Immunohistochemical evaluation of the antidiabetic potentials of S-allyl-cysteine (Garlic) and mangiferin (Mango) in type 2 diabetic rat models

Abstract

Background: Diabetes mellitus is now one of the largest emerging pandemics of our time. Of the different types of diabetes mellitus, type 2 accounts for 90% of diabetic cases in humans worldwide. Insulin resistance followed by abnormal secretion of insulin from the pancreatic β-cells underlies the symptomatology of type 2 diabetes mellitus. Most investigations have assessed the hypoglycaemic potentials of s-allyl-cysteine and mangiferin by focusing on the biochemical and or pathophysiological changes. The histological and immunohistochemical changes have on the other hand received less attention. Aim: To evaluate the anti-diabetic potentials of s-allyl-cysteine (SAC), mangiferin (MAN) and a composite mixture of both (COM) in equal volume ratio (1:1) in type 2 diabetic Wistar rat models. Objective: This was achieved by evaluating the secretion of insulin in the pancreatic islets of diabetic and non-diabetic rats using immunohistochemistry techniques. Methodology: Eighteen (18) apparently healthy male albino Wistar rats (Rattus norvegicus) were grouped into 6 groups designated as non-diabetic control (NDC), diabetic control (DC), SAC, MAN, COM and glibenclamide (GLC). Insulin resistance was induced by first feeding the rats with a high-fat diet for a period of 10 weeks followed by a low dose of streptozotocin injection to induce type 2 diabetes mellitus. Therapeutic interventions was by the administration of 50 mg/kg body weight of SAC solution, 40 mg/kg body weight of MAN solution, equal volume ratio of both (SAC:MAN) and 5 mg/kg body weight of GLC. Results: Therapeutic interventions with the bioactive compounds significantly improved the glucose tolerance ability by ameliorating the hyperglycaemic condition in the diabetic rats which was significant at P < 0.05. Similarly, immunohistochemistry evaluation of the islet β-cells showed an increase in insulin secretion suggesting an improvement in glycaemic control and an eventual commitment of glucose to glycolysis. Conclusion: The amelioration of the type 2 diabetic mellitus by the bioactive compound therapies was due to the bioactive-mediated anti-hyperglycaemic and insulin release potentials. These potentials were observed to be more pronounced in the SAC group, followed by MAN group, then GLC group and lastly by COM group.