QiShenYiQi ameliorates salt-induced hypertensive nephropathy by balancing ADRA1D and SIK1 expression in Dahl salt-sensitive rats

Hypertension is a leading risk factor for developing kidney disease. Current single-target antihypertensive drugs are not effective for hypertensive nephropathy, in part due to its less understood mechanism of pathogenesis. We recently showed that QiShenYiQi (QSYQ), a component-based cardiovascular Chinese medicine, is also effective for ischemic stroke. Given the important role of the brain-heart-kidney axis in blood pressure control, we hypothesized that QSYQ may contribute to blood pressure regulation and kidney protection in Dahl salt-sensitive hypertensive rats.The therapeutic effects of QSYQ on blood pressure and kidney injury in Dahl salt-sensitive rats fed with high salt for 9 weeks were evaluated by tail-cuff blood pressure monitoring, renal histopathological examination and biochemical indicators in urine and serum. RNA-seq was conducted to identify QSYQ regulated genes in hypertensive kidney, and RT-qPCR, immunohistochemistry, and Western blotting analysis were performed to verify the transcriptomics results and validate the purposed mechanisms.QSYQ treatment significantly decreased blood pressure in Dahl salt-sensitive hypertensive rats, alleviated renal tissue damage, reduced renal interstitial fibrosis and collagen deposition, and improved renal physiological function. RNA-seq and subsequent bioinformatic analysis showed that the expression of ADRA1D and SIK1 genes were among the most prominently altered by QSYQ in salt-sensitive hypertensive rat kidney. RT-qPCR, immunohistochemistry and Western blotting results confirmed that the mRNA and protein expression levels of alpha-1D adrenergic receptor (ADRA1D) in the kidney tissue of the QSYQ-treated rats were markedly down-regulated, while the mRNA and protein levels of salt inducible kinase 1 (SIK1) were significantly increased.QSYQ not only lowered blood pressure, but also alleviated renal damage via reducing the expression of ADRA1D and increasing the expression of SIK1 in the kidney of Dahl salt-sensitive hypertensive rats.