The effect of gonadotropin-releasing hormone on growth hormone and gonadotropin subunit gene expression in the pituitary of goldfish, Carassius auratus.
The goldfish brain contains at least two forms of gonadotropin-releasing hormone (GnRH): sGnRH and cGnRH-II. In goldfish sGnRH and cGnRH-II are present both in the brain and pituitary, and exert direct effects via specific GnRH receptors stimulating growth hormone (GH) and gonadotropin hormone (GtH) synthesis and secretion. In this study, we investigated the effects of sGnRH and cGnRH-II on GtH subunit (alpha, FSH-beta and LH-beta) and GH mRNA levels in the goldfish pituitary in vivo and in vitro. Injection of goldfish with sGnRH or cGnRH-II (4 microg/fish) stimulated GtH-alpha, FSH-beta and LH-beta mRNA levels after 24 h. For in vitro studies, goldfish pituitary fragments were treated continuously for 12 h with 10(-7) M sGnRH or cGnRH-II. Both sGnRH and cGnRH-II stimulated GtH-alpha, FSH-beta, LH-beta and GH mRNA levels, however, cGnRH-II appeared to have a more pronounced effect. Similar experiments were carried out using cultured dispersed goldfish pituitary cells. In this study, treatments for 12 h with 10(-7) M sGnRH or cGnRH-II also stimulated GtH and GH gene expression. The present results provide a basis for the investigation of the signal transduction pathways that mediate GnRH-induced changes in GtH subunit and GH mRNA levels in the goldfish pituitary.
Klausen
C
C
Department of Biological Sciences, University of Calgary, 2500 University Drive N.W., Calgary, T2N 1N4, Alberta, Canada.
Chang
J P
JP
Habibi
H R
HR
D000818:Animals; D005640:Follicle Stimulating Hormone / Q000235:genetics; D037201:Follicle Stimulating Hormone, beta Subunit; D005786:Gene Expression Regulation / Q000187:drug effects*; D015292:Glycoprotein Hormones, alpha Subunit / Q000235:genetics; D006054:Goldfish / Q000235:genetics*; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D006062:Gonadotropins / Q000235:genetics*; D013006:Growth Hormone / Q000235:genetics*; D007986:Luteinizing Hormone / Q000235:genetics; D010902:Pituitary Gland / Q000187:drug effects* / Q000378:metabolism; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D037201:Follicle Stimulating Hormone, beta Subunit; D015292:Glycoprotein Hormones, alpha Subunit; D006062:Gonadotropins; D021122:Protein Subunits; D012333:RNA, Messenger; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D013006:Growth Hormone