Abstract: Objective To study the effect of ethanol on the activity of P70S6K and ERK1/2 in rat primary hepatocytes. Methods Primary hepatocytes were isolated from adult male Sprague-Dawley rat and then treated with increased concentrations of etnanol (0, 50, 100 and 200 mmol/L) for 4h, respectively, or with increased duration of treatment with 200 mmol/L ethanol ( 0, 1, 2 or 4h). P70S6K activity was then evaluated by Western blot. Primary hepatocytes were also treated with mTOR inhibitor rapamycin (100nmol/L) or MEK1/2 inhibitor U0126 (10μmol/L) for 24h and then analyzed for the activity of P70S6K and ERK1/2 and the expression of PPARγ by Western blot, and PPAR? activity by electrophoretic mobility shift assay. Results The activity of P70S6K decreased with the increased concentration of ethanol and duration of ethanol exposure. Ethanol also inhibited activity of ERK1/2. Rapamycin inhibited the activity of P70S6K and enhanced the activity of ERK1/2. But U0126 inhibited both the activation of P70S6K and ERK1/2. Ethanol did not affect the expression and activity of PPARγ. Conclusion Ethanol inhibited the activity of P70S6K in primary hepatocytes in a time- and concentration-dependent manner. The activity of P70S6K was regulated by ERK1/2 but P70S6K also negative regulate ERK1/2 in rat primary hepatocytes.

Key words: primary hepatocyte, P70S6K, ERK1/2, PPARγ, rapamycin, U0126