Chronic‐Intermittent Ethanol Exposure During Adolescence Prevents Normal Developmental Changes in Sensitivity to Ethanol‐Induced Motor Impairments

Abstract

Background Recent evidence indicates that adolescent and adult rats are differentially sensitive to many of the acute effects of ethanol. Little is known about the neurobehavioral consequences of repeated ethanol exposure during adolescence relative to adulthood. In the present study we examined the impact of repeated ethanol exposure during adolescence and adulthood on subsequent sensitivity to ethanol‐induced motor impairments.Methods The tilting plane test was used to assess the impact of acute ethanol (3.0 g/kg) on motor coordination before (test 1), 2 days after (test 2), and 16 days after (test 3) a 20 day period of chronic‐intermittent ethanol (CIE; 5.0 g/kg intraperitoneally every 48 hrs for 20 days) or isovolumetric chronic‐intermittent saline (CIS) treatment in adolescent (postnatal (PD) 30) and adult (PD 70) rats.Results Adolescent subjects were less sensitive than adults to the effects of ethanol on motor coordination during test 1. Adolescent CIS‐treated subjects exhibited an increase in sensitivity to ethanol‐induced motor impairments that reached adult levels by test 2 (PD 51) and remained stable between test 2 and test 3 (PD 65). Adolescent CIE‐treated subjects did not exhibit this age‐related increase in sensitivity. In this group, the effects of acute ethanol remained unchanged across the three testing days. Adult CIE‐treated subjects exhibited a small degree of tolerance between test 1 and test 2 (PD 91) that was no longer evident during test 3 (PD 105). In adult CIS‐treated subjects, the effects of acute ethanol remained stable across the three testing days. Blood ethanol concentrations assessed during testing suggest that age‐related changes in sensitivity to ethanol‐induced motor impairments are not related to changes in ethanol metabolism.Conclusions The data suggest that CIE exposure during adolescence has a lasting impact on sensitivity to ethanol‐induced motor impairments. This effect might stem from a disruption of normal developmental processes.