Changes of plasma steroid concentrations associated with spontaneous or induced ovulation in yellow perch Perca flavescens

摘要: This study examined the changes in plasma steroids during natural (Experiment 1) and induced (Experiment 2) final maturation yellow perch Perca flavescens. In experiment 1, ovulating were stripped of eggs blood samples collected to determine concentrations testosterone (T), estradiol-17β (E2), 17,20β-dihydroxy-4-pregnen-3-one (17,20βP). Eggs from individual females weighed fertilized. Fertilization rate was determined at embryo eyed stage. experiment 2, randomly assigned one following treatment groups: (1) saline (0.7% NaCl), (2) des-Gly10[D-Ala6] LHRH-ethylamide (100 μg LHRHa/kg), (3) LHRHa plus 17,20βP (100 μg LHRHa/kg + 2 mg 17,20βP/kg). Fish injected intraperitoneally with two doses a two-day interval. Blood prior injections time ovulation/spawning T, E2, (free conjugated) determined. experiment 1, low recorded spawning. all surviving fish (5 5) released their spontaneously week injections. None control (0 ovulated this period, whereas only 1 3 eggs. group, E2 did not show significant differences over experimental T increased significantly. LHRHa, significantly after first injection but then declined ovulation/spawning. It also appears that conjugated its sulfated form. Mortality reached 62.5% group indicating severe. Thus, alone highly effective inducing ovulation perch.