Antidiabetic effect of a new peptide from Squalus mitsukurii liver (S-8300) in alloxan-diabetes.

1. The purpose of the present study was to evaluate the antidiabetic effect of S-8300 in alloxan diabetic mice. 2. Diabetes was induced by single intravenous injection of alloxan (60 mg/kg bodyweight). 3. The effects of S-8300 on diabetic mice were investigated by observing changes in the glycometabolic index (fasting plasma glucose, glycosylated haemoglobin), the lipometabolic index (triglyceride, cholesterol, free fatty acids), anti-oxidant index (superoxide dismutase, malondialdehyde) and in the degree of injury of beta-cells in the pancreatic islets. 4. A significant decrease in fasting plasma glucose, glycosylated haemoglobin, triglycerides, cholesterol, free fatty acids in the plasma and malondialdehyde in the tissues, as well as a significant increase in the activity of superoxide dismutase, was observed in diabetic mice treated with 10, 3 and 1 mg/kg S-8300. 5. Treatment with S-8300 also attenuated the degree of injury of beta-cells. 6. A comparison was made between the action of S-8300 and 6 U/kg insulin. The effects of S-8300 were similar to those of insulin.