title: Pituitary alterations involved in the decline of growth hormone gene expression in the pituitary of aging rats.
abstract: Growth hormone (GH) declines during aging. This study investigates whether pituitary constitutive alterations may be involved in the GH decline. Two groups of male Wistar rats were studied (young: 3-month-old; old: 24-month-old). The old rats showed lower pituitary GH messenger RNA (mRNA) levels, immunoreactive rat (IR)-GH content, and GH secretion with no difference in pituitary Pit-1 and cAMP-response element-binding protein (CREB) expression. Pituitary GH releasing hormone receptor (GHRH-R), GH secretagogue receptor (GHS-R), sstr2, and sstr5 mRNA levels were significantly reduced in old rats. The percentage of GH immunoreactive cells was similar in both groups. In vitro, pituitary IR-GH response to GHRH, forskolin (FK), ghrelin, and insulin-like growth factor I (IGF-I) was similar when compared with respective basal secretion and somatostatin-diminished GHRH- and ghrelin-induced IR-GH release in both groups. These results indicate that, as somatotrope function is maintained in aging, the changes observed in GH gene expression and secretion could be reversed by GHS.
authors.affiliation: Endocrine Service, Hospital Carlos III, C/ Sinesio Delgado, 10, Madrid, Spain.
authors.forename: Miriam G San
authors.initials: MG
authors.lastname: Frutos
authors.forename: Lucinda
authors.initials: L
authors.lastname: Cacicedo
authors.forename: Carolina F
authors.initials: CF
authors.lastname: Méndez
authors.forename: David
authors.initials: D
authors.lastname: Vicent
authors.forename: Miguel
authors.initials: M
authors.lastname: González
authors.forename: Franco
authors.initials: F
authors.lastname: Sánchez-Franco
mesh_terms: D000375:Aging / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics; D015870:Gene Expression / Q000235:genetics*; D054439:Ghrelin; D013006:Growth Hormone / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D008297:Male; D036361:Peptide Hormones / Q000494:pharmacology; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000235:genetics; D054440:Receptors, Ghrelin; D018013:Receptors, Neuropeptide / Q000235:genetics; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics; D017481:Receptors, Somatostatin / Q000235:genetics; D050817:Transcription Factor Pit-1 / Q000235:genetics
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D054439:Ghrelin; D036361:Peptide Hormones; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D017481:Receptors, Somatostatin; D050817:Transcription Factor Pit-1; D005576:Colforsin; D007334:Insulin-Like Growth Factor I; C094573:somatostatin receptor 5; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C093733:somatostatin receptor 2; C048250:somatotropin releasing hormone receptor