Changes in brain mRNA levels of gonadotropin-releasing hormone, pituitary adenylate cyclase activating polypeptide, and somatostatin during ovulatory luteinizing hormone and growth hormone surges in goldfish

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2008-12, Vol.295 (6), p.R1815-R1821
• Main Authors: Canosa, Luis Fabian, Stacey, Norm, Peter, Richard Ector
• Format: Article
• Language: English
• Subjects: Animals; Brain; Brain - drug effects; Brain - metabolism; Dinoprost - pharmacology; Female; Fish; Fish Proteins - genetics; Fish Proteins - metabolism; Gene expression; Goldfish - genetics; Goldfish - metabolism; Gonadotropin-Releasing Hormone - genetics; Gonadotropin-Releasing Hormone - metabolism; Growth Hormone - metabolism; Hormones; Luteinizing Hormone - metabolism; Mesencephalon - metabolism; Oviposition - drug effects; Ovulation - genetics; Peptides; Pituitary Adenylate Cyclase-Activating Polypeptide - genetics; Pituitary Adenylate Cyclase-Activating Polypeptide - metabolism; Prosencephalon - metabolism; Ribonucleic acid; RNA; RNA, Messenger - metabolism; Salmon; Sexual Behavior, Animal - drug effects; Somatostatin - genetics; Somatostatin - metabolism; Temperature; Time Factors
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00166.2008

1 Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; 2 Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Buenos Aires, Argentina; and 3 Bamfield Marine Sciences Centre, Bamfield, British Columbia, Canada Submitted 4 March 2008 ; accepted in final form 22 September 2008 In goldfish, circulating LH and growth hormone (GH) levels surge at the time of ovulation. In the present study, changes in gene expression of salmon gonadotropin-releasing hormone (sGnRH), chicken GnRH-II (cGnRH-II), somatostatin (SS) and pituitary adenylate cyclase activating polypeptide (PACAP) were analyzed during temperature- and spawning substrate-induced ovulation in goldfish. The results demonstrated that increases in PACAP gene expression during ovulation are best correlated with the GH secretion profile. These results suggest that PACAP, instead of GnRH, is involved in the control of GH secretion during ovulation. Increases of two of the SS transcripts during ovulation are interpreted as the activation of a negative feedback mechanism triggered by high GH levels. The results showed a differential regulation of sGnRH and cGnRH-II gene expression during ovulation, suggesting that sGnRH controls LH secretion, whereas cGnRH-II correlates best with spawning behavior. This conclusion is further supported by the finding that nonovulated fish induced to perform spawning behavior by prostaglandin F 2 treatment increased cGnRH-II expression in both forebrain and midbrain, but decreased sGnRH expression in the forebrain. teleost; neuroendocrine control; spawning behavior; gene expression Address for reprint requests and other correspondence: L. F. Canosa, Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Camino de Circunvalación Laguna Km 6, (B7130IWA) Chascomús, Provincia de Buenos Aires, Argentina (e-mail: lcanosa{at}intech.gov.ar )