葡萄糖转运载体4、葡萄糖转运载体2在罗非鱼不同组织中的表达及其对注射葡萄糖的响应

Expression of Glucose Transporter 4 and Glucose Transporter 2 in Different Tissues of Tilapia and Its Response to Glucose Injection

本试验旨在研究葡萄糖转运载体(GLUT)4、CLUT2在罗非鱼不同组织中的表达及其对注射葡萄糖的响应。利用实时荧光PCR的方法从罗非鱼肌肉中克隆得到GLUT4的c DNA片段,其Gen Bank登录号为JN900493,大小为603 bp,编码200个氨基酸。通过实时荧光半定量PCR检测,比较G LUT4和G LUT2在肌肉、心脏和肝脏中的表达差异,结果显示G LUT4在肌肉和心脏中的表达量较高,而在肝脏中GLUT4的表达量则较低;GLUT2在肝脏中的表达量最高,而在肌肉和心脏中则表现出极低的表达量。选取体重约为80 g的罗非鱼150尾,随机分2个组,每组3个重复,每个重复25尾。试验组腹腔注射葡萄糖(每100 g体重30 mg),对照组以相同剂量腹腔注射0.7%的无菌生理盐水。在注射前(0 h)和注射后的1、3、6和12 h分别进行采样测定。结果显示:1)试验组血浆葡萄糖含量在注射葡萄糖后1 h时达到最高,并显著高于对照组(P<0.05),而后开始下降,3 h后恢复到正常水平;试验组血浆胰岛素含量在葡萄糖注射后3 h时达到最高,并显著高于对照组(P<0.05),而后开始下降,12 h后恢复到正常水平。2)试验组肌肉中GLUT4 mRNA的相对表达量在注射葡萄糖后3 h开始升高,在12 h时达到最高,此时显著高于对照组(P<0.05);试验组心脏中GLUT4 mRNA的相对表达量在注射葡萄糖后1 h即较对照组显著升高(P<0.05),而后随着时间的推移逐渐降低,在6 h时恢复到正常水平;注射葡萄糖后,肝脏中GLUT2 mRNA的相对表达量没有显著变化(P>0.05)。结果表明,注射葡萄糖后瞬时升高了罗非鱼的血浆葡萄糖含量,相对于血浆葡萄糖含量的升高,血浆胰岛素含量的升高相对延迟,而肌肉中GLUT4 mRNA相对表达量的提高又延迟于胰岛素含量的升高,从而加重了罗非鱼对葡萄糖的代谢负担。

This experiment was conducted to determine the expression of glucose transporter（ G LUT） 4 and G LUT2 in different tissues of tilapia（ Oreochromis niloticus） and its response to glucose injection. A partial c DNA of G LUT4 was cloned from muscle of tilapia by real-time PCR method. The partial c DNA of G LUT4（ Gen Bank accession No. was JN900493） was 603 bp,and encoded 200 amino acids. The expression differences of G LUT4 and G LUT2 in muscle,heart and liver were compared by semi-quantitative real-time PCR detection. The results showed that the expression level of G LUT4 in muscle and heart was higher,while that in liver was lower; the expression level of G LUT2 in liver was higher,while that in muscle and heart was very low. A total of 150 tilapia with the body weight about 80 g were randomly allotted to 2 groups with 3 replicates per group and 25 fish per replicate. In experimental group,glucose with the dose of 30 mg per 100 g body weight was injected intraperitoneally into the fish,while the fish in control group were injected with 0.7% sterile saline water as the same dose and method. Samples were collected and measured before infection（ 0 h） and at 1,3,6 and 12 h after infection,respectively. The results showed as follows： 1） the maximum plasma glucose content of experimental group was observed at 1 h after injection which was significantly higher than that of control group（ P〈 0.05）,and then began to decreaseed and returned to normal level at 3 h after injection;the maximum plasma insulin content of experimental group was observed at 3 h after injection which was significantly higher than that of control group（ P〈 0.05）,and then began to decrease and returned to normal level at12 h after injection. 2） The relative expression level of G LUT4 mRNA in muscle of experimental group began to increase at 3 h after injection,and reached the maximum at 12 h after injection which was significantly higher than that of control group（ P〈 0.05）; the relative expression level of G LUT4 mRNA in heart at 1 h after injection of experimental group was significantly higher than that of control group（ P〈 0.05）,and then decreased gradually with the passage of time and return to normal level at 6 h after injection; the relative expression level of G LUT4 mRNA in liver had no significant change after glucose injection（ P〉 0.05）. The results suggest that injecting glucose can instantaneously increase the plasma glucose content of tilapia,but the increase of plasma insulin content is relatively delayed compare with plasma glucose content,and the relative expression level of G LUT4 mRNA in muscle showa delayed increase relative to plasma insulin content,then the burden of glucose metabolism in tilapia is increased.