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Environment associated with morphine and experience of aggression modulate behaviors of postdependent mice
M Rodríguez-Arias1, C M Felip, M A Aguilar
1Area de Psicobiología, Facultad de Psicología, Universitat de Valencia, 46071 Valencia, Spain.
Abstract:
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.
Insights
Drug-associated environments can influence withdrawal and aggression. Morphine-paired contexts reduce withdrawal signs and aggression in mice post-abstinence, suggesting environmental cues impact drug-seeking behaviors.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
- Addiction Research
Background:
- Environmental contexts associated with drug use gain secondary reinforcing properties.
- Context-specific withdrawal represents a persistent learned response.
- Understanding environmental influences on drug-seeking behavior is crucial for addiction treatment.
Purpose of the Study:
- To investigate the long-term effects of morphine-associated environments on aggression and withdrawal.
- To determine if environmental conditioning influences behavior after prolonged abstinence.
- To evaluate the impact of aggression experienced during withdrawal on subsequent behavior.
Main Methods:
- Male mice received saline or morphine in distinct environments or home cages.
- Spontaneous and naloxone-induced withdrawal were assessed, with some groups experiencing agonistic encounters.
- Aggression tests were conducted in the distinctive environment after 15 days of abstinence.
Main Results:
- Aggression during spontaneous withdrawal increased subsequent aggression in drug-free mice.
- Morphine-associated environments reduced conditioned physical withdrawal signs.
- Environmental conditioning also showed a moderate decrease in aggression levels.
Conclusions:
- Experience of aggression during withdrawal exacerbates subsequent aggressive behavior.
- Environmental cues paired with morphine can mitigate withdrawal symptoms and abnormal behaviors in postdependent mice.
- Contextual factors play a significant role in modulating the long-term consequences of opioid exposure.