Effect of in vivo administration of somatostatin on cell-free protein synthesis of pituitary and of adrenal ribosomes

Abstract Somatostatin has been found to inhibit the secretion of pituitary and of intestinal hormones. 1 However, the spectrum of its actions seems not to be restricted to endocrine tissues but includes many effects 2–4 that are mediated by cyclic nucleotides. 5,6 In experiments using liver slices incubated with somatostatin and/or cyclic AMP with consecutive protein synthesis of ribosomes prepared of these liver slices, a neutralizing effect of somatostatin on the stimulative action of cyclic AMP was demonstrated. 7 Similar to the synthesis of a few pituitary hormones, the synthesis of adrenal steroids is preceded by an increase of cyclic AMP 8 with cyclic AMP stimulating protein synthesis by inducing phosphorylation of ribosomal proteins. 9 It was therefore felt of interest to examine the influence of somatostatin on cell-free protein synthesis of pituitary and of adrenal ribosomes.