Abstract:

Objective   To examine the effect of glucagon-like peptide-1 (GLP-1) on the levels of fatty acid binding protein 4 (FABP-4) and carnitine palmitoyltransferase 1A (CPT-1A) during 3T3-L1 preadipocyte differentiation process. Methods   In this paper, the traditional “Cocktail method” was adopted to induce the 3T3-L1 preadipocyte differentiation and 1×10-8 mol/L GLP-1 was added to the medium. At the 6th day and the 8th day of differentiation, Oil Red O staining was used to examine the lipid accumulation; RT-PCR and Western blotting were employed to test the levels of FABP-4 and CPT-1A. Results   ①It is found that about forty percent of the cells appeared lipid droplets at the 6th day; about eighty percent of the cells had differentiated to mature adipocytes at the 8th day. ②The results of Oil Red O staining showed that the lipid accumulations in GLP-1 group were slightly increased at the 6th day while modestly decreased at the 8th day (both P>0.05), as compared to the control group. ③RTPCR results indicated that the mRNA level of FABP-4 in GLP-1 group was significantly increased at the 6th day and the 8th day. And the mRNA level of CPT-1A was also enhanced at the 8th day (P<0.05). ④ Western blotting results showed that the protein expression of FABP-4 in GLP-1 group was improved markedly at the 6th day and the 8th day (P<0.05). The protein level of CPT-1A in control group was not changed significantly. While it was greatly increased in the cells treated with GLP-1, which was increased 3.57 times as compared to control group at the 8th day (P<0.01). Conclusion   GLP-1 can significantly promote the expressions of FABP-4 and CPT-1A during the process of 3T3-L1 preadipocyte differentiation, which indicates that GLP-1 can simultaneously promote the fatty acid absorption and decomposition and it has played an important role in improving the free fatty aicd induced insulin resistance.

Key words: Glucagon-like peptide-1 (GLP-1); Preadipocyte differentiation; FABP-4; CTP-1A