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Response changes after repeated low apomorphine: dopamine autoreceptor desensitization or learning?
Psychopharmacology
|January 1, 1984
Summary
Repeated low-dose apomorphine (APO) altered rat behavior, suggesting drug experience and environment, not just dopamine receptor sensitivity changes, influence responses. This highlights the complex interaction between pharmacology and context.
Area of Science:
- Neuroscience
- Pharmacology
- Behavioral Science
Background:
- Apomorphine (APO) selectively interacts with dopamine (DA) autoreceptors.
- Repeated low-dose APO administration can alter DA autoreceptor sensitivity.
Purpose of the Study:
- To investigate the effects of repeated low-dose apomorphine on yawning and open-field behaviors in rats.
- To determine if observed behavioral changes are solely due to altered DA receptor sensitivity or if environmental factors play a role.
Main Methods:
- Rats were repeatedly injected with low doses of apomorphine.
- Behavioral responses, including yawning and open-field activity, were monitored.
- The influence of the testing environment following drug administration was assessed.
Main Results:
- Repeated APO induced initial DA autoreceptor desensitization followed by hypersensitivity in yawning responses.
- APO accelerated intrasession response decrement and enhanced intersession response decrement in open-field tests.
- Behavioral changes were only observed when both APO injections and testing occurred in the same environment.
Conclusions:
- Behavioral plasticity after repeated low-dose APO is not solely mediated by changes in DA receptor sensitivity.
- Drug experience combined with environmental context significantly influences behavioral outcomes.
- Environmental context plays a critical role in modulating the effects of repeated dopaminergic drug administration.