The effect of metformin and exercise on serum lipids, nitric oxide synthase and liver nitric oxide levels in streptozotocin-nicotinamide induced diabetic rats

The objective of this study was to determine the effects of metformin treatment and exercise intervention on lipid metabolism, nitric oxide (NO), nitric oxide synthase (NOS) and glucose levels in streptozotocin-nicotinamide (STZ-NA) induced diabetic rats. Male wistar rats were used to conduct the study and they were  divided into five groups of 8 rats in each. These groups are: Control group, diabetes group (STZ-NA), diabetes and metformin (DMet) group, diabetes and exercise (DE) group, and diabetes + exercise + metformin (DEMet) group. The STZ-NA induced diabetic rats were used as a model of type 2 diabetes. Metformin was orally administered to rats. For exercise intervention, rats were forced to run in a running wheel for 10 min each day (20 m/min/day). At the end of experimental period, blood glucose, glycated hemoglobin (HbA1c) levels, plasma lecithin:cholesterol acyltransferase (LCAT) levels, serum triglyceride (TG), cholesterol, high density lipoprotein (HDL), Apo A-I, NOS and liver NO levels were determined. Metformin caused beneficial changes in blood glucose, HbA1c levels, and HDL in type 2 diabetic rats. Both administration of metformin and exercise intervention independently caused beneficial changes in blood glucose. However, the surprising result found was that exercise intervention did not optimize the result of metformin treatment. The other finding of this study was that exercise intervention increased cholesterol and NOS level but exercise combined with metformin was not better than exercise alone. Thus, it appears from the present study that metformin and exercise combination has no effect.    Key words: Diabetes, exercise, lecithin:cholesterol acyltransferase (LCAT), metformin, nitric oxide synthase.