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Prenatal exposure to bisphenol A impairs predator odor-induced fear behavior in young rat offspring
1Department of Physiology, Osaka Dental University, 8-1, Kuzuha-Hanazono Cho, Hirakata 573-1121, Japan.
Insights
Prenatal exposure to high-dose bisphenol A (BPA) alters stress responses in young rats, causing habituation to predator odor and affecting normal defensive behaviors. This endocrine disruptor impacts behavioral and physiological reactions to stress.
Area of Science:
- Endocrinology
- Neuroscience
- Toxicology
Background:
- Bisphenol A (BPA) is an environmental endocrine disruptor with potential developmental effects.
- Prenatal exposure to endocrine disruptors may alter offspring's stress response and behavior.
- Understanding BPA's impact on the developing endocrine and nervous systems is crucial.
Purpose of the Study:
- To evaluate behavioral and endocrine changes in rat offspring postnatally exposed to BPA.
- To determine if prenatal BPA exposure affects normal stress responses to a predator odor.
- To assess the dose-dependent effects of BPA on stress-related behaviors and corticosterone levels.
Main Methods:
- Rats were exposed prenatally to low-dose (BPA-L) or high-dose (BPA-H) BPA, or served as controls.
- Offspring were assessed at postnatal day 20 for spontaneous behaviors (rearing, ambulation, grooming, freezing).
- Behavioral responses to a predator odor (TMT) and blood corticosterone levels were measured.
Main Results:
- TMT increased freezing in controls but not in the BPA-H group, which showed increased grooming.
- BPA-L group exhibited increased freezing and grooming in response to TMT.
- Corticosterone levels increased with TMT exposure in all groups, with no significant differences between BPA-exposed and control groups.
Conclusions:
- High-dose prenatal BPA exposure leads to habituation to predator odor-induced stress.
- BPA alters the normal stress response, specifically diminishing defensive behaviors like freezing.
- These findings highlight BPA's potential to disrupt neurodevelopment and stress system maturation.
Objectives:
This study evaluated the changes in behaviors and the endocrine system in rat offspring at postnatal day 20 following prenatal exposure to bisphenol A (BPA), a major environmental endocrine disruptor.
Design:
Using A predator odor (2,4,5-trimethylthiazoline [TMT]) as a stressor, I evaluate behavioral and endocrine responses to check whether the normal stress response is affected by BPA.
Materials And Methods:
A low-dose group (BPA-L; 0.015 mg/kg/day) and a high-dose group (BPA-H; 1.5 mg/kg/day) were compared to assess dose dependency. The control group was not exposed to BPA. Spontaneous behaviors (rearing, ambulation, grooming, and freezing) were assessed in the presence or absence of TMT odor.
Results:
In the control group, TMT odor increased freezing but not grooming behaviors. Conversely, in the BPA-H group, freezing was unchanged, but grooming behavior increased; however, increased freezing and grooming behaviors were observed following TMT odor exposure in the BPA-L group. In addition, blood corticosterone levels increased following TMT odor exposure in all three groups, but there was no difference between the BPA-exposure groups and the control group. Therefore, in the BPA-H group, despite the activation of the hypothalamus-pituitary-adrenal axis by TMT, freezing behavior did not increase, suggesting the absence of defensive behaviors.
Conclusion:
These findings suggest that prenatal exposure to high-dose BPA causes habituation to stress induced by the predator odor and alters the normal stress response in young rat offspring.
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