Effects of Short-Term Streptozotocin-Induced Diabetes and Vitamin C on Platelet Non-Enzymatic Glycation

Diabetes mellitus is one of the most prevalent metabolic syndromes worldwide. Glycation, a chemical modification of proteins with reducing sugars, indicates a possible explanation for the association between hyperglycemia and the wide variety of tissue pathologies. Non-enzymatic glycation (NEG) of platelet proteins is one of the key mechanisms in the pathogenesis of diabetic complications and may be significant in diabetic atherothrombosis. The aim of this study was to investigate the effects of streptozotocin (STZ)-induced short-term experimental diabetes on the glycation of platelets and to find out if vitamin C affected this glycation. A total of 40 male Wistar albino rats, 200-250 g, were randomly divided into 4 groups (2 diabetic and 2 control groups). The diabetic groups were made diabetic by intraperitoneal injection of STZ (65 mg/kg, citrate buffer pH 4.5). By daily intraperitoneal injection, 80 mg/kg vitamin C (Roche, Turkey) was administered until the end of the experiment. Blood glucose levels of the diabetic groups were significantly higher than those at day 0 and also higher than those of the non-diabetic control groups. The changes in total protein, NEG and vitamin C levels were not statistically significant. Although the differences among the groups were not statistically significant, vitamin C administration increased NEG levels in the diabetic group. The results of this study demonstrate that 8 days of STZ-induced short-term diabetes did not cause a significant increase in NEG of platelets. However, the effect of vitamin C on platelet NEG needs to be further investigated. Copyright (C) 2011 S. Karger AG, Base

The effects of Corylus Avellana on serum lipid profile and oxidative stress in hyperlipidemic-diabetic rats

Background and Aim: There is limited evidence suggesting that nuts improve plasma antioxidant potential. The aim of this study is to investigate the effects of hazelnut consumption on serum lipids, atherogenic indexes and oxidant-antioxidant status in hyperlipidemic-diabetic rats. Methods: Wistar-albino rats of both sexes, weighing 200-250 g were used in this study. The group of animals used in this study, which consisted of 32 rats, were divided into 4 groups: control, control + hazelnut, hyperlipidemic-diabetic, hyperlipidemic-diabetic + hazelnut. Each group was fed with control or hyperlipidemic diets with the same amount of hazelnut (0.63%) added for 12 weeks. Diabetes has been induced by streptozotocin (STZ) injection in diabetic groups. Blood glucose, serum lipids, glutathione (GSH), lipid peroxidation (LPO) and atherogenic indexes (AI and AIP) have been evaluated after the experiment was over. Results: In hyperlipidemic-diabetic group atherogenic indexes, LPO and serum lipid levels were found to have increased significantly, whereas HDL-cholesterol (HDL-C) and GSH levels were found to have decreased significantly in comparison with the control group (p < 0.01). Hyperglycemia was also seen to have increased in this group. Impaired antioxidant-oxidant balance was noted to have improved, GSH increased while triglyceride (TG) decreased significantly (p < 0.01). Hazelnut consumption also increased blood GSH levels and atherogenic index levels in the control group. Conclusions: Consumption of hazelnut at this dose (0.63%) may improve oxidant-antioxidant balance in healthy and hyperlipidemic-diabetic status without increasing blood lipids. Keywords: Hazelnut, hyperlipidemia, diabetes, lipids, glutathione, lipid peroxidation