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Reinforcing effects of methamphetamine in planarians
1Department of Psychology, Keio University, Tokyo, Japan.
Neuroreport
|August 16, 2000
Summary
Dopamine agonist methamphetamine reinforced planarian behavior, showing a preference for associated environments. This effect was blocked by dopamine antagonists, suggesting ancient origins of drug reinforcement in invertebrates.
Area of Science:
- Neuroscience
- Behavioral Pharmacology
- Invertebrate Biology
Background:
- Dopamine plays a crucial role in reward and reinforcement in vertebrates.
- Understanding the evolutionary basis of dopaminergic reinforcement is essential for comprehending its mechanisms.
Purpose of the Study:
- To investigate the reinforcing properties of the dopamine agonist methamphetamine in planarians.
- To determine if dopamine receptor antagonists can block methamphetamine-induced place preference in planarians.
Main Methods:
- Conditioned Place Preference (CPP) procedure was employed.
- Planarians were exposed to methamphetamine and distinct environmental cues.
- The effects of non-selective (haloperidol) and selective (SCH23390, sulpiride) dopamine antagonists were assessed.
Main Results:
- Planarians exhibited a significant preference for the environment paired with methamphetamine administration.
- Pretreatment with haloperidol abolished the methamphetamine-induced place preference.
- Selective D1 and D2 dopamine antagonists (SCH23390 and sulpiride) also successfully blocked the reinforcing effect.
Conclusions:
- Methamphetamine exhibits reinforcing properties in planarians, mediated by dopaminergic pathways.
- The findings suggest that the fundamental mechanisms of dopaminergic reinforcement may be conserved across a wide range of species, including invertebrates.
- This study provides evidence for the ancient evolutionary origins of drug reinforcement pathways.