The presence and ancestral role of gonadotropin-releasing hormone in the reproduction of scleractinian coral, Euphyllia ancora.
The objectives of this study were to investigate the presence of immunoreactive GnRH (irGnRH) in scleractinian coral, Euphyllia ancora, study its seasonal variation, and evaluate its biological activity. irGnRH was detected and quantified in coral polyps. The biological activity of coral irGnRH was tested on pituitary cells from black porgy by evaluating its ability to stimulate LH release. Coral extracts (10(-9)-10(-5) M irGnRH) as well as mammalian (m) GnRH agonist (10(-10)-10(-6) M) had a similar dose-dependent effect on LH release. Furthermore, GnRH receptor antagonist dose-dependently inhibited the stimulation of LH release in response to coral extracts (10(-5) M irGnRH) and mGnRH agonist (10(-6) M). Peak levels of irGnRH (10-fold increase) were observed during the spawning period in a 3-yr investigation. Significantly higher aromatase activity and estradiol (E2) levels were also detected during the period of spawning compared with the nonreproductive season. In in vivo experiments, mGnRH agonist time- and dose-dependently stimulated aromatase activity as well as the concentrations of testosterone and E2 in free and glucuronided forms in coral. In conclusion, our data indicate that irGnRH does exist in coral, with its ability to stimulate LH release in fish. Seasonal variations of coral irGnRH, with a dramatic increase during the spawning period, concomitant to that in aromatase and E2, as well as the ability of mGnRH agonist to stimulate coral aromatase, steroidogenesis, and steroid glucuronization suggest that irGnRH plays an important role in the control of oocyte growth and mass spawning in corals.
Twan
Wen-Hung
WH
Institute of Marine Biology, Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan.
Hwang
Jiang-Shiou
JS
Lee
Yan-Horn
YH
Jeng
Shan-Ru
SR
Yueh
Wen-Shiun
WS
Tung
Ying-Hsiu
YH
Wu
Hua-Fang
HF
Dufour
Sylvie
S
Chang
Ching-Fong
CF
D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D001141:Aromatase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000494:pharmacology; D012098:Reproduction / Q000187:drug effects / Q000502:physiology; D012621:Seasons; D014020:Tissue Extracts
D014020:Tissue Extracts; D007987:Gonadotropin-Releasing Hormone; D007986:Luteinizing Hormone; D001141:Aromatase