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Release-regulating dopamine autoreceptors in human cerebral cortex
E Fedele1, G C Andrioli, A Ruelle
1Institute of Pharmacology and Pharmacognosy, University of Genova, Italy.
British Journal of Pharmacology
|September 1, 1993
Summary
Human brain dopamine D2 receptors on axon terminals in the mesocortical pathway were identified. These D2 autoreceptors regulate dopamine release, as shown by experiments with quinpirole and (-)-sulpiride.
Area of Science:
- Neuroscience
- Pharmacology
- Neurochemistry
Background:
- The mesocortical pathway is crucial for cognitive functions.
- Dopaminergic neurotransmission plays a key role in the brain.
- Autoreceptors on dopaminergic terminals modulate dopamine release.
Purpose of the Study:
- To investigate the presence and type of dopamine autoreceptors on human mesocortical pathway axon terminals.
- To characterize the pharmacological properties of these autoreceptors.
Main Methods:
- Human neocortical slices were obtained during neurosurgery.
- [3H]-dopamine labeling and electrical stimulation were employed.
- Effects of dopamine receptor agonists (quinpirole, SKF 38393) and antagonists ((-)-sulpiride) were assessed on tritium overflow.
Main Results:
- Quinpirole, a selective dopamine D2 receptor agonist, significantly inhibited stimulated tritium overflow (EC50 = 25 nM).
- The D1 receptor agonist SKF 38393 showed no effect up to 10 microM.
- (-)-Sulpiride, a D2 antagonist, effectively antagonized quinpirole's effect (apparent pA2 = 8.26).
Conclusions:
- Dopaminergic axon terminals in the human mesocortical pathway possess functional D2 autoreceptors.
- These D2 autoreceptors regulate dopamine release, suggesting a role in modulating neurotransmission.