The Laryngoscope
C 2013 The American Laryngological,
V
Rhinological and Otological Society, Inc.
Oral Homeostasis Disruption by Medical Plasticizer Component
Bisphenol A in Adult Male Rats
Mireille Folia, MD; Sofiane Boudalia; Franck Menetrier, MSc; Laurence Decocq; Bruno Pasquis, MSc;
Charles Schneider, MSc; Raymond Bergès, PhD; Yves Artur; Marie-Chantal Canivenc-Lavier, PhD
Objectives/Hypothesis: Bisphenol A (BPA) is a synthetic estrogen-like chemical mimetic widely used in the manufacture of polycarbonate plastics and epoxy resins found in numerous consumer products including food packaging, medical
devices, and dental sealants. Because it is recovered in fluids and it can reach high levels in saliva, this study aimed to evaluate its safety on oral homeostasis by examining its effects on salivary glands, mouth epithelium, water consumption, and salt
preference, each parameter being estrogen sensitive.
Study Design: Randomized controlled trial involving rats.
Methods: A dose-response study was conducted in adult Wistar rats randomized into five groups (n ¼ 12). BPA was
administered over 6 weeks via drinking water to obtain daily dose exposures of 0 lg/kg, 5 lg/kg, 50 lg/kg, 5 mg/kg, and
12.5 mg/kg of body weight. To evaluate salt preference, 1% NaCl solution and pure water intakes were measured for 3 days
by offering two-bottle choices. The rats were then killed; oral biopsies were done and submandibular glands were removed
for histologic and morphometric analysis.
Results: According to the dose-response curve, BPA decreased total drinking but increased salt preference, which was
inversely proportional to water consumption (Kruskal-Wallis, P < .01). It also causes oral dryness and histologic changes in
the acinar structures of the submandibular glands at the lowest doses (Kruskal-Wallis, P < .01).
Conclusions: This study shows that oral exposure to BPA in the rat disrupts thirst and buccal homeostasis and raises
questions about the salivary gland secretions.
Key Words: Salt preference, mouth dryness, thirst, salivary gland, endocrine disruptors.
Level of Evidence: N/A.
Laryngoscope, 123:1405–1410, 2013
INTRODUCTION
Oral homeostasis and oral well-being depend on
several factors, including a healthy oral epithelium, an
appropriate qualitative and quantitative secretion of saliva, and the ability to recognize and appreciate food.
These factors vary with hormonal status, and their relationship to the sex hormones has long been established,
notably owing to the existence of sexual dimorphism1–3
and neuroendocrine system regulation of salivary secretions, some of which are involved in the gustative
From CHU (Hospital-University Center) (M.F.), General Hospital, 3
rue Faubourg Raines, F-21000 Dijon; CNRS (M.F., S.B., F.M., L.D., B.P., R.B.,
Y.A., M.-C.C.-L.), UMR6265, Center of Food and Taste Sciences, F-21000
Dijon; INRA (M.F., S.B., F.M., L.D., B.P., R.B., Y.A., M.-C.C.-L.), UMR1324, Center
of Food and Taste Sciences, F-21000 Dijon; Universit
e de Bourgogne (M.F.,
S.B., F.M., B.P., R.B., Y.A., M.-C.C.-L.), Center of Food and Taste Sciences, F21000 Dijon; INRA (National Institut of Agronomic Research) (C.S.), UMR
1347 of Agroecology, F-21000 Dijon, France.
Editor’s Note: This Manuscript was accepted for publication
September 19, 2012.
This work was funded by the National Program for Research on
Endocrine Disruptors (PNR-PE 2008-20112; contract MEDD CV 05147)
and the Burgundy Regional Council (Contract AGRAL 1 ‘‘Sensory Perceptions and Feeding Behavior’’).
The authors have no other funding, financial relationships, or conflicts of interest to disclose.
Send correspondence to Marie-Chantal Canivenc-Lavier, PhD,
CSGA UMR 1324, INRA, 17 Rue Sully 21000 Dijon, France.
E-mail: [email protected]
DOI: 10.1002/lary.23791
Laryngoscope 123: June 2013
mechanism,4,5 as well as the presence of ERb receptors
within the oral epithelium and salivary glands.
The role of salivary glands in maintaining oral
homeostasis and gustative perception is also well known.
Their sexual dimorphism highlights their sensitivity to the
sex hormones, and many studies have shown the effects of
steroid and thyroid hormones on their morphogenesis and
endocrine and exocrine secretions.6,7 In rodents, chronic
exposure to xenoestrogens (including phytoestrogens and
antiestrogenic compounds such as tamoxifen) cause structural changes to the submandibular glands.8–10 Few
studies have been conducted to examine the effects of
estrogen on salivary glands in males, but experimental
studies have shown that synthetic estrogen can cause hypertrophy of secretory structures (granulated convoluted
tubules) similar to those caused by androgens.11
Furthermore, several experimental studies in
rodents have reported the specific effects of estrogen on
salt preference. In adult males, chronic estrogen exposure leads to an increase in salt preference, reflected by
a shift toward female nutritional behavior.12,13
Therefore, the presence of sexual dimorphism in
gustative preferences14 and the presence of estrogen
receptors, most specifically the ERb receptor, in oral
tissues15,16 have led to concern regarding the effects of
such endocrine disruptors on oral homeostasis.
Bisphenol A (BPA) is an estrogenic compound used in
the manufacture of food packaging (cans, bottles, and
Folia et al.: Bisphenol A and Oral Homeostasis
1405
tins) and medical equipment (catheters, infusion bags,
and meal trays), as well as certain dental sealants. Several studies have shown that BPA monomers can be
released from the polymer matrix.17,18 Some authors have
demonstrated the deleterious effects of BPA at doses significantly lower than 50 lg/kg, which is the acceptable
daily intake as defined by regulatory authorities.19
Oral exposure to BPA via food packaging and dental
treatments directly affects the oral cavity. Exposure
from drinking bottled water can reach between 17.6 and
324 ng/L.20 Salivary concentration is generally low (<10
ng/mL); however, in individuals with dental sealants it
can reach much higher levels (up to 100 ng/mL).21–23
The effects of oral exposure to BPA at doses consistent
with exposure via food packaging or consecutive to dental treatments in adults are unknown.
We used male rats to examine the effects of BPA on
three potential estrogen targets—salt preference, histology of the oral epithelium, and histology of the
submandibular glands—to identify the potential effects of
BPA on oral homeostasis.
each morning at the same time. The results are expressed as a
value relative to the daily quantity consumed (milliliters) in
relation to body weight (milliliters consumed per day per 100 g
body weight). Gustative preference was defined as the relationship between the mean consumption of saline water and the
mean of total water consumption during the 3 days.
Sampling and Analysis of the Salivary Glands
At the end of the testing period, the animals were euthanized by anesthesia with isoflurane (2.5%), and the salivary
glands were removed. Submandibular glands were included in
the optimal cutting temperature and frozen in an isopentane
bath (70 C) for histologic analysis. Several 5-lm-thick cryostat
cross-sections were made (Leica CM 3050S, 20 C/18 C,
Solms, Germany) and placed on a glass slide. After staining
with Masson’s trichome stain, the structures were examined
under a microscope (Nikon Eclipse E600, 10, Nikon, Japan)
using white light. Excretory ducts, acini, and granulate convoluted tubules (GCTs) were analyzed for each rat based on 15
photographs per rat (DXM 1200C, NIS El
ements Br 3.0, Nikon).
To identify and specify changes to the structures due to BPA,
we assessed the quantity and surface of the acini and GCT with
programmed image analysis using Visilog software (Visilog 6.9;
Noesis, Crolles, France).
MATERIALS AND METHODS
Chemical Agents
BPA and high-purity sodium chloride (at least 98%) were
obtained from Sigma-Aldrich (St. Louis, MO). Chemicals used
for histologic analysis were from standard commercial sources
and of the highest quality available.
Animals and BPA Exposure Conditions
The experimental procedure was approved by the University of Bourgogne’s ethics committee. Upon arrival, 60 fiveweek-old male Wistar rats (Harlan France SARL, Gannat,
France) were acclimatized to the animal facilities (22 C, 55%
relative humidity, 12-hour day/night alteration) with housing
conditions designed to isolate rats from all potential sources of
estrogenic contamination via the environment and food. To
achieve this, the rats were housed in polypropylene cages (3 to
4 per cage, plastic not containing BPA) and fed a synthetic diet
ad libitum devoid of phytoestrogen (diet L5, INRA, Jouy-enJosas, France24). The water was decontaminated of all traces of
pesticides through activated carbon filtration and distributed in
drinking bottles that were also constructed of polypropylene. At
12 weeks of age (weight 440–450 g), the rats were placed in
individual cages and randomly separated into five BPA groups
(12 rats per group): a control group and four groups exposed to
BPA over 6 weeks via drinking water (0, 0.12, 1.2, 120, and 300
mg/L) through administration of the following daily doses: 0 lg/
kg, 5 lg/kg, 50 lg/kg, 5 mg/kg, and 12.5 mg/kg of body weight.
The highest dose corresponded to a saturated BPA solution (solubility, 300 mg/L). Conditions of the animals were assessed
twice weekly by weight gain and food and water consumption.
Salt Preference Test
Salt preference was assessed over 3 consecutive days during the final week of exposure by offering a choice of two
bottles, one containing pure water and the other containing
saline solution (1% NaCl). The rats had been familiarized with
the presence of the two bottles for 3 days before testing. During
the test period, the bottles’ positions were reversed each day
and water consumption measured by weighing the two bottles
Laryngoscope 123: June 2013
1406
Epithelial Histology
Samples of the right jugal mucosa were taken from euthanized rats. This procedure was carried out using a scalpel following
dislocation of the lower jaw. The samples were fixed in 4% formalin
for 24 hours and later embedded in paraffin. Cross-sections (5-lm
thick) were made and stained using hemalum-eosin. Random photographs of distinct and nonoverlapping zones of the oral
epithelium were acquired using a microscope (Nikon Eclipse E600,
10) and analyzed using Nis-Br software. Epithelial and stratum
corneum thicknesses were measured. Twenty measurements out of
10 photographs were carried out per rat. The thickness of the corneal and epithelial layers was then examined.
Statistical Analysis
Statistical analysis was conducted using StatEL software
(Adsciences, Paris, France). The data represent the mean value
obtained from each group (mean 6 standard deviation, n ¼ 12/
group). The data were then subjected to analysis based on the
Kruskal-Wallis nonparametric variance test, followed by comparison of mean values using the Mann Whitney U test (P < .05).
RESULTS
Effect of BPA on Food Intake and Health Status
No indication of suffering or abnormal behavior was
observed during treatment. The mean weight of the rats
from each group was similar at the beginning of the
experiment (442 6 15 g). BPA exposure did not influence
the nutritional behavior of the animals (data not shown),
and at the end of the exposure period, the rats’ mean
weight did not differ between groups (482 6 36 g), confirming the absence of acute BPA toxicity under our
experimental conditions. However, although there was
no difference in average water consumption between the
five groups at the beginning of the experiment (17.5 6
3.8 mL/day per rat), a diminution in water consumption
occurred from the first few days in the group receiving
Folia et al.: Bisphenol A and Oral Homeostasis
Fig. 1. Bisphenol A effect on water intake in male adult rat. Values
are the mean 6 standard deviation of water intake (grams per 100
g body weight [BW]). Letters indicate values significantly different
(Kruskal-Wallis followed by Mann Whitney U test, P < .05).
the highest dose of BPA. This effect was progressively
confirmed in each of the other groups and proved to be
highly significant (P < .01, Fig. 1).
Effect of BPA on Salt Preference
As shown in Figure 2, ingestion of BPA caused a
significant increase in saline water consumption for the
high-exposure doses (P < .05, Fig. 2A); however, water
consumption remained lower than in the control group
(P < .05 Fig. 2B). This resulted in an increase in salt
preference, which increased significantly according to
the linear dose-response curve (< .05, Fig. 2C).
Effect of BPA on Oral Epithelium
During euthanasia, exploration of the oral cavity
using a cotton swab revealed severe oral dryness in all
Fig. 3. Effect of bisphenol A on oral epithelium: thickness of
epithelial layer (A), stratum corneum (B), ratio stratum corneum/
(stratum corneum and epithelial layer) (C), and photo of
oral mucosa (D). Letters indicate values significantly different
(Kruskal-Wallis followed by Mann Whitney U test, P < .05).
animals treated. This dryness, very pronounced even at
the lowest doses, appears to be independent of exposure
dose. The histologic results of the jugal mucosa (Fig. 3)
revealed a thicker epithelial layer at 5 mg (P < .05) with
a stratum corneum identical to the control group. The
ratio of stratum corneum to epithelial layer, which eliminates cross-section bias, revealed no difference between
Fig. 2. Effect of bisphenol A on NaCl preference: 1% NaCl intake (A), water intake (B), and NaCl preference (C). Values are the mean 6
standard deviation of water consumption (grams per 100 g body weight [BW]). Letters indicate values significantly different (Kruskal-Wallis
followed by Mann Whitney U test, P < .01).
Laryngoscope 123: June 2013
Folia et al.: Bisphenol A and Oral Homeostasis
1407
Fig. 4. Bisphenol A effect on secretory organs of the submandibular gland from adult male rat: granulated convoluted tubules (GCT) number (A), GCT area (B), acini number (C), acini area (D), and photo of submandibular structures (E). EC ¼ excretory canal. Letters indicate
values significantly different (Kruskal-Wallis followed by Mann Whitney U test, P < .01).
the control and BPA groups. Thus, BPA has little effect
on the histology of the oral epithelium.
Effect of BPA on the Submandibular Glands
Histologic analysis of the submandibular glands
was conducted to evaluate secretory structures, GCT,
and acini (Fig. 4). Our results did not reveal a highly
significant effect on the GCT, although all rats exposed
to BPA presented a slightly higher abundance of GCT
than the control group (Fig. 4A) and a weaker surface
on average (Fig. 4B). Conversely, the acini were significantly less abundant but more voluminous in rats
exposed to BPA (P < .01, Fig. 4C), with a significantly
greater surface compared to the lowest exposure doses
(P < .01, Fig. 4D).
DISCUSSION
Oral dryness was induced following oral ingestion
of BPA, accompanied by an effect on salt taste preference and changes to secretory structures of the
submandibular glands in adult male rats. BPA may
have an effect on oral homeostasis corresponding to the
hormonal effect that has been described in previous
studies examining other organs.25,26
Laryngoscope 123: June 2013
1408
These modifications in salt preference and oral dryness may be interpreted as a disruption of oral
homeostasis. Indeed, during dissection of our rats, we
observed mouth dryness, an indication of decreased plasticizer levels in salivary gland secretions, although there
were no obvious changes to the histology of the oral epithelium. Therefore, BPA does not affect oral epithelium
regulation in the same ways as estrogens by inducing
maturation and keratinization.16 However, our results
show modification of the submandibular gland secretory
structures. In rodents, GCTs are secretory structures
that are particularly sensitive to sex hormones,27 which
cause structural hypertrophy and stimulate secretion,
particularly epithelial growth factor (EGF),28 nerve
growth factor (NGF), and transforming growth factor
secretions, which are involved in maintaining the oral
epithelium29 and taste bud integrity.5 The same concept
applies to the serous acini, which are responsible for
exocrine secretions of salivary proteins.7
Like most mammalians, rodents present a very pronounced dimorphism of the salivary glands,3 which
reflects the effect of steroid hormones on the morphogenesis and secretory processes of salivary glands.
Synthesis of polypeptides (such as EGF and NGF) by
GCTs is therefore essentially androgen dependent, even
in females,6,30,31 and salivary flow is also regulated by
Folia et al.: Bisphenol A and Oral Homeostasis
estrogen.32,33 In our study, because BPA exposure had
little effect on GCT morphometry, even at high doses, we
hypothesize that growth factor secretions likely do not
decrease; this can be explained by the nonalteration of
the oral epithelium. Conversely, BPA induces significant
hypertrophy of the acini in a dose-dependent manner.
Because this significant effect appears at the lowest
doses, similar to oral dryness, histologic modification of
the submandibular is associated with qualitative and/or
quantitative modifications of saliva.
The effect of BPA on salivary glands and their
secretions may therefore explain the effect of BPA on
salt preference. It has been demonstrated that salt preference depends on the concentration of sodium chloride
in the saliva34 and that a higher saline concentration in
the saliva causes a reduction in sensitivity to salt taste.
Acini modification increases the salt detection threshold
and accounts for an increase in saline water consumption and therefore salt preference. According to riskassessment agencies,35 the oral route is one of the main
exposures to BPA in humans. In adults, the average
exposure to BPA via food is approximately 0.033 lg/kg
body weight per day.36 This dose is much lower than the
established acceptable daily intake (50 lg/kg body
weight per day). However, according to Joskow et al.,18
salivary BPA concentration is higher in patients treated
with certain dental sealants and varies according to the
stability of the sealant, ranging from 5.5 to 110 lg/mL of
saliva. Thus, dental sealants and disposable plastics for
medical use or food packaging may be a source of continuous exposure to low doses of BPA; based on our results
in adult rats, this may affect oral homeostasis.
Although this theory may explain the observed
modifications to salt preference and the salivary glands, it
fails to account for the decreased water consumption in all
animals treated. Adipsia may have resulted from thirst
perception loss and thus could have been a result of modified neural signals. Our rats may have experienced chronic
dehydration due to an effect on hormonal regulation
pathways involved in hydric homeostasis. Two systems are
implicated in dehydration: the renin-angiotensinaldosterone system and the arginin-vasopressin system.
The renin-angiotensin-aldosterone system is controlled in
part by estrogen, which causes a decrease in angiotensin II
secretions, an increase in renin and angiotensin I, and
diminished thirst sensation, leading to reduced fluid
intake.37–39 However, if this system was involved, we
would have expected a reduction in salt intake.
With regard to the arginin-vasopressin system,
estrogens increase vasopressin expression through the
intermediary of its beta receptors in its supraoptic and
paraventricular nuclei; this results in fluid retention,
causing a decrease in water consumption.40 The increase
in vasopressin levels is due to a lowering of the osmotic
threshold at which it is released.41 This phenomenon
can also occur with the absence of thirst, as is the case
with elderly individuals. The relative dehydration of our
rats may explain their increased salt intake during the
gustative test. Our findings therefore suggest that BPA
may have an effect on thirst via an estrogen mimetic
effect of central origin.
Laryngoscope 123: June 2013
CONCLUSION
This study identifies the deleterious effects of oral
BPA exposure on buccal homeostasis in the rat by evidencing the effect of BPA on mouth dryness and salivary
gland structures and a decreasing effect on thirst. Taken
together, our results allow us to highlight the submandibular glands as new targets of BPA activity and raise
questions regarding possible defects of endocrine and/or
exocrine salivary gland secretions related to taste events
and buccal health. However, further investigations are
necessary to draw a precise conclusion. Particularly, it is
necessary to determine whether changes in acini structures result in modifications to endocrine and exocrine
function associated with maintaining oral homeostasis
and/or gustative perception and whether other gustative
preferences are affected. Therefore, we are now studying
the effect of BPA exposure on mRNA expression of
growth factors and salivary proteins in the submandibular salivary glands.
Further studies must be conducted in humans to
validate our results in rats, and if they do, the use of
medical materials containing BPA (probes, transfusion
bags, tubing, etc.) in health facilities may need to be
reconsidered, particularly for vulnerable individuals.
BIBLIOGRAPHY
1. Valenstein ES, Kakolewski JW, Cox VC. Sex differences in taste preference
for glucose and saccharin solutions. Science 1967;156:942–943.
2. Wade GN, Zucker I. Hormonal and developmental influences on rat saccharin preferences. J Comp Physiol Psychol 1969;69:291–300.
3. Jayasinghe NR, Cope GH, Jacob S. Morphometric studies on the development and sexual dimorphism of the submandibular gland of the mouse.
J Anat 1990;172:115–127.
4. Deville De Periere D. Neuroendocrine control of the salivary glands. In:
Fabrics Unmineralized and Oral Environment. Paris: Masson,
1993;101–117.
5. Morris-Wiman J, Sego R, Brinkley L, Dolce C. The effects of sialoadenectomy and exogenous EGF on taste bud morphology and maintenance.
Chem Senses 2000;25:9–19.
6. Gresik EW, Barka T. Precocious development of granular convoluted
tubules in the mouse submandibular gland induced by thyroxine or by
thyroxine and testosterone. Am J Anat 1980;159:177–185.
7. Sawada K, Noumura T. Effects of castration and sex steroids on sexually
dimorphic development of the mouse submandibular gland. Acta Anat
(Basel) 1991;140:97–103.
8. Presman J, Rins de David ML. Effect of tamoxifen on sublingual and submaxillary glands in the rat [in Spanish]. Rev Fac Odontol Univ Nac
(Cordoba) 1981;13:7–30.
9. Carvalho VD, Silveira VA, do Prado RF, Carvalho YR. Effect of estrogen
therapy, soy isoflavones, and the combination therapy on the submandibular gland of ovariectomized rats. Pathol Res Pract 2011;207:
300–305.
10. Kouidhi W, Desmetz C, Nahdi A, et al. In utero and lactational exposure
to low-dose genistein-vinclozolin mixture affects the development and
growth factor mRNA expression of the submandibular salivary gland in
immature female rats. Toxicol Pathol 2012;40:593–604.
11. Islander U, Hasseus B, Erlandsson MC, et al. Estren promotes androgen
phenotypes in primary lymphoid organs and submandibular glands.
BMC Immunol 2005;6:16.
12. Curtis KS, Davis LM, Johnson AL, Therrien KL, Contreras RJ. Sex differences in behavioral taste responses to and ingestion of sucrose and
NaCl solutions by rats. Physiol Behav 2004;80:657–664.
13. Kochli A, Tenenbaum-Rakover Y, Leshem M. Increased salt appetite in
patients with congenital adrenal hyperplasia 21-hydroxylase deficiency.
Am J Physiol Regul Integr Comp Physiol 2005;288:R1673–1681.
14. Clarke SN, Ossenkopp KP. Taste reactivity responses in rats: influence of
sex and the estrous cycle. Am J Physiol 1998;274:R718–724.
15. Valimaa H, Savolainen S, Soukka T, et al. Estrogen receptor-beta is the
predominant estrogen receptor subtype in human oral epithelium and
salivary glands. J Endocrinol 2004;180:55–62.
16. Leimola-Virtanen R, Salo T, Toikkanen S, Pulkkinen J, Syrjanen S.
Expression of estrogen receptor (ER) in oral mucosa and salivary
glands. Maturitas 2000;36:131–137.
17. Lakind JS, Naiman DQ. Daily intake of bisphenol A and potential sources
of exposure: 2005-2006 National Health and Nutrition Examination Survey. J Expo Sci Environ Epidemiol 2011;21:272–279.
Folia et al.: Bisphenol A and Oral Homeostasis
1409
18. Joskow R, Barr DB, Barr JR, Calafat AM, Needham LL, Rubin C. Exposure to bisphenol A from bis-glycidyl dimethacrylate-based dental sealants. J Am Dent Assoc 2006;137:353–362.
19. Richter CA, Birnbaum LS, Farabollini F, et al. In vivo effects of bisphenol
A in laboratory rodent studies. Reprod Toxicol 2007;24:199–224.
20. Li X, Ying GG, Su HC, Yang XB, Wang L. Simultaneous determination
and assessment of 4-nonylphenol, bisphenol A and triclosan in tap
water, bottled water and baby bottles. Environ Int 2010;36:557–562.
21. Zimmerman-Downs JM, Shuman D, Stull SC, Ratzlaff RE. Bisphenol A
blood and saliva levels prior to and after dental sealant placement in
adults. J Dent Hyg 2010;84:145–150.
22. Kang YG, Kim JY, Kim J, Won PJ, Nam JH. Release of bisphenol A from
resin composite used to bond orthodontic lingual retainers. Am J Orthod
Dentofacial Orthop 2011;140:779–789.
23. Sasaki N, Okuda K, Kato T, et al. Salivary bisphenol-A levels detected by
ELISA after restoration with composite resin. J Mater Sci Mater Med
2005;16:297–300.
24. Stroheker T, Chagnon MC, Pinnert MF, Berges R, Canivenc-Lavier MC.
Estrogenic effects of food wrap packaging xenoestrogens and flavonoids
in female Wistar rats: a comparative study. Reprod Toxicol 2003;17:
421–432.
25. Stroheker T, Picard K, Lhuguenot JC, Canivenc-Lavier MC, Chagnon MC.
Steroid activities comparison of natural and food wrap compounds in
human breast cancer cell lines. Food Chem Toxicol 2004;42:887–897.
26. Rubin BS. Bisphenol A: an endocrine disruptor with widespread exposure
and multiple effects. J Steroid Biochem Mol Biol 2011;127:27–34.
27. Gresik EW, Hosoi K, Kurihara K, Maruyama S, Ueha T. The rodent
granular convoluted tubule cell—an update. Eur J Morphol 1996;34:
221–224.
28. Gresik EW, Wenk-Salamone K, Onetti-Muda A, Gubits RM, Shaw PA.
Effect of advanced age on the induction by androgen or thyroid hormone
of epidermal growth factor and epidermal growth factor mRNA in the
submandibular glands of C57BL/6 male mice. Mech Ageing Dev 1986;34:
175–189.
29. Egea JC, Hirtz C, Valcarcel J, Deville De Periere D. Epidermal growth factor: a probable oral and digestive health protector [in French]. Pathol
Biol (Paris) 2002;50:608–612.
Laryngoscope 123: June 2013
1410
30. Barka T. Biologically active polypeptides in submandibular glands.
J Histochem Cytochem 1980;28:836–859.
31. Barthe PL, Bullock LP, Mowszowicz I, Bardin CW, Orth DN. Submaxillary
gland epidermal growth factor: a sensitive index of biologic androgen activity. Endocrinology 1974;95:1019–1025.
32. Laine M, Leimola-Virtanen R. Effect of hormone replacement therapy on
salivary flow rate, buffer effect and pH on perimenopausal and postmenopausal women. Arch Oral Biol 1996;41:91–96.
33. Laine M, Pienihakkinen K, Ojanotko-Harri A, Tenovuo J. Effects of lowdose oral contraceptives on female whole saliva. Arch Oral Biol 1991;36:
549–552.
34. Delwiche J, O’Mahony M. Changes in secreted salivary sodium are sufficient to alter salt taste sensitivity: use of signal detection measures
with continuous monitoring of the oral environment. Physiol Behav
1996;59:605–611.
35. EFSA. Opinion of the Scientific Panel on Food Additives, Flavourings,
Processing Aids and Materials in Contact with Food on a request from
the Commission related to Bisphenol A. EFSA Journal 2006;428:1–75.
36. Lim DS, Kwack SJ, Kim KB, Kim HS, Lee BM. Potential risk of bisphenol
A migration from polycarbonate containers after heating, boiling, and
microwaving. J Toxicol Environ Health A 2009;72:1285–1291.
37. Fitzsimons JT. Angiotensin, thirst, and sodium appetite. Physiol Rev 1998;
78:583–686.
38. Kisley LR, Sakai RR, Fluharty SJ. Estrogen decreases hypothalamic angiotensin II AT1 receptor binding and mRNA in the female rat. Brain
Res 1999;844:34–42.
39. Mecawi AS, Lepletier A, Araujo IG, Fonseca FV, Reis LC. Oestrogenic
influence on brain AT1 receptor signalling on the thirst and sodium
appetite in osmotically stimulated and sodium-depleted female rats. Exp
Physiol 2008;93:1002–1010.
40. Grassi D, Amorim MA, Garcia-Segura LM, Panzica G. Estrogen receptor
alpha is involved in the estrogenic regulation of arginine vasopressin
immunoreactivity in the supraoptic and paraventricular nuclei of ovariectomized rats. Neurosci Lett 2010;474:135–139.
41. Stachenfeld NS, Taylor HS. Sex hormone effects on body fluid and sodium
regulation in women with and without exercise-associated hyponatremia.
J Appl Physiol 2009;107:864–872.
Folia et al.: Bisphenol A and Oral Homeostasis