The Research Of Skeletal Muscle-derived Adiponectin Through P38MAPK Signaling Pathways To Affect The Expression Of GLUT4in Skeletal Muscle Insulin Resistance Model

SummaryObjective: To establish palmitic acid-induced insulin resistance model in rat’s L6muscle cells,we cultured L6muscle cells in vitro and induced their differentiation andmaturation. We give the different conditions to explore muscle-derived adiponectin(APN) influenced the expression of GLUT4in the model of insulin resistance, and therole of p38MAPK signal pathway.Methods:(1) We cultured rat L6muscle cells in vitro and induced to differentiate intomature skeletal muscle L6cells, treated with various concentration（0.2、0.4、0.6、0.8、1.0mmol/L）of palmitic acid,and measured supernatant glucose concentration atdifferent times(2,4,8,12,24,36h), GOD-POD were used to detect residual glucoseconcentration in each group medium to observe the influence of different concentrationsof PA on glucose uptake in L6cells. Therewith judge whether the insulin resistancemodel was established or not.(2) According to the different conditions of intervention,the experiment was divided into four groups: NC group (control group,rat L6cellsgroup); NC+SB group (control plus blocker SB203580group); IR group (insulinresistance model group); IR+PIO group (insulin resistance model plus pioglitazonegroup). Protein expression levels of the APN, p-p38MAPK and GLUT4were detecteddifferently by Western blot in four groups.Results:(1) We found,0.4mmol/L palmitic acid for12，24，36hours or0.6，0.8mmol/L palmitic acid for8，12，24，36h, or1.0mmol/L palmitic acid for4，8，12， 24，36h，the supernatant content of glucose compaired with the NC group, it wassignificantly higher than it(P <0.05). On the account of this, the insulin resistancemodel was established.（2）Western blot showd:①Compared with NC group, Theprotein expression of APN and GLUT4in IR group was significantly lower (P<0.05);the expression of p-p38MAPK was decreased,but the difference was notstatistically significant (P>0.05).②Compared with NC group, The expression ofp-p38MAPK and GLUT4in NC+SB group was significantly lower (P <0.05);theexpression of APN was decreased,but the difference was not statistically significant (P>0.05).③Compared with IR group, The expression of APN, p-p38MAPK andGLUT4in IR+PIO group were increased, the difference was statisticallysignificant (P <0.05).Conclusion:（1）L6muscle cells from rats were cultured and induced by a certainconcentration and a certain time palmitic acid stimulation, it can create insulinresistance model;（2）L6muscle cells from rats can secrete and express adiponectin andaffect the expression of skeletal Muscle’s GLUT4;（3）Muscle-derived adiponectin mayincrease GLUT4expression, which p38MAPK signal pathway maybe one of theimportant signal pathway（;4）Pioglitazone can increase the secretion of APN in L6cells.Which improve insulin sesitivity maybe relate to p38MAPK signal pathway.