EFFECT OF D-LYS(6) SALMON SGNRH ALONE AND IN COMBINATION WITH DOMPERIDONE ON THE SPAWNING OF COMMON CARP DURING THE LATE SPAWNING SEASON

The effect of [D-Lys(6)] salmon gonadotropin-releasing hormone alone ( sGnRH) and in combination with domperidone, a dopamine antagonist, on the spawning of common carp, Cyprinus carpio, was investigated during the late spawning season (when mature fish stop spawning under natural conditions when males and females are put together). Fish were induce d to spawn by [D-Lys(6)]-sGnRH salmon gonadotropin-releasing hormone a nalogue (sGnRH-X) only when injected in combination with domperidone a t doses of 10 mu g kg(-1) and 20 mg kg(-1) body weight respectively. [ D-Lys(6)]-sGnRH-X alone did not induce spawning at a dose as high as 1 00 mu g kg(-1) body weight. Fish injected with domperidone alone did n ot spawn either. These results demonstrate that [D-Lys(6)]-sGnRH-X in combination with a dopamine antagonist is effective in inducing spawni ng during the late spawning season.