title: Crowding stress inhibits serotonin 1A receptor-mediated increases in corticotropin-releasing factor mRNA expression and adrenocorticotropin hormone secretion in the Gulf toadfish.
abstract: Stimulation of the serotonin 1A (5-HT1A) receptor subtype by 5-HT has been shown to result in an elevation in plasma corticosteroid levels in both mammals and several species of teleost fish, including the Gulf toadfish (Opsanus beta); however, in the case of teleost fish, it is not clearly known at which level of the hypothalamic-pituitary-interrenal axis the 5-HT1A receptor is stimulated. Additionally, previous investigations have revealed that chronic elevations of plasma cortisol mediate changes in brain 5-HT1A receptor mRNA and protein levels via the glucocorticoid receptor (GR); thus, we hypothesized that the function of centrally activated 5-HT1A receptors is reduced or abolished as a result of chronically elevated plasma cortisol levels and that this response is GR mediated. Our results are the first to demonstrate that intravenous injection of the 5-HT1A receptor agonist, 8-OH-DPAT, stimulates a significant increase in corticotropin-releasing factor (CRF) precursor mRNA expression in the hypothalamic region and the release of adrenocorticotropic hormone (ACTH) from the pituitary of teleost fish compared to saline-injected controls. We also provide evidence that cortisol, acting via GRs, attenuates the 5-HT1A receptor-mediated secretion of both CRF and ACTH.
authors.affiliation: Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, 33149-1098, USA, lmedeiros@uidaho.edu.
authors.forename: Lea R
authors.initials: LR
authors.lastname: Medeiros
authors.forename: Maria C
authors.initials: MC
authors.lastname: Cartolano
authors.forename: M Danielle
authors.initials: MD
authors.lastname: McDonald
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D024541:Batrachoidiformes / Q000378:metabolism / Q000502:physiology*; D003346:Corticotropin-Releasing Hormone / Q000235:genetics*; D006854:Hydrocortisone / Q000097:blood; D008969:Molecular Sequence Data; D012333:RNA, Messenger; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D006854:Hydrocortisone