Effects Of Early Intervention On Structure And Function Of Liver Cell In KKay Mice And Discussion On Its Mechanism

Objective1、 To confirm the state of prediabetes accompanied by hyperinsulinemia in KKaymice.2、 To clarify the relationship between the non-alcoholic fatty liver disease and insulinresistance.3、 To investigate the effects of exercise and DPP-4inhibitor on improving hepaticsteatosis.Methods1、Preliminary test:KKay (4weeks old) mice were acclimated for1week and thenrandomly divided into two groups(PKND:normal diet、PKHD: high fat diet)，C57BL/6j (CND:normal diet) served as control group after acclimated for1week.through comparing the concentration of plasma glucose、insulin and status of glucosetolerance every week with group CND, The time of KKay mice getting into the stage ofPrediabetes with hyperinsulinemia can be identified.2、Formal test： At the stage of prediabetes with hyperinsulinemia, KKay mice wererandomly divided into control group(CG) and intervening group(IG), control group iscomposed of two subgroups：normal diet group（KND:n=10） and high fat dietgroup(KHD:n=8)，meanwhile, C57BL/6j mice (CND:n=9)served as normal controlgroup(NCG).the intervening group is composed of sports group(KE:swim40min/d,n=16) and medication group(KM:MK-0626,n=16),data(plama glucose、insulin weight、OGTT、IPITT) were collected during the8weeks’ intervening period。 Resultspreliminary test:identification of prediabetes with hyperinsulinemia: it’s found that，when themice are at7weeks old, the insulin level of KKay mice in group KHD have a sharpincrease compared with the group KND and CND,the differences are bothstatistically significant(P<0.05)，the fasting plasma glucose levels are still inrelatively normal range,and the random plasma glucose levels are still under thediagnostic criteria of diabetes, indicating7week-old KKay mice is a good modelfor prediabetes with hyperinsulinemia.1、 Formal test:2.1plasma glucose(unit:mmol/L): there are no significant difference between thegroups(CND:7.8±1.10、KND9.52±1.53、KE:7.92±1.00、KM:6.96±2.99)except the KHD (21.14±6.41)in FPG, but RPG is significantly differentbetween the intervening group(KE:10.1±2.23、KM:10.4±2.12) and controlgroup(NCD:9.6±0.83、KCD:20.2±3.59、KHD:35.2±1.10). Most importantly,after8weeks intervention, mice in the intervening group didn’t develop intodiabetes(RPG≥16.7mmol/L),while mice in the control group(KCD and KFD)all meet the diagnostic criteria of diabetes, especially in group KFD.2.2insulin(ng/ml):the level of insulin in the intervening group(KE:1.02±0.09、KM:1.17±0.14) is significantly higher than the controlgroup(KND:1.33±0.07、 KHD:3.00±0.46),indicating both of the interventioncould prevent the progressive damage of β cells.2.3OGTT and IPITT: compared with group CND、KE and KM,the status ofglucose tolerance in control group(KND and KFD) is much worse(P<0.01),and there’s no significant difference in the status of glucose tolerance betweenthe group CND and intervening group. Insulin sensitivity of mice in group CND is much better than that in intervening group(KE and KM) and controlgroup(KND and KFD),the differences are all statistically significant(P<0.05),while after8weeks intervention, mice in intervening group have abetter insulin sensitivity than that in control group(KND andKFD).(P<0.05)2.4weight(unit:g):there are no significant difference between the interveninggroup(KE:28.1±2.26、KM:28.4±2.02) and normal controlgroup(CND:27.3±2.43),while compared with the controlgroup(KND:32.8±2.48、KFD:41.8±1.98),the weight of mice in interveninggroup have a significant reduction(P<0.01).2.5liver weight(unit:g): liver weight in control group(KND and KFD) aresignificantly heavier than that of intervening group(KE:1.02±0.09、KM:1.17±0.14), and the differences are statisticalsignificant(P<0.01),reflecting that both of the intervention could improvehepatic steaotosis2.6concentration of DAG(ng/ml) and TG(IOD) in liver: compared with the controlgroup(KND:2.001±0.17、KFD:3.206±0.45), the concentration of DAG inliver cells of the intervening group(KE:1.221±0.25、KM:1.238±0.32) had asharp decrease (P<0.01).similarly, concentration of TG in liver cells of theintervening group(KE：53±7.6、KM：71±10.8) are obviously lower than thatin control group(KND:115±12.5、 KFD：247±15.3)，the difference areall statistically significant(P<0.01).2.7expression of PKCε and the phosphorylation of tyrosine of insulin receptorsubstrate-1(IRS-1tyr):the PKCε and the phosphorylation of tyrosine ofinsulin receptor substrate-1were measured by Immunohistochemical Stainingand western blot analysis,the level of PKCε in intervening group is less than that in control group(P<0.01), meanwhile compared with the expressionof IRS-1tyr,the level of IRS-1tyr in the intervening group have a obviouslyincrease(P<0.01)Conclusions1、7weeks old KKay mice were in the stage of prediabetes with hyperinsulinemia,High fat diet could promote the onset of the state of prediabtes withhyperinsulinemia.8weeks intervention (exercise and DPP-4I) with the drawingback of high fat diet could bring the dysfunction back to nearly normal.2、 KKay mice will spontaneously get fatty liver, especially in high fat diet group,early intervention could (exercise and DPP-4I) remarkably improve hepaticsteatosis.3、 Exercise and DPP-4I could reduce the synthesis of DAG in liver cells, and activityof PKCε,eventually improve the hepatic insulin resistance and glyeolipidmetabolism disorder...