Prediction of Ethanol-induced reinforcement and ethanol intake in adolescent rats

PAUTASSI RM

Binghamton

Jornada; Festschrift in honor of Norman E. Skip Spear; 2014

Binghamton University, State University of New York

It has been known for a decade or more that the prevalence of alcohol disorders is higher during adolescence than in any other developmental stage. What are the factors leading to this higher prevalence? A theory put forward by Dr. Linda Spear indicates that age-related differences in the effects of ethanol may promote this greater consumption in adolescents. We have been gathering evidence that supports this theory. Adult rats do not exhibit preference for cues paired with the effects of alcohol. As you can see in the figure, level of preference for a given CS is similar in adults that experimented alcohol or vehicle paired with that CS. This does not seem to be the case for adolescents, which exhibit conditioned place preference for the CS paired with ethanol. This suggest greater perception of ethanol reward in adolescent than in adults. A proxy for ethanol reward is the motor stimulating effect of the drug. Adults are barely sensible to this effect and they exhibit mostly a strong and long lasting ethanol-induced motor depression ? the white circle is the control ?. Adolescents, on the other, exhibited significant motor stimulation and were also completely insensitive to the motor sedative effect. Moreover, passive exposure to alcohol in naive individuals has a much more facilitatory effect, in terms of later alcohol intake, when it ocurrs during adolescence than when it ocurrs in adulthood. This a recent experiment made in our lab, in which adolescents that had been passively exposed to alcohol, in 2 or 5 ocassions, then exhibited much greater etanol intake than un-exposed controls. Stress exposure is another factor that can greatly affect ethanol Intake and Marcelo Lopez will talk about it in much more detail than I could do. But let me show you this recent experiment. We used a short, 2-h drinking test and found that, under these conditions, adolescents and adults drank roughly the same amount of alcohol. Yet, if adolescents and adults were exposed to chronic stress adolescents drink significantly more than adults do, particularly at the 4% ethanol concentration. It seems that adolescents are much more sensitive than their adult counterparts to stress-induce alcohol drinking.