Bisphenol S induces Agrp expression through GPER1 activation and alters transcription factor expression in immortalized hypothalamic neurons: A mechanism distinct from BPA-induced upregulation.

The increasing prevalence of obesity around the world has brought concern upon ubiquitously present obesogenic environmental compounds, such as bisphenol A (BPA). Increasingly tightened regulations on the industrial use of BPA have prompted a transition to a structurally similar alternative, bisphenol S (BPS). BPS displays endocrine-disrupting behaviours similar to those of BPA and increases body weight, food intake and the hypothalamic expression of Agrp in vivo. However, the mechanisms behind this deleterious effect are unclear. Here, we report an increase in the mRNA level of Agrp at 4 h following BPS treatment in immortalized murine hypothalamic cell lines of embryonic and adult origin (mHypoE-41, mHypoA-59). BPS-induced changes in the expression of transcription factors and estrogen receptors that occurred concurrently with Agrp upregulation demonstrated similarities to BPA-induced changes, however, there were also changes that were unique to BPS. Specifically, while Chop, Atf3, Atf4, Atf6, Klf4, and Creb1 were upregulated and Gper1 was downregulated by both BPA and BPS, Esr1 mRNA levels were upregulated and Foxo1 and Stat3 levels remained unchanged by BPS. Finally, inhibition of GPER1 by G15 prevented BPS-mediated Agrp upregulation, independent of Atf3 and Klf4 upregulation. Overall, our results demonstrate the ability of BPS to increase Agrp mRNA expression through GPER1 signaling and to alter transcription factor expression in hypothalamic neurons, further elucidating the endocrine-disrupting potential of this alternative industrial chemical.