SUN-241 Adult Exposure to Iodoacetic Acid Leads to Abnormal Expression of Key Genes Related to Hypothalamic and Pituitary Control of Reproductive Function

Abstract Water disinfection byproducts (DBPs) are formed when chemicals used to decontaminate water come into contact with natural or synthetic organic material. DBPs have been linked to a range of health concerns including reproductive disfunction. One such DBP, the monohalogenated iodoacetic acid (IAA), is formed when iodide reacts with a disinfectant, for example, chlorine. IAA is of particular health concern; not only is iodide widely present in the water supply, especially in coastal communities and those near fracking sites, but IAA has been found to be one of the most cyto- and genotoxic DBPs. Further, a previous study has indicated that in vitro IAA exposure significantly inhibits antral follicle growth and reduces estradiol levels in ovaries. However, little is known about how IAA affects the other major components of the reproductive axis: the hypothalamus and pituitary. The reproductive axis relies on homeostatic release of hormones to communicate from one organ to another and alterations at any level may impact reproduction. So, we set out to test the hypothesis that exposure to IAA would lead to disrupted expression of key hypothalamic and pituitary genes related to reproductive function. We continually exposed female adult CD1 mice to 0.5, 10, 100, or 500 mg/L IAA in their drinking water for approximately 35 days (postnatal day 40 (P40) to their first day in diestrus following P75.) Whole pituitaries and hypothalamic punches containing the arcuate nucleus (ARC), anteroventral periventricular zone (AVPV), and medial preoptic nucleus (mPOA) were collected and processed for qPCR analysis. We find that while kisspeptin (Kiss1) expression in the AVPV - the population responsible for generating the LH surge - is unchanged, 0.5 mg/L IAA exposure significantly increases Kiss1 in the ARC, which controls pulsatile GnRH release, and there is a trending increase (p=.056) at 10mg/L. We also measured ARC expression of Neurokinin B (NKB; Tac2), a neuropeptide secreted by kisspeptin co-expressing neurons to autosynaptically stimulate Kiss1 release. We found no change in mRNA levels of Tac2. We also saw no significant changes in GnRH (Gnrh1) mRNA expression. At the level of the pituitary, there is no change in Lhb mRNA levels. Exposure to 10 mg/L IAA leads to significantly reduced Fshb expression, however FSH serum levels are not significantly changed. These data, taken together with previous findings in the ovary, indicate that IAA has the potential to disrupt each major level of the reproductive axis: ovarian follicle development and steroid synthesis, hypothalamic arcuate Kiss1 synthesis, and Fshb synthesis from the pituitary. Further research is necessary to elucidate at which levels IAA acts directly and at which it acts through action on another component of the axis. Additionally, future studies can clarify the mechanism through which IAA has these effects.