外源激素对花鲈(Lateolabrax japonicus)血清IGF-1含量及肝脏IGF-1和IGFBP-1 mRNA表达的影响

Effects of Exogenous Hormone Injection on the Serum IGF-1 and the Expression of IGF-1 mRNA and IGFBP-1 mRNAin the Liver of Japanese Sea Bass (Lateolabrax japonicus)

中文关键词: 花鲈  类胰岛素生长因子1；类胰岛素生长因子结合蛋白1；促黄体激素释放激素；人体绒毛膜促性腺激素

英文关键词: Japanese sea bass (Lateolabrax japonicus)  IGF-1  IGFBP-1  LHRH-A3  HCG

中文摘要:

      对花鲈(Lateolabrax japonicas)成鱼腹腔注射促黄体激素释放激素类似物(LHRH-A3)和人体绒毛膜促性腺激素(HCG)，利用放射性免疫激素测定方法(RIA)检测了花鲈血清中类胰岛素生长因子(Insulin-like growth factor 1, IGF-1)在注射后6、12、24、48 h内的变化情况，同时还利用荧光实时定量PCR技术检测了花鲈肝脏中IGF-1和类胰岛素生长因子结合蛋白1(Insulin-like gro¬wth factor-binding protein 1, IGFBP-1)mRNA的相对表达量的变化情况。结果表明，注射LHRH-A3的花鲈血清中IGF-1的含量在24 h后出现了明显的降低(P < 0.05)，而花鲈肝脏中IGF-1 mRNA的相对表达量在注射6 h后较对照组明显升高(P < 0.05)，而肝脏中IGFBP-1 mRNA的相对表达量则呈现下降趋势。注射HCG的花鲈血清中IGF-1的含量在注射后12 h出现了明显降低(P < 0.05)，24 h后血清中IGF-1含量持续降低。肝脏中IGF-1 mRNA的相对表达量在注射后的24 h内均保持稳定，而在处理后的48 h出现了显著上升(P < 0.05)。肝脏中IGFBP-1 mRNA的相对表达量在注射后12 h检测到显著升高(P < 0.05)。研究结果表明，LHRH-A3和HCG均可以通过直接或间接的刺激作用来触发花鲈IGF系统的应答反应，但是其中具体机制尚不明了。

英文摘要:

      Japanese sea bass (Lateolabrax japonicus) is a highly profitable fish in aquaculture industry. They are widely cultivated in the southern and northern coastal provinces in China. The mechanisms underlying the effects of steroids hormones on the growth of this fish are still unclear. In this study, we investigated the effects of luteinizing hormone releasing hormone-A3 (LHRH-A3) and human chorionic gonadotropin (HCG) on the insulin-like growth factor (IGF) family genes of Japanese sea bass. We measured the level of serum IGF-1 using Radiate Immuno Assay (RIA) at 6 h, 12 h, 24 h and 48 h after the intraperitoneal injection of the hormones. In the meanwhile, we also applied fluorescent real-time quantitative RT-PCR to examine the levels of IGF-1 mRNA and insulin-like growth factor-binding protein 1 (IGFBP-1) mRNA in the liver. We divided the subjects into three groups — the PS (Physiological Saline) group, the LHRH-A3 (3 µg/kg) group, and the HCG (1000 U/kg) group. In the LHRH-A3 group, the serum IGF-1 level decreased significantly at 24 h after the injection of LHRH-A3 (P < 0.05), and the level of IGF-1 mRNA in the liver was higher than the PS group at 6 h (P < 0.05); the level of IGFBP-1 mRNA showed a constant decreasing pattern in 6 h after the injection. In the HCG group, the serum IGF-1 level decreased significantly at 12 h after the injection (P < 0.05); the level of IGF-1 mRNA dropped at 48 h after injection (P < 0.05); the level of IGFBP-1 mRNA increased significantly at 12 h. In conclusion, our results showed that the injection of LHRH-A3 and HCG caused dramatic increase in the mRNA level in the liver and IGF-1 level in the serum. It is most likely that LHRH-A3 and HCG can trigger the response of IGFs system in Japanese sea bass directly or indirectly. Future study will be needed to reveal the underlying mechanisms.