Abstract

BACKGROUND
It has recently been suggested that fat overload on pancreatic beta cells is responsible for the abnormal pattern of insulin secretion in type 2 diabetes mellitus. Antioxidant treatment was reported to preserve beta cell function in animal models of diabetes. This study was undertaken to examine the effects of various free fatty acids and triglyceride on insulin secretion in isolated rat pancreatic islets. In addition, we examined the effects of antioxidants. METHODS: Pancreatic islets of normal Sprague-Dawley rats were isolated by intraductal injection of collagenase and Ficoll-gradient centrifugation. The islets were treated with palmitat0e (C16:0), oleate (C18:1), linoleate (C18:2), and triglyceride emulsions (intralipid) for 72hours. Basal and glucose-stimulated insulin secretions were measured. The effects of the antioxidants, vitamin E, alpha-lipoic acid, and N-acetyl cysteine, were examined on the fat-induced change of insulin secretion. RESULTS: All of the free fatty acids and the triglyceride increased the basal insulin secretion. In contrast, insulin secretion stimulated by 27 mM glucose was significantly decreased after the treatment with free fatty acids or triglycerides. The antioxidant could not prevent the fat-induced inhibition of insulin secretion. CONCLUSION: These results show that various free fatty acids and triglyceride commonly cause defects in insulin secretion. However, we could not confirm the the hypothesis that increased oxidative stress may be involved in the pathogenesis of insulin secretory defect associated with fat overload.

• Keywords: Insulin secretion;Free fatty acids;Triglyceride;Antioxidants;Rat pancreatic islets