Puerarin improve insulin resistance of adipocyte through activating Cb1 binding protein path

Abstract

To explore the molecular mechanism of puerarin (Pue) in improving insulin resistance through observing its effect on the insulin resistance of 3T3-Li lipocyte induced by free fatty acid (FFA). 3T3-L1 preadipocyte was induced by a culture solution containing insulin, isobutyo-menthyl-xanthine, and dexamethasone to mature lipocyte, and it was divided into six groups: the control group (normal cells), the model group (untreated model cells), and the four drug treatment group exposed to dimethyl biguanide (Met group), highdose puerarin (PueH group), low-dose puerarin (PueL group), and propylene glycol (PG group), respectively. Mature lipocytes in various groups, except those in the normal group, were established into insulin resistance model by FFA induction and treated respectively with corresponding drugs. Peroxisome proliferator-activated receptor-γ (PPAR-γ) mRNA expressions at the fourth, sixth, and eighth day were observed using reverse transcription polymerase chain reaction (RT-PCR); glucose transportation in various groups were observed by 2-deoxy-[(3)H]-D-glucose intake method; mRNA expression of Cb1 binding protein (CAP) was determined by RT-PCR; and glucose transporter-4 (Glut-4) transposition was detected by immune-fluorescence method. PPAR-γmRNA expression increased gradually, and it showed lower levels at the fourth, sixth, and eighth day in all treatment groups than that in the model group. Glucose transportation determination showed that the transportation in the model group was 2.23±0.63, significantly lower than that in the normal group 5.05 ± 0.66 (P<0.01); as compared with the model group, they were significantly higher in the PueH and the PueL groups. In addition, the CAP mRNA expression and membranous distribution of Glut-4 were higher in the two Pue treated groups than those in the model group, respectively. Pue could markedly improve the insulin resistance of 3T3-L1 lipocyte, which is realized possibly by way of inactivating CAP path, promoting Glut-4 transposition to cell membrane to increase the transportation of glucose.