ObjectiveTo investigate the expressions of glucose transporter-4 (GLUT-4) and secreted protein acidic and rich in cysteine (SPARC) in adipose tissue of Goto-Kakizaki (GK)/Wister rats after gastric bypass operation (GBP), and to explore the possible mechanism of GBP improving insulin resistance.MethodsHealthy male GK rats were randomly divided into diabetic operation group (DO group, underwent GBP), diabetic sham operation group (DS group, underwent sham-operation), and diabetic control group (DC group, received no-treatment), Wister rats were set as normal control group (NC group, received no-treatment). The weight, fasting blood glucose (FPG), fasting serum insulin (Fins), and HbA1c were measured before operation and at the 1st, 2nd, 4th, and 8th week after operation. Quantitative insulin sensitivity check index (QUICKI) was measured in before operation and at the 8th week after operation, and the expressions of GLUT-4 and SPARC protein in adipose tissues were measured by Western Blot method at the 8th week after operative too.Results① Weight: the weight of the DO group was lower than preoperative at the 2nd and 4th week after GBP (P<0.05), but increased to the normal level at the 8th week after GBP (P>0.05). The weight of the DO group was lower than those of the DS group, DC group, and NC group at the same time point of 2nd, 4th, and 8th week (P<0.05). ② FPG: the FPG level of the DO group was lower than preoperative at the 2nd, 4th, and 8th week after GBP (P<0.05), and lower than those of the DS group and the DC group from 2nd to 8th week after GBP (P<0.05). The FPG level between the DS group and the DC group had no statistical significance (P>0.05). ③ Fins: the Fins level of the DO group was higher than preoperative at the 2nd week after GBP (P<0.05), and decreased gradually at 4th and 8th week but not significantly differed from the NC group at the same time point. At the 2nd week after GBP, the Fins level of the DO group was higher than those of the DS group and the DC group (P<0.05), but there was no statistical significance between the DS group and the DC group (P>0.05). ④ HbA1c: the HbA1c level of the DO group started to decrease but there was no statistical significance between preoperative and all time after GBP (P>0.05). There was no statistical significance among the 4 groups at the 8th week after GBP (P>0.05). ⑤ QUICKI: at the 8th week, the QUICKI value of the DO group was higher than preoperative (P<0.05), and at the same time, the QUICKI value of the DO group and the NC group were higher than those of the DS group and the DC group (P<0.05), but there was no statistical significance between the DO group and the NC group (P>0.05), as well as the DS group and the DC group (P>0.05). ⑥ GLUT-4 protein and SPARC protein: the expression of GLUT-4 protein of the DO group was dramatically higher than those of the DC, DS, and NC group (P<0.05), and the expression of SPARC protein of the DO group was dramatically lower than those of the DC, DS, and NC group (P<0.05) at the 8th week. But the expressions of GLUT-4 and SPARC protein had no statistical significance among the DS, DC, and NC group at the 8th week after GBP (P>0.05).ConclusionGBP may improve and increase the sensitivity of insulin resistance by regulating the expressions of GLUT-4 and SPARC protein in adipose tissue of GK rats.
ObjectiveTo observe expressions of E3 ubiquitin ligase—mitsugmin53 (MG53) protein, MG53 mRNA, and insulin receptor substrate 1 (IRS-1) mRNA in skeletal muscle of non-obese type 2 diabetic mellitus (T2DM) rats after gastric bypass operation (GBP), and to investigate possible mechanism of GBP in improving insulin resistance.MethodsTwenty-four healthy male GK rats were randomly divided into diabetic operation group, diabetic sham operation group, and diabetic control group, 8 rats in each group; besides, 8 male Wistar rats were served as normal control group. The expressions of MG53 protein in skeletal muscle tissue were detected by using Western blot method on week8 after operation. The mRNA levels of IRS-1 and MG53 in skeletal muscles tissue were measured by RT-PCR methods on week 8 after operation.Results① The expressions of MG53 protein and MG53 mRNA in the diabetic sham operation group and diabetic control group were significantly higher than those in the diabetic operation group and the normal control group on week 8 after operation (P<0.05), respectively, which had no significant differences between the diabetic operation group and the normal control group (P>0.05), and between the diabetic sham operation group and the diabetic control group (P>0.05) on week 8 after surgery. ② Compared with the normal control group, the expression of IRS-1 mRNA was significantly decreased in the diabetic operation group, the diabetic sham operation group, and the diabetic control group (P<0.05), while there were no significant differences between the diabetic operation group, diabetic sham operation group, and the diabetic control group on week 8 after operation (P>0.05).ConclusionExpression of E3 ubiquitin ligase—MG53 protein in skeletal muscle tissue in T2DM rats following GBP is decreased, thus reduces the IRS-1 ubiquitin-degradation, increase the expression of IRS-1 protein in insulin signaling pathway of skeletal muscle tissue, and improve insulin resistance of skeletal muscle.