Diosmetin Attenuates Akt Signaling Pathway by Modulating Nuclear Factor Kappa-Light-Chain-Enhancer of Activated B Cells (NF-κB)/Inducible Nitric Oxide Synthase (iNOS) in Streptozotocin (STZ)-Induced Diabetic Nephropathy Mice

Abstract

BACKGROUND We evaluated the nephroprotective effect of diosmetin in streptozotocin (STZ)-induced diabetic nephropathy (DN) mice. MATERIAL AND METHODS Diabetes was induced by injecting STZ (50 mg/kg) i.p. for 5 days. Biochemical parameters, such as fasting blood glucose, creatinine, BUN in the serum, and albumin in the urine, were determined in STZ-induced DN mice after the 8th week of STZ administration. The level of inflammatory mediators in the serum and oxidative stress parameters in the tissue homogenate was estimated in STZ-induced DN mice. Expressions of Akt, NF-κB, and iNOS in the tissue homogenate were assessed by Western blot analysis. RESULTS Our data reveal that treatment with diosmetin significantly reduces the fasting blood glucose (FBG), serum creatinine, and blood urea nitrogen (BUN) in the serum and albumin in urine compared to the negative control group. Treatment with diosmetin attenuated the altered level of oxidative stress parameters and inflammatory cytokines in the STZ-induced DN mice. Expression of Akt and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) was significantly reduced and inducible nitric oxide synthase (iNOS) was enhanced in the tissue homogenate of diosmetin-treated mice compared to the negative control group. Data from immunohistochemical analysis suggest that the expressions of NF-κB was significantly reduced in tissues of the diosmetin-treated group compared to the negative control group. CONCLUSIONS Our study shows that diosmetin protects against renal injury in STZ-induced diabetic nephropathy mice by modulating the Akt/NF-κB/iNOS signaling pathway.

Figure 1

Effect of diosmetin on the serum concentration of fasting blood glucose and kidney/body weight in STZ-induced DN mice. Mean ±SEM (n=10), ^## p<0.01 compared to control group; * p<0.05, ** p<0.01 compared to negative control group.

Figure 2

Effect of diosmetin on the biochemical parameters in serum and urine of STZ-induced DN mice. Mean ±SEM (n=10), ^## p<0.01 compared to control group; * p<0.05, ** p<0.01 compared to negative control group.

Figure 3

Effect of diosmetin on the concentration of inflammatory mediators in the serum of STZ-induced DN mice. Mean ±SEM (n=10), ^## p<0.01 compared to control group; * p<0.05, ** p<0.01 compared to negative control group.

Figure 4

Effect of diosmetin on the oxidative stress parameters in the kidney tissue homogenate of STZ-induced DN mice. Mean ±SEM (n=10), ^## p<0.01 compared to control group; * p<0.05, ** p<0.01 compared to negative control group.

Figure 5

Effect of diosmetin on the expressions of p-Akt, NF-κB, and iNOS in the kidney tissue homogenate of STZ-induced DN mice. Mean ±SEM (n=10), ^## p<0.01 compared to control group; * p<0.05, ** p<0.01 compared to negative control group.

Figure 6

Effect of diosmetin on the immunohistochemical analysis of NF-κB in the tissue homogenate of kidney of STZ-induced DN mice (×400). (A) Control; (B) Negative control; (C) Diosmetin 25 mg/kg; (D) Diosmetin 50 mg/kg; (E) Diosmetin 100 mg/kg.