INCREASED AGGRESSION AFTER ETHANOL SELF-ADMINISTRATION IN MALE RESIDENT RATS

In order to study experimental alcohol intake that leads to heightened aggression, we established ethanol self-administration in aggressive rats. The focus was on low doses of self-administered ethanol and to a ssess their effects on aggressive behavior in resident rats, using a l imited access paradigm followed by a 5-min confrontation with an intru der. In the first phase of the experiment, rats were established as '' residents'' and their consistent aggressive behavior in confrontations with an intruder was verified. In the second phase, these resident ra ts were trained to self-administer alcohol, using a sucrose-fading tec hnique. In the third phase, alcohol self-administration was followed b y intruder confrontations in order to study the effect of alcohol on a ggression. Confrontations after ethanol consumption leading to low (5- 20 mg/dl) and moderate (20-50 mg/dl) blood alcohol concentration (BAG) were compared to confrontations without alcohol, each animal serving as its own control. On average, the group showed no change in aggressi ve behavior after low or moderate ethanol intake. However six out of 1 6 individuals significantly increased the number of attack bites and t he duration of aggressive behavior by up to 90% after alcohol self-adm inistration. When these rats were assigned post-hoc to an alcohol heig htened aggression group, the group was characterized by a 40% increase in number of attack bites and a 90% increase in aggressive posture ov er control (BAG 0 mg/dl), whereas the alcohol non-heightened aggressio n group showed no significant changes. These results extend previous o bservations of increased aggression in a subpopulation of animals afte r experimenter-administered ethanol in mice, rats and monkeys to self- administered alcohol. Using this animal model, individuals showing enh anced or reduced aggression after oral alcohol self-administration can be characterized behaviorally, physiologically, and neurochemically.