RF22 | PMON04 Sex- and Dose-Dependent Effects of In Utero Endocrine Disruptor Exposure on Offspring Behavior and Brain Monoamines

Exposure to endocrine disruptors (EDs), including the well-known plasticizers bisphenol A (BPA) and di(2-Ethylhexyl) phthalate (DEHP), during the highly sensitive gestational period, can produce long-lasting behavioral changes in offspring. In this study, we hypothesized that gestational exposure to BPA and/or DEHP at various doses would alter stress-related behaviors and monoaminergic activity in a region-specific manner in exposed offspring. To test this, female Sprague-Dawley dams were orally administered saline (control group - 10 µL/kg BW), BPA (5 µg/kg body weight (BW)), DEHP (5 µg/kg BW or 7.5 mg/kg BW), a combination of BPA and low-dose (LD) DEHP (5 µg BPA + 5 µg DEHP/kg BW), or a combination of BPA and high-dose (HD) DEHP (5 µg BPA + 7.5 mg DEHP/kg BW) during days 6 through 21 of pregnancy. The male and female offspring of these dams underwent a battery of behavioral tests in adulthood. Brains collected from the offspring were microdissected to obtain the medial prefrontal cortex (mPFC), paraventricular hypothalamic nucleus (PVN), and hippocampus (HC), which were analyzed for monoamine and metabolite levels using High-Performance Liquid Chromatography (HPLC). While BPA and B+D (LD) female offspring demonstrated anxiolytic effects in the Open Field Test, DEHP (HD) male offspring showed feminized anxiety-like behavior in the Elevated Plus Maze. The offspring also displayed impaired fear responses in the Shock Probe Defensive Burying (SPDB) test. Males in most ED groups buried less than their control counterparts. Furthermore, low-dose ED treatments led to a robust preference for passive coping strategies in both male and female offspring. Within the brain, male offspring in the BPA, LD and HD DEHP, and B+D (HD) groups had diminished dopamine (DA) levels in the PVN, which corresponded with their reduced SPDB burying levels. Moreover, DEHP (LD) male offspring had elevated DA turnover in the mPFC, whereas B+D (LD) female offspring had enhanced norepinephrine levels in the HC, which may underlie their behavioral outcomes in the SDPB. The findings of this study have implications for sex differences in mood and anxiety disorders following prenatal exposures to BPA, DEHP, and their mixtures.

Presentation: Sunday, June 12, 2022 12:36 p.m. - 12:41 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

SAT-717 Region-Specific Effects of the Exposome on Brain Monoamine Levels in Female Rats

Prenatal programming with endocrine disrupting chemicals (EDCs), in particular the ubiquitous plasticizers bisphenol A (BPA) and di(2-ethylhexyl) phthalate (DEHP), can induce long-lasting behavioral changes in rats. Additionally, changes in estrogen are correlated with the development of mood disorders in women; however, the underlying neurobiological mechanisms are unclear. This study was conducted to determine the cumulative effects of prenatal exposure to EDCs followed by chronic estradiol treatment in adult female rats on monoamine levels in the prefrontal cortex (PFC) and hippocampus (HC). Dams were orally administered saline (control; 10 µL/kg), BPA (B; 5 µg/kg), DEHP (D; 7.5 mg/kg) or a combination of BPA+DEHP (B+D) during days 6 through 21 of pregnancy. Adult female offspring were sham-implanted or implanted with pellets that release 17β-estradiol (E2) for 90 days (20 ng/day; Innovative Research America). The offspring then underwent a battery of behavioral tests at the end of treatment. Brains collected from the offspring were sectioned and the PFC and HC were microdissected and analyzed for levels of norepinephrine (NE), dopamine (DA) and serotonin (5-HT), using High-Performance Liquid Chromatography (HPLC). Significant reductions in monoamine levels were observed in the PFC while NE and 5-HT levels were markedly reduced in the HC after prenatal exposure to D or BD. BPA’s effects on monoamines were comparatively modest. E2 exposure increased DA but decreased 5-HT levels in the PFC of control animals. Prenatal exposure to EDCs made the offspring non-responsive to E2. The marked reduction in monoamine levels could have implications for learning and memory.