G-protein-coupled receptors (GPCRs) are recognized as the largest protein receptor superfamily, which are widely distributed in various tissues and organs. In addition, GPCRs are involved in many physiological and pathological longitudinal responses. Studies have indicated that putative receptor protein related to AT1 (APJ receptor) is an orphan GPCRs until its endogenous ligand apelin is found. Recently, Elabela, a new APJ receptor endogenous ligand was also found. Some evidence showed that the APJ receptor is distributed in the central nervou...
