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Morphological evidence for dopamine interactions with pallidal neurons in primates
1Department of Psychiatry and Neuroscience, Centre de Recherche de l'Institut Universitaire en Santé Mentale de Québec, Université Laval Quebec City, QC, Canada.
Frontiers in Neuroanatomy
|September 1, 2015
Summary
Dopamine (DA) projections to the primate globus pallidus have similar densities in the external (GPe) and internal (GPi) segments. This DA innervation modulates pallidal neurons, influencing basal ganglia function in health and disease.
Area of Science:
- Neuroscience
- Cellular Biology
- Neuroanatomy
Background:
- The primate globus pallidus, comprising external (GPe) and internal (GPi) segments, receives dopaminergic (DA) innervation.
- This innervation primarily originates from the substantia nigra pars compacta.
Purpose of the Study:
- To characterize the density, distribution, and synaptic organization of DA axonal projections in the primate globus pallidus.
- To elucidate the functional implications of DA innervation in the GPe and GPi.
Main Methods:
- Tyrosine hydroxylase (TH) immunohistochemistry in squirrel monkey brains.
- Light and electron microscopy.
- Unbiased stereological quantification of TH-positive axon varicosities and neuronal populations.
Main Results:
- Similar densities of TH-positive axon varicosities were found in the GPe and GPi, with regional variations.
- TH-positive varicosities in the GPe were smaller than in the GPi.
- A low percentage of TH-positive varicosities formed synaptic contacts in both GPe and GPi, suggesting a predominantly volume transmission mode of action.
Conclusions:
- Dopamine exerts a key modulatory effect on pallidal neurons via volumic transmission.
- This DA pallidal innervation is crucial for the functional organization of the primate basal ganglia.
- Understanding this pathway is vital for both normal function and pathological conditions.
