Investigating ovarian effects of perfluorooctanoic acid in post-pubertal pigs during thermal neutral and heat stress conditions

Perfluorooctanoic acid (PFOA) is associated with disrupted female endocrine and reproductive function. In this study, the ovarian impact of PFOA exposure was investigated in post-pubertal pigs housed in thermal neutral (TN) or heat stress (HS) environments. Gilts (n = 48) were housed in either TN conditions (21.0 ± 0.10 °C) or cyclical HS (32.2 ± 0.1 °C to 26.2 ± 0.1 °C) for 19 d and assigned randomly to TN vehicle control (TC; n = 12), TN PFOA (TP; n = 12, 70 ng PFOA/kg), HS control (HC; n = 12), and HS PFOA (HP; n = 11; 70 ng PFOA/kg) treatments. Relative to TC, ovarian weight was decreased in TP (P = 0.03) and tended to be decreased in HP (P = 0.08). Follicular fluid estradiol tended (P = 0.08) to be decreased in HP relative to HC gilts. Dominant follicle size, vulva size, uterine weight and follicular fluid progesterone level were not altered by treatment. The number of ovarian primordial, primary, and secondary follicles was not affected by PFOA treatment, but tertiary follicles tended (P = 0.08) to be decreased by HS. In HP gilts, there were more primordial (P = 0.05), secondary (P = 0.002) and empty (P = 0.008) follicles and a tendency for increased primary (P = 0.06) and tertiary (P = 0.08) follicles compared to TC gilts. The abundance of ovarian microsomal epoxide hydrolase (EPHX1) was reduced in HP relative to TC (P = 0.005) and HC (P = 0.006) gilts. In TP gilts, 3β-hydroxysteroid dehydrogenase (3BHSD) was reduced (P = 0.02) and both cytochrome P450 family 19 subfamily A member 1 (CYP19A1) tended (P = 0.06) to be reduced, while 3BHSD tended to be reduced in HP compared to HC gilts (P = 0.09). Thus, there were ovarian impacts of PFOA exposure in TP gilts with some additive impacts in heat-stressed pigs.