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A General Method for Evaluating Deep Brain Stimulation Effects on Intravenous Methamphetamine Self-Administration
Published on: January 22, 2016
Chronic methamphetamine increases fighting in mice
Boris P Sokolov1, Charles W Schindler, Jean Lud Cadet
1Molecular Neuropsychiatry Branch, National Institute on Drug Abuse, NIH, DHHS, 5500 Nathan Shock Drive, Baltimore, MD 21224, USA.
Abstract:
A propensity for violent behaviors to develop in chronic methamphetamine (METH) abusers has been noted. The idea that increased aggressiveness might result from chronic METH administration was tested in mice after chronic (long-term intermittent, 8 weeks) or single exposures to the drug. A single injection of METH (6 mg/kg) did not augment fighting. In contrast, chronic METH administration significantly increased the number of animals that initiated bite attacks. This regimen also shortened the latency before the first attack. Latency before the first attack was shorter at 20 h after the METH injection than at 15 min after injection. Locomotor activity was not different at 20 h after METH injection, indicating that increased fighting was not secondary to METH-induced hyperactivity. METH-induced increases in fighting were not related to the duration of persistent sniffing after the initial encounter with an intruder since the duration of this behavior was significantly increased at 15 min after METH but not at 20 h post drug. These results indicate that repeated injections of METH can increase fighting behaviors and also alter social interactions in mice. Thus, intermittent administration of METH might be useful as a pharmacological model to study the biochemical and molecular bases of aggressiveness.
Insights
Chronic methamphetamine (METH) exposure increases aggression in mice, not hyperactivity. Repeated METH administration enhances fighting behaviors and alters social interactions, suggesting a model for studying aggressiveness.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Chronic methamphetamine (METH) abuse is linked to increased violent behaviors.
- The neurobiological underpinnings of METH-induced aggression require further investigation.
Purpose of the Study:
- To investigate the effects of chronic versus single methamphetamine exposure on aggressive behaviors in mice.
- To determine if METH-induced aggression is secondary to hyperactivity or other behavioral changes.
Main Methods:
- Mice were subjected to chronic (8-week intermittent) or single METH administration.
- Aggressive behaviors, including bite attacks and latency to attack, were assessed.
- Locomotor activity and persistent sniffing were measured to control for confounding factors.
Main Results:
- Single METH injection did not increase fighting behavior.
- Chronic METH administration significantly increased the incidence and initiation of bite attacks.
- Latency to the first attack was reduced after chronic METH exposure.
- Increased fighting was not attributable to METH-induced hyperactivity or altered sniffing duration at later time points.
Conclusions:
- Repeated methamphetamine administration increases fighting behaviors and modifies social interactions in mice.
- Intermittent METH administration may serve as a valuable pharmacological model for studying the neurobiological basis of aggression.
