Effects of starvation and obesity on somatostatin, insulin, and glucagon release from an isolated perfused organ system

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Abstract
The effects of starvation and of obesity on somatostatin, insulin and glucagon release from an isolated perfused organ system in fed and 3 and 5 day fasted Holtzman rats and in obese (fa/fa) and lean (Fa/?) Zucker rats were studied. Fasting for 3 days significantly decreased basal (-71%) and amino acid-stimulated (-62%) somatostatin output. After 5 days of starvation, there was a significant increase over the 3 day level of somatostatin output stimulated by amino acid plus glucose (+540%) and by amino acids plus tolbutamide (+238%). Three and 5 days of starvation severely depressed insulin output while having no statistically significant effects on glucagon secretion. Somatostatin output from obese Zucker rats was significantly greater than that from lean controls in response to amino acids (41.2 .+-. 13.2 vs. 16.3 .+-. 10.3 ng/25 min, P < 0.05). Insulin output was greatly increased from obese compared to lean Zucker rats, whereas there were no statistically significant differences in glucagon output. Fasting decreases and obesity increases both somatostatin and insulin release. Altered stimulation by nutrients apparently was primarily responsible for changes in somatostatin and insulin release observed in starving and obese rats.