| Abstract: | Epidemiological data indicate that diabetes is one of the major contributing factors to the high incidence and prevalence rates of dialysis in Taiwan. Approximately fifty percent of dialysis patients were originated from diabetes. Guava is one of the popular and widely processed fruits in Taiwan. In folk medicine, the roots, bark, leaves, and fruits of Guava are used to treat diarrhea, hyperglycemia, and a number of other conditions. This study thus was designed to explore the potential protective effects of fresh guava juice on oxidation, inflammation, and kidney injury in STZ-induced diabetic rats.
Male Sprague-Dawley rats, based on their initial body weights, were randomly divided into four groups: control, streptozotocin (STZ), STZ plus low concentration guava juice (STZGL), and STZ plus high concentration guava juice (STZGH). Diabetic state was induced by intraperitoneal injection of 45 mg/kg body weight STZ. After induction of diabetes, the animals were treated with or without fresh guava juice for 12 weeks.
Analytical results showed that fresh guava juice displayed good antioxidant properties. It could not reduce the body weights and blood sugar levels of diabetic rats. However, the kidney malondialdehyde, urine creatinine and protein levels, and erythrocyte aldose reductase activity were significantly lower (p<0.05) in the STZGH group as compared to the STZ group. The activities of kidney superoxide dismutase and catalase and the level of erythrocyte glutathione were significantly higher (p<0.05) in the STZGH group than in the STZ group. Moreover, when compared with the STZ group, serum triglycerol, nitric oxide, interleukin-6 levels of the STZGH group decreased 27.7%, 36.0%, and 12.8%, respectively, while serum interleukin-10 level and renal glutathione peroxidase activity raised 22.5% and 28.5%, respectively. The Western blot results revealed that fresh guava juice significantly suppressed (p<0.05) transforming growth factor-β1 protein expression in the kidney, but it had no effect on the protein expression of protein kinase C-?. Histological examination showed that fresh guava juice obviously reduced renal injury, such as glomerular basement membrane thickening and mesangial matrix expansion.
The findings of present study implied that fresh guava juice could not improve hyperglycemia in STZ-induced diabetic rats, but its potential antioxidantive and anti-inflammatory capacities could ameliorate kidney injury. |
