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.