Role and Mechanism of MicroRNA-7a-5p in Paraventricular Nucleus on Sympathetic Overactivity in the Spontaneously Hypertensive Rats

Background To investigate the role and mechanism of microRNA-7a-5p (miR-7a-5p) in paraventricular nucleus on sympathetic overactivity in the spontaneously hypertensive rats (SHR). Methods Wistar-Kyoto (WKY) rats and SHR aged 12 weeks were randomly divided into recombinant adeno-associated virus (rAAV) overexpressing miR-7a-5p mimic, miR-7a-5p negative control (NC), antimiR-7a-5p, or NC of antimir-7a-5p treatment groups (n = 6 per group). In addition, WKY rats and SHR aged 12 weeks were randomly divided into rAAV overexpressing GABRA1, GABRA1 NC, GABRA1 shRNA, or NC of GABRA1 shRNA treatment groups (n = 6 per group). Four weeks later, hemodynamic parameters, renal sympathetic nerve activity (RSNA), and plasma norepinephrine levels were observed. Results Four weeks after injection of rAAV into the paraventricular nucleus, overexpression of miR-7a-5p mimic increased RSNA and mean arterial pressure (MAP) in WKY and SHR (all P < 0.05). The number of FosB positive neurons in paraventricular nucleus was significantly upregulated (all P < 0.01) while the number of GABRA1 positive neurons in paraventricular nucleus was significantly downregulated (all P < 0.01). Overexpression of GABRA1 in hypothalamic paraventricular nucleus decreased RSNA and MAP in WKY and SHR (all P < 0.05). Compared with WKY, the overexpression or knockdown of miR-7a-5p/GABRA1 had more significant effect on RSNA and MAP in SHR (all P < 0.05). The expression of miR-7a-5p in hypothalamic paraventricular nucleus in SHR was significantly upregulated (P < 0.01) while GABRA1 protein levels were significantly downregulated (P < 0.01). miR-7a-5p mimic transfection in primary brain neurons or NG108 cells resulted in significant downregulation of GABRA1 protein expression. TargetScan prediction showed that there was sequence binding at the 3′UTR end of GABRA1 mRNA by miR-7a-5p. Dual luciferase reporter assay confirmed that miR-7a-5p can target GABRA1 gene. Conclusions miR-7a-5p in hypothalamic paraventricular nucleus increases RSNA by inhibiting GABRA1 expression, and may contribute to the development of hypertension.