title: Modulation of pancreatic islets-stress axis by hypothalamic releasing hormones and 11beta-hydroxysteroid dehydrogenase.
abstract: Corticotropin-releasing hormone (CRH) and growth hormone-releasing hormone (GHRH), primarily characterized as neuroregulators of the hypothalamic-pituitary-adrenal axis, directly influence tissue-specific receptor-systems for CRH and GHRH in the endocrine pancreas. Here, we demonstrate the expression of mRNA for CRH and CRH-receptor type 1 (CRHR1) and of protein for CRHR1 in rat and human pancreatic islets and rat insulinoma cells. Activation of CRHR1 and GHRH-receptor significantly increased cell proliferation and reduced cell apoptosis. CRH stimulated both cellular content and release of insulin in rat islet and insulinoma cells. At the ultrastructural level, CRHR1 stimulation revealed a more active metabolic state with enlarged mitochondria. Moreover, glucocorticoids that promote glucose production are balanced by both 11b-hydroxysteroid dehydrogenase (11β-HSD) isoforms; 11β-HSD-type-1 and 11β-HSD-type-2. We demonstrated expression of mRNA for 11β-HSD-1 and 11β-HSD-2 and protein for 11β-HSD-1 in rat and human pancreatic islets and insulinoma cells. Quantitative real-time PCR revealed that stimulation of CRHR1 and GHRH-receptor affects the metabolism of insulinoma cells by down-regulating 11β-HSD-1 and up-regulating 11β-HSD-2. The 11β-HSD enzyme activity was analyzed by measuring the production of cortisol from cortisone. Similarly, activation of CRHR1 resulted in reduced cortisol levels, indicating either decreased 11β-HSD-1 enzyme activity or increased 11β-HSD-2 enzyme activity; thus, activation of CRHR1 alters the glucocorticoid balance toward the inactive form. These data indicate that functional receptor systems for hypothalamic-releasing hormone agonists exist within the endocrine pancreas and influence synthesis of insulin and the pancreatic glucocorticoid shuttle. Agonists of CRHR1 and GHRH-receptor, therefore, may play an important role as novel therapeutic tools in the treatment of diabetes mellitus.
authors.affiliation: Department of Medicine III, University Hospital Carl Gustav Carus, 01307 Dresden, Germany.
authors.forename: Janine
authors.initials: J
authors.lastname: Schmid
authors.forename: Barbara
authors.initials: B
authors.lastname: Ludwig
authors.forename: Andrew V
authors.initials: AV
authors.lastname: Schally
authors.forename: Anja
authors.initials: A
authors.lastname: Steffen
authors.forename: Christian G
authors.initials: CG
authors.lastname: Ziegler
authors.forename: Norman L
authors.initials: NL
authors.lastname: Block
authors.forename: Yassemi
authors.initials: Y
authors.lastname: Koutmani
authors.forename: Mathias D
authors.initials: MD
authors.lastname: Brendel
authors.forename: Katia P
authors.initials: KP
authors.lastname: Karalis
authors.forename: Charmaine J
authors.initials: CJ
authors.lastname: Simeonovic
authors.forename: Julio
authors.initials: J
authors.lastname: Licinio
authors.forename: Monika
authors.initials: M
authors.lastname: Ehrhart-Bornstein
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Bornstein
mesh_terms: D042842:11-beta-Hydroxysteroid Dehydrogenases / Q000502:physiology*; D000818:Animals; D003346:Corticotropin-Releasing Hormone; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism*; D007328:Insulin / Q000096:biosynthesis; D007340:Insulinoma / Q000473:pathology; D007515:Islets of Langerhans / Q000378:metabolism*; D010906:Pituitary Hormone-Releasing Hormones / Q000502:physiology*; D010913:Pituitary-Adrenal System / Q000378:metabolism*; D012333:RNA, Messenger; D051381:Rats; D018019:Receptors, Corticotropin-Releasing Hormone / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000378:metabolism; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000378:metabolism; D000099052:CRF Receptor, Type 1
chemical_list: D007328:Insulin; D010906:Pituitary Hormone-Releasing Hormones; D012333:RNA, Messenger; D018019:Receptors, Corticotropin-Releasing Hormone; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D000099052:CRF Receptor, Type 1; D003346:Corticotropin-Releasing Hormone; D042842:11-beta-Hydroxysteroid Dehydrogenases; C048250:somatotropin releasing hormone receptor