Abstract

BACKGROUND
Hyperglycemia is a well-recognized pathogenic factor of long term complications in diabetes mellitus and hyperglycemia also generates reactive oxygen species (ROS) in beta cells when ROS accumulate in excess for prolonged periods of time, they cause chronic oxidative stress and adverse effects. Unfortunately, the islet contacts low capacity of endogenous antioxidant effects. But, gamma-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme for glutathione synthesis, is well represented in islets. METHODS: This study is to evaluate the changes in the activity of gamma-GCS, glutathione in beta-cells exposed to high glucose, in pancreatic tissue of OLETF (Otsuka Long Evans Tokushima Fatty) and LETO (Long-Evans Tokushima Otsuka) rats, in leukocytes from patients with Korean type 2 DM (T2DM) and to disclose the effects of high blood glucose on this impairment in patients with T2DM. We divided our patients into 3 groups by HbA1c (controls: n = 20, well controls diabetes: n=24, poorly controlled diabetes: n = 36). RESULTS: We observed that decreased glutathione level, gamma-GCS expression, glucose-stimulated (GSIS) and increased intracellular peroxide level in the INS-1 cells exposed to 30 mM glucose condition. Also decreased glutathione level at erythrocytes, gamma-GCS expression at leukocytes and increased oxidized LDL, MDA (malondialdehyde) level at plasma from patients with T2DM compared to controls (esp, poorly controlled patients). CONCLUSION: These results suggest that insufficient antioxidant defenses by the glutathione pathway may be one of the factors responsible for development of complications in T2DM.

• Keywords: gamma-glutamylcysteine synthetase (gamma-GCS) mRNA;glutathione (GSH);INS-1 Cells;Insulin secretion;Type 2 Diabetes Mellitus;