PLASMA-INSULIN IN RESPONSE TO ENTEROSTATIN AND EFFECT OF ADRENALECTOMY IN RATS

Enterostatin has previously been reported to alter serum insulin and c orticosterone levels after central administration of the peptide, The purpose of the present study was to investigate the effect of peripher al administration of enterostatin on insulin and corticosterone levels as well as the response of plasma insulin to enterostatin administrat ion in adrenalectomized rats, Female Sprague-Dawley rats were given a bolus Infection intravenously with enterostatin alone or together with glucose, Enterostatin increased basal plasma levels of insulin, but s ignificantly inhibited the increase in plasma insulin stimulated by gl ucose, Plasma corticosterone levels were not altered after a single in travenous injection of enterostatin. In rats infused chronically with enterostatin, plasma insulin levels were significantly reduced and pla sma corticosterone levels were increased, The daily food intake was lo wer in these rats, but there was no effect on body weight. After adren alectomy, the responsiveness of plasma insulin to enterostatin infusio n was completely abolished, Furthermore, adrenalectomy itself reduced basal plasma levels of insulin and increased plasma levels of endogeno us enterostatin, These results suggest that peripheral enterostatin ad ministration produces a similar effect as central infusion of the pept ide, and that the glucocorticoid hormones are involved in the regulati on of plasma insulin by enterostatin.