猪Ghrelin基因表达质粒构建及其促生长作用

Construction of pGhrelin Eukaryotic Expression Plasmid and Investigation of Its Somatotropic Efficacies

通过RT-PCR获得猪Ghlelin基因cDNA片段,克隆入pcDNA3.1(+)质粒中构建真核表达质粒pcDNA-pGhl,并将该质粒注射到大鼠和新西兰兔后腿肌肉中,以研究pGhlelin真核表达质粒对动物生长和血液相关激素分泌的影响。大鼠试验表明:pcDNA-pGhl在注射初期的1个月内有增加大鼠体重及在整个试验期有降低料重比的趋势。在注射质粒后第6天,试验组个体增重提高10.6%,差异显著;饲料转化率提高10%,差异极显著。新西兰兔试验表明:试验组血液GH水平一直高于对照组,且在注射后2周高出35%,同时随着GH浓度的增加,血液中SS的浓度相应升高。注射重组质粒pcDNA-sGhl有增加血浆GH和SS水平趋势。以上结果表明,Ghrelin基因真核表达质粒通过促进GH的分泌促进生长,但其促生长效能较短暂,可能是由于同时促进生长抑素分泌。

The full length cDNA of pGhrelin was obtained by RT-PCR and was subsequently inserted into pcDNA3. 1 （＋） to construct eukaryotic expression vector pcDNA-pGhl. The growth promoting efficacies of pcDNA pGhl were examined by weight gains in rats and secretions of GH and SS in rabbits. Growth and feed efficiency were both improved after the injection of pcDNA-pGhl, that by day 6 post in jection the body weight in the treatment rats was 10. 6% higher （P〈0. 05）, and the feed/gain ratio was also more significantly reduced by 10% （P〈0. 01） than in the control rats. Injection of 600 μg pcDNA- sGhl plasmid into rabbit slightly increased blood GH concentrations by 350//oo compared with the controls at 2 weeks post-injection（P=0. 108 6）, while at the same time increased somatostatin concentration which by day 35 was significantly higher （P〈0. 05） than in the non-treated control rabbits. These re suits demonstrated that eukaryotic expression plasmid of Ghrelin stimulates growth by stimulation of GH secretions, but the growth promoting efficacy was short lived by the simultaneous stimulation of somatostatin secretion.