Reproduction Abstracts

Introduction: In our previously published study we focused on actions of ghrelin on ovarian steroidogenesis in prepubertal period and indicated that as adipokines produced by adipose tissue (such as leptin or resistin), ghrelin acts on accelerate puberty. This data had been performing to determine whether also in cycling animals ghrelin acts on ovarian steroidogenesis similarly to leptin and resistin.

Material and methods: Small (SFs), medium (MFs), and large (LFs) ovarian follicles were collected on days 4–6, 10–12, and 16–18 of the estrous cycle from cycling pigs and exposed to 20, 100, and 500 pg/ml ghrelin for 24 h. In additional experiments, MFs were exposed to ghrelin plus 100 ng/ml FSH or LH. Levels of progesterone (P4), testosterone, and E₂ in culture medium were determined by ELISA, and the expression of the steroid pathway enzymes 3β-HSD, 17β-HSD, and CYP19 was evaluated by western blotting.

Results: Ghrelin at dose of 20 pg/ml had no effect on steroid secretion, whereas in dose of 100 pg/ml and 500 pg/ml ghrelin significantly decreased P4, testosterone, and E₂ secretion. Moreover, all concentrations of ghrelin decreased steroid secretion in FSH- and LH-stimulated follicles. Western blot analysis showed that ghrelin inhibited expression of 3β-HSD, 17β-HSD, and CYP19 proteins.

Conclusion: The presented study indicate very clearly that, as adipokines produced by adipose tissue, ghrelin acts on accelerate puberty, while in contrast to the adipokines, during sexual maturity prevents from excessive secretion of steroids by ovarian follicles.

Supported by K/ZDS/004194 Jagiellonian University in Krakow, Poland.