title: Corticotropin-releasing hormone: Mediator of vertebrate life stage transitions?
abstract: Hormones, particularly thyroid hormones and corticosteroids, play critical roles in vertebrate life stage transitions such as amphibian metamorphosis, hatching in precocial birds, and smoltification in salmonids. Since they synergistically regulate several metabolic and developmental processes that accompany vertebrate life stage transitions, the existence of extensive cross-communication between the adrenal/interrenal and thyroidal axes is not surprising. Synergies of corticosteroids and thyroid hormones are based on effects at the level of tissue hormone sensitivity and gene regulation. In addition, in representative nonmammalian vertebrates, corticotropin-releasing hormone (CRH) stimulates hypophyseal thyrotropin secretion, and thus functions as a common regulator of both the adrenal/interrenal and thyroidal axes to release corticosteroids and thyroid hormones. The dual function of CRH has been speculated to control or affect the timing of vertebrate life history transitions across taxa. After a brief overview of recent insights in the molecular mechanisms behind the synergic actions of thyroid hormones and corticosteroids during life stage transitions, this review examines the evidence for a possible role of CRH in controlling vertebrate life stage transitions.
authors.affiliation: Department of Anatomy, Physiology and Microbiology, La Trobe University, Bundoora, Victoria 3086, Australia. Electronic address: y.watanabe@latrobe.edu.au.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Anatomy, Physiology and Microbiology, La Trobe University, Bundoora, Victoria 3086, Australia. Electronic address: s.grommen@latrobe.edu.au.
authors.forename: Sylvia V H
authors.initials: SVH
authors.lastname: Grommen
authors.affiliation: Department of Anatomy, Physiology and Microbiology, La Trobe University, Bundoora, Victoria 3086, Australia. Electronic address: b.degroef@latrobe.edu.au.
authors.forename: Bert
authors.initials: B
authors.lastname: De Groef
mesh_terms: D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000502:physiology*; D014714:Vertebrates / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003346:Corticotropin-Releasing Hormone
keywords: Corticosteroid; Corticotropin-releasing hormone; Metamorphosis; Thyroid hormone; Thyrotropin; Vertebrate life stage transition