Shen-Kang protects 5/6 nephrectomized rats against renal injury by reducing oxidative stress through the MAPK signaling pathways

Chronic kidney disease (CKD) is a worldwide public health concern with limited treatment options. The incidence of CDK is increasing and the disease is associated with a poor quality of life and a high financial cost of treatment. Shen-Kang (SK), a traditional Chinese herbal medicine, has been used clinically in the treatment of renal diseases for decades. This study was carried out to validate the therapeutic effects of SK on renal injury induced by 5/6 nephrectomy, as well as its effects on the apoptosis of proximal tubule epithelial cells (HK-2 cells), in an aim to elucidate its mechanisms of action. For this purpose, an animal model of renal injury was created by subjecting rats to a 5/6 nephrectomy. The rats in the sham-operated and model groups received distilled water, while the rats in the SK and enalapril (EN) groups were treated with SK or EN. The levels of blood urea nitrogen (BUN) and serum creatinine (SCr) were measured. Kidney tissues obtained from the rats were stained with hematoxylin and eosin. HK-2 cells were employed to investigate the effects of SK on the apoptosis of renal proximal tubule epithelial cells induced by treatment with hydrogen peroxide (H(2)O(2)). In addition, cell viability was measured by MTT assay. Apoptotic events were monitored by western blot analysis, flow cytometric analysis and nuclear morphological anlaysis. The levels of intracellular reactive oxygen species (ROS) were measured by flow cytometric analysis with dihydroethidium staining. The results revealed that the administration of SK to 5/6 nephrectomized rats for 1 week significantly decreased the levels of SCr and BUN. The morphological observations of the kidneys also indicated the amelioration of damage to renal tissue. Treatment of the HK-2 cells with SK significantly protected the cells from H(2)O(2)-induced apoptosis, as indicated by an increase in cell viability, the decrease in the cleavage of poly(ADP-ribose) polymerase (PARP) and fewer condensed nuclei. H(2)O(2)-induced ROS production was also attenuated by treatment with SK. Of note, the increase in the levels of phosphorylated extracellular signal-regulated kinase (ERK) and phosphorylated p38 which occurred in response to exposure to H(2)O(2) was inhibited by treatment with SK. No changes were observed in the levels of phosphorylated JNK under the same treatment conditions. Thus, the mitogen-activated protein kinase (MAPK) signaling pathways play an essential role in the development of CKD. SK alleviated renal injury in rats induced by 5/6 nephrectomy and prevented the H(2)O(2)-induced apoptosis of HK-2 cells through the MAPK signaling pathways.