EFFECT OF LUTEINISING HORMONE-RELEASING HORMONE ANALOGUE AND HUMAN CHORIONIC GONADOTROPIN ON OVULATION, PLASMA AND OVARIAN LEVELS OF GONADAL STEROIDS IN GREENBACK FLOUNDER RHOMBOSOLEA TAPIRINA
C.W. Poortenaar, N.W. Pankhurst-2000
Journal of the World Aquaculture Society, 31 (2) : 175-185 (from Current Contents)
Abstract :
Female greenback flounder Rhombosolea tapirina were treated with either des Gly(10) [D-Ala(6)] LHRH ethylamide (LHRH-a) at 50 or 100 mu g/kg intraperitoneal injection (ipi), LHRH-a cholesterol pellet (LNRH-a pellet) 100 mu g/kg implanted intraperitoneally, or human chorionic gonadotropin (hCG) 1,000 IU/kg ipi, Treatment with hCG, LHRH-a (50 mu g/kg) ipi and LHRH-a pellet increased the total number of ovulations above control levels. LHRH-a (100 mu g/kg) ipi was not consistently more effective than the control and both LHRH-a (50 mu g/kg) ipi and LHRH-a pellet induced more ovulations than LHRH-a (100 mu g/kg) ipi. Of those fish that ovulated, most ovulated more than twice, and most ovulations occurred at daily intervals. Oocyte diameters increased and oocyte stage advanced significantly in response to all exogenous hormone treatments. This was accompanied by increases in plasma and ovarian levels of 17 beta-estradiol (E-2), and in most cases, plasma and ovarian levels of testosterone (T). Plasma and ovarian levels of 17,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta P) were not consistently elevated in association with reproductive events.
(Natl Inst Water & Atmospher Res Ltd, POB 109-695, Auckland, New Zealand)
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