LHRH-A和5-HT拮抗剂的协同作用对草鱼鱼种生长激素分泌活动和生长的影响

Effects of LHRH-A and 5-HT antagonist on growth hormone secretion and body growth acceleration in juvenile grass carp(Ctenopharyngodon idellus)

促性腺激素释放激素(LHRH)能够促进鱼类生长激素(GH)的释放,而5-羟色胺(5-HT)抑制鱼类GH的释放。将促性腺激素释放激素类似物(D-Ala6-Pro9-NEt-LHRH,LHRH-A,5μg/g饵料)和5-HT的特异性拮抗剂盐酸米安色林(Mianserin hydrochloride MIS,0.5 mg/g饵料)拌在饵料中投喂草鱼(Ctenopharyngodon idellus)鱼种6周,可促使血清GH水平显著提高,并使食物转化率升高,生长速率加快,肥满度增加;且两者促生长的协同作用比单独使用LHRH-A或MIS好。对草鱼鱼种体质和主要生化组成的分析表明,LHRH-A和MIS的促生长作用既没有引起鱼体可食部分的蛋白质含量减少,也不会使脂肪、水分含量和内脏质量增加,因而其促进的是草鱼种苗均衡、正常的生长。由此说明在生产应用中,使用高活性的神经内分泌因子,通过拌饵方式投喂对于促进养殖鱼类苗种的生长、缩短养殖周期,是有效而且安全的。

LHRH-A （D-Ala6-Prog-NEt-LHRH, an analog of GnRH） and Mianserin hydrochloride （MIS, 5- HT antagonist） was orally administrated as a feed stuff additive to enhance the growth of juvenile grass carp （Ctenopharyngodon idellus）. The results demonstrated that feeding LHRH-A （5 μg/g diet）, in combination with MIS （0.5 mg/g diet） twice daily for 6 weeks,resulted in higher levels of serum GH, food conversion ratio, growth rate and condition factor than those feeding LHRH-A or MIS alone. Meanwhile, growth enhancement of juvenile grass carp by feeding LHRH-A and MIS were normal, which did not have any effect on visceral weight and body composition of protein, lipid and moisture. The study confirmed that by dietary delivery, some neuroendocrine factors, such as LHRH-A and MIS, which stimulate dendogenous GH secretion, could be absorbed and transported into the circulation immunoactively and bioactively, and subsequently resulted in an increase in serum GH level, food conversion ratio, growth rate and condition factor of juvenile grass carp. It has been demonstrated that administration of some neruoendocrine factors in diet on large scale to accelerate the growth rate of cultured fish has promising potential. [Journal of Fishery Sciences of China, 2007,14 （3） ： 473 - 477 ]