ACTA ENDOCRINOLOGICA (BUC)

Gastrointestinal complaints are common among diabetic patients. The gastrointestinal tract contains melatonin. The binding sites of melatonin have been identified in all GIT tissues. Melatonin can modify activities of the gut and liver. The aim of this study was to evaluate the possible protective effects of melatonin against gastric motility and secretary responses in Streptozotocin-induced diabetes in rats. Methods. Streptozotocin was injected intraperitoneally at a single dose of 60 mg/kg for diabetes induction. One week after inducing diabetes, Melatonin (5, 10, 20 mg/ kg/day, IP.) was injected for 14 days. Gastric acid and mucus were measured in all animals by chemical methods. Gastric motility was investigated by powerlab system. Results. Streptozotocin induced a significant increase in blood glucose levels (p<0.001) and significant decrease in gastric acid, mucus, motility and body weight in diabetic groups. Treatment of diabetic rats with melatonin significantly reduced blood glucose (p<0.001) and increased gastric mucus (p<0.001) and motility (p<0.01 and p<0.05 in groups 4 and 5 respectively) with no effect on body weight and gastric acid concentration. Conclusion. These data suggested that melatonin treatment has a therapeutic effect on diabetic gastrointestinal disturbances by reduction of serum glucose and increasing gastric motility and gastric mucus levels, but no effect on gastric acid and body weight.

Objective. The aim of this study was to evaluate the possible protective effects of MT against gastric oxidative stress and dyslipidemia in streptozotocin (STZ) - induced diabetic rats. Methods. Forty male Wistar rats were randomly divided into five groups: control, diabetic, MT 5 mg/kg+ STZ, MT 10 mg/kg+ STZ and MT 20 mg/kg+ STZ. STZ (60 mg/kg) was intraperitoneally (ip) injected as a single dose for diabetes induction. One week after STZ administration, MT was injected daily as ip for 14 days. The levels of malondialdehyde (MDA), total thiol and glutathione, as well as superoxide dismutase (SOD) and catalase activities were measured in gastric tissue. Serum concentrations of triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL) and low density lipoprotein (LDL) were also determined. Results. Serum glucose significantly increased in diabetic group compared to control group. STZ induced a significant decrease in gastric tissue levels of total thiol, glutathione, catalase and SOD activities and a significant increase in MDA concentration. In diabetic rats, serum TG, LDL and TC were significantly higher and HDL was significantly lower than in the control group. Treatment of diabetic rats with MT caused a significant increase in gastric total thiol content and glutathione concentration as well as SOD and catalase activities. Gastric MDA concentration and serum LDL, TG and TC were significantly lower in MTtreated groups when compared with diabetic group. Conclusion. These data suggested that MT has a therapeutic effect on gastric oxidative damage and dyslipidemia induced by diabetes that possibly may be due to its antioxidant effects.