鲤、鲢、草鱼促性腺激素垂体含量及血清浓度日周期变化的关系

ON THE MODE OF PITUITARY GONADOTROPIN RELEASING IN CARPS

摘要:

淡水鱼类有的在池塘中能自然产卵,如鲤(Cyprinus carpio)、鳊(Megalobrama amblyocep-hala)等,有的鱼必须给予外源激素才能产卵,如青鱼(Mylopharyngodon piceus)、草鱼(Cteno-pharyngodon idellus)、鲢(Hypophthalmichghys molitrix)、鳙(Aristichthys nobilis)。为探索产生这种差别的原因,本文用放射免疫方法测定了鲤、鲢、草鱼产卵季节促性晚激素(GTH)在垂体中的含量和血清中浓度的日周期变化。 鲤、草、鲢24小时血清GTH浓度呈脉冲式波动,白天出现3-4次高峰,夜间雌的有时还有一次高峰。鲤高峰值多在20-40毫微克/毫升血清,峰谷在5-15毫微克/毫升血清,GTH浓度始终保持高水平,而草、鲢高峰值仅2—8毫微克/毫升血清,峰谷0.1—1毫微克/毫升血清。草、鲢每只垂体 GTH 含量较高,约为鲤的2.5倍。以上数据说明草、鲢垂体释放GTH比鲤少。这种差别可能反映了在池塘中鲤能自产,而草、鲢不能自产的原因。 草鱼垂体离体培养,白天和黑夜取材,对LRH-A的反应性不同,白天的反应较弱,对此进行了讨论。

Abstract:

The diurnal fluctuation of serum gonadotropin concentration during the spawningseason was studied in the common carp and two species of the "domestic carps", the grasscarp (Ctenopharyngodon idellus)and the silver carp (Hypophthalmichthys molitrix). In allthe species similar rhythmic surges are observed, mainly occurring in daytime. However,the peak and valley values of the serum gonadotropin concentration of the commoncarp (20-40 vs. 5-15 ng/ml)are considerably higher than those of the grass and silvercarps (2--8 vs. 0. 1--1 ng/ml). This difference suggests that the secretion of gonadotropinof common carp is high enough for modulating its reproductive activity while, the grassand silver carps cannot spawn, unless exogeneous hormones are given. In the presence of LRH--A, the in vitro GTH relcases of the pituitaries collected inthe night is greater than thet in daytime. The significance of this phenomenon isdiscussed.