Insulin-potentiating action of a synthetic amino-terminal fragment of human growth hormone (hGH 1--15) in streptozotocin-diabetic rats.

The hypoglycemic activity of the synthetic peptide fragment of human growth hormone, hGH 1--15, is insulin dependent, although it does not alter the circulating levels of plasma insulin in normal and diabetic rats. In severe diabetes induced by streptozotocin, the peptide had no effect on the basal levels of blood glucose, but enhanced insulin sensitivity during intravenous insulin tolerance tests in 16-h-fasted rats. Radioreceptor binding studies show increased binding of insulin by hepatic plasma membranes prepared from rats pretreated with hGH 1--15. These results suggest that the biologic action of the peptide is, at least in part, on insulin receptors of plasma membranes.