A physiologic role for somatostatin 28 as a regulator of insulin secretion.
Somatostatin 28 (S-28) is a peptide produced in the intestinal tract which rises in the circulation during nutrient absorption. We tested the hypothesis that S-28 regulates B-cell function by (a) studying the effects on insulin secretion of "physiologic" infusions of S-28 and (b) measuring insulin responses during elevated nutrient-stimulated endogenous S-28 levels. (a) Synthetic S-28 was infused on separate days into six healthy men at rates of 25 and 50 ng/kg per h which mimicked postprandial levels. Subjects were given a bolus of glucose (0.1 g/kg) after 120 min. Insulin responses during S-28 infusions were compared to a control study using a saline infusion in the same individuals. Glucose-stimulated insulin secretion was inhibited during the infusion of 50 ng/kg per h S-28 when compared to control (P less than 0.05). (b) Insulin secretion during elevations of endogenous S-28 was studied in healthy men who received a bolus of 2.5 g arginine (n = 14) or 25 U of secretin (n = 8) 120 min after swallowing 50 g fat, or, on a separate day, an equivalent volume of water. S-28 levels rose significantly after fat ingestion but did not change after water. Arginine and secretin-stimulated insulin secretion was inhibited following ingestion of fat compared with intake of water (P less than 0.05). Arginine-enhanced glucagon secretion was not changed by fat ingestion. We conclude that elevations in plasma S-28 levels, occurring during the postprandial state, attenuate B-cell secretion and this peptide may be a physiologic modulator of nutrient-stimulated insulin release.
D'Alessio
D A
DA
Department of Medicine, University of Washington, Seattle 98195.
Sieber
C
C
Beglinger
C
C
Ensinck
J W
JW
D000284:Administration, Oral; D000328:Adult; D001120:Arginine / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged; D011498:Protein Precursors / Q000008:administration & dosage / Q000097:blood / Q000502:physiology; D012633:Secretin / Q000008:administration & dosage; D013004:Somatostatin / Q000008:administration & dosage / Q000097:blood / Q000502:physiology*; D053561:Somatostatin-28
D004041:Dietary Fats; D007328:Insulin; D011498:Protein Precursors; D012633:Secretin; D013004:Somatostatin; D053561:Somatostatin-28; D001120:Arginine