Dietary zinc reduces endoplasmic reticulum stress and autophagy to protect against diabetic renal damage in streptozotocin-induced diabetic rats

Most of the patients with type 2 diabetes mellitus suffer from renal injury. The current study explored the protective effects of dietary zinc against diabetic renal injury and the underlying molecular mechanisms. In experiments, ZnSO₄ at 15 mg/kg was intragastrically administrated into type 2 diabetes mellitus-like Wistar rat models daily for continuously 53 days. Biochemical assay was performed to detect serum fasting blood glucose, blood urea nitrogen (BUN), creatinine, and insulin. The H&E staining, immunohistochemical assay, and Western blotting were performed to detect the changes in kidney tissues. In results, dietary zinc reduced the lipid peroxidation malondialdehyde levels and enhanced the total anti-oxidation capacity levels. The pathological changes in diabetic kidney were improved. The percentage of autophagy-associated LC3-II positive cells was lowered. Western blot levels of LC3-II proteins and endoplasmic reticulum (ER) stress-associated GRP78 proteins were lowered. In conclusion, dietary zinc can relieve ER stress and autophagy in diabetic kidney to improve kidney conditions of type 2 diabetes mellitus-like rat models. These findings may be useful to treat patients with diabetic renal injury.