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Behavioral supersensitivity to methamphetamine following chronic treatment with (--)-sulpiride in the rat
Abstract:
Hyperactivity induced by methamphetamine (4 mg/kg i.p.) was actographically evaluated in rats chronically treated with sulpiride stereoisomers and haloperidol. The trial was repeated with half dose of the stimulant after 8 days of neuroleptic withdrawal. (--)-Sulpiride and haloperidol antagonized the response to the full dose of methamphetamine and induced behavioral supersensitivity to the challenging dose. (+)-Sulpiride strongly enhanced the effect of 4 mg/kg of methamphetamine, but no relevant changes in dopaminergic sensitivity followed.
Insights
Chronic treatment with (-)-sulpiride and haloperidol antagonized methamphetamine hyperactivity, but induced supersensitivity upon withdrawal. (+)-Sulpiride enhanced methamphetamine effects without altering dopaminergic sensitivity.
Area of Science:
- Neuropharmacology
- Behavioral Neuroscience
- Psychopharmacology
Background:
- Methamphetamine induces hyperactivity, a response modulated by dopaminergic pathways.
- Antipsychotics like haloperidol and sulpiride interact with dopamine receptors.
- Stereoisomers of drugs can exhibit distinct pharmacological profiles.
Purpose of the Study:
- To investigate the effects of chronic sulpiride stereoisomers and haloperidol treatment on methamphetamine-induced hyperactivity in rats.
- To assess the impact of neuroleptic withdrawal on the behavioral response to methamphetamine.
- To explore changes in dopaminergic sensitivity following chronic neuroleptic exposure.
Main Methods:
- Actographic evaluation of rat behavior following methamphetamine administration.
- Chronic administration of sulpiride stereoisomers ((+)- and (-)-sulpiride) and haloperidol.
- Testing after an 8-day withdrawal period from neuroleptic treatment.
Main Results:
- (-)-Sulpiride and haloperidol antagonized acute methamphetamine hyperactivity and induced behavioral supersensitivity after withdrawal.
- (+)-Sulpiride significantly potentiated the hyperactivity induced by methamphetamine.
- No significant alterations in dopaminergic sensitivity were observed with (+)-sulpiride treatment.
Conclusions:
- Chronic administration of (-)-sulpiride and haloperidol leads to complex adaptations in dopaminergic systems, including withdrawal-induced supersensitivity.
- The stereoisomers of sulpiride display differential effects on methamphetamine-induced behaviors, suggesting stereospecific dopaminergic interactions.
- These findings highlight the importance of stereochemistry in neuroleptic drug action and their long-term effects on dopamine system responsivity.