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Evidence for substance P in the striato-nigral tract
Brain Research
|April 15, 1977
Summary
Researchers investigated substance P in the mammalian brain, finding its highest concentration in the substantia nigra. Lesion studies in rats revealed that descending pathways, particularly the striato-nigral tract, are crucial sources of this neurotransmitter.
Area of Science:
- Neuroscience
- Neurochemistry
Background:
- The reticular part of the substantia nigra contains the highest known concentration of substance P in the mammalian brain.
- Understanding the origin of substance P in this region is key to elucidating nigropetal pathways.
Purpose of the Study:
- To identify the sources and pathways of substance P-containing fibers projecting to the substantia nigra.
Main Methods:
- Unilateral knife cuts transecting the medial forebrain bundle and medial crus cerebri.
- Incomplete electrolytic lesions of the globus pallidus in rats.
- Measurement of substance P content in the substantia nigra.
Main Results:
- Knife cuts resulted in a 90% reduction of substance P in the ipsilateral substantia nigra.
- Globus pallidus lesions caused a 50% decrease in substance P.
- These effects were primarily ipsilateral, indicating uncrossed pathways.
Conclusions:
- Descending uncrossed pathways are the primary source of substance P in the reticular substantia nigra.
- The striato-nigral tract is a significant contributor to the substance P content in this brain region.