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Dopamine receptor subtypes colocalize in rat striatonigral neurons
D J Surmeier1, J Eberwine, C J Wilson
1Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee, Memphis 38163.
Summary
Striatonigral neurons express functional dopamine receptors D1, D2, and D3. Contrary to segregation theories, these receptors are often co-localized within single neurons, impacting sodium currents.
Area of Science:
- Neuroscience
- Molecular Biology
Background:
- Dopaminergic neurons from the substantia nigra are crucial for neostriatum neuromodulation.
- Previous studies suggested dopamine receptors are segregated in striatonigral and striatopallidal neurons.
Purpose of the Study:
- To investigate the hypothesis of dopamine receptor segregation in striatonigral neurons.
- To examine the functional expression of dopamine receptors in these neurons.
Main Methods:
- Acutely isolated, retrogradely labeled striatonigral neurons were used.
- Neuromodulatory effects of selective dopaminergic agonists (D1, D2) on Na+ currents were assessed.
- Single-cell antisense RNA populations were probed with dopamine receptor cDNAs.
Main Results:
- D1 agonist SKF 38393 reduced Na+ currents in most neurons (20/31).
- D2 agonists had mixed effects, reducing currents in most (23/42) but increasing in some (8/42).
- Single-cell analysis revealed co-localization of D1, D2, and D3 receptor mRNAs in striatonigral neurons (5/5).
Conclusions:
- Striatonigral neurons co-localize functional D1, D2, and D3 dopamine receptors.
- The strict segregation hypothesis of dopamine receptors is challenged by these findings.