Effect of metformin on advanced glycation endproduct formation and peripheral nerve function in streptozotocin-induced diabetic rats

Increased accumulation of skin advanced glycation end-products precedes and correlates with clinical manifestation of diabetic neuropathy

“…The peripheral nervous system and, to a lesser extent, the central nervous system have been shown to be vulnerable to AGE accumulation in diabetes [16,33]. Both intensive metabolic control of diabetic patients [13] and treatment with aminoguanidine (AGE inhibitor) in diabetic rats decrease the accumulation of AGE and the progression of diabetic neuropathy; they also reduce abnormal nerve conduction [16,34]. Interestingly, we found increased skin autofluorescence in parallel with reduced nerve conduction velocity and amplitude in diabetic patients without clinical manifestations of diabetic neuropathy (Fig.…”

Cholesterol oxides as biomarkers of oxidative stress in type 1 and type 2 diabetes mellitus

“…In fact, metformin has several effects that might contribute to minimize the oxidative stress. In particular, it can reduce the rate of AGE formation [21], platelet superoxide anion production [22] and lipid peroxidation [23], as well as increase the levels of intracellular glutathione [19] and the activity of the antioxidant enzymes superoxide dismutase (Cu-Zn-SOD) and catalase [24]. In this context, ACEi can decrease the levels of angiotensin II and the production of superoxide anion by vascular endothelial cells, besides increasing the levels of other substances with important roles in vascular oxidative stress [25].…”

Ethanol extract of mango (Mangifera indica L.) peel inhibits α-amylase and α-glucosidase activities, and ameliorates diabetes related biochemical parameters in streptozotocin (STZ)-induced diabetic rats

“…Upon treatment of diabetic rats with metformin, gallic acid and different doses of mango peel extracts, significant increase (p<0.001) in the CAT, SOD, GPx and GST 0.23±0.09 0.71±0.09a*** 0.51±0.08b* 0.45±0.07b** 0.38±0.09b*** 0.36±0.08b*** 0.54±0.09b* Glycated Heamoglobin (%) 2.3±0.48 10.9±1.05a*** 8.7±0.94b** 7.2±0.89b*** 6.5±0.68b*** 5.5±0.91b*** 9.70±0.85b** Fasting plasma Insulin (μU/mL) 15.3±1.50 5.4±0.87a*** 8.0±0.89b*** 11.9±1.90b*** 12.4±1.93b*** 12.0±1.81 b*** 8.1±1.09b*** All values represent mean±SD *P<0.05; **P<0.01; ***P<0.001; ANOVA, by Turkey's multiple comparison test a Compared to normal control b Compared to diabetic control The results suggest that metformin, gallic acid and all the doses of mango peel extracts increased the enzyme activities of CAT, SOD, GPx and GST, but mango peel extract at a dosage of 200 mg/kg was more effective in increasing the antioxidant enzyme activities in diabetic rats, compared with other doses of mango peel extract. It has been reported that metformin exert its in vivo antioxidant activity by different pathways such as increasing the antioxidant enzyme activities, and decreasing the markers of lipid peroxidation (Tessier et al 1999;Pavlovic et al 2000;Tanaka et al 1999). Earlier reports also indicate that metformin reduces the oxidative stress in STZ-induced diabetic animal models (Alhaider et al 2011).…”