Intervention Study Of Piperine On AMPK Signaling Pathway Upstream Targets In Insulin Resistance Model Rats

Objective:To observe the effects of piperine(PIP) on the glucose and lipid metabolic disorder in IR model rats, the insulin resistance(IR) model rats were induced by gaving high fat-sugar-salt diet and the effects of PIP on AMPKα and adiponectin(ADI), leptin(LEP) of the key factors in AMPK signal pathway, wish to explore the possible mechanism of PIP in improving IR.Methods:1. Using high fat sugar salt diet induced IR model. 90 male SD rats of weighing about 180-220 g were adaptive fed for 1 week and randomly divided into normal control group(15 rats)was given normal die and high-fat diet group(75 rats)fed with high-fat diet. After 4 weeks, the rats were randomly divided into 5 groups: model group, rosiglitazone group(ROG, 3mg/kg), PIP(15mg/kg) group, PIP(30mg/kg)group and PIP(60mg/kg). The model control group were given high fat diet, the drug intervention group fed with high fat diet combined with the treatments of PIP(15mg/kg, 30mg/kg and 60mg/kg)and ROG(3 mg/kg) with oral gavage(0.5ml/100 g.BW)for 8weeks. The normal control group and model group were given equal volume of solvent.2. The fasting blood glucose(FBG), serum insulin(FINS), insulin sensitivity index(ISI), glucose tolerance(OGTT), serum triglyceride(TG), serum free fatty acid(FFA), ambulatory blood pressure(BP) were measured every 4 weeks, the changes of body weight(BW) were observed every 2 weeks and the oral glucose tolerance test(OGTT) was observed after treatment with ROG and PIP for 8 weeks,which evaluated model and efficacy. PIP and ROG intervention in IR rats for 8 weeks, the m RNAlevels of AMPKαl, AMPKα2,Adiponectin and Leptin in liver tissue were detectd by RT-PCR. The protein levels of AMPKα, p-AMPK, ADI and LEP in liver tissue were tested using Western-blot and the content of AMP/ATP in liver was detected by HPLC.Results:1. High fat-sugar-salt diet fed rats 12 weeks, IR rats model was successfully established. PIP and ROG intervention IR rats for 8 weeks, compared with model group, FBG, FINS, TG, FFA, BP were decreased, ISI was increased,abnormal glucose tolerance was improved, the level of serum ADI was significantly increased and the levels of serum LEP and LEP/ADI was decreased.2. PIP and ROG intervention IR rats for 8 weeks, compared with IR model group,the expression of p-AMPK protein in liver was increased, AMP/ATP was also increased. The expression level of m RNA and protein of adiponectin in liver were increased and m RNA expression level of leptin was decreased, however leptin protein expression level had no significant change.Conclusion:PIP and ROG could improve the abnormal of glucose and lipid metabolism in insulin resistance model rats and showed improvement in IR. Its action mechanism may be related to the activation of AMPK, mainly through increasing p-AMPKαprotein expression levels, significantly increasing AMP/ATP ratio in liver tissue and raised the AMPK pathway upstream ADI m RNA and protein expression.