Hypoglycemic and anti apoptotic effect of garlic in streptozotocin induced diabetic rats

Abstract

Diabetes mellitus is caused by many factor include oxidative stress that leads to apoptosis of beta cells of the pancreas and so the antioxidant therapy strongly correlated with decrease risk of diabetes mellitus. The aim of the present study was to investigate the efficacy of an aqueous extract of raw garlic in controlling serum glucose, plasma c peptide of insulin, level of reduced glutathione and catalase activity in pancreatic tissue, also to estimate caspase 3 activity expression in pancreatic tissue in streptozotocin induced diabetic rats treated daily with garlic extract intraperitoneally (IP) for 6 weeks. This study was carried on 30 rats: grouped into 3 group. Group 1, the control normal group, was injected IP daily with 0.5 ml saline and group 2; diabetic group was injected with streptozotocin, 60 mg/Kg body weight (BWt) IP in 0.5 ml saline once and group 3; garlictreated group, was injected IP daily with 500 mg/kg of the garlic extract 2 weeks before streptozotocin and 4 week after streptozotocin injection. There was a significant increase in blood glucose in streptozotocin group II (p = 0.001) as compared with control groups (331.3 ± 16.15 vs 101.8 ±4.02 mg/dl) respectively and significantly decreased after treatment with garlic extract (161.5 ± 5.28 mg/dl). C peptide was significantly decreased in streptozotocin group II (p = 0.001) as compared with control groups (0.034 ± 0.003 vs 0.053±0.001 ng/ml) respectively and significantly increased after treatment with garlic extract (0.046 ± 0.003). Catalase activity of pancreatic tissue was significantly decreased in streptozotocin group (p = 0.001) as compared with control groups (11.10 ± 0.73 vs 25.7 ± 0.55 U/gm tissue) respectively and significantly increased after treatment with garlic extract (20.3 ± 0.66). Reduced glutathione content of pancreatic tissue was significantly decreased in streptozotocin group (p = 0.001) as compared with control groups (0.67 ± 0.055 vs 1.23 ± 0.076 mg/g tissue) respectively and significantly increased after treatment with garlic extract (0.89 ± 0.080 mg/g tissue). Also it was observed that the expression of caspase 3 protein in the pancreatic tissue was decreased after garlic treatment using western blot technique. These results revealed that aqueous extract of raw garlic may have antioxidant and antiapoptotic activity that could be used in treatment of diabetes mellitus.

Key word: Diabetes mellitus, STZ, antioxidant, Caspase, garlic