Insulin-sensitizing Agent Influence Liver And C-Jun N-terminal Kinase Signalling Pathway In Obese Diabetic Mice

Objective :â‘ .To analyse pathologic changes in the liver of experimental diabetic rats;â‘¡.To study activation of JNK and transcription of JNK signalling pathway in hepatic of diabetic rat;â‘¢.To investigate the effects of insulin-sensitizing agent on JNK signalling pathway in hepatic ,induced by diabetic concomitancy insulin resistance.Methods :T2DM with insulin resistance rat model was established by high fat/ high glucose diet. Four groups of diabetic rat included normal control (NC, n = 12) ,models(DM,n=9),models with Pioglitazone (Pioglitazone,10mg/kg/d,PIO,n=10) and with Metformin(Metformin,160mg/kg/d,MET,n=11) treatment for 6 weeks, then sacrificed by dislocating the cervical vertebrae.The liver specimens were harvested. Hematoxylin and eosin-staining, and expression of JNK, p-JNK protein was measured by immunohistochemical technique.Reverse transcription polymerase chain reaction (RT-PCR) were used to evaluate JNK mRNA of liver expression. The level of JNK, p-JNK proteins of liver was analyzed by Western blot.Results:â‘ Pathological changes of liver structure:We observed the pathological changes of rat liver tissue in the diabetes mellitus group (DM), and found that,compared with normal control group(NC), hepatic cells were swollen and developed granular degeneration, fatty degeneration;hepatic cells appeared many necrotic areas, inflammatory cell infiltration. Compared with DM group, in the PIO and MET groups , liver cell cords were clear, liver antrum almost recovered to normal, hepatic cells developed slightly granular degeneration.â‘¡Immunol histochemistry(IHC):There was was little JNK and P-JNK expression in the liver of NC group. JNK, p-JNK proteins expression and the ratio of p-JNK protein expression level to JNK protein expression level (p-JNK /JNK) of liver in DM group increased dramatically when compared with that in NC group, increased when compared with that in PIO group and MET group;that in PIO group and MET group increased in contrast to that of NC group ,with statistical significance(P<0.05). That in PIO group compared with MET group had no statistical significance(P> 0.05).â‘¢RT-PCR: There was almost no JNK mRNA expression in NC group.The JNK mRNA expression in DM group increased dramatically when compared with that in NC group.JNK mRNA expression level of PIO group and MET group decreased remarkably in contrast to that of DM group ,but increased in contrast to that of NC group..â‘£Western Blot: P-JNK and JNK protein expression of DM group increased dramatically when compared to that of NC group,and the difference was statistically significant(P<0.05),increased when compared with that of PIO group and MET group,with statistical significance (P<0.05).The ratio of JNK protein expression level to P-JNK protein expression level in DM group increased dramatically when compared to that of NC group,and the difference was statistically significant(P<0.05),increased when compared with that of PIO group and MET group,with statistical significance(P<0.05).JNK and P-JNK protein expression level and their ratio in PIO group and MET group increased when compared with that of NC group,and there was statistical significance(P>0.05).Conclusions :High fat/ high glucose diet and T2DM would induce that hepatic cells were swollen and developed granular degeneration, fatty degeneration;hepatic cells appeared many necrotic areas,inflammatory cell infiltration.Treatment of PIO and MET can decrease the liver damage induced by T2DM in rats. This effect may be attributed to the inhibition of the JNK signalling pathway activation to decrease JNK , p-JNK expression.