Co-localization of tyrosine hydroxylase and glutamate decarboxylase in a subpopulation of single nigrotectal projection neurons

Brain Res. 1991 Sep 6;558(2):239-44. doi: 10.1016/0006-8993(91)90774-p.


The neurotransmitter phenotype(s) of nigral neurons innervating the superior colliculus (SC) in the rat was examined using a combination of immunohistochemical techniques and fluorescent retrograde tracing. After double-immunofluorescent histochemistry for tyrosine hydroxylase (TH) and glutamate decarboxylase (GAD), single cells in the rostral ventrolateral portion of the substantia nigra pars reticulata (SNr) and to a lesser extent the substantia nigra pars lateralis (SN1) displayed immunoreactivity to both antigens. Furthermore, following True blue (TB) injections into the SC and incubation for both TH and GAD immunoreactivity, a considerable number of cells in the SNr retrogradely labeled with TB (approximately 10%) were also immunopositive for both synthetic enzymes. The present study provides evidence for the coexistence of TH and GAD and thus, the coexistence of dopamine and GABA in a subpopulation of single nigrotectal projection cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dopamine / metabolism
  • Fluorescent Antibody Technique
  • Fluorescent Dyes
  • Glutamate Decarboxylase / metabolism*
  • Immunohistochemistry
  • Neural Pathways / cytology
  • Neurons / enzymology*
  • Phenotype
  • Rats
  • Rats, Inbred Strains
  • Substantia Nigra / anatomy & histology
  • Substantia Nigra / cytology
  • Substantia Nigra / enzymology*
  • Superior Colliculi / cytology
  • Superior Colliculi / enzymology
  • Tyrosine 3-Monooxygenase / metabolism*
  • gamma-Aminobutyric Acid / metabolism


  • Fluorescent Dyes
  • gamma-Aminobutyric Acid
  • Tyrosine 3-Monooxygenase
  • Glutamate Decarboxylase
  • Dopamine