IGF—ImRNA在不同年龄鲤表达的差异和LHRH—A对IGF—ImRNA表达的影响

利用RNA酶保护法对7月龄性未成熟幼鲤和2龄性成熟鲤组织胰岛素样生长因子-I（IGF-I）mRNA的表达水平进行测定，结果表明成鱼肝和肾脏组织IGF-ImRNA的丰度显著高于幼鱼，对鲤成鱼和幼鱼腹腔注射促性腺激素释放激素类似物（LHRH-A，D-Ala^6-Pro^9-NEt-LHRH)使血清生长激素（GH）水平和肝组织IGF-ImRNA水平都显著升高，而成鱼生殖腺IGF-ImRNA的丰度比对照组显著增加，研究结果提示鲤在不同发育阶段肝组织IGF-ImRNA的丰度比对照组显著增加，研究结果提示鲤在不同发育阶段肝组织IGF-ImRNA的表达存在差别，其中2龄成鱼大于7月龄幼鱼；LHRH-A可能通过刺激垂体GH的释放间接促进肝组织IGF-ImRNA的表达，亦可能通过某种未知途径刺激生殖腺IGF-ImRNA的表达。

DIFFERENTIAL EXPRESSION AND EFFECT OF LHRH-A ON EXPRESSION OF IGF-I mRNA IN JUVENILE AND ADULT COMMON CARP (CYPRINUS CARPIO)

IGF I mRNA expression of 7-month old juvenile and 2-year old adult common carp were determined by RNase Protection Assay. Results showed that the hepatic IGF I mRNA level of adult fish was significantly higher than that of 7-month old juvenile fish; while in other tissues there was no significant difference between the two fish groups except that kidney IGF I mRNA level of adult fish was higher than that of juvenile fish. After twice i. p. injections of LHRH A, the levels of serum GH and hepatic IGF I mRNA in fish of both ages increased greatly, and the IGF I mRNA level of gonadal tissue in adult fish increased when compared with controls. No changes in amount of IGF I mRNA in other tissues were observed after injections of LHRH A. It is suggested that the level of hepatic IGF I mRNA expression changes with different developmental stages; LHRH A may stimulate the production of IGF I by promoting the synthesis and release of pituitary GH; and probably, LHRH A stimulates the IGF I expression in gonads by other mechanism.