Effect and mechanism of TSH on GLUT4 in skeletal muscle of diabetic rats

BACKGROUND: To explore the effect of TSH on skeletal muscle tissue GLUT4 and its possible mechanism in diabetic rats.METHODS: Wistar rats were divided into four groups: group Control, T2DM, T2DM+T4 and T2DM+T4+TSH, in which group T2DM, T2DM+T4 and T2DM+T4+TSH were given subcutaneous injection of T4 to stabilize the level of serum thyroxine and subcutaneous injection of TSH after the thyroid tissue of diabetic rats was removed. After that, blood glucose, glucose tolerance, GLUT4, p38 and MEF2A levels of skeletal muscle tissue were measured.RESULTS: In IPGTT, the glucose tolerance of group D was better than that of group C at 60 min, 90 min and 120 min, but there was no significant difference (P>0.05). The concentration of T4: there was no significant difference in the concentration of T4 between the two groups (P>0.05). The concentration of TSH: the concentration of TSH in group D was significantly higher than that in group B and C (P<0.05). The increase of TSH concentration was positively correlated with the improvement of glucose tolerance. The level of TSH was positively correlated with the expression of GluT-4; the level of TSH was positively correlated with the expression of p-MEF2A; the level of TSH was negatively correlated with the expression of p-p38; while the level of TSH was not correlated with the expression of MEF2A and p38.CONCLUSIONS: In diabetic rats, TSH can improve insulin resistance by increasing the level of GLUT4 in skeletal muscle, which affects the level of GLUT4 by increasing p-MEF2A and decreasing p-p38MAPK.