Circadian and genetic effects on ethanol elimination in LS and SS mice.

Behavioral studies using mice have suggested circadian influences on response to ethanol. Studies examining possible circadian influences on ethanol elimination are ambiguous as to whether changes in elimination contribute to circadian variations in response. Therefore, the linear declines in blood alcohol concentrations (BACs) were assessed in long-sleep (LS) and short-sleep (SS) male mice at 0300, 0900, 1500, or 2100 hr following an intraperitoneal injection of either 2.5 or 4.1 g/kg ethanol. Overall mean BAC for LS mice was significantly higher than for SS mice at both ethanol doses. With the 4.1 g/kg dose, LS mean BAC was higher at 2100 hr than at 0900 hr. Both lines of mice exhibited faster elimination rates at 0300 and 0900 hr than at 1500 and 2100 hr. SS mice generally showed a more rapid decline in BAC than did LS mice at this dose. With the 2.5 g/kg dose, the rate of decline was faster at 0900 hr than at 2100 hr for both lines of mice. SS mice showed a significantly greater overall rate of decline than did LS mice. The line differences in blood alcohol concentration and elimination rate may have resulted from a change in the doses used to select these mice and may contribute to circadian influences on ethanol response.