerged
recovery chamber at room temperature artificial cerebrospinal
fluid (aCSF) bubbled with 95% O2 and 5% CO2 for at least 1 h before
recording. The aCSF contained (in mM): NaCl, 125; KCl, 2.5; CaCl2,
1.2; MgCl2, 1.2; NaHCO3, 25; NaH2PO4, 1.25; glucose, 25. Compared
groups had always the same time of recovery in aCSF.
2.5. Field excitatory post-synaptic potentials recordings
2. Methods and materials
2.1. Animals
Adult (350–400 g) Wistar rats were housed 3–4 to a cage under
reversed cycle lighting (lights on: 19:00–7:00 h) with ad lib food
and water. All experimental protocols conformed to the guidelines
of the Institutional Animal Care and Use Committee of Tel-Aviv
University, Israel, and to the guidelines of the NIH (animal welfare
assurance number A5010-01).
2.2. Prenatal poly I:C treatment
Prenatal treatment was performed as described previously
(Zuckerman et al., 2003; Zuckerman and Weiner, 2003;
Extracellular field excitatory post-synaptic potentials (fEPSPs)
were recorded from hippocampal slices of male and female offspring of poly I:C and saline injected mothers at PNDs 18–20, 34,
70, 90. Slices were placed in the recording chamber and perfused
(2 ml/min) with aCSF bubbled with 95% O2 and 5% CO2 at room
temperature. The recording pipette (1–2 MΩ) was filled with aCSF
and placed in the stratum radiatum of CA1 to record fEPSPs. Synaptic events were evoked by bipolar stimulating platinum iridium
electrode in the Schaffer collateral using isolated stimulating unit
(digitimer LTD). Data were acquired using pClamp 10.3 software
(Molecular Devices) in conjunction with a multiclamp700B interface digitized with DigiData 1440A (Molecular Devices). At the
beginning of each experiment, slices were repeatedly stimulated
at 0.03 Hz in order to validate the slice’s stability. For fEPSP recordings, Schaffer collaterals were stimulated with a series of increas-
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E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
ing stimulus intensities (200–1400 lA) at 0.1 Hz. fEPSPs were
monitored for not inducing short-term plasticity resulting from
the repeated stimulation of the slice. The basal synaptic transmission was examined by plotting input/output curves of the relationships between: (i) stimulation current and fiber volley (FV)
amplitude; (ii) stimulation current and slope fEPSPs (S-fEPSP);
(iii) FV and S-fEPSP. Paired pulse facilitation (PPF) was performed
by delivering paired stimuli at various interpulse intervals ranging
from 25 to 1000 ms. PPF was assessed as the S-fEPSP in response to
the second pulse divided by that of the first pulse. 5 action potentials (5-AP) bursts were induced at inter-spike intervals of either
40 Hz or 70 Hz and inter-burst interval of 30 s. Facilitation was calculated as the ratio between each S-fEPSP response to the first SfEPSP response.
ANOVA (prenatal treatment preventive treatment age) was
performed for S-fEPSP and FV amplitudes with repeated measurement factors (current stimulation), separately for male and female
offspring. For I/O slopes, a three-way ANOVA (prenatal treatment preventive treatment age) was performed, separately
for male and female offspring. For MRI statistical analysis, a twoway ANOVA (prenatal treatment preventive treatment) was performed with repeated measurement factors (age), separately for
male and female offspring. Significant interactions were followed
by LSD post hoc comparisons.
3. Results
3.1. Effects of poly I:C treatment on hippocampal basal glutamatergic
synaptic transmission
2.6. Magnetic resonance imaging
MRI scans were performed under inhalational isoflurane (1–2%;
Minrad) anesthesia in 98% O2. Body temperature was maintained
by circulating water at 37 °C under the ‘‘bed” in which the animals
were lying during the scans. Respiration was kept at 60–80 breath
cycles per minute.
2.6.1. MRI scan
MRI was performed on a 7.0 T/30 spectrometer (Bruker, Rheinstetten, Germany) using a volume coil for excitation and a rat
quadrature coil for acquisition. The coronal T2-weighted image of
the brain were obtained with RARE sequence, with repetition
time = 3000 ms and effective echo time = 49 ms, RARE factor 8, 4
averages, field of view of 3 3 cm, matrix dimensions of
256 128 (zero filled to 256 256) and 18 slices of 1 mm thickness with no gap. For image analysis, 18 coronal sections used
for the volumetric analyses were taken perpendicular to a line connecting the superior end of the olfactory bulb with the anterior line
of the cerebellum.
2.6.2. Image analysis for volume calculation
The hippocampus volume was obtained from the T2-weighted
images using manual segmentation (Medical Image Analysis version 2.4 MATLAB). Hippocampal volumes were calculated by combining all slices where they appeared (approximately 2.1 to
6.7 mm from Bregma), and multiplied by slice thickness. Hippocampal volume was measured from 5 consecutive slices in
which the hippocampus was clearly visible. The starting rostral
slice was defined by the Cornu Ammonis and DG and coincided
with the dorsal hippocampal commissure approximately
2.12 mm from Bregma. The caudal boundary was defined by loss
of contrast between the external capsule and the subiculum and
the clear separation of the 2 cerebral hemispheres. In addition,
the aquaduct opened up and became a clearly visible, round circle.
2.7. Data analysis
Data analysis was performed using the Clampfit program
(pClamp 10.3; Molecular Devices), Microsoft Excel (Microsoft, Redmond, WA), StatView 5.0 (SAS Institute, Inc.) and Prism 5.0 (GraphPad Software, Inc., San Diego, CA). All data are presented as
mean ± SEM. Statistically significant differences were assessed
using a significance level of p < 0.05. For statistical analysis of the
S-fEPSP and FV amplitudes, a two-way ANOVA (prenatal treatment age) was performed with repeated measurement factors
(current stimulation), separately for male and female offspring.
For statistical analysis of I/O slopes, a two-way ANOVA (prenatal
treatment age) was performed, separately for male and female
offspring. For statistical analysis after RIS treatment, a three-way
To assess the impact of poly I:C treatment on basal glutamatergic synaptic transmission, we stimulated (at 0.1 Hz) Schaffer collaterals and monitored the FV amplitude, the S-fEPSP and the slope
input–output (I/O) relation of fEPSPs at synapses onto CA1 pyramidal neurons in male and female offspring hippocampal slices from
PNDs 18–20, 34, 70 and 90.
At PNDs 18–20 and 34, the S-fEPSP and the FV amplitudes in
male offspring from the poly I:C group were significantly smaller
(2-fold) than those from the saline group, suggesting a decrease
in glutamatergic transmission subsequent to maternal poly I:C
treatment (Fig. 1A–D, Table S1; n = 13–16 slices). A similar decrease
in the S-fEPSP subsequent to maternal poly I:C treatment persisted
in adult male offspring from the poly I:C group (PNDs 70 and 90).
However, no significant changes in FV amplitudes were detected
in adult male offspring at PNDs 70 and 90 (Fig. 1E–H, Table S1;
n = 10–12 slices). There was also a decrease in the slope of the I/O
relation in male offspring from poly I:C group compared to saline
in juvenile, peri-adolescent and adult animals. Two way ANOVA
with main factors of prenatal treatment and age, yielded main effect
of prenatal treatment (Fig. 3A–E, Table S1 F(1, 96) = 21.78,
p < 0.0001). Overall, the significant depression of glutamatergic
transmission (S-fEPSP and I/O) found in the juvenile period
(PND18–20) persisted at the peri-adolescence (PND34) and adult
stages (PNDs 70 and 90) in male offspring from poly I:C-treated
mothers as compared to the saline group (Figs. 1 and 3A–E,
Table S1) (fEPSP slope, p < 0.0001). For FV amplitudes, post hoc analysis of current stimulation prenatal treatment age interaction
confirmed significant differences in FV amplitudes between poly I:
C and saline males offspring at PND 18–20 and 34 (p’s < 0.04) at
all current stimulations (Fig. 1, Table S1).
In contrast to the data obtained with the males, no effect was
found for the S-fEPSP in juvenile and peri-adolescent female offspring (PND18–20 and 34) (Fig. 2A–D, Table S1; n = 15–16 slices).
However, at later stages (PND 70 and 90), the S-fEPSP was significantly smaller in female offspring from the poly I:C group than
from the saline group. Post-hoc analysis of current stimulation prenatal treatment age interaction confirmed significant
differences in S-fEPSP between poly I:C and saline female offspring
at PND 70 and 90 (p’s < 0.04) at all current stimulations (Fig. 2E–H,
Table S1; n = 8–12 slices). In contrast to male offspring, no
differences were observed between poly I:C and saline groups in
the FV amplitude at any developmental stage and the slope of
the I/O relations from the female offspring of the poly I:C group
was similar to that of the saline group in young animals at PNDs
18–20 and 34. However, post hoc analysis of age prenatal treatment interaction indicated significant differences in the slope of
the I/O relation between poly I:C and saline female offspring at
adult stage (PND 70) but not on PND90 (Fig. 3F–J, Table S1,
p’s < 0.02). Thus, while reduced S-fEPSP and I/O slopes were
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
243
Fig. 1. Basal synaptic excitatory transmission in the hippocampal CA1 region from male offspring of poly I:C and saline treated mothers. (A, C, E and G) Representative traces
of fEPSP at 500 lA recorded in the CA1 area of hippocampal slices of male offspring at PNDs 18–20 (n = 13–15 slices), 34 (n = 16 slices), 70 (n = 10–11 slices) and 90 (n = 11–12
slices), respectively. (B, D, F and H) Indicate current stimulation/FV amplitudes (left panel) and current stimulation/S-fEPSP relations (right panel) for increasing stimulation
intensities in male offspring at different PNDs from saline (black) and poly I:C (red) injected dams, respectively. *Significance between poly I:C and saline offspring as revealed
in post hoc analysis (all p’s < 0.04). #Significance main effect of prenatal treatment between poly I:C and saline offspring (all p’s < 0.0003). (For interpretation of the references
to color in this figure legend, the reader is referred to the web version of this article.)
already observed at the juvenile period (PND18–20) and maintained until adulthood in male offspring of the poly I:C group,
the appearance of similar abnormalities were delayed to the adult
stage (PND70) in female offspring derived from the same group.
Short-term synaptic plasticity was examined by PPF of fEPSP.
This form of plasticity occurs through presynaptic mechanisms
and it can be used as a presynaptic index for probability of neurotransmitter release (Kamiya and Zucker, 1994; Zucker and Regehr,
2002). We applied paired stimuli to the Schaffer collaterals at varying interpulse intervals (from 25 to 1000 ms) and determined the
paired-pulse ratio as the slope of the second fEPSP divided by that
of the first fEPSP. No differences were found in PPF (on PNDs
18–20, 70 and 90) in male and female offspring of saline and poly
I:C treated mothers (Fig. S1, Table S2). Short-term plasticity was
also assessed by applying bursts of 5 action potentials (5-AP) at frequencies of either 40 Hz or 70 Hz in offspring of both groups at
PND 34. No differences were found in 5-AP ratios in both male
and female offspring from saline and poly I:C treated mothers
(Fig. S1, Table S2).
3.2. Effects of RIS administration during PNDs 34–37 on the depressed
hippocampal glutamatergic neurotransmission of offspring from poly
I:C treated mothers
Our recent studies indicate that brain structural abnormalities,
specifically a decrease in hippocampal volume is prevented by the
administration of APDs like clozapine or RIS during the asymptomatic period of peri-adolescence of the offspring (Piontkewitz
et al., 2009a, 2011a, 2012a,b). This was paralleled by prevention
of schizophrenia-like behavioral abnormalities, attentional deficit
and hypersensitivity to amphetamine (Piontkewitz et al., 2012a).
Here we explored the impact of RIS administration during the
peri-adolescence period (PNDs 34–47) on the depressed excitatory
transmission by measuring S-fEPSP and FV amplitudes at PNDs 70
and 90. The following groups were examined: SS = offspring of
dams injected with saline, pretreated with saline; SR = offspring
of dams injected with saline, pretreated with RIS; PS = offspring
of dams injected with poly I:C, pretreated with saline; PR = offspring of dams injected with poly I:C, pretreated with RIS.
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E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
Fig. 2. Basal synaptic excitatory transmission in the hippocampal CA1 region from female offspring of poly I:C and saline treated mothers. (A, C, E and G) Representative
traces of fEPSP at 500 lA recorded in the CA1 area of hippocampal slices of female offspring at PNDs 18–20 (n = 15–16 slices), 34 (n = 16 slices), 70 (n = 11–12 slices) and 90,
(n = 8 slices), respectively. (B, D, F and H) Indicate current stimulation/FV amplitudes (left panel) and current stimulation/S-fEPSP relations (right panel) for increasing
stimulation intensities in female offspring at different PNDs from saline (black) and poly I:C (red) injected dams. *Significance between poly I:C and saline offspring as
revealed in post hoc analysis (all p’s < 0.04). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
The RIS treatment in male offspring from poly I:C treated mothers (PR) corrected the decrease in S-fEPSP and in the slope of I/O
relations at both PNDs 70 and 90 without affecting the control
(SR) offspring. Post hoc analysis of current stimulation prenatal
treatment preventive treatment age interaction, confirmed
the significant differences in the S-fEPSP between PS and all the
other groups (SS, SR, PR) at all current stimulation (Fig. 4,
Table S3, p < 0.002; n = 10–12 slices). Post-hoc analysis of the prenatal treatment preventive treatment interaction confirmed significant differences in the slope of the I/O relation between PS and
all the other groups (SS, SR, PR) (Fig. 4, Table S3, p’s < 0.02). In
female offspring, treatment with RIS significantly prevented,
though not to the SS level, the depressed S-fEPSP at PNDs 70 and
90. Post hoc analysis of stimulation current prenatal treatment preventive treatment, confirmed the significant differences
in S-fEPSP between PS versus SS and PR. However, significant differences were found between SR and SS at all current stimulation
(Fig. 5, Table S4, p < 0.05; n = 8–12 slices). RIS treatment in female
offspring not only prevented the reduction of FV amplitudes but
even slightly increased it in adult poly I:C female offspring at PNDs
70 and 90. Post hoc analysis of current stimulation prenatal
treatment preventive treatment interaction, confirmed signifi-
cant differences between PS versus SS and PR and between SR
and SS at all current stimulation (Fig. 5, Table S4, p < 0.04). In contrast to male offspring, RIS treatment did not prevent the
depressed slope of I/O relations at PNDs 70 and 90 in female offspring (Fig. 5, Table S4).
3.3. Changes in hippocampal volume of female and male offspring
following maternal immune activation and RIS treatment during PNDs
34–47
A longitudinal MRI study revealed a progressive increase with
age in hippocampal volume of male and female offspring from poly
I:C and saline groups. A significantly reduced hippocampal volume
was found in male and female offspring from poly I:C-treated dams
after puberty, but not at PND 34 prior to RIS treatment. The
decreased hippocampal volume in both male and female offspring
of the poly I:C group was prevented by RIS as found at adulthood
(at PNDs 70 and 90). In male offspring, post hoc analysis of
age prenatal treatment preventive treatment interaction, confirmed significant differences between PS and all the other groups
(SS, SR, PR) at PNDs 70 and 90 (Fig. 6A and C, Table S5, p < 0.0001;
n = 5–16 offspring). In female offspring, post hoc analysis of
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
245
Fig. 3. Input/output relations in offspring from saline and poly I:C treated mothers. (A–D) Input (FV amplitude)/output (S-fEPSP) I/O relations of saline (black) and poly I:C
(red) male offspring at PNDs 18–20 (n = 13–15 slices), 34 (n = 16 slices), 70 (n = 10–11 slices) and 90 (n = 11–12 slices), respectively. (E) The slopes of the I/O relations in male
offspring from the poly I:C group are smaller than those from the saline group as revealed by two-way ANOVA which yielded main effect for prenatal treatment (p < 0.0001).
(F–I) I/O relations of saline (black) and poly I:C (red) female offspring at PNDs 18–20 (n = 15–16 slices), 34 (n = 16 slices), 70 (n = 11–12 slices) and 90 (n = 8 slices),
respectively. (J) The slopes of the I/O relations in female offspring from the poly I:C group are smaller than those from the saline group at PND 70. *Significance between poly I:
C and saline offspring as revealed in post hoc analysis (p < 0.02). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of
this article.)
age prenatal treatment preventive treatment interaction,
confirmed significant differences between PS versus SS and PR.
However, RIS affected the control showing significant differences
between SS and SR at PNDs 70 and 90 (Fig. 6B and D, Table S5,
p < 0.03; n = 8–16 offspring). As noticed for its effect on glutamatergic transmission, the RIS treatment by itself reduced the hippocampal volume in adult female offspring from saline-treated
dams.
4. Discussion
The main findings of this study show (Benes et al., 1991) a maturation and sex dependent depression of the hippocampal excitatory synaptic transmission in the offspring of poly I:C treated
pregnant mothers. This neurophysiological defect appears early
in males, at juvenile age, but has a delayed expression in female
offspring, manifesting in adulthood only. (Boyer et al., 2007)
Treatment with RIS at peri-adolescence fully prevents these deficits in males but only partially in females. (Harrison, 1999) Adult
male and female offspring of poly I:C treated dams exhibit reduced
hippocampal size that was also prevented by RIS administration
during peri-adolescence. (Harrison and Eastwood, 2001) RIS treatment by itself decreases the S-fEPSP, FV amplitude as well as the
hippocampal volume of adult female offspring from salinetreated mothers.
Presynaptic function as assessed by FV amplitude or PPF at CA3CA1 synapses was not prominently altered by prenatal poly I:C
treatment. Although the FV amplitudes were reduced in juvenile
male offspring (PNDs 18–34) of poly I:C-treated dams, they were
unaffected in adult males as well as at all ages in female offspring
compared to saline. In addition, PPF was unaltered by maternal
poly I:C treatment at all ages of both male and female offspring.
It is possible that in juvenile male offspring (PNDs 18–34), the
integrity of the Schaffer collaterals may be transiently compromised by the MIA, which could affect presynaptic fiber excitability.
We have no direct experimental explanations for the slight
increase in fiber volley as animals age. However, a previous study
revealed abnormal expression of myelination genes and MRI alterations in white matter fractional anisotropy in offspring from prenatal viral influenza infection of pregnant mice (Fatemi et al.,
2009). While reduced fractional anisotropy (FA), which reflects
delayed maturation, was observed in several brain areas, increased
in FA was found in other neuronal regions that might suggest
accelerated maturation (Fatemi et al., 2009). Increased FA was paralleled by upregulation of myelination genes (Fatemi et al., 2009).
Hypermyelination and accelerated brain growth are commonly
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E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
Fig. 4. Effect of RIS pretreatment on the basal synaptic excitatory transmission in the hippocampal CA1 region from male offspring of poly I:C and saline treated mothers. RIS
(0.045 mg/kg) or saline injections were performed at PNDs 34–47 and excitatory transmission was measured at PNDs 70 and 90. (SS = offspring of dams injected with saline,
pretreated with saline (black, n = 11–12 slices), SR = offspring of dams injected with saline, pretreated with RIS (gray, n = 10–11 slices), PS = offspring of dams injected with
poly I:C, pretreated with saline (red, n = 10–11 slices), PR = offspring of dams injected with poly I:C, pretreated with RIS (blue, n = 12 slices). (A and B) Representative traces of
fEPSP at 500 lA recorded in the CA1 area of hippocampal slices at PND70 and PND90, respectively. (C and D) Current stimulation/S-fEPSP relations at PND70 and 90 for
increasing stimulation intensities, respectively. *Significant difference between PS versus SS and PR as revealed in post hoc analyses (p < 0.02). (E and F) Current stimulation/
FV amplitudes relations at PND70 and 90 for increasing stimulation intensities, respectively. (G and H) I/O relations of SS, PS, PR and SR offspring at PND70 and 90,
respectively. (I) Slopes of the I/O relations in SS, PS, PR and SR at PNDs 70 and 90. The Inset depicts the prenatal treatment preventive treatment interaction. *Significance
between PS and the other groups as revealed in post hoc analysis (all p’s < 0.002). (For interpretation of the references to color in this figure legend, the reader is referred to
the web version of this article.)
observed in children with autism (Ben Bashat et al., 2007). Therefore, we cannot exclude that in the poly I:C rat model, more collaterals appear as animals age.
Our results are partly in line with previous studies using MIA
models, where reduction in FV amplitude was found in juvenile
male offspring (PND 20–28) following poly I:C (Oh-Nishi et al.,
2010) or LPS prenatal treatment (Lowe et al., 2008). Inconsistent
results were obtained by different laboratories exploring alterations in hippocampal synaptic transmission and plasticity following MIA. Using prenatal injection of LPS to pregnant rats, Lowe
et al., found like in the present work that in CA1 pyramidal neurons
of offspring hippocampal slices the S-fEPSP and the FV amplitudes
are smaller in the LPS group compared to controls (Lowe et al.,
2008). However, in contrast to our data, the slopes of I/O relations
were larger in the LPS group and PPF was attenuated, suggesting
compensatory enhancements in postsynaptic glutamatergic
response and impairment of short-term plasticity, respectively
(Lowe et al., 2008). A different study performed in the offspring
of poly I:C-treated mothers found no alterations in PPF from CA1
pyramidal neurons (Ito et al., 2010), while another group using
the same poly I:C model showed decreased S-fEPSP and FV amplitudes but increased PPF (Oh-Nishi et al., 2010). An additional work
found no change in PPF and in slopes of I/O relations subsequent to
prenatal LPS injection of pregnant mothers (Lante et al., 2007).
These contradicting results may arise from differences between
the nature of the MIA trigger, LPS or poly I:C, from different times
of LPS or poly I:C injection (GD15 and GD19) and in most cases
from lack of gender animal consideration.
The impaired presynaptic transmission in the hippocampus of
juvenile but not of adult male offspring could be a result of
impaired myelination and axonal development as suggested previously (Fatemi et al., 2009; Makinodan et al., 2008). More recently,
reduction in the expression of the myelin-related proteins, myelin
basic protein isoform 3 (MBP1) and rhombex 29, were observed in
the prefrontal cortex of rat offspring following prenatal poly I:C
exposure (Farrelly et al., 2015). Compensatory plastic mechanisms
may occur later in development to normalize presynaptic fiber
excitability.
In contrast to the FV amplitude, the reduction in S-fEPSP persists throughout all postnatal ages in male offspring. Importantly,
in the offspring of the poly I:C group the slopes of I/O relations
were smaller compared to saline along all postnatal stages examined in male but only at PND70 in females. Altogether our results
suggest that maternal poly I:C treatment leads in CA1 pyramidal
neurons to decreased postsynaptic excitatory function rather than
to presynaptic alterations.
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
247
Fig. 5. Effect of RIS pretreatment on the basal synaptic excitatory transmission in the hippocampal CA1 region from female offspring of poly I:C and saline treated mothers.
RIS (0.045 mg/kg) or saline injections were performed at PNDs 34–47 and excitatory transmission was measured at PNDs 70 and 90. (SS = offspring of dams injected with
saline, pretreated with saline (black, n = 8–12 slices), SR = offspring of dams injected with saline, pretreated with RIS (gray, n = 12 slices), PS = offspring of dams injected with
poly I:C, pretreated with saline (red, n = 8–11 slices), PR = offspring of dams injected with poly I:C, pretreated with RIS (blue, n = 11 slices). (A and B) Representative traces of
fEPSP at 500 lA recorded in the CA1 area of hippocampal slices at PND70 and PND90, respectively. (C and D) Stimulation current/S-fEPSP relations at PNDs 70 and 90 for
increasing stimulation intensities, respectively. *Significance difference between PS versus SS and PR as revealed in post hoc analyses (p < 0.04). (E and F) Current stimulation/
FV amplitudes relations at PND70 and 90 for increasing stimulation intensities, respectively. (G) ANOVA revealed no interaction for age therefore the data for PNDs 70 and 90
was analyzed together. *Significance difference between PS versus SS and PR as revealed in post hoc analyses (p < 0.04). (H) I/O relations of SS, PS, PR and SR offspring at
PND70 and 90, respectively. (I) Slopes of the I/O relations in SS, PS, PR and SR at PNDs 70 and 90. (For interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article.)
Our data indicate that offspring gender modulates the maturational impact of poly I:C treatment on hippocampal excitatory
synaptic transmission. Our previous work showed delayed emergence of structural and behavioral deficits in poly I:C female offspring (Piontkewitz et al., 2011b), which now applies in this
study for depressed hippocampal excitatory transmission. The
delayed emergence of abnormalities in poly I:C female offspring
is in line with the delayed onset of the disease in women compared
to men (DeLisi, 1992; DeLisi et al., 1989; Grigoriadis and Seeman,
2002; Hafner and an der Heiden, 1998; Leung and Chue, 2000;
Hafner, 2003). A neuroprotective effect of estrogen against
schizophrenia was suggested to account for the late age onset
and the illness course in women (Grigoriadis and Seeman, 2002;
Leung and Chue, 2000; Hafner, 2003; Rao and Kolsch, 2003;
Seeman and Lang, 1990; Riecher-Rossler and Hafner, 2000). A
recent work showed that estradiol acting via the IGF-1 receptor
could protect the functional integrity of hippocampal CA1 synapses
in the face of global ischemia (Takeuchi et al., 2014). Studies monitoring estrogen plasma levels demonstrated a negative correlation
between 17b-estradiol levels and severity of schizophrenia symptoms in women (Bergemann et al., 2007), which prompted recent
clinical studies to evaluate estrogens and estrogen receptor modulators as effective augmentation strategies in the treatment of
schizophrenia (Heringa et al., 2015). Estrogens were shown to
interact with the dopamine and serotonin systems, in a way similar
to neuroleptics. A previous work showed that a single pulse of
estradiol induces a significant increase in the density of 5-HT2A
receptors in female rat forebrain (Summer and Fink, 1995). While
no consistent gender differences are found in the dopaminergic
pathways, the serotonergic system is more expressed in females
and 5-HT levels are significantly higher in females than in males
in various rat brain regions (Carlsson and Carlsson, 1988). More
recently, accumulating evidence suggest that estrogens may exert
their effects via an interaction with brain-derived neurotrophic
factor (BDNF) signaling Wu et al., 2013. Estrogens and BDNF modulate major neurotransmitter systems, including serotonergic
pathways. For example, in mice, chronic treatment with the
antidepressant and selective serotonin re-uptake inhibitor (SSRI),
fluoxetine, increased BDNF protein levels in the hippocampus
and induced sex-specific effects on cell survival and neurogenesis
(Hodes et al., 2010). Estradiol treatment acutely reduced BDNF
gene expression and inhibited the increase of BDNF mRNA levels
induced by the 5-HT2A/2C receptor agonist, DOI (Cavus and
Duman, 2003). Thus, a strong body of evidence from clinical and
animal data suggests that estrogen signaling is a mediator of sex
differences in schizophrenia and some of its actions may be
exerted via modulation of BDNF pathways (Wu et al., 2013).
In line with our previous work (Piontkewitz et al., 2009, 2011a,
b, 2012b), we found that there were no differences in hippocampal
volumes at the juvenile stage in offspring of poly I:C and saline
treated dams (at PND34). In contrast, hippocampal volumes were
smaller in adult offspring (both female and male) of poly I:C than
248
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
Fig. 6. Changes in hippocampal volume of female and male poly I:C or saline offspring and following RIS pretreatment. Male and female offspring were pretreated with RIS
(0.045 mg/kg) or saline at PNDs 34–47 (SS = offspring of dams injected with saline, pretreated with saline (black), SR = offspring of dams injected with saline, pretreated with
RIS (gray), PS = offspring of dams injected with poly I:C, pretreated with saline (red), PR = offspring of dams injected with poly I:C, pretreated with RIS (blue)). (A and B)
Representative T2-weighted images at the level of the hippocampus of male (left panel) and female (right panel) offspring of saline and poly I:C treated dams at PNDs 34
(upper panel, n = 16 offspring in each group), at PND 70 (n = 5–8 offspring in each group) following RIS or saline (middle panel) and at PND 90 (n = 5–8 offspring in each
group) following RIS or saline (lower panel). (C and D) Mean hippocampal volume (±SEM) of male and female, respectively poly I:C and saline offspring pretreated with RIS or
saline at PNDs 34–47 at two time points after treatment (PND70 and 90). *Significance between PS and the other three groups as revealed in post hoc analyses (all
p’s < 0.0001). **Significance between PS and SS, PS and PR and SR and SS as revealed in post hoc analyses (all p’s < p < 0.03). (For interpretation of the references to color in this
figure legend, the reader is referred to the web version of this article.)
in saline treated dams. The hippocampus plays a critical role in
schizophrenia, and structural as well as functional abnormalities
in this region are believed to mediate at least some of the cognitive
defects in schizophrenia. Impaired neurogenesis, disturbed microvascularization and loss of parvalbumin-expressing hippocampal
interneurons were suggested to play a role in these structural
anomalies (Piontkewitz et al., 2012b). A recent study showed that
dysbindin-1C deficiency leads to a decrease in hippocampal mossy
fiber cells, causing the delayed maturation of newborn neurons
(Wang et al., 2014). The delayed maturation of adult-born neurons
is expected to affect the hippocampal CA3-CA1 functionality
(Wang et al., 2014). Impaired mitochondrial function and myelin
formation were also suggested to be involved in these deficiencies
(Farrelly et al., 2015; Robicsek et al., 2013).
Our data suggest that pharmacological intervention with a very
low dose of RIS during peri-adolescence can successfully treat early
occurring hippocampal synaptic deficits resulting from in utero
insult in male offspring. It is important to note that the effect of
the treatment remained constant both at PND70 and 90 (more than
a month after RIS treatment), implying that the impact of RIS is not
transient. These results are consistent with our previous work
showing that the same RIS regimen prevented brain structural
alterations and behavioral abnormalities following prenatal polyI:C exposure. (Piontkewitz et al., 2011a, 2012a,b). RIS combines a
potent 5HT2 receptor antagonism with a milder, but yet potent,
D2 antagonism. Previous in vivo and ex vivo quantitative receptor
autoradiography studies showed that at low doses, RIS has significant 5HT2A receptor antagonism and weak D2 receptor occupancy
(Janssen et al., 1988; Leysen et al., 1993; Schotte et al., 1996). At
high RIS doses, 5HT2A occupancy is high, while binding increases
to receptor populations with lower affinity, including dopamine
receptors D2, D3, and D4, and serotonin 5HT2C and 5HT1A receptors (Janssen et al., 1988; Leysen et al., 1993; Schotte et al., 1996;
Arnt and Skarsfeldt, 1998). We previously showed that RIS administration during the asymptomatic period of adolescence could
prevent the emergence of brain structural pathology and behav-
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
ioral abnormalities in the rat poly I:C model of schizophrenia
(Piontkewitz et al., 2011a). The fact that a low RIS dose (45 lg/
kg) was as effective as a high dose (1.2 mg/kg) indicated that
5HT2A antagonism is involved in the preventive effects of RIS
(Piontkewitz et al., 2011a). Likewise, in the present study, we used
a low of dose of RIS (45 lg/kg) that mainly acts as a 5HT2A antagonist without appreciable D2 antagonism (Leysen et al., 1993;
Schotte et al., 1996), which suggests that RIS prevention of early
occurring hippocampal synaptic deficits involves 5HT2 receptor
antagonism. The serotonergic system plays a crucial role in brain
development (Gaspar et al., 2003; Sodhi and Sanders-Bush, 2004;
Whitaker-Azmitia, 2001). The 5HT2 receptor level is approximately 10-fold higher in the developing brain compared to adult
brain and it has been shown that the serotonergic pathway is more
sensitive to the effects of RIS in the juvenile and adolescent stages
of development than in adulthood (Choi et al., 2010). Alterations in
5HT2A receptors in prefrontal cortex, hippocampus and caudate
have been reported in APD-naive first episode patients and in
high-risk individuals (Erritzoe et al., 2008; Hurlemann et al.,
2008; Rasmussen et al., 2010). In addition, it has been argued that
frontal cortical 5HT2A receptors are involved in the pathophysiology of psychotic symptoms in the initial emergence of psychosis
(Rasmussen et al., 2010; Geyer and Vollenweider, 2008). Thus,
selective 5HT2A receptor antagonism may be a promising strategy
for psychosis prevention (Piontkewitz et al., 2011a; Hurlemann
et al., 2008; Richtand and McNamara, 2008).
Major sex differences were found in RIS effects on offspring
derived from prenatal poly-I:C or saline exposures. In contrast to
male, RIS treatment at peri-adolescence did not prevent the
depressed slope of I/O relations at PNDs 70 and 90 in female
offspring from poly I:C-treated dams. Moreover, in adult female
offspring from saline-treated mothers, RIS treatment reduced the
S-fEPSP, FV amplitude as well as the hippocampal volume. This
effect of RIS on female offspring only, is in line with a previous
study showing that this low dose of RIS caused abnormal locomotor response in the saline group (Richtand et al., 2011) and may
result from the high sensitivity of the serotonergic system in
females (Richtand et al., 2011; DeLisi et al., 1989).
The mechanism by which RIS treatment restores hippocampal
synaptic deficits in male offspring of the poly I:C group is not
known yet. Several possibilities may be invoked: (1) RIS is able
to prevent abnormal hippocampal neurogenesis in the offspring
of poly I:C treated dams (Piontkewitz et al., 2012b); (2) RIS can
restore the defective myelination observed in male offspring of
rat poly I:C-injected mothers (Farrelly et al., 2015); (3) RIS may
exert anti-apoptotic action. It was recently found that RIS attenuates mitochondrial dysfunction and mitochondria-dependent
apoptosis in hippocampus, hypothalamus, pre-frontal cortex, and
amygdala in animal model of post-traumatic stress disorder
(Garabadu et al., 2015). (4) The efficacy of low dose of RIS suggests
a possible involvement of the serotonergic system in the developing brain (Gaspar et al., 2003; Sodhi and Sanders-Bush, 2004; Choi
et al., 2010; Pletnikov et al., 2000; Fatemi et al., 2008; Zavitsanou
et al., 2013), including effects on excitotoxicity and oxidative stress
(Lieberman et al., 2008). Along this line, a recent study suggests
that oxidative stress in the prefrontal cortex is a core feature mediating cellular, electrophysiological and behavioral abnormalities
induced by the neonatal ventral hippocampal lesion model (NVHL),
and antioxidant treatment like N-acetyl cysteine prevents these
alterations (Cabungcal et al., 2014). In the NVHL model, Cabungcal
et al. detected oxidative stress and nitrosative stress in prefrontal
cortex pyramidal neurons and parvalbumin interneurons of juvenile rats prior to the onset of electrophysiological and behavioral
deficits (Cabungcal et al., 2014). It is possible that in juvenile male
offspring, the deleterious effect of early occurring oxidative stress
leads hippocampal CA1 pyramidal neurons to a diseased state that
249
will manifest into impaired excitatory postsynaptic function.
Female offspring at the same juvenile period may be less prone
to this stressor thanks to estrogen protection, leading to delayed
emergence of the neurophysiological defects.
5. Conclusions
Our longitudinal study clearly indicates that the depression of
hippocampal excitatory transmission occurs well before (PND18–
20) the structural and behavioral abnormalities observed in male
offspring (this study and Piontkewitz et al., 2012a). The timing of
prenatal poly I:C treatment at the exact period of offspring hippocampal development, may cause the early impairment of excitatory postsynaptic function in juvenile male rats. These
abnormalities occurring at critical stages of hippocampal development, may ultimately lead to alterations in the prefrontal cortex,
where behavioral deficits would only emerge when prefrontal cortex circuits would mature during adolescence.
Financial disclosures
The authors have no conflicts of interest.
Acknowledgments
This work was supported by funds of the Israel Science Foundation (ISF-2092/14). Bernard Attali holds the Andy Libach Professorial Chair in clinical pharmacology and toxicology.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bbi.2015.08.021.
References
Arnold, S.E., 1999. Neurodevelopmental abnormalities in schizophrenia: insights
from neuropathology. Dev. Psychopathol. 11, 439–456.
Arnt, J., Skarsfeldt, T., 1998. Do novel antipsychotics have similar pharmacological
characteristics? A review of the evidence. Neuropsychopharmacology 18, 63–
101.
Beckmann, H., 1999. Developmental malformations in cerebral structures of
schizophrenic patients. Eur. Arch. Psychiatry Clin. Neurosci. 249 (Suppl. 4),
44–47.
Ben Bashat, D., Kronfeld-Duenias, V., Zachor, D.A., Ekstein, P.M., Hendler, T.,
Tarrasch, R., et al., 2007. Accelerated maturation of white matter in young
children with autism: a high b value DWI study. Neuroimage 37, 40–47.
Benes, F.M., Sorensen, I., Bird, E.D., 1991. Reduced neuronal size in posterior
hippocampus of schizophrenic patients. Schizophr. Bull. 17, 597–608.
Bergemann, N., Parzer, P., Runnebaum, B., Resch, F., Mundt, C., 2007. Estrogen,
menstrual cycle phases, and psychopathology in women suffering from
schizophrenia. Psychol. Med. 37, 1427–1436.
Bilbo, S.D., Schwarz, J.M., 2012. The immune system and developmental
programming of brain and behavior. Front. Neuroendocrinol. 33, 267–286.
Boksa, P., 2010. Effects of prenatal infection on brain development and behavior: a
review of findings from animal models. Brain Behav. Immun. 24, 881–897.
Boyer, P., Phillips, J.L., Rousseau, F.L., Ilivitsky, S., 2007. Hippocampal abnormalities
and memory deficits: new evidence of a strong pathophysiological link in
schizophrenia. Brain Res. Rev. 54, 92–112.
Brown, A.S., Cohen, P., Greenwald, S., Susser, E., 2000. Nonaffective psychosis after
prenatal exposure to rubella. Am. J. Psychiatry 157, 438–443.
Cabungcal, J.H., Counotte, D.S., Lewis, E.M., Tejeda, H.A., Piantadosi, P., Pollock, C.,
et al., 2014. Juvenile antioxidant treatment prevents adult deficits in a
developmental model of schizophrenia. Neuron 83, 1073–1084.
Carlsson, M., Carlsson, A., 1988. A regional study of sex differences in rat brain
serotonin. Prog. Neuropsychopharmacol. Biol. Psychiatry 12, 53–61.
Cavus, I., Duman, R.S., 2003. Influence of estradiol, stress, and 5-HT2A agonist
treatment on brain-derived neurotrophic factor expression in female rats. Biol.
Psychiatry 54, 59–69.
Choi, Y.K., Moran-Gates, T., Gardner, M.P., Tarazi, F.I., 2010. Effects of repeated
risperidone exposure on serotonin receptor subtypes in developing rats. Eur.
Neuropsychopharmacol. 20, 187–194.
Coyle, J.T., 2006. Glutamate and schizophrenia: beyond the dopamine hypothesis.
Cell. Mol. Neurobiol. 26, 365–384.
250
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
DeLisi, L.E., 1992. The significance of age of onset for schizophrenia. Schizophr. Bull.
18, 209–215.
DeLisi, L.E., 2008. The concept of progressive brain change in schizophrenia:
implications for understanding schizophrenia. Schizophr. Bull. 34, 312–321.
DeLisi, L.E., Dauphinais, I.D., Hauser, P., 1989. Gender differences in the brain: are they
relevant to the pathogenesis of schizophrenia? Compr. Psychiatry 30, 197–208.
Ducharme, G., Lowe, G.C., Goutagny, R., Williams, S., 2012. Early alterations in
hippocampal circuitry and theta rhythm generation in a mouse model of
prenatal infection: implications for schizophrenia. PLoS One 7, e29754.
Erritzoe, D., Rasmussen, H., Kristiansen, K.T., Frokjaer, V.G., Haugbol, S., Pinborg, L.,
et al., 2008. Cortical and subcortical 5-HT2A receptor binding in neurolepticnaive first-episode schizophrenic patients. Neuropsychopharmacology 33,
2435–2441.
Escobar, M., Crouzin, N., Cavalier, M., Quentin, J., Roussel, J., Lante, F., et al., 2011.
Early, time-dependent disturbances of hippocampal synaptic transmission and
plasticity after in utero immune challenge. Biol. Psychiatry 70, 992–999.
Farrelly, L., Focking, M., Piontkewitz, Y., Dicker, P., English, J., Wynne, K., et al., 2015.
Maternal immune activation induces changes in myelin and metabolic proteins,
some of which can be prevented with risperidone in adolescence. Dev. Neurosci.
37, 43–55.
Fatemi, S.H., Reutiman, T.J., Folsom, T.D., Huang, H., Oishi, K., Mori, S., et al., 2008.
Maternal infection leads to abnormal gene regulation and brain atrophy in
mouse offspring: implications for genesis of neurodevelopmental disorders.
Schizophr. Res. 99, 56–70.
Fatemi, S.H., Folsom, T.D., Reutiman, T.J., Abu-Odeh, D., Mori, S., Huang, H., et al.,
2009. Abnormal expression of myelination genes and alterations in white
matter fractional anisotropy following prenatal viral influenza infection at E16
in mice. Schizophr. Res. 112, 46–53.
Fatemi, S.H., Folsom, T.D., Rooney, R.J., Mori, S., Kornfield, T.E., Reutiman, T.J., et al.,
2012. The viral theory of schizophrenia revisited: abnormal placental gene
expression and structural changes with lack of evidence for H1N1 viral presence
in placentae of infected mice or brains of exposed offspring.
Neuropharmacology 62, 1290–1298.
Garabadu, D., Ahmad, A., Krishnamurthy, S., 2015. Risperidone attenuates modified
stress-re-stress paradigm-induced mitochondrial dysfunction and apoptosis in
rats exhibiting post-traumatic stress disorder-like symptoms. J. Mol. Neurosci.
56, 299–312.
Gaspar, P., Cases, O., Maroteaux, L., 2003. The developmental role of serotonin: news
from mouse molecular genetics. Nat. Rev. Neurosci. 4, 1002–1012.
Gattaz, W.F., Vogel, P., Riecher-Rossler, A., Soddu, G., 1994. Influence of the
menstrual cycle phase on the therapeutic response in schizophrenia. Biol.
Psychiatry 36, 137–139.
Geyer, M.A., Vollenweider, F.X., 2008. Serotonin research: contributions to
understanding psychoses. Trends Pharmacol. Sci. 29, 445–453.
Grigoriadis, S., Seeman, M.V., 2002. The role of estrogen in schizophrenia:
implications for schizophrenia practice guidelines for women. Can. J.
Psychiatry 47, 437–442.
Hafner, H., 2003. Gender differences in schizophrenia. Psychoneuroendocrinology
28 (Suppl. 2), 17–54.
Hafner, H., an der Heiden, W., Behrens, S., Gattaz, W.F., Hambrecht, M., Loffler, W.,
1998. Causes and consequences of the gender difference in age at onset of
schizophrenia. Schizophr. Bull. 24, 99–113.
Harrison, P.J., 1999. The neuropathology of schizophrenia. A critical review of the
data and their interpretation. Brain 122 (Pt 4), 593–624.
Harrison, P.J., 2004. The hippocampus in schizophrenia: a review of the
neuropathological evidence and its pathophysiological implications.
Psychopharmacology 174, 151–162.
Harrison, P.J., Eastwood, S.L., 2001. Neuropathological studies of synaptic
connectivity in the hippocampal formation in schizophrenia. Hippocampus
11, 508–519.
Hellstrom, I.C., Danik, M., Luheshi, G.N., Williams, S., 2005. Chronic LPS exposure
produces changes in intrinsic membrane properties and a sustained IL-betadependent increase in GABAergic inhibition in hippocampal CA1 pyramidal
neurons. Hippocampus 15, 656–664.
Heringa, S.M., Begemann, M.J., Goverde, A.J., Sommer, I.E., 2015. Sex hormones and
oxytocin augmentation strategies in schizophrenia: a quantitative review.
Schizophr. Res.
Hodes, G.E., Hill-Smith, T.E., Suckow, R.F., Cooper, T.B., Lucki, I., 2010. Sex-specific
effects of chronic fluoxetine treatment on neuroplasticity and pharmacokinetics
in mice. J. Pharmacol. Exp. Ther. 332, 266–273.
Hultman, C.M., Sparen, P., Takei, N., Murray, R.M., Cnattingius, S., 1999. Prenatal and
perinatal risk factors for schizophrenia, affective psychosis, and reactive
psychosis of early onset: case-control study. BMJ 318, 421–426.
Hurlemann, R., Matusch, A., Kuhn, K.U., Berning, J., Elmenhorst, D., Winz, O., et al.,
2008. 5-HT2A receptor density is decreased in the at-risk mental state.
Psychopharmacology 195, 579–590.
Ito, H.T., Smith, S.E., Hsiao, E., Patterson, P.H., 2010. Maternal immune activation
alters nonspatial information processing in the hippocampus of the adult
offspring. Brain Behav. Immun. 24, 930–941.
Janssen, P.A., Niemegeers, C.J., Awouters, F., Schellekens, K.H., Megens, A.A., Meert,
T.F., 1988. Pharmacology of risperidone (R 64 766), a new antipsychotic with
serotonin-S2 and dopamine-D2 antagonistic properties. J. Pharmacol. Exp. Ther.
244, 685–693.
Javitt, D.C., Schoepp, D., Kalivas, P.W., Volkow, N.D., Zarate, C., Merchant, K., et al.,
2011. Translating glutamate: from pathophysiology to treatment. Sci. Trans.
Med. 3, 102mr102.
Jonsson, S.A., Luts, A., Guldberg-Kjaer, N., Ohman, R., 1999. Pyramidal neuron size in
the hippocampus of schizophrenics correlates with total cell count and degree
of cell disarray. Eur. Arch. Psychiatry Clin. Neurosci. 249, 169–173.
Kamiya, H., Zucker, R.S., 1994. Residual Ca2+ and short-term synaptic plasticity.
Nature 371, 603–606.
Lante, F., Meunier, J., Guiramand, J., Maurice, T., Cavalier, M., de Jesus Ferreira, M.C.,
et al., 2007. Neurodevelopmental damage after prenatal infection: role of
oxidative stress in the fetal brain. Free Radic. Biol. Med. 42, 1231–1245.
Lawrie, S.M., McIntosh, A.M., Hall, J., Owens, D.G., Johnstone, E.C., 2008. Brain
structure and function changes during the development of schizophrenia: the
evidence from studies of subjects at increased genetic risk. Schizophr. Bull. 34,
330–340.
Leung, A., Chue, P., 2000. Sex differences in schizophrenia, a review of the literature.
Acta Psychiatr. Scand. Suppl. 401, 3–38.
Leysen, J.E., Janssen, P.M., Schotte, A., Luyten, W.H., Megens, A.A., 1993. Interaction
of antipsychotic drugs with neurotransmitter receptor sites in vitro and in vivo
in relation to pharmacological and clinical effects: role of 5HT2 receptors.
Psychopharmacology 112, S40–S54.
Lieberman, J.A., Bymaster, F.P., Meltzer, H.Y., Deutch, A.Y., Duncan, G.E., Marx, C.E.,
et al., 2008. Antipsychotic drugs: comparison in animal models of efficacy,
neurotransmitter regulation, and neuroprotection. Pharmacol. Rev. 60, 358–
403.
Lowe, G.C., Luheshi, G.N., Williams, S., 2008. Maternal infection and fever during
late gestation are associated with altered synaptic transmission in the
hippocampus of juvenile offspring rats. Am. J. Physiol. Regul. Integr. Comp.
Physiol. 295, R1563-1571.
Makinodan, M., Tatsumi, K., Manabe, T., Yamauchi, T., Makinodan, E., Matsuyoshi,
H., et al., 2008. Maternal immune activation in mice delays myelination and
axonal development in the hippocampus of the offspring. J. Neurosci. Res. 86,
2190–2200.
Mednick, S.A., Machon, R.A., Huttunen, M.O., Bonett, D., 1988. Adult schizophrenia
following prenatal exposure to an influenza epidemic. Arch. Gen. Psychiatry 45,
189–192.
Meyer, U., Feldon, J., Schedlowski, M., Yee, B.K., 2005. Towards an immunoprecipitated neurodevelopmental animal model of schizophrenia. Neurosci.
Biobehav. Rev. 29, 913–947.
Meyer, U., Spoerri, E., Yee, B.K., Schwarz, M.J., Feldon, J., 2010. Evaluating early
preventive antipsychotic and antidepressant drug treatment in an infectionbased neurodevelopmental mouse model of schizophrenia. Schizophr. Bull. 36,
607–623.
Moghaddam, B., Javitt, D., 2012. From revolution to evolution: the glutamate
hypothesis of schizophrenia and its implication for treatment.
Neuropsychopharmacology 37, 4–15.
Murray, R.M., Lewis, S.W., 1987. Is schizophrenia a neurodevelopmental disorder?
Br. Med. J. (Clin. Res. Ed.) 295, 681–682.
Murray, R.M., O’Callaghan, E., Castle, D.J., Lewis, S.W., 1992. A neurodevelopmental
approach to the classification of schizophrenia. Schizophr. Bull. 18, 319–332.
Nelson, M.D., Saykin, A.J., Flashman, L.A., Riordan, H.J., 1998. Hippocampal volume
reduction in schizophrenia as assessed by magnetic resonance imaging: a metaanalytic study. Arch. Gen. Psychiatry 55, 433–440.
Oh-Nishi, A., Obayashi, S., Sugihara, I., Minamimoto, T., Suhara, T., 2010. Maternal
immune activation by polyriboinosinic–polyribocytidilic acid injection
produces synaptic dysfunction but not neuronal loss in the hippocampus of
juvenile rat offspring. Brain Res. 1363, 170–179.
Ozawa, K., Hashimoto, K., Kishimoto, T., Shimizu, E., Ishikura, H., Iyo, M., 2006.
Immune activation during pregnancy in mice leads to dopaminergic
hyperfunction
and
cognitive
impairment
in
the
offspring:
a
neurodevelopmental animal model of schizophrenia. Biol. Psychiatry 59, 546–
554.
Piontkewitz, Y., Assaf, Y., Weiner, I., 2009. Clozapine administration in adolescence
prevents postpubertal emergence of brain structural pathology in an animal
model of schizophrenia. Biol. Psychiatry 66, 1038–1046.
Piontkewitz, Y., Arad, M., Weiner, I., 2011a. Risperidone administered during
asymptomatic period of adolescence prevents the emergence of brain structural
pathology and behavioral abnormalities in an animal model of schizophrenia.
Schizophr. Bull. 37, 1257–1269.
Piontkewitz, Y., Arad, M., Weiner, I., 2011b. Abnormal trajectories of
neurodevelopment and behavior following in utero insult in the rat. Biol.
Psychiatry 70, 842–851.
Piontkewitz, Y., Arad, M., Weiner, I., 2012a. Tracing the development of psychosis
and its prevention: what can be learned from animal models.
Neuropharmacology 62, 1273–1289.
Piontkewitz, Y., Bernstein, H.G., Dobrowolny, H., Bogerts, B., Weiner, I., Keilhoff, G.,
2012b. Effects of risperidone treatment in adolescence on hippocampal
neurogenesis, parvalbumin expression, and vascularization following prenatal
immune activation in rats. Brain Behav. Immun. 26, 353–363.
Pletnikov, M.V., Rubin, S.A., Schwartz, G.J., Carbone, K.M., Moran, T.H., 2000. Effects
of neonatal rat Borna disease virus (BDV) infection on the postnatal
development of the brain monoaminergic systems. Brain Res. Dev. Brain Res.
119, 179–185.
Rana, S.A., Aavani, T., Pittman, Q.J., 2012. Sex effects on neurodevelopmental
outcomes of innate immune activation during prenatal and neonatal life. Horm.
Behav. 62, 228–236.
Rao, M.L., Kolsch, H., 2003. Effects of estrogen on brain development and
neuroprotection–implications for negative symptoms in schizophrenia.
Psychoneuroendocrinology 28 (Suppl. 2), 83–96.
E. Patrich et al. / Brain, Behavior, and Immunity 51 (2016) 240–251
Rasmussen, H., Erritzoe, D., Andersen, R., Ebdrup, B.H., Aggernaes, B., Oranje, B.,
et al., 2010. Decreased frontal serotonin2A receptor binding in antipsychoticnaive patients with first-episode schizophrenia. Arch. Gen. Psychiatry 67, 9–16.
Richtand, N.M., McNamara, R.K., 2008. Serotonin and dopamine interactions in
psychosis prevention. Prog. Brain Res. 172, 141–153.
Richtand, N.M., Taylor, B., Welge, J.A., Ahlbrand, R., Ostrander, M.M., Burr, J., et al.,
2006. Risperidone pretreatment prevents elevated locomotor activity following
neonatal hippocampal lesions. Neuropsychopharmacology 31, 77–89.
Richtand, N.M., Ahlbrand, R., Horn, P., Stanford, K., Bronson, S.L., McNamara, R.K.,
2011. Effects of risperidone and paliperidone pre-treatment on locomotor
response following prenatal immune activation. J. Psychiatry Res. 45, 1194–
1201.
Riecher-Rossler, A., Hafner, H., 2000. Gender aspects in schizophrenia: bridging the
border between social and biological psychiatry. Acta Psychiatr. Scand Suppl.,
58–62
Robicsek, O., Karry, R., Petit, I., Salman-Kesner, N., Muller, F.J., Klein, E., et al., 2013.
Abnormal neuronal differentiation and mitochondrial dysfunction in hair
follicle-derived induced pluripotent stem cells of schizophrenia patients. Mol.
Psychiatry 18, 1067–1076.
Romero, E., Ali, C., Molina-Holgado, E., Castellano, B., Guaza, C., Borrell, J., 2007.
Neurobehavioral and immunological consequences of prenatal immune
activation in rats. Influence of antipsychotics. Neuropsychopharmacology 32,
1791–1804.
Roumier, A., Pascual, O., Bechade, C., Wakselman, S., Poncer, J.C., Real, E., et al., 2008.
Prenatal activation of microglia induces delayed impairment of glutamatergic
synaptic function. PLoS One 3, e2595.
Schotte, A., Janssen, P.F., Gommeren, W., Luyten, W.H., Van Gompel, P., Lesage, A.S.,
et al., 1996. Risperidone compared with new and reference antipsychotic drugs:
in vitro and in vivo receptor binding. Psychopharmacology 124, 57–73.
Seeman, M.V., Lang, M., 1990. The role of estrogens in schizophrenia gender
differences. Schizophr. Bull. 16, 185–194.
Shi, L., Fatemi, S.H., Sidwell, R.W., Patterson, P.H., 2003. Maternal influenza infection
causes marked behavioral and pharmacological changes in the offspring. J.
Neurosci. 23, 297–302.
Sodhi, M.S., Sanders-Bush, E., 2004. Serotonin and brain development. Int. Rev.
Neurobiol. 59, 111–174.
251
Summer, B.E., Fink, G., 1995. Estrogen increases the density of 5-hydroxytryptamine
(2A) receptors in cerebral cortex and nucleus accumbens in the female rat. J.
Steroid Biochem. Mol. Biol. 54, 15–20.
Takeuchi, K., Yang, Y., Takayasu, Y., Gertner, M., Hwang, J.Y., Aromolaran, K., et al.,
2014. Estradiol pretreatment ameliorates impaired synaptic plasticity at
synapses of insulted CA1 neurons after transient global ischemia. Brain Res.
Wang, H., Yuan, Y., Zhang, Z., Yan, H., Feng, Y., Li, W., 2014. Dysbindin-1C is required
for the survival of hilar mossy cells and the maturation of adult newborn
neurons in dentate gyrus. J. Biol. Chem. 289, 29060–29072.
Weinberger, D.R., 1987. Implications of normal brain development for the
pathogenesis of schizophrenia. Arch. Gen. Psychiatry. 44, 660–669.
Whitaker-Azmitia, P.M., 2001. Serotonin and brain development: role in human
developmental diseases. Brain Res. Bull. 56, 479–485.
Wu, Y.C., Hill, R.A., Gogos, A., van den Buuse, M., 2013. Sex differences and the role
of estrogen in animal models of schizophrenia: interaction with BDNF.
Neuroscience 239, 67–83.
Yolken, R.H., Karlsson, H., Yee, F., Johnston-Wilson, N.L., Torrey, E.F., 2000.
Endogenous retroviruses and schizophrenia. Brain Res. Brain Res. Rev. 31,
193–199.
Zavitsanou, K., Dalton, V.S., Walker, A.K., Weickert, C.S., Sominsky, L., Hodgson, D.M.,
2013. Neonatal lipopolysaccharide treatment has long-term effects on
monoaminergic and cannabinoid receptors in the rat. Synapse 67, 290–299.
Zucker, R.S., Regehr, W.G., 2002. Short-term synaptic plasticity. Annu. Rev. Physiol.
64, 355–405.
Zuckerman, L., Weiner, I., 2003. Post-pubertal emergence of disrupted latent
inhibition following prenatal immune activation. Psychopharmacology 169,
308–313.
Zuckerman, L., Weiner, I., 2005. Maternal immune activation leads to behavioral
and pharmacological changes in the adult offspring. J. Psychiatry Res. 39, 311–
323.
Zuckerman, L., Rehavi, M., Nachman, R., Weiner, I., 2003. Immune activation during
pregnancy in rats leads to a postpubertal emergence of disrupted latent
inhibition, dopaminergic hyperfunction, and altered limbic morphology in the
offspring:
a
novel
neurodevelopmental
model
of
schizophrenia.
Neuropsychopharmacology 28, 1778–1789.