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This Article Full Text Full Text (PDF) All Versions of this Article: 295/6/R1815    most recent 00166.2008v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Canosa, L. F. Articles by Peter, R. E. Search for Related Content PubMed PubMed Citation Articles by Canosa, L. F. Articles by Peter, R. E.

ENDOCRINE PHYSIOLOGY AND METABOLISM

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

Luis Fabián Canosa,^1,2 Norm Stacey,¹ and Richard Ector Peter^1,3,

¹Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada; ²Instituto de Investigaciones Biotecnológicas-Instituto Tecnológico de Chascomús, Buenos Aires, Argentina; and ³Bamfield 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 F₂ treatment increased cGnRH-II expression in both forebrain and midbrain, but decreased sGnRH expression in the forebrain.

teleost; neuroendocrine control; spawning behavior; gene expression