Kisspeptin regulates the development of caprine primordial follicles in vitro

Kisspeptin, a neuropeptide and the master controller of reproductive axis upstream to GnRH neurons, and its receptor are also expressed in extrahypothalamic tissues, such as ovaries. As systemic kisspeptin has been shown to modulate follicular dynamics in cattle, we hypothesized that kisspeptin has direct actions on the ovarian follicular development. We also hypothesized that kisspeptin regulation of primordial follicle development is via modulation of VEGF expression. In order to test these hypotheses, we cultured caprine ovarian cortical strips in vitro for 7 days with supplementation of kisspeptin at 1, 10 and 100 μM concentration and observed the development of primordial follicles into intermediate, primary and secondary follicles. We also studied the alteration in the expression profile of VEGF and VEGF transcript variant 2 mRNA during follicular development in the presence of kisspeptin. We confirmed the presence of GPR54 in goat ovaries in our preliminary studies. Supplementation of kisspeptin at 1 and 10 μM concentration facilitated the development of primordial follicles into intermediate, primary and secondary follicles with less number of degenerated follicles while the same at 100 μM resulted in degeneration of follicles. We observed a drastic increase in the expression profile of VEGF and VEGF transcript variant 2 mRNA upon culture which was independent of kisspeptin treatment. In conclusion, our studies show that kisspeptin facilitates ovarian primordial development in vitro.