Effects of Conjugated Linoleic Acid on Proliferation and Differentiation of Bovine (Bos taurus) Intramuscular Preadipocyte
WAN Rong1,*, NONG Si-Wei1, ZHOU Zhen-Ming2, MENG Qing-Xiang2
1 Agriculture and Food Engineering College/Industrial College of Subtropical Characteristic Agriculture, Baise University, Baise 533000, China; 2 Beef Cattle Research Center, China Agricultural University, Beijing 100193, China
Abstract：The degree of proliferation and differentiation of adipocytes deposited in muscle fibers or between muscle bundles determines the level of beef marbling index directly, which affects the quality level of beef. This study was to assess the effects of conjugated linoleic acid (CLA) on the proliferation and differentiation of intramuscular preadipocytes in Luxi cattle (Bos taurus). In vitro cell model was developed for proliferation of bovine intramuscular preadipocytes which were cultured in growth medium supplemented with CLA (50, 100 and 150 μmol/L) for 4 d. 100 μmol/L CLA significantly increased the proportion of S phase cells (P<0.05, increased by 1.63 times), decreased the proportion of G0/G1 phase cells (P<0.05, decreased by 9.2%), and the other treatment groups had no significant difference (P>0.05). The results showed that 100 μmol/L CLA significantly increased the proliferation rate of bovine intramuscular preadipocyte by flow cytometry (P<0.05). Bovine intramuscular preadipocytes were cultured in differentiation media with different doses of CLA, the induction of adipogenesis were indicated by measuring the lipid droplets. Six days later, lots of lipid droplets were observed in differentiated preadipocytes, in which cytosolic lipid content remarkably increased at 100 and 150 µmol/L CLA, respectively (P<0.05). Four combination of CLA (100 µmol/L), insulin (10 μg/mL) and dexamethasone (0.25 μg/mL) was designed and cultured cells were induced for 6 d with CLA, insulin and dexamethasone. When dexamethasone, insulin or CLA were removed, fat content in the cytoplasm decreased by 74%, 68% and 31%, respectively. The combination of CLA, insulin, and dexamethasone also resulted in the greatest cytosolic lipid content. 100 μmol/L CLA can increase the expression of peroxisome proliferator-activated receptor-γ (PPARγ) gene by about 3 times, and the expression level of CCAAT/enhancer-binding protein-α (C/EBPα) gene by about 2 times (P<0.05). Taken together, the present findings indicated that CLA may promote bovine intramuscular preadipocyte proliferation and differentiation, which highlighted the potential use of CLA on bovine intramuscular preadipocyte proliferation and differentiation to improve beef quality.
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