Evidence for a distinct nigropallidal dopaminergic projection in the squirrel monkey

Brain Res. 1989 Mar 20;482(2):381-6. doi: 10.1016/0006-8993(89)91205-5.


Injections of the retrograde fluorescent tracer fast blue in the striatum (STR) and nuclear yellow in the internal segment of the globus pallidus (GPi) in the squirrel monkey (Saimiri sciureus) revealed a nigropallidal projection whose cellular origin was largely distinct from that of the nigrostriatal pathway. Neurons containing the tracer injected in GPi were scattered throughout the substantia nigra-ventral tegmental area complex where they formed approximately 20-25% of the total number of retrogradely labeled cells. Only about 5-10% of all positive neurons were double-labeled after STR-GPi injections. In experiments combining the use of the fluorescent tracer propidium iodide with immunofluorescence, the majority of neurons projecting to GPi displayed tyrosine hydroxylase immunoreactivity. Hence, in addition to their important role at striatal level, midbrain dopaminergic neurons may influence directly the output neurons of the basal ganglia at pallidal level in primates.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cebidae / anatomy & histology*
  • Fluorescent Dyes
  • Globus Pallidus / cytology*
  • Globus Pallidus / metabolism
  • Globus Pallidus / physiology
  • Neural Pathways / anatomy & histology
  • Saimiri / anatomy & histology*
  • Saimiri / metabolism
  • Substantia Nigra / cytology*
  • Substantia Nigra / metabolism
  • Substantia Nigra / physiology
  • Tyrosine 3-Monooxygenase / metabolism


  • Fluorescent Dyes
  • Tyrosine 3-Monooxygenase