Effects of LHRH-A₂ on induced spawning and responses of plasma biochemical indices of Coilia nasus

Effects of LHRH-A₂ on induced spawning and plasma biochemical indices responses of Coilia nasus were studied in order to accomplish the artificial breeding protocol of this species. LHRH-A₂ was used in those farm-raised, two-year-old (over 2 winters) C. nasus to analyze the function of induced spawning. Plasma biochemical indices of female C. nasus were determined using radioimmunoassay and chemiluminescent. Our results indicated that the average mortality rate of C. nasus was 16.67% ± 3.34% while female fish were injected a dose of 30 μg LHRH-A₂/kg body mass and male fish were injected with a dose of the half of the amount for female fish. The time of oxytocin induction in those survival fish ranged from 21 to 24 h, the average spawning rate was 83.33% ± 3.34% and the average fertilization rate was 75.06% ± 6.19%. The concentration of plasma 17β- estradiol (E2), prolactin thyroxine (T4), cortisol, total protein (TP) and lactic acid (lactate) increased initially and decreased thereafter while the contents of triiodothyronine (T3), triglyceride (TG) and chloride ion (Cl^-) decreased constantly and the contents of alanine aminotransferase (ALT), aspartate aminotransferase (AST), osmotic pressure, potassium (K⁺) and sodium (Na⁺) increased continuously within 21 hours after the LHRH-A₂ was used. The results also indicated that high cortisol, total protein, triglycerides, osmotic pressure, sodium ions, and potassium ions plasma environment, and a low 17β- estradiol, prolactin, lactic acid, thyroxine, triiodothyronine, chloride, alanine aminotransferase and aspartate aminotransferase plasma environment occurred in those spawned C. nasus. The opposite results occurred in those not spawned individuals. In summary, the normal functions of liver and kidney of C. nasus were influenced by the manipulation of inducing spawning, which resulted in the fact that the regulation of oxytocin LHRH-A₂ to egg maturation was restricted. This preliminary study revealed the effect of LHRH-A₂ on induced spawning and responses of plasma biochemical indices of C. nasus and provided the basis for the commercially artificial breeding of C. nasus.