Renin activates PI3K‐Akt‐eNOS signalling through the angiotensin AT1and Mas receptors to modulate central blood pressure control in the nucleus tractus solitarii

BACKGROUND AND PURPOSEThe renin‐angiotensin system (RAS) is critical for the control of blood pressure by the CNS. Recently, direct renin inhibitors were approved as antihypertensive agents. However, the signalling mechanism of renin, which regulates blood pressure in the nucleus tractus solitarii (NTS) remains unclear. Here we have investigated the signalling pathways involved in renin‐mediated blood pressure regulation, at the NTS.EXPERIMENTAL APPROACHDepressor responses to renin microinjected into the NTS of Wistar‐Kyoto rats were elicited in the absence and presence of the endothelial nitric oxide synthase (eNOS)‐specific inhibitor, N(5)‐(‐iminoethyl)‐L‐ornithine, Akt inhibitor IV and LY294002, a PI3K inhibitor and GP antagonist‐2A [Gqinhibitor]. Lisinopril (angiotensin converting enzyme inhibitor), losartan, valsartan (angiotensin AT1receptor antagonists), D‐Ala7‐Ang‐(1‐7) (angiotensin‐(1‐7) receptor antagonist) were used to study the involvement of RAS on renin‐induced depressor effects.KEY RESULTSMicroinjection of renin into the NTS produced a prominent depressor effect and increased NO production. Pretreatment with Gq‐PI3K‐Akt‐eNOS pathway‐specific inhibitors significantly attenuated the depressor response evoked by renin. Immunoblotting and immunohistochemical studies further showed that inhibition of PI3K significantly blocked renin‐induced eNOS‐Ser117and Akt‐Ser473phosphorylationin situ. In addition, pre‐treatment of the NTS with RAS inhibitors attenuated the vasodepressor effects evoked by renin. Microinjection of renin also increased Ras activation in the NTS.CONCLUSIONS AND IMPLICATIONSTaken together, these results suggest renin modulated blood pressure at the NTS by AT1and Mas receptor‐mediated activation of Gqand Ras to evoke PI3K‐Akt‐eNOS signalling.