Pulsatile blood alcohol and CYP2E1 induction during chronic alcohol infusions in rats

Adult male Sprague-Dawley rats were treated with alcohol for 35 days using a total enteral nutrition model. Intragastric cannulae were inserted into rats and they were infused with a diet designed to promote normal growth in male rats. Alcohol was infused at 35% of total calories for 35 days. Urine and blood alcohol concentrations were determined and found to be pulsatile during continuous alcohol infusion, having values between near zero and greater than 500 mg/dl. Twenty-four-hour urine alcohol concentrations were found to be excellent indicators of blood alcohol concentrations (BACs). Cytochrome P450 CYP2E1 was induced in a two-step manner. Step one occurred at BACs below 250 mg/dl and was characterized by significant (p < or = 0.05) elevations in activities and apoprotein levels with no changes in steady-state mRNA. Step two occurred with BACs greater than 300 mg/dl and resulted in significant (p < or = 0.05) elevations in steady-state mRNA levels. We propose that the pulsatile BACs are caused by an ethanol concentration-dependent regulation of an ethanol metabolizing system, perhaps CYP2E1.