Salvianolic acid A attenuates kidney injury and inflammation by inhibiting NF-κB and p38 MAPK signaling pathways in 5/6 nephrectomized rats

Salvianolic acid A (SAA) is a minor phenolic carboxylic acid extracted from Salviae miltiorrhizae Bunge (Danshen). SAA exhibits a variety of pharmacological activities, such as antioxidative, anti-thrombotic, neuroprotective, and anti-fibrotic effects, as well as protection from myocardial ischemia and prevention of diabetes and other diseases. Furthermore, SAA has shown renal-protective effects in doxorubicin-induced nephropathy. However, there has been limited research regarding the effects of SAA and underlying mechanisms in chronic kidney disease (CKD). Here, we examined the effects and molecular mechanisms of SAA in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The rats were injected with SAA (2.5, 5, and 10 mg/kg per day, intraperitoneally (ip)) for 28 days. SAA dose-dependently lowered the levels of urine protein, blood urea nitrogen, serum creatinine, plasma total cholesterol, and plasma triglycerides in 5/6Nx rats. Histological examination revealed that SAA dose-dependently attenuated renal pathological lesions, evidenced by reduced renal tubulointerstitial fibrosis by decreasing the expression levels of tumor growth factor-beta 1; and alpha-smooth muscle actin in 5/6Nx rats. Moreover, SAA dose-dependently inhibited the activation of nuclear factor-kappa B (NF-kappa B) and p38 mitogen-activated protein kinase (MAPK) signaling pathways, subsequently attenuating the secretion of tumor necrosis factor-alpha and interleukin-1 beta and inhibiting the expression of monocyte chemotactic protein-1, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 in kidneys of 5/6Nx rats. The above results were consistent with those obtained in lipopolysaccharide-induced HK-2 cells in vitro (a recognized in vitro inflammatory model). In conclusion, our results demonstrated that SAA effectively attenuates kidney injury in 5/6Nx rats. The therapeutic effects of SAA on kidney injury can be attributed to its anti-inflammatory activities through inhibition of the activation of the NF-kappa B and p38 MAPK signaling pathways.