RESUMO
OBJECTIVE: To study the mechanism of renal injury in Lepr db/ db mice with the leptin receptor homozygous deficiency. METHODS: Ten male of 28-week-old Lepr db/+ mice with leptin receptor heterozygous deficiency were selected as control group and ten male Lepr db/ db mice with leptin receptor homozygous deficiency were used in this study. After fasting for 8 hours, the body mass, fasting blood glucose (FBG) and glycosylated hemoglobulin (HbA1c) of the mice were measured. Blood of the mice was obtained from femoral artery before euthanasia. Serum creatinine (CRE), blood urea nitrogen (BUN), superoxide dismutase (SOD), glutathione (GSH) and malonaldehyde (MDA) were detected by corresponding kits, and serum interleukin-1ß (IL-1ß), monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) were measured using enzyme-linked immunosorbent assay (ELISA) method. The kidney was taken for pathological observation. The expression levels of nuclear factor E2-related factor 2 (Nrf2) and nuclear factor kappa B (NF-κB) in renal were analyzed by Western blot. The mitochondria of renal was isolated by the corresponding kit. Meanwhile, the expression level of lipoic acid synthase (LIAS) in renal mitochondria was measured by Western blot. RESULTS: The body mass, FPG, HbA1c, CRE and BUN levels of the Lepr db/ db mice were significantly increased in comparison with the Lepr db/+ mice ( P<0.05). Compared with the Lepr db/+ mice, the Lepr db/ db mice renal exhibited glomerular hypertrophy, thickened basement membrane and capillary wall, the mesangial matrix expansion and mesangial cell hyperplasia. Compared with the Lepr db/+ mice, the serum level of GSH in the Lepr db/ db mice was decreased significantly ( P<0.05). The levels of MDA and concentrations of MCP-1, IL-1ß and TNF-α in serum of the Lepr db/ db mice were higher than those of the Lepr db/+ mice ( P<0.05). Compared with the Lepr db/+ mice, the expression of LIAS and Nrf2 protein in the Lepr db/ db mice renal were decreased ( P<0.05), while the expression of NF-κB protein was increased ( P<0.05). CONCLUSION: LIAS, Nrf2 and NF-κB might play significant roles through regulation of oxidative stress and inflammation in the renal injury of Lepr db/ db mice.