Antidiabetic effect of a new peptide from Squalus mitsukurii liver (S-8300) in streptozocin-induced diabetic mice.

We have evaluated the antidiabetic effect of S-8300 (a peptide extracted from shark liver (Squalus mitsukurii)) in streptozocin (streptozotocin)-diabetic mice. Diabetes was induced by a single intravenous injection of streptozocin (150 mg kg(-1)). The effects of S-8300 (3 or 10 mg kg(-1)) on diabetic mice were investigated by observing the changes in the levels of fasting plasma glucose, glycosylated haemoglobin, hepatic glycogen, triglycerides, cholesterol, free fatty acid, superoxide dismutase, and malondialdehyde. Body weight, kidney weight and the degree of injured beta-cells in pancreatic islets were recorded also. Diabetic mice treated with S-8300 showed a significant decrease in the levels of fasting plasma glucose, glycosylated haemoglobin, triglycerides, cholesterol, free fatty acid in plasma and malondialdehyde in tissues. The animals showed a significant increase in the content of hepatic glycogen and the activity of superoxide dismutase. Treatment with S-8300 attenuated the degree of injured beta-cells in the pancreatic islets. The effect of S-8300 was similar to that of glibenclamide (5 mg kg(-1)).