1462-P: Effect of Energy Restriction on the Intracellular Metabolism of Rodent Pancreatic ß-Cells In Vitro and Obese Mice

Abstract

Background: In pancreatic β-cells under diabetic conditions, metabolic stressors cause mitochondrial dysfunction and reduce oxidative phosphorylation, resulting in impaired intracellular metabolism. It has been suggested that aberrant activation of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) plays a role in this impairment. However, it is not clear whether the defect in activation of PFKFB3 is reversible. We investigated the effects of energy restriction on PFKFB3 and other metabolic enzymes in pancreatic β-cells. Methods: INS-1 832/13 cells and islets from C57BL/6J mice were cultured in medium containing a low (5.5 mM; low-G) or a high (22 mM: high-G) glucose concentration for 48 hours, or high-G for 24 hours followed by low-G for another 24 hours. The protein expression of glycolysis-related enzymes was measured using western blotting (WB) . Next, 6-week-old ob/+ and ob/ob mice were fed a standard chow diet ad lib or the same diet restricted to 2 g/day for 4 weeks. The body mass, blood glucose concentration, glucose tolerance, and insulin resistance of the mice were compared. The expression of glycolytic enzymes in the pancreatic islets was evaluated using WB and immunohistochemical staining. Results: In both INS-1 832/13 cells and isolated islets, higher expression of PKFFB3 was observed in the high-G group than in the low-G group. However, this was normalized by changing from a high-G to a low-G environment. Ad lib-fed ob/ob mice showed hyperglycemia and greater weight gain than ob/+ mice. The expression of PFKFB3, isocitrate dehydrogenase, and hexokinase was higher in ad lib-fed ob/ob mice. Restricted feeding suppressed weight gain and improved glucose tolerance versus ad lib-fed ob/ob mice. The high expression of PFKFB3 was ameliorated by restricted feeding. Conclusion: The intracellular metabolic changes in pancreatic β cells that are associated with obesity and diabetes are flexible. Disclosure K. Chiba: Research Support; Grant for Young Researcher from Japan Association for Diabetes Education and Care, Japan Diabetes Society Junior Scientist Development Grant, Japan Society for the Promotion of Science, MSD Life Science Foundation, Promotion for Young Research Talent and Network, The Akiyama Life Science Foundation, The Uehara Memorial Foundation. H. Nomoto: None. R. Izumihara: None. H. Kameda: None. K. Cho: None. H. Miyoshi: Research Support; Abbott Japan Co., Ltd., Boehringer Ingelheim International GmbH, Daiichi Sankyo, Kowa Company, Ltd., LifeScan, Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd. Speaker's Bureau; Astellas Pharma Inc., Boehringer Ingelheim International GmbH, Eli Lilly and Company, Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanofi K.K., Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd. T. Atsumi: Consultant; AbbVie Inc., AstraZeneca, MEDICAL & BIOLOGICAL LABORATORIES CO., Nippon Boehringer Ingelheim Co. Ltd., Novartis Pharma K.K., Ono Pharmaceutical Co., Ltd., Pfizer Inc. Research Support; AbbVie Inc., Alexion Pharmaceuticals, Inc., Astellas Pharma Inc., Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo, Mitsubishi Tanabe Pharma Corporation, Nippon Boehringer Ingelheim Co. Ltd., Otsuka Pharmaceutical Co., Ltd., Pfizer Inc., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, Teijin Pharma Limited. Speaker's Bureau; AbbVie Inc., Astellas Pharma Inc., Bristol-Myers Squibb Company, Chugai Pharmaceutical Co., Ltd., Daiichi Sankyo, Eisai Co., Ltd., Eli Lilly and Company, Kyowa Kirin Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Novartis Pharma K.K., Pfizer Inc., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, UCB, Inc.