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Apomorphine and electrical self-stimulation of rat brain
1School of Psychology, University of Ottawa, Ont., Canada.
Behavioural Brain Research
|November 30, 1992
Summary
Apomorphine, a dopamine receptor agonist, altered brain stimulation reward thresholds in rats. Low doses increased thresholds, while high doses decreased them, suggesting a shift in dopamine receptor activation.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
- Pharmacology
Background:
- Dopamine neurons play a crucial role in reward pathways.
- Understanding dopamine's role in brain stimulation reward is essential for neuroscience research.
- Apomorphine is a direct dopamine receptor agonist used to study dopaminergic system function.
Purpose of the Study:
- To investigate the role of dopamine in reward produced by electrical brain stimulation.
- To examine how apomorphine affects self-stimulation thresholds in rats.
Main Methods:
- Rats were trained to lever-press for brain stimulation reward.
- Self-stimulation thresholds were measured after injections of varying doses of apomorphine or vehicle.
- A within-subject design was employed, tracking thresholds for 2 hours post-injection.
Main Results:
- Low doses of apomorphine (0.01-0.10 mg/kg) increased self-stimulation thresholds.
- High doses of apomorphine (0.30 and 1.00 mg/kg) decreased self-stimulation thresholds.
- A dose-dependent biphasic effect of apomorphine on reward thresholds was observed.
Conclusions:
- The findings suggest a complex role for dopamine in reward processing.
- The shift in apomorphine's effect may reflect a transition from presynaptic to postsynaptic dopamine receptor activation.
- This study provides insights into the neurobiological mechanisms of reward and dopamine modulation.