Differential effects of ethanol on motor coordination in adolescent and adult rats

Recent evidence suggests that adolescence represents a unique period of sensitivity to the effects of ethanol. Adolescent animals are more sensitive than adults to many of the effects of ethanol, including ethanol-induced learning and memory impairments, while being less sensitive to others, including ethanol-induced sedation. It is well known that ethanol produces dramatic impairments in balance and motor coordination. While previous research suggests that adolescents and adults do not differ in their sensitivity to the effects of relatively low doses of ethanol on motor coordination, it is not known whether differences in performance would emerge at higher doses. The present study compared the impact of a range of ethanol doses (1.0, 2.0 and 3.0 g/kg) on motor coordination in adolescent [postnatal day (PD) 35-40] and adult (PD 70-75) rats. Motor coordination was assessed using the tilting plane test before ethanol administration (baseline) and at 15, 30, 60, 120 and 180 min after ethanol administration. Performance was not affected by 1.0 g/kg ethanol in either age group. However, adults were more impaired than adolescents at nearly every time point following administration of both 2.0 and 3.0 g/kg ethanol. The results provide further evidence that adolescents and adults are differentially sensitive to the behavioral effects of ethanol. Given the critical role of motor coordination in the ability to operate motor vehicles and the central role of balance and coordination in field sobriety tests, these data could have important implications if extended to human subjects.