Effect of crude oil contaminants on streptozotocin induced diabetes in wistar rats treated with aqueous extract of allium sativum

Abstract

Diabetes mellitus is rapidly increasing in prevalence and petroleum hydrocarbons exposure contributes to its pathogenesis, prevalence and distribution. This study investigated the effect of crude oil exposure on the management of diabetes mellitus in rats treated with metformin and Allium sativum extract. A total of 54 adult male albino rats were used for this study and grouped into 9 groups of 6 rats. Diabetes was induced by single intraperitoneal injection of 65mg/kg streptozotocin dissolved in citrate buffer using insulin syringe and confirmed after 48 h. Rats were exposed to crude oil and treated with extract plus metformin for a period of four weeks. Effects on fasting blood glucose, lipid profile, antioxidant enzymes, fasting plasma insulin, β-cell function, insulin resistance, inflammatory markers were evaluated and histological studies carried out. The result indicated decreased in body weight with significant (p<0.05) increase in fasting blood glucose, total cholesterol, triglyceride, and low density lipoprotein cholesterol in untreated diabetic rats, untreated diabetic rats exposed to crude oil with significant (p<0.05) decrease in fasting blood glucose, total cholesterol, triglyceride and low density lipoprotein in rats that received the Allium sativum extract plus metformin despite crude oil exposure. Also, there was significant (p<0.05) increase in superoxide dismutase (SOD) and reduced glutathione (GSH) in untreated diabetic rats and untreated diabetic rats exposed to crude oil as in control rats compared to rats that received the ASE plus metformin. The level of malondialdehyde was highest in untreated diabetic rats and untreated diabetic rats exposed to crude oil. β cell dysfunction and insulin resistance were significantly (p<0.05) low in rats treated with Allium sativum plus metformin. IL-6 and TNFα level were significantly (p<0.05) increased in untreated rats exposed to crude oil, and untreated diabetic rats plus standard (metformin) drug treated rats exposed to crude oil. Histological examination of pancreas revealed changes in the cyto-architecture of pancreas of all diabetic rats. Treatment with the extract of Allium sativum plus metformin had helped maintain/improved the structure of the pancreas. Exposure to crude oil therefore affects diabetes management with metformin by increasing hyperglycemia, oxidative stress indices, up-regulation of inflammation, and promote insulin resistance and β cell dysfunction. Therefore, treatment with Allium sativum extract plus metformin would help improve or maintain the quality of life of people living in areas of crude oil exposure.

Key words: Allium sativum, Antioxidants, β-cell function, Crude Oil, Diabetes Mellitus, Metformin, Pancreas, Oxidative stress.