Effects of Testosterone, 17β-estradiol, and Progesterone on the Differentiation of Bovine Intramuscular Adipocytes

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The aim of this study was to investigate the effects of testosterone, 17β-estradiol, and progesterone on the differentiation of bovine intramuscular adipocytes (BIA). Stromal-vascular (SV) cells were obtained from M. longissimus dorsi of 20 months old Korean (Hanwoo) steers, and were cultured in DMEM containing 5% FBS. The proliferated BIA were induced to differentiate with 0.25 µM dexamethasone, 0.5 mM 1-methyl-3-isobutyl-xanthine and 10 µg/ml insulin. During differentiation, the cells were treated with testosterone, 17β-estradiol, and progesterone at concentrations of 10 -10 , 10 -9 , and 10 -8 M, respectively, for 12 days. Regardless of its concentration, testosterone remarkably reduced lipid droplets in the cytosol of BIA. On the other hand, 17β-estradiol and progesterone increased the accumulation of lipid droplets in BIA. Testosterone significantly (p<0.05) decreased GPDH activities with a dose-dependent pattern. 17β-Estradiol treatment onto BIA during differentiation, however, increased GPDH activity showing the highest activity (11.3 nmol/mg protein/min) at 10 -10 M. Treatment of BIA with progesterone also increased (p<0.05) GPDH activity with the highest activity (13.8 nmol/mg protein/min) at 10 -9 M. In conclusion, the results in the current study suggest that testosterone inhibits differentiation of BIA by suppressing GPDH activity while 17β-estradiol and progesterone have adverse effects. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 11 : 1589-1593)