Effects of Imeglimin, a New Oral Hyperglycemic Agent, on High Glucose and Low Glucose-Induced Cell Death and Mitochondrial Dysfunction in Schwann Cells

It is known that hyperglycemia-induced oxidative stress is a major cause of the pathogenesis of diabetic neuropathy, and hyperglycemia-induced mitochondrial ROS production is considered as one pivotal mechanism of increased oxidative stress. On the other hand, imeglimin is a new class of oral hypoglycemic agents called “glymines” containing tetrahydrotriazines, which targets mitochondrial dysfunction. We investigated the effects of imeglimin on cell death and mitochondrial dysfunction induced by high glucose and low glucose in Schwann cells. Immortalized adult mouse Schwann (IMS32) cells were cultured for 1 hour in the medium with normal glucose concentration of 5.5 mM, low glucose of 2.5 mM, and high glucose of 25 mM. Compared to normal glucose, not only high glucose but also low glucose decreased cell viability of IMS32 cells and increased mitochondrial oxidative stress. Mitochondrial membrane potential was also decreased either by high glucose or low glucose. In addition, mitochondrial oxygen consumption rate (OCR) was increased by low glucose as well as high glucose. Mitochondria isolated from IMS32 cells exposed to high glucose and low glucose for 1 hour exhibited increased activity of complex I. The expression of complex I protein was unchanged by high glucose for 1 hour. Imeglimin ameliorated the decrease in cell viability and improved the mitochondrial dysfunctions via inhibiting the increase of mitochondrial oxidative stress, OCR and the activity of complex I caused by high glucose and low glucose. These results indicate that hyperglycemia and hypoglycemia induce mitochondrial dysfunction in nerves, and that imeglimin may prevent against diabetic neuropathy by attenuation mitochondrial dysfunction and cell death in Schwann cells. Disclosure T. Himeno: None. J. Nakamura: None. H. Kamiya: Research Support; Abbott Japan Co., Ltd., Eli Lilly and Company, Japan Tobacco Inc., Kissei Pharmaceutical Co., Ltd., Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taiho Pharmaceutical Co. Ltd., Takeda Pharmaceutical Company Limited, Terumo Corporation. Speaker's Bureau; Astellas Pharma Inc., AstraZeneca, Boehringer Ingelheim International GmbH, Daiichi Sankyo, Eli Lilly and Company, Kissei Pharmaceutical Co., Ltd., Kowa Company, Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novartis Pharma K.K., Novo Nordisk, Ono Pharmaceutical Co., Ltd., Sanofi K.K., Sanwa Kagaku Kenkyusho, Sumitomo Dainippon Pharma Co., Ltd., Taisho Pharmaceutical Holdings Co., Ltd. K. Sango: None. K. Kato: None.