Kisspeptin-10 Promotes Hormone Secretion, Ovarian Follicles Development and Fecundity via PI3K/AKT/ERK Signal Pathway...

The present study aimed to comprehensively elucidate how KP-10 modulates hormone secretion, the proliferation and autophagy of ovarian follicles by regulating in-vivo and in-vitro levels of associated genes and proteins.

Follicular granulosa cells (FGCs) were cultured in EMDM/F12 medium. The proliferation viability, apoptosis, and autophagy rates of FGCs were determined, respectively. For in-vivo tests, 0, 5, 10, 20, 40 μg/g of KP-10 were injected into 75 mice allocated into control group (CG) and four KP-10 treated groups (including KP-1, KP-2, KP-3, and KP-4 groups). Maximum transverse diameter (MTD), maximum longitudinal diameter (MLD) and follicle-wall thickness (FWT) of secondary follicles were measured in days 0, 5, 10, 15, and 25. RT-qPCR and Western blot were employed to determine the contents of genes and proteins.

The KP-10-treated groups exhibited increased FGCs proliferation, accompanied by decreased apoptosis and autophagy rates as compared with the control group (CG). The expression levels of KISS1R, Bcl-2, LC3-II, mTOR, p62/Sqstm1, PI3K, AKT, and ERK genes and proteins in FGCs were significantly enhanced (p < 0.05). Additionally, the number of secondary follicles, MTD, MLD, FWT, and the serum concentrations of progesterone and estradiol were notably elevated (p < 0.05). Moreover, the in-vivo levels of PI3K, AKT, ERK mRNAs, as well as StAR and CYP11A1 genes and proteins, were significantly higher than those in CG. FGCs proliferation in KP-10-treated groups was increased with reduction of apoptosis and autophagy rates. Levels of KISS1R, Bcl-2, LC3-Ⅱ, mTOR, p62/Sqstm1, PI3K, AKT and ERK genes and proteins in FGCs were enhanced (p < 0.05). Numbers of the secondary follicles, MTD, MLD, FWT and serum concentrations of progesterone and estradiol were significantly promoted (p < 0.05). In-vivo levels of PI3K, AKT, ERK mRNAs, StAR and CYP11A1 genes and proteins were accelerated as compared to CG.

KP-10 accelerated the proliferation and suppressed the apoptosis and autophagy of FGCs, facilitated the development of the secondary follicles, and nd enhanced the synthesis and secretion of P4 and E2. Ten microgram per gram KP-10 had the best efficacy. Our study first time explored comprehensively the effects and mechanisms KP-10 in-vitro and in-vivo regulating reproductive hormone secretion, ovarian follicles development and fecundity in mice. These effects of KP-10 were achieved probably by activation of PI3K/AKT/ERK signal pathway. The findings held great promise for improving the reproductive function and fecundity of both animals and humans.