Impact of adrenocorticotropin hormone administration on the endocrinology, estrus onset, and ovarian function of weaned sows.

Chronic stress affects the reproductive health of mammals; however, the impact of adrenocorticotropin hormone (ACTH) level elevation during chronic stress on the reproduction of weaned sows remains unclear. In this study, nine weaned sows with the same parturition date were randomly divided into control group (n = 4) and ACTH group (n = 5). Each group received intravenous administration of ACTH three times daily for 7 days. Blood samples were collected every 3 h after injection. A radioimmunoassay was used to measure the concentrations of cortisol, luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P4) and estradiol-17β (E2) in the blood. Estrus was determined according to changes in the vulva and the boar contact test. The mRNA expressions of glucocorticoid receptor, FSH receptor, LH receptor (LHR) in the corpus luteum (CL) were detected by qRT-PCR. The results showed that ACTH administration substantially delayed the initiation of estrus and the pre-ovulatory LH peak. The sows of control group ovulated within 10 days and the ovulation rate was 100%, while it was 60% in the ACTH group. Two sows of ACTH group showed pseudo-estrus. The E2 concentrations significantly decreased in the ACTH group at 36 h, 42 h and 66 h of the experimental period. The P4 concentrations in the ACTH group significantly decreased at 132, 138, and 147 h of the experimental period. ACTH significantly reduced the LHR mRNA expression in CLs. In conclusion, long-term repeated ACTH administration affects the endocrinology, estrus onset, and ovarian function of weaned sows.