title: alpha-MSH analogues and adrenal zona glomerulosa function.
abstract: Recent studies on the control of adrenal zona glomerulosa function and aldosterone secretion have focussed attention on the role of MSH-like peptides. In particular, at low concentrations, alpha-MSH has a specific stimulatory effect on rat adrenal glomerulosa cells. The synthesis of alpha-MSH analogues which have potent and prolonged effects on melanocyte systems offers new methods of examining the specificity of this response. Two peptides were tested in which potential for a beta-turn configuration was stabilised. These were: [Nle4, D-Phe7]-alpha-MSH and the cyclic [Cys4, Cys10]-alpha-MSH. In contrast to their effects on melanocyte systems, only [Cys4, Cys10]-alpha-MSH stimulated glomerulosa cells, and it was equipotent with alpha-MSH, while [Nle4, D-Phe7]-alpha-MSH and shorter fragments had no effect when added alone. [Nle4, D-Phe7]-alpha-MSH, however, augmented the response of cells already maximally stimulated with alpha-MSH and in this respect its actions resembled those of gamma-MSH and related peptides. The augmentation produced by [Nle4, D-Phe7]-alpha-MSH and gamma 3-MSH was not additive when the two peptides were added together with alpha-MSH. The results suggest that the specificity of the alpha-MSH receptors in rat adrenal glomerulosa cells and the peptide structure-function relationships in this system are different from those described for melanocytes.
mesh_terms: D015070:18-Hydroxydesoxycorticosterone / Q000494:pharmacology; D000302:Adrenal Cortex / Q000187:drug effects*; D000450:Aldosterone / Q000096:biosynthesis; D000818:Animals; D003345:Corticosterone / Q000096:biosynthesis; D005260:Female; D008297:Male; D009074:Melanocyte-Stimulating Hormones / Q000031:analogs & derivatives* / Q000494:pharmacology; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism; D011979:Receptors, Pituitary Hormone; D000521:alpha-MSH / Q000031:analogs & derivatives*
chemical_list: D015070:18-Hydroxydesoxycorticosterone; C034542:MSH, 4-half-Cys-10-half-Cys-alpha-; D011956:Receptors, Cell Surface; D011979:Receptors, Pituitary Hormone; D000450:Aldosterone; D000521:alpha-MSH; C027756:MSH, 4-Nle-7-Phe-alpha-; C029446:MSH receptor; D009074:Melanocyte-Stimulating Hormones; D003345:Corticosterone