Effects Of Psidium Guajava Linn Leaves-15 (PGL-15) On Cell Differentiation And Metabolism Of Glucose, Fatty Acids And The Action Mechanisms In 3T3-L1 Preadipocytes

Objective:To observe the effects of PGL-15 on metabolism of glucose and fatty acids and cell differentiation of 3T3-L1 preadipocytes and study its possible mechanisms.Methods:1.3T3-L1 preadipocytes were induced by a classic cocktail of hormones method to differentiate into adipocytes. The differentiated adipocytes can be determined by oil red O staining. The successfully differentiated adipocytes were then divided into two large groups, with or without insulin. After treatment with different concentrations of PGL-15 (0.3μM,1μM,3μM,10μM,30μM), the glucose consumption of adipocytes were detected with glucose oxidase method.2. When the 3T3-L1 preadipocytes were induced to differentiate, all the cells were divided into vehicle control group, different PGL-15 groups (1μM,3μM,10μM, 30μM) and rosiglitazone (10μM) group and treated with these substances respectively. After oil red O staining, the results of 3T3-L1 adipocytes induction were analyzed by colorimetry.3. The successfully differentiated adipocytes were treated with different concentrations of PGL-15 (1μM,3μM,10μM,30μM), The free fatty acid (FFA) of the supernatants in each group was detected by enzyme linked immunosorbent assay.4. The 3T3-L1 preadipocytes were divided into vehicle group,30μM PGL-15 group and rosiglitazone (10μM) group. After treatment with the corresponding agents in each group for 72 hours, the mRNA expression of PPAR-y and GLUT-4 in adipocytes was detected by RT-PCR.Results:1. The 3T3-L1 preadipocyte induction model was established Successfully. Mature adipocytes had abundant cytoplasm, containing a large number of lipid droplets. Lipid droplets distributed around the nucleus to form a "ring-like" structure, and this was the typical morphology of adipocytes. 2. PGL-15 significantly enhanced glucose consumption in 3T3-L1 adipocytes. No matter whether there was insulin or not, the consumption of glucose in each PGL-15 group (1-30μM) were much more than that in the vehicle group (P<0.05 or P<0.01), and in the groups with insulin, this effect of PGL-15 on glucose consumption is more significant (P<0.05 or P<0.01). This effect of PGL-15 on glucose was in a dose-dependent manner.3. PGL-15 promoted the differentiation of 3T3-L1 adipocytes significantly. Within the concentration range of 3-30μM, the absorbance value of oil red O staining in each PGL-15 group was significantly larger than that in the vehicle group (P＜0.05 or P＜0.01).4. PGL-15 significantly inhibited the production of free fatty acid in 3T3-L1 adipocytes. Within the range of 3-30μM, the inhibition effects of PGL-15 on free fatty acid enhanced with the increase of the concentrations of PGL-15 (P<0.05 or P<0.01). The the free fatty acid level in the 30μM PGL-15 group was only 47.2% of the vehicle group. This was significantly lower than that in the vehicle group (P<0.01).5. Compared with the vehicle group,30pM PGL-15 significantly increased the mRNA expression of PPAR-y and GLUT-4 in 3T3-L1 adipocytes (P＜0.05).Conclusios:1. The 3T3-L1 preadipocyte induction model was established successfully with oil red O staining.2. PGL-15 promotes the differentiation of 3T3-L1 preadipocytes, increases the consumption of glucose in 3T3-L1 adipocytes, and reduce the level of the FFA in 3T3-L1 adipocytes.3. The increased mRNA expression of PPAR-y and GLUT-4, and the enhanced sensitivity to insulin of adipocytes may be involved in the possible mechanism of PGL-15.