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Olfactory receptor neurons express D2 dopamine receptors
N L Koster1, A B Norman, N M Richtand
1Department of Cell Biology, Neurobiology and Anatomy, University of Cincinnati, Cincinnati, Ohio 45267, USA.
The Journal of Comparative Neurology
|July 28, 1999
Summary
Dopamine (DA) D2 receptors are found on olfactory receptor neurons (ORNs) in the olfactory bulb (OB). This suggests dopamine presynaptically influences olfactory nerve transmission via D2 receptors.
Area of Science:
- Neuroscience
- Olfactory System Research
- Receptor Pharmacology
Background:
- Dopamine's role in the olfactory bulb (OB) is under investigation.
- Dopamine receptors (DARs) of the D2-like family (D2, D3, D4) were previously localized to outer OB layers.
- This localization suggested presynaptic D2-like receptors on olfactory receptor neuron (ORN) terminals.
Purpose of the Study:
- To investigate the hypothesis that D2-like receptors are located presynaptically on ORN terminals in the OB.
- To determine which cells in the OB express DARs, specifically focusing on D2-like subtypes.
Main Methods:
- Utilized radioligand binding assays in rat OB outer layers.
- Destroyed ORNs using nasal lavage with zinc sulfate (ZnSO(4)).
- Employed in situ hybridization to detect D2 and D3 mRNA in olfactory epithelial tissue and after bulbectomy.
Main Results:
- D2-like radioligand binding in the OB was significantly reduced after ORN destruction.
- D2 mRNA, but not D3 mRNA, was detected in adult rat olfactory epithelial tissue.
- D2 mRNA was localized to ORN perikarya and eliminated by bulbectomy, indicating expression in mature ORNs.
Conclusions:
- Mature ORNs express D2 DARs, with functional receptors translocated to their axons and terminals in the OB.
- Dopamine released from juxtaglomerular (JG) interneurons may presynaptically modulate neurotransmission at olfactory nerve terminals via D2 receptors.