金雀异黄素对尼罗罗非鱼(Oreochromis niloticus)生长及生长轴相关基因表达的影响

Effects of genistein on the growth and gene expressions of the growth axis in the Nile tilapia Oreochromis niloticus

为了分析大豆异黄酮对鱼类生长的作用及其作用机理,以金雀异黄素含量为0、30、300μg/g和3 000μg/g的等氮、等能饲料饲喂尼罗罗非鱼幼鱼8周,分析了金雀异黄素对罗非鱼特定生长率、存活率、摄食率和饲料系数的影响,并利用Real-time PCR方法检测了尼罗罗非鱼垂体GH、肝脏GHRs和肝脏IGF-I m RNA表达的变化。结果表明,与对照组相比,30μg/g和300μg/g金雀异黄素对罗非鱼终末均重和特定生长率均未产生显著影响(P>0.05),3 000μg/g金雀异黄素显著降低了罗非鱼的生长(P<0.05),而各处理组对罗非鱼的摄食率和饲料系数均未产生显著影响(P>0.05)。随着金雀异黄素含量的增加,罗非鱼垂体GH和肝脏IGF-I m RNA表达量逐步降低,而且3 000μg/g组比对照组显著降低(P<0.05)。各处理组对罗非鱼肝脏GHR1 m RNA表达量没有显著影响,而3 000μg/g组显著降低了GHR2 m RNA表达量。以上结果表明,高浓度的金雀异黄素可通过抑制尼罗罗非鱼生长轴相关基因的表达,进而抑制鱼类的生长。

Soybean meal has been considered as important alternative ingredients for fishmeal. How-ever, isoflavones, as phenolic compounds, are rich in practical soybean meal products. The effect ofisoflavones on fish growth and its mechanism remain unclear. In this study, an 8-week feeding ex-periment was performed to evaluate the effects of dietary genistein on special growth rate, survivalrate, feed intake and feed efficiency ration of juvenile Nile tilapia（Oreochromis niloticus）, and GH、GHRs and IGF-I m RNA expression levels were further examined by real-time PCR. The resultsshowed that the final average weight and SGR of fish fed with diet containing 30, 300 μg/g genis-tein had no significant change compared with the control group, while those of the fish fed with3 000 μg/g genistein greatly reduced. No significant difference in feed intake and feed efficiency ra-tion were found among all dietary treatments. With the increase of the content of genistein, them RNA expression levels of pituitary GH and liver IGF-I gradually reduced, and those of fish fedwith diet containing 3 000 μg/g genistein greatly decreased. There was no significant difference inGHR1 m RNA expression levels among all dietary treatments with graded supplementation of genis-tein. However, the GHR2 m RNA expression levels were significantly inhibited by the diet containing3 000 μg/g genistein. These results suggested that the higher genistein could depress the growth offish through inhibiting the expression levels ofrelevant genes along the GH/IGF-I axis in Niletilapia（O. niloticus）.