Apelin-13 is a 13-amino acid peptide sequence found in the central and peripheral nervous system that is an endogenous ligand for the G protein-coupled receptor angiotensin II protein J (APJ), with an EC50 value of 0.37 nM for APJ.Apelin-13 has vasodilatory and antihypertensive activity and can be used to study type 2 diabetic syndrome. Apelin-13 has vasodilatory and antihypertensive activities and can be used to study type 2 diabetes syndrome.

APJ:0.37 nM

In cultured PC12 cells, the same protective effects were also observed.?Silencing Nrf2 gene with its siRNA abolished the Apelin 13's prevention of I/R-induced PC12 cell injury, oxidative stress, and inflammation.?Inhibition of AMPK by its siRNA decreased the level of Apelin 13-induced Nrf2 expression and diminished the protective effects of Apelin 13.?The interplay relationship between GSK-3β and Nrf2 was also verified with relative overexpression.?Using selective inhibitors, we further identified the upstream of AMPK/GSK-3β/Nrf2 is AR/Gα/PLC/IP3/CaMKK.

Administered intraperitoneally at a daily dosage of 200 µg/kg for 4 weeks, Apelin-13 improves cardiac function, insulin resistance, and lipid metabolism. It significantly decreases serum levels of TNF-α and leptin, induces the expression of Apelin-12 in serum, and markedly elevates levels of GLUT4 and p-AMPKα2[2].
When delivered via intracerebroventricular injection at single dosages of 10 and 100 μM, Apelin-13 increases the spontaneous discharges in the majority of pallidal neurons[3].

For in vitro study, PC12 cells were used,proteases inhibitors or siRNA were used.?Protein levels were investigated by western blotting.

In vivo, the I/R model was induced and Apelin 13 was given intracerebroventricularly 15 min before reperfusion.?The neurobehavioral scores, infarction volumes, and some cytokines in the brain were measured.