Abstract: Epigallocatechin gallate (EGCG) is an antioxidant and anti-inflammatory natural active ingredient, and fewer studies have been conducted on the antioxidant and anti-inflammatory effects of EGCG in DKD and the regulatory mechanisms. This study investigated the effect and mechanism of EGCG on diabetic kidney damage in non-obese GK rats with idiopathic T2DM. Two different doses of EGCG (10 mg·kg^-1 and 120 mg·kg^-1) were administered to GK rats for 4 weeks. The body weight and daily food intake of rats were monitored during the experiment. At the end of the experiment, the serum and kidney tissues were collected to detect some kidney biochemical and pathological indicators and Nrf2-Keap1/MAPK signaling pathway related gene expression levels. The results show that EGCG could improve the kidney morphology and significantly increase the activities of antioxidant enzymes (such as SOD, CAT and GSH-Px), and inhibit the release of proinflammatory cytokines (MCP-1, IL-1β). In addition, EGCG could restrain oxidant stress by up-regulate the expression level of Nrf2 and inhibit inflammation by down-regulating the expression levels of JNK, NF-κB and P38 genes in kidney. The improvement effect of high dose was better than that of low dose in the experimental range. In conclusion, these results indicate that EGCG could ameliorate kidney injury caused by diabetes, and its mechanism might be related to anti-oxidative stress mediated by Nrf2-Keap1/MAPK signaling pathways.

Key words: EGCG, diabetic kidney damage, oxidant stress, inflammation, diabetes, GK rats