title: Orexins stimulate corticosterone secretion of rat adrenocortical cells, through the activation of the adenylate cyclase-dependent signaling cascade.
abstract: Orexins-A and B are two novel hypothalamic peptides, which, like leptin and neuropeptide-Y (NPY), are involved in the central regulation of feeding. Since leptin and NPY were found to modulate adrenal function, we have examined whether orexins are able to directly affect rat adrenal steroid secretion. Both orexin-A and orexin-B raised basal corticosterone secretion of dispersed rat zona fasciculata-reticularis (ZF/R) cells, their maximal effective concentration being 10(-8) M. In contrast, orexins did not affect either maximally ACTH (10(-9) M)-stimulated corticosterone production by ZF/R cells or the basal and agonist-stimulated aldosterone secretion of dispersed zona glomerulosa cells. The ACTH-receptor antagonist corticotropin-inhibiting peptide (10(-6) M) annulled corticosterone response of ZF/R cells to ACTH (10(-9) M), but not to orexins (10(-8) M). Orexins (10(-8) M) enhanced cyclic-AMP release by ZF/R cells, and the selective inhibitor of protein-kinase A (PKA) H-89 (10(-5) M) abolished corticosterone responses to both ACTH (10(-9) M) and orexins (10(-8) M). A subcutaneous injection of both orexins (5 or 10 nmol/kg) evoked a clear-cut increase in the plasma concentration of corticosterone (but not aldosterone), the effect of orexin-A being significantly more intense than that of orexin-B. Collectively, these findings suggest that orexins exert a selective and direct glucocorticoid secretagogue action on the rat adrenals, acting through a receptor-mediated activation of the adenylate cyclase/PKA-dependent signaling pathway.
authors.affiliation: Department of Histology and Embryology, School of Medicine, Poznan, Poland.
authors.forename: L K
authors.initials: LK
authors.lastname: Malendowicz
authors.forename: C
authors.initials: C
authors.lastname: Tortorella
authors.forename: G G
authors.initials: GG
authors.lastname: Nussdorfer
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000494:pharmacology*; D002478:Cells, Cultured; D003345:Corticosterone / Q000096:biosynthesis / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D005260:Female; D006727:Hormone Antagonists / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D007546:Isoquinolines / Q000494:pharmacology; D009479:Neuropeptides / Q000494:pharmacology*; D000068797:Orexins; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013449:Sulfonamides; D015383:Zona Fasciculata / Q000502:physiology; D015384:Zona Glomerulosa / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D006727:Hormone Antagonists; D047908:Intracellular Signaling Peptides and Proteins; D007546:Isoquinolines; D009479:Neuropeptides; D000068797:Orexins; D010446:Peptide Fragments; D013449:Sulfonamides; D000450:Aldosterone; C026034:ACTH (7-38); D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D003345:Corticosterone