Endocrine Abstracts

Visfatin is one of adipokines that particularly regulates metabolic homeostasis. Literature data of the last decade indicate also that visfatin participates in the regulation of ovarian follicles’ steroid synthesis and oocyte maturation in women, mice, hens, and cows. However, there is still a gap in knowledge about the effect of this adipokine on the corpus luteum (CL) functions. Our previous study documented visfatin mRNA and protein expression in the porcine CL. Therefore, the aim of the present study was to determine the impact of visfatin on endocrine functions of the porcine CL during the estrous cycle. Corpora lutea were collected from gilts on days 2–3, 10–12, 14–16 of the estrous cycle and luteal cells were treated with visfatin (1, 10, 100 ng/ml) alone or together with visfatin blocker FK866 (10 µM). Then, we analyzed the secretion of progesterone (P₄), prostaglandin E₂ (PGE₂) and F_2α (PGF_2α) as well as protein expression of steroidogenic enzymes (StAR, CYP11A1, 3βHSD) and prostaglandins’ receptors (PTGER1, PTGFR). Moreover, we investigated the impact of visfatin (10 ng/ml) on activation of MAPK, AMPK, and AKT kinases as well as the involvement of these kinases and insulin receptor (INSR) in visfatin action. Statistical analysis was performed using one-way ANOVA and Tukey’s post-hoc test. The results of the study demonstrated that visfatin decreased P₄secretion by luteal cells from days 2-3 and 14-16, while increased on days 10-12 of the cycle. These results were confirmed by visfatin stimulatory effect on protein levels of StAR, CYP11A1 and 3βHSD on days 10-12. We noted that visfatin enhanced PGE₂ secretion by the cells from days 2-3 and 10-12, while decreased PGF_2a release on days 14-16 of the cycle. These changes were also accompanied by increased luteal PTGER1 protein expression on days 10-12 and decreased PTGFR on days 14-16 of the cycle. Treatment with the visfatin blocker, FK866, suppressed the observed visfatin effect on steroids’ and prostaglandins’ secretion. Interestingly, visfatin in time-dependent manner stimulated MAPK, AKT and AMPK pathways. Moreover, MAPK, AKT, AMPK and INSR were involved in visfatin effect on P₄, while MAPK and INSR on prostaglandins’ secretion. The obtained results indicate that visfatin affects luteal endocrine functions, depending on the phase of the estrous cycle, and could be the new regulator of the porcine ovary. Supported by National Science Center, Poland (OPUS project no.: 2018/31/B/NZ9/00781) and Jagiellonian University programs: Excellence Initiative – Jagiellonian University and Research Module (U1U/W18/NO/28.20).