Adolescent intermittent ethanol exposure induces sex-dependent divergent changes in ethanol drinking and motor activity in adulthood in C57BL/6J mice

Abstract

With alcohol readily accessible to adolescents, its consumption leads to many adverse effects, including impaired learning, attention, and behavior. Adolescents report higher rates of binge drinking compared to adults. They are also more prone to substance use disorder in adulthood due to physiological changes during the adolescent developmental period. We used C57BL/6J male and female mice to investigate the long-lasting impact of binge ethanol exposure during adolescence on voluntary ethanol intake and open field behavior during later adolescence (Experiment 1) and during emerging adulthood (Experiment 2). The present set of experiments were divided into four stages: (1) adolescent intermittent vapor inhalation exposure, (2) abstinence, (3) voluntary ethanol intake, and (4) open field behavioral testing. During adolescence, male and female mice were exposed to air or ethanol using intermittent vapor inhalation from postnatal day (PND) 28-42. Following this, mice underwent short-term abstinence from PND 43-49 (Experiment 1) or protracted abstinence from PND 43-69 (Experiment 2). Beginning on PND 50-76 or PND 70-97, mice were assessed for intermittent voluntary ethanol consumption using a two-bottle choice drinking procedure over 28 days. Male adolescent ethanol-exposed mice showed increased ethanol consumption following short-term abstinence and following protracted abstinence. In contrast, female mice showed no changes in ethanol consumption following short-term abstinence and decreased ethanol consumption following protracted abstinence. There were modest changes in open field behavior following voluntary ethanol consumption in both experiments. These data demonstrate a sexually divergent shift in ethanol consumption following binge ethanol exposure during adolescence and differences in open field behavior. These results highlight sex-dependent vulnerability to developing substance use disorders in adulthood.

Keywords: AIE; adolescence; alcohol; dependence; development; mouse; sex differences.

Figure 1:

Schematic of experimental procedures.

Figure 2:

Intermittent voluntary ethanol consumption expressed as grams of ethanol consumed per kilogram of body weight (g/kg) across days (24 hr) following air or ethanol exposure during adolescence from PND 28–42. Panels A and B show ethanol consumption from experiment 1 in male and female mice from PND 50–74. Panels C and D show ethanol consumption from experiment 2 in male and female mice from PND 71–97. The line graphs are presented as mean +/− SEM. The summary figures are presented as the median value with the box containing the 25^th and 75^th percentile. The whiskers mark the 5^th and 95^th percentiles. * indicates difference between ethanol-exposed mice compared to air-exposed mice. # indicates female air-exposed mice drank more ethanol than female ethanol-exposed mice on that day.

Figure 3:

Preference for ethanol expressed as preference (%) computed as {(EtOH (ml)/ [EtOH (ml) + Water (ml))*100]} across days (24 hr) following air or ethanol exposure during adolescence from PND 28–42. Panels A and B show ethanol preference from experiment 1 in male and female mice from PND 50–74. Panels C and D show ethanol preference from experiment 2 in male and female mice from PND 71–97. The line graphs are presented as mean +/− SEM. The summary figures are presented as the median value with the box containing the 25^th and 75^th percentile. The whiskers mark the 5^th and 95^th percentiles. * indicates difference between ethanol-exposed mice compared to air-exposed mice.

Figure 4:

Voluntary ethanol consumption expressed as relative percent of control in ethanol-exposed mice across days (24 hr) following air or ethanol exposure during adolescence from PND 28–42. Control mice were set to 0 and ethanol intake was expressed relative to control, with higher scores indicating an increase in ethanol consumption relative to air-exposed mice and lower scores indicating a decrease in ethanol consumption relative to air-exposed mice. Panel A shows percent change from control ethanol consumption in ethanol-exposed mice from experiment 1 in male and female mice from PND 50–74. Panel B shows percent change from control ethanol consumption in ethanol-exposed mice from experiment 2 in male and female mice from PND 71–97. Data are presented as stacked values with median with 95% confidence intervals. * indicates males are significantly greater than females.

Figure 5:

Total distance traveled (cm) during the open field test for the entire arena and total distance traveled in the center zone following the 28 day voluntary ethanol drinking paradigm from Experiment 1(Panels A and B) Experiment 2 (Panels C and D) are shown. Data are presented as mean +/− SEM. * indicates ethanol-exposed mice are significantly different from air-exposed mice. # indicates female mice significantly different from male mice. ** indicates female air-exposed mice are significantly different from female ethanol-exposed mice.