6533b7d8fe1ef96bd126b76f

RESEARCH PRODUCT

Environment associated with morphine and experience of aggression modulate behaviors of postdependent mice

subject

description

Contexts associated with drug use can acquire secondary reinforcing properties. Furthermore, context-specific withdrawal has been observed to reflect a relatively long-lasting learned response. The aim of this study was to evaluate the effect of the environment paired with morphine after 15 days of abstinence. In the first experiment, isolated male mice received saline or morphine either in their home cage or in the distinctive environment, performing two agonistic encounters in the distinctive environment during spontaneous withdrawal. Similar groups were assigned but without aggression encounters during withdrawal. In the second experiment, animals received saline or morphine as previously described but suffered two naloxone-induced withdrawals during agonistic encounters. In all cases, after the second withdrawal, animals were drug-free during 15 days and then an aggression test took place in the distinctive environment. Results show that experience of aggression during this spontaneous withdrawal causes an increase in the level of aggression exhibited when animals are drug free, in comparison with others in which this experience does not exist. Environment associated with morphine administration decreases conditioned physical signs of withdrawal and to a smaller extent aggression. It could be suggested that environment associated with morphine administration decreases the abnormal behaviors exhibited in postdependent mice.