title: Regulation of a putative corticosteroid, 17,21-dihydroxypregn-4-ene,3,20-one, in sea lamprey, Petromyzon marinus.
abstract: In higher vertebrates, in response to stress, the hypothalamus produces corticotropin-releasing hormone (CRH), which stimulates cells in the anterior pituitary to produce adrenocorticotropic hormone (ACTH), which in turn stimulates production of either cortisol (F) or corticosterone (B) by the adrenal tissues. In lampreys, however, neither of these steroids is present. Instead, it has been proposed that the stress steroid is actually 17,21-dihydroxypregn-4-ene-3,20-dione (11-deoxycortisol; S). However, there have been no studies yet to determine its mechanism of regulation or site of production. Here we demonstrate that (1) intraperitoneal injections of lamprey-CRH increase plasma S in a dose dependent manner, (2) intraperitoneal injections of four lamprey-specific ACTH peptides at 100μg/kg, did not induce changes in plasma S concentrations in either males or females; (3) two lamprey-specific gonadotropin-releasing hormones (GnRH I and III) and arginine-vasotocin (AVT), all at single doses, stimulated S production as well as, or to an even greater extent than CRH; (4) sea lamprey mesonephric kidneys, in vitro, converted tritiated 17α-hydroxyprogesterone (17α-P) into a steroid that had the same chromatographic properties (on HPLC and TLC) as S; (5) kidney tissues released significantly more immunoassayable S into the incubation medium than gill, liver or gonad tissues. One interpretation of these results is that the corticosteroid production of the sea lamprey, one of the oldest extant vertebrates, is regulated through multiple pathways rather than the classical HPI-axis. However, the responsiveness of this steroid to the GnRH peptides means that a reproductive rather than a stress role for this steroid cannot yet be ruled out.
authors.affiliation: Department of Zoology, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Brent W
authors.initials: BW
authors.lastname: Roberts
authors.affiliation: Department of Zoology, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Wes
authors.initials: W
authors.lastname: Didier
authors.affiliation: Department of Zoology, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors.forename: Satbir
authors.initials: S
authors.lastname: Rai
authors.affiliation: USGS, Great Lakes Science Center, Hammond Bay Biological Station, Millersburg, MI 49759, USA.
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Johnson
authors.affiliation: Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Scot
authors.initials: S
authors.lastname: Libants
authors.affiliation: Fisheries Centre, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. Electronic address: s.yun@fisheries.ubc.ca.
authors.forename: Sang-Seon
authors.initials: SS
authors.lastname: Yun
authors.affiliation: Department of Zoology, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada; Fisheries Centre, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. Electronic address: close@zoology.ubc.ca.
authors.forename: David A
authors.initials: DA
authors.lastname: Close
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000097:blood; D002855:Chromatography, Thin Layer; D003345:Corticosterone / Q000097:blood*; D003346:Corticotropin-Releasing Hormone / Q000737:chemistry / Q000494:pharmacology*; D003350:Cortodoxone / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006728:Hormones / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D007274:Injections, Intraperitoneal; D007798:Lampreys / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D011863:Radioimmunoassay; D017386:Sequence Homology, Amino Acid; D014668:Vasotocin / Q000494:pharmacology*
chemical_list: D000893:Anti-Inflammatory Agents; D006728:Hormones; D007987:Gonadotropin-Releasing Hormone; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D014668:Vasotocin; D003345:Corticosterone; D003350:Cortodoxone
keywords: 17,21-Dihydroxypregn-4-ene-3,20-dione; Adrenocorticotropic hormone; Corticotropin releasing hormone; Lamprey; Steroid hormone; Stress axis