Expression and localization of apelin and apelin receptor (APJ) in buffalo ovarian follicles and corpus luteum and the in-vitro effect of apelin on steroidogenesis and survival of granulosa cells

Apelin is an adipose tissue-derived hormone with many physiological functions, including the regulation of female reproduction. It acts through an orphan G protein-coupled receptor APJ/APLNR. The present study aimed to investigate the expression of apelin and its receptor APJ in the ovarian follicles and corpus luteum (CL) and the role of apelin on steroidogenesis and cell survival. Ovarian follicles were classified into four groups based on size and estradiol (E