Novel Mechanism of Lowering Blood Pressure by Electroacupuncture:MicroRNA9/P2RX7  

Backgroud Our previous studies have reported electroacupuncture(EA) can regulate the relevant indicators of essential hypertension(EH) such as angiotensinII(ANGII),ANG(1-7) and inflammatory cytokines.But the mechanism of EA remains unclear. The goal of this study was to verify P2RX7 as one direct target of miRNA-9,which triggers the release of ANGII and PICs(TNF-α, IL-6)in the PVN.The system of miRNA-9/P2RX7 might be a novel mechanism of lowering blood pressure. Method: Spontaneously Hypertensive Rats(SHRs) were selected as an animal model of hypertension while WKY rats were considered as a blank group.Bipolar cannula implantation were used to inject inhibitors in the paraventricular nucleus(PVN).We measured the systolic blood pressure(SBP) of animals on different days of acupuncture therapy(0,3,7,10,14).We examined the level of microRNA-9 by RealTime-PCR.RT-PCR and western blot was utilized to detect the mRNA and protein levels of P2RX7 in each group.The activation of microglias was detected by immunohistochemistry staining with antibody Iba1.ANGII,IL-6 and TNF-α were detected by ELISA in the PVN and plasma. Results: Our results showed that EA reduces systolic blood pressure of SHRs.EA increased the level of miR-9 notably comparing to sham groups.In addition,SHRs in the EA group had significantly lower P2RX7 protein and mRNA levels than those in the sham group,while miR9-inhibitor downregulated the expression of P2RX7 in the PVN comparing to EA groups. Immunohistochemistry staining showed that EA treatment and P2RX7 inhibitor significantly inhibited the activation of microglia.We also found that the combination of P2RX7-inhibitor and EA had a better anti-inflammatory effect and better inhibition of ANGII,while using miR9-inhibitor prevented the effect. Conclusion: Taken together, our data demonstrates that P2RX7 is a direct downstream receptor of miRNA-9.Regulating system, miRNA-9/P2XR7, decreases the release of ANGII and alleviates inflammation in the PVN and plasma of SHRs,which indicates a novel microRNA-mediated mechanism of EA.Furthermore, the present investigation provides the combination treatment of P2RX7-inhibitor and EA as a better intervention in the area of anti-inflammatory.