Abstract：OBJECTIVE: To investigate the effects of ghrelin on the proliferation and differentiation of 3T3-L1 preadipocyte, and study the possible mechanisms. METHODS: 3T3-L1 preadipocytes were cultured in vitro. The proliferation potentials of 3T3-L1 preadipocytes that were treated with different concentrations of ghrelin were evaluated by MTT methods. The levels of c-myc and thymidine kinase mRNA were detected using RT-PCR. 3T3-L1 preadipocytes were differentiated into the matured adipocytes with insulin (INS) or ghrelin. The morphological changes of 3T3-L1 adipocytes were observed and the differentiation rate was assayed by oil-red O staining. Total RNA was extracted from adipocytes at various times, and the levels of peroxisome proliferation activated receptor γ (PPARγ) and CAAT/enhancer binding protein(C/EBPα) mRNA expressions were detected using RT-PCR. RESULTS: Ghrelin at concentrations of 10-7 to 10-15 mol/L significantly stimulated preadipocyte proliferation (P<0.05). The levels of c-myc and thymidine kinase mRNA significantly increased in 3T3-L1 preadipocytes with 10-9 mol/L and 10-11 mol/L ghrelin treatment (P<0.01). The 3T3-L1 preadipocytes treated with 10-11 mol/L ghrelin had lots of lipid droplets in the cytoplasma, but the differentiation rate was lower than those treated with INS. Ghrelin of 10-11 mol/L significantly increased the mRNA expression of PPARγ and C/EBPα in the course of 3T3-L1 preadipocyte differentiation, compared with the normal control group (P<0.05). The PPARγ and C/EBPα mRNA expression increased with the prolonged differentiation of preadipocytes induced by ghrelin or INS. There were significant differences in the levels of PPARγ and C/EBPα mRNA expression between the 2nd and 8th days of differentiation（P<0.01）. CONCLUSIONS: Ghrelin promotes the proliferation and differentiation of 3T3-L1 preadipocytes. The proliferation of 3T3-L1 preadipocytes induced by ghrelin may be associated with increased c-myc levels. Ghrelin may promote differentiation of 3T3-L1 preadipocytes by increasing mRNA expression of PPARγ and C/EBPα, thus enhances the sensitivity of adipocytes to INS.［Chin J Contemp Pediatr, 2009, 11 (1):69-73］
LIU Jing,LIN Han-Hua,CHENG Pei-Xuan et al. Effects of ghrelin on the proliferation and differentiation of 3T3-L1 preadipocytes and its possible mechanisms[J]. CJCP, 2009, 11(01): 69-73.
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