PFAS Modulate Osmotic Signaling Independent of Gravimetric Changes in the Rat Uterus

Various PFAS have been identified as potential endocrine-disrupting chemicals due to estrogen receptor activation, impacts on puberty timing, or impacts on hormonally sensitive endpoints in fish. This study screened multiple PFAS in the rat uterotrophic assay to determine potential estrogenic effects on the uterus with PFAS exposure. This study also explored PFAS-dependent uterine signaling with an osmotic stress mRNA gene expression array. Briefly, Sprague–Dawley rats (26–39 days old) were ovariectomized, and uterine tissue was allowed to regress for a 3-week period of recovery. Animals were then exposed daily via oral gavage to PFAS for 4 days, and then uterine weight was determined. In contrast to the positive control estrogens, the PFAS tested (4:2, 6:2, and 8:2FTOH; perfluorooctanesulfonamide (PFOSA), perfluorononanoic acid (PFNA), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), nafion byproduct 2 (NBP2), 1H,1H,8H,8H-perfluorooctane-1,8-diol (FC8-diol) and 1H,1H,10H,10H-perfluorodecane-1,10-diol (FC10-diol)) caused no significant changes in the uterine weight. Hormonally active compounds can act as carcinogens, and because earlier rodent work has demonstrated that chronic PFOA exposure is associated with increased risk of uterine cancer, uterine mRNA gene expression was explored with an osmotic stress RT-qPCR array. PFAS exposure significantly upregulated multiple genes across the array, with PFOSA being the compound most similar to the reference estrogens (estradiol benzoate and ethinyl estradiol) in its expression pattern. Also, across all PFAS, pathway analysis revealed that the paxillin pathway, a pathway important in tumor suppressor gene SHP-2 signaling, was significantly upregulated with PFAS exposure. These results demonstrate that in vitro estrogen screens or impacts in fish may show different responses from direct impacts on mammalian uterine weight as assessed with the uterotrophic assay. This study also builds out new mechanisms that may contribute to understanding of carcinogenic changes seen in the uterus after PFAS exposure. Keywords:  PFAS; uterus; reproductive toxicology; endocrine disruptors; cancer signaling

Impact/Purpose

The ubiquitous PFAS chemicals are suspected endocrine disrupting compounds. Earlier work has shown various PFAS activate estrogen receptor pathways in vitro. This work using the rodent uterotrophic assay explores whether the PFAS impact the uterus in vivo to determine potential estrogenic activity of the PFAS in mammalian models. This work also develops signaling pathways using genetic arrays. This sub-product will describe data generated from acute exposure to ovarectomized females and/or pubertal exposure to intact females. PFAS that were positive for estrogenic activity on estrogen receptor assays will be screened in these animal assays. Endpoints assayed include female reproductive organ weight (uterus), gene expression changes, serum concentrations of PFAS, timing of vaginal opening and other pubertal milestones.

Citation

Dixon, A., E. Rowan, A. Yackley, AND E. Hines. PFAS Modulate Osmotic Signaling Independent of Gravimetric Changes in the Rat Uterus. MDPI, Basel, SWITZERLAND, 12(3):170, (2024). [DOI: 10.3390/toxics12030170]

DOI: PFAS Modulate Osmotic Signaling Independent of Gravimetric Changes in the Rat Uterus