Role of apelin/APJ system in hypothalamic-pituitary axis

Apelin and its G protein-coupled receptor APJ are specifically expressed in endocrine organs. As well known, the hypothalamus is the regulatory center of endocrine activity, which combined with the pituitary and other gonads form regulatory axes involved in endocrine function. Evidence to date has shown that the apelin/APJ system plays an important role in mediating these axes, such as food intake, acute stress, steroid release, as well as, an anti-depressant-like activity. Here we review the effect of the apelin/APJ system on hypothalamic-pituitary-thyroid, hypothalamic-pituitary-adrenal and hypothalamic-pituitary-gonadal axes. Although the apelinergic system exerts a positive effect on these axes, there are contradictory reports on the role of apelin in endocrine disease caused by hypothalamic-pituitary disorders. Thus, as research continues to evolve we expect that apelin-related drugs can be used as a treatment for clinical diseases resulting from hypothalamic-pituitary dysfunction.