The insulin-like action of beta-cell-tropin on glucose and lipid metabolism in adipocytes.
The insulin-like activity of the pituitary pars-intermedia insulin secretagogue beta-cell-tropin, ACTH22-39, has been studied on rat adipocytes. The peptide was prepared by tryptic digestion of synthetic human CLIP, ACTH18-39. beta-Cell-tropin stimulated the incorporation of 3H2O into total lipids. The 50% maximal activity concentration was 5 X 10(-2) ng/ml-1 about 2.5 X 10(-11) M. Iodination of tyrosine, the penultimate amino-acid of the N-terminal, eliminated lipogenic activity, and acetylation of the N-terminal valine reduced activity. ACTH and CLIP (ACTH18-39) had no lipogenic action on the adipocyte system studied. beta-Cell-tropin stimulated the oxidation of glucose and the conversion of glucose into saponified fatty acids and glyceride glycerol. The influence of beta-cell-tropin and insulin on the incorporation of glucose into total lipids, saponified fatty acids and glyceride glycerol was not additive. The results suggest that beta-cell-tropin is either a potent lipogenic hormone, stimulating the conversion of glucose into lipids or that it activates endogenous insulin. The biological activity is associated with the N-terminal amino-acids of the peptide. The possible significance of beta-cell-tropin in obesity is discussed.
D000273:Adipose Tissue / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D053497:Corticotropin-Like Intermediate Lobe Peptide; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000494:pharmacology; D050356:Lipid Metabolism; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D010907:Pituitary Hormones / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D007328:Insulin; D010446:Peptide Fragments; D010907:Pituitary Hormones; D053497:Corticotropin-Like Intermediate Lobe Peptide; C026834:beta-cell tropin; D000324:Adrenocorticotropic Hormone; D005947:Glucose