Apelin in Reproductive Physiology and Pathology of Different Species: A Critical Review.

Apelin has been isolated from the bovine stomach extracts as an endogenous ligand of the previously orphan receptor APJ. Expression of the apelinergic system (apelin and APJ) was described in many organs where pleiotropic effects like regulation of food intake, body weight, or cardiovascular and immune function were described. Recent studies have shown that apelin also plays an important role in the regulation of female and male reproduction.

Apelin and apelin receptor at different stages of corpus luteum development and effect of apelin on progesterone secretion and 3β-hydroxysteroid dehydrogenase (3β-HSD) in pigs.

Recent studies have suggested that apelin has a role in controlling female reproduction. The aims of the present study were, firstly, to investigate the gene expression (mRNA and protein) and immunolocalization of apelin and its receptor APJ in corpora lutea (CL) of pigs collected during the early (CL1), middle (CL2) and late (CL3) luteal phase. Using real time PCR and immunoblotting techniques, it was observed that apelin gene expression was similar in CL1 and CL2, and less in CL3, while relative abundance APJ mRNA and abundance of the protein were similar in CL1 and CL3 and greater in CL2.