Crowding stress inhibits serotonin 1A receptor-mediated increases in corticotropin-releasing factor mRNA expression and adrenocorticotropin hormone secretion in the Gulf toadfish

• Published in: Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology Vol. 184; no. 2; pp. 259 - 271
• Main Authors: Medeiros, Lea R., Cartolano, Maria C., McDonald, M. Danielle
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2014; Springer Nature B.V
• Subjects: 8-Hydroxy-2-(di-n-propylamino)tetralin - pharmacology; Adrenocorticotropic Hormone - blood; Adrenocorticotropic Hormone - secretion; Amino Acid Sequence; Animal Physiology; Animals; Batrachoidiformes - metabolism; Batrachoidiformes - physiology; Biochemistry; Biomedical and Life Sciences; Biomedicine; Corticotropin-Releasing Hormone - genetics; Hormones; Human Physiology; Hydrocortisone - blood; Life Sciences; Molecular Sequence Data; Original Paper; Plasma; Receptor, Serotonin, 5-HT1A - metabolism; Receptors, Glucocorticoid - metabolism; RNA, Messenger; Sequence Homology, Amino Acid; Serotonin; Serotonin Receptor Agonists - pharmacology; Steroids; Stress, Physiological - drug effects; Zoology; Florida; United States > US; Hypothalamic–pituitary–interrenal (HPI) axis; RU486; Antalarmin; Stress; 8-OH-DPAT
• ISSN: 0174-1578; 1432-136X
• DOI: 10.1007/s00360-013-0793-9

Stimulation of the serotonin 1A (5-HT 1A ) 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-HT 1A receptor is stimulated. Additionally, previous investigations have revealed that chronic elevations of plasma cortisol mediate changes in brain 5-HT 1A  receptor mRNA and protein levels via the glucocorticoid receptor (GR); thus, we hypothesized that the function of centrally activated 5-HT 1A 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-HT 1A 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-HT 1A receptor-mediated secretion of both CRF and ACTH.