Dose-dependent inhibitory and non-inhibitory action of somatostatin on insulin release in rats.
The dose-dependent effect of intravenously infused synthetic somatostatin-14 on basal and postprandial insulin and gastrin release was assessed in anesthetized rats. Infusion of 1 ng . kg-1 . min-1 elicited a significant reduction of basal and postprandial insulin levels compared to the saline control groups. At 15 ng . kg-1 . min-1 basal insulin was not affected but postprandial insulin levels were still significantly reduced. At 30 ng . kg-1 . min-1 neither basal nor stimulated insulin levels were affected. At the highest concentration of 120 ng . kg-1 . min-1 basal and postprandial insulin levels were suppressed similar to lowest infusion rate of 1 ng . kg-1 . min-1. Basal gastrin levels were significantly reduced only at the highest rate of 120 ng . kg-1 . min-1. A significant reduction of postprandial gastrin levels was observed at 15 ng . kg-1 . min-1 and all higher infusion rates employed. Measurements of plasma somatostatin-like immunoreactivity (SLI) demonstrated that plasma SLI levels during the lowest infusion rate of 1 ng . kg-1 . min-1 were not different from the controls. No significant rise of plasma SLI levels was observed in response to the test meal. The higher infusion rates elicited a dose-dependent increase in plasma SLI levels. These data demonstrate that in rats somatostatin exerts a biological effects on insulin release at very low doses while certain greater infusion rates hae no suppressive effect. Gastrin secretion is inhibited in a more linear pattern.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004435:Eating; D005755:Gastrins / Q000378:metabolism; D007263:Infusions, Parenteral; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D051381:Rats; D013004:Somatostatin / Q000008:administration & dosage*
D005755:Gastrins; D007328:Insulin; D013004:Somatostatin