β-酪啡肽-7对大鼠生长、相关激素及生长素受体mRNA表达的影响

目的: 探讨β-酪啡肽-7(β-CM-7)对大鼠生长、生长相关激素和生长因子以及生长素受体(GHR)mRNA表达的影响。方法: 将30只生长期雄性SD大鼠随机分为对照组和实验组,分别被灌饲生理盐水和β-CM-7,并记录大鼠日采食量。饲养1个月后检测大鼠的增重情况,应用放射免疫法测定血清中生长相关激素和生长因子的含量,用相对定量RT-PCR法研究两组大鼠肝脏GHR mRNA表达水平的差异。结果: 实验组大鼠与对照组比,增重有提高的趋势,增重率提高8.67%。实验组大鼠的日采食量增加了13.08%(P<0.05)。与对照组相比,实验组大鼠血清中生长激素(GH)和胰岛素显著或极显著升高(P<0.05或P<0.01),三碘甲腺原氨酸(T3)和胰岛素样生长因子-I(IGF-I)有升高趋势,而甲状腺素(T4)有下降趋势。实验组大鼠肝脏的GHR mRNA表达水平显著提高(P<0.05),增加了19.83%。结论: β-CM-7能促进生长期大鼠的生长,增加采食量,影响生长相关激素和生长因子的分泌,并且上调肝脏GHR mRNA表达水平,从而增加生长激素的敏感性。

EFFECT OF β-CASOMORPHIN-7 ON GROWTH,GROWTH-RELATED HORMONE AND GHR Mrna EXPRESSION IN RATS

Objective:To investigate the effect of β-casomorphin-7 on growth, growth-related hormones, growth factor and liver growth hormone receptor (GHR) mRNA expression in rats. Methods:Thirty male Sprague-Dawley (SD) rats were randomly divided into control and experimental groups, which were administrated with physiological saline and -casomorphin-7 (β-CM-7) respectively via gastric cannula for 30 d. Daily feed intakes were recorded in rats. After 30 d, weight gains were calculated in rats. The serum growth-related hormones and growth factor levels were measured by RIA in two groups, and the liver expression of liver GHR mRNA was detected by semi-quantitative RT-PCR in control and experimental groups. Results: The weight gain of rats in experimental group was obviously higher than that in control group, increased by 8.67%. Compared with control group, the feed intake of rats was improved by 12.84% (P<0.05) in experimental group. The serum growth hormone (GH) and insulin concentrations of rats were significantly or very significantly higher for experimental group vs. control group (P<0.05 or P<0.01). Triiodothyronine (T3) and insulin-like growth factor-I (IGF-I) levels of rats in experimental group trended to rise in contrast with control group, but tetraiodothyronine (T4) concentration in experimental group was lower. The results also showed the liver GHR mRNA expression of rats was significantly increased by 19.83% in experimental group opposed to control group (P<0.05). Conclusions:β-CM-7 could promote rats?growth, influence growth-related hormones and growth factor levels in rat serum, and up-regulate GHR mRNA expression in order to increase sensitivity of GH in rat liver.