Selective effect of some somatostatin analogs on glucagon as opposed to insulin release in rats in vivo

Abstract

Cyclic somatostatin, at a dose of 700 but not 70 ng/kg/min, inhibited arginine-induced insulin and glucagon release as well as glucose stimulated insulin release in rats in vivo. Three somatostatin (S-S) analogs (D-Cys 14-S-S, D-Trp 8-D-Cys 14-S-S and Ala 2-D-Trp 8-D-Cys 14-S-S), at a dose of 70 ng/kg/min, suppressed arginine-induced glucagon but not insulin release. At the same dose, the first two of these analogs had no effect on glucose-induced insulin release, while the third one, Ala 2-D-Trp 8-D-Cys 14-somatostatin, enhanced insulin release induced by glucose. A fourth analog, D-Trp 8-somatostatin, was more potent than somatostatin with regard to arginine stimulated insulin and glucagon release, and equipotent with somatostatin with respect to glucose stimulated insulin release. These studies show, firstly, that the inhibitory effect of somatostatin analogs on arginine induced insulin release may be different from that when glucose is used as a stimulant and, secondly, that Ala 2-D-Trp 8-D-Cys 14-somatostatin inhibits arginine-induced glucagon release while enhancing insulin release on glucose stimulation.