Diabetes & Metabolism Journal

Original Article

Effects of Antioxidants on Ethidium Bromide-induced Inhibition of Insulin Secretion in Rat Pancreatic Islets.: Chul Hee Kim, Chan Hee Kim, Hyeong Kyu Park, Kyo Il Suh, Ki Up Lee; Korean Diabetes J. 2002;26(3):179-187. Published online June 1, 2002

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Abstract PDF: BACKGROUND
It was recently shown that mitochondrial function in pancreatic beta-cells is essential in nutrient-stimulated insulin secretion. The inhibition of mitochondrial DNA (mtDNA) transcription by ethidium bromide (EtBr) has been reported to suppress glucose-induced insulin secretion in beta-cell lines. This study was undertaken to examine the effects of EtBr on insulin secretion in isolated normal rat pancreatic islets, and to see whether antioxidants could protect the beta-cell function against the EtBr-induced impairment. METHODS: Pancreatic islets of normal Sprague-Dawley rats were isolated by intraductal injection of collagenase followed by Ficoll-gradient centrifugation. Isolated islets were treated with 0.2 +/- 2.0 microgram/mL of EtBr for 2 to 6 days, and the glucose-stimulated insulin secretion measured. The effects of the antioxidant, vitamin E and alpha-lipoic acid, on the EtBr-induced inhibition of insulin secretion were also examined. RESULTS: EtBr inhibited the basal and glucose-stimulated insulin secretion in normal rat pancreatic islets in a dose- and time-dependent manner. Vitamin E and alpha-lipoic acid prevented the EtBr-induced inhibition of insulin secretion. CONCLUSION: Our results show that antioxidant can protect normal rat pancreatic islets from the EtBr-induced inhibition of insulin secretion. This suggests that oxidative stress is involved in the pathogenesis of the insulin secretory defect associated with mitochondrial dysfunction.

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