The substantia nigra contains among the highest dynorphin A (Dyn A) and α-neo-endorphin (α-Neo) concentrations in the central nervous system. No dynorphin positive cell bodies are found there, only a dense network of nerve fibers and terminals. The present study provides evidence that the Dyn A and α-Neo in the substantia nigra are in neural processes arising from cells located in the head of the caudate nucleus. This neuronal system has been characterized by assaying Dyn A and α-Neo in the substantia nigra after a number of surgical transections of neuronal pathways in the rat forebrain and midbrain. Fibers containing dynorphins and neo-endorphins seem to pass through the internal capsule, ansa lenticularis, and medial forebrain bundle on their way from the striatum to the substantia nigra.
ASJC Scopus subject areas
- Endocrine and Autonomic Systems
- Cellular and Molecular Neuroscience