Substance P synaptic interactions with GABAergic and dopaminergic neurons in rat substantia nigra: an ultrastructural double-labeling immunocytochemical study.
The distribution of substance P (SP), tyrosine hydroxylase (TH), and glutamic acid decarboxylase (GAD) immunoreactivity in the substantia nigra of the rat was studied by means of an ultrastructural double-labeling immunocytochemical method. Direct synaptic contact between SP-immunoreactive terminals and GAD-positive nigral neurons was more often observed in the pars lateralis than the pars reticularis and was rarely observed in the pars compacta. Substance P-positive terminals also formed synapses with cell bodies and dendrites of TH-positive, dopaminergic neurons in the pars compacta and pars reticulata. Multiple SP-immunoreactive terminals were often observed with symmetrical and, less frequently, asymmetrical synapses on individual TH-containing dendrites. Evidence of SP-containing terminals contacting both GABAergic and dopaminergic neurons in the substantia nigra suggests a direct excitatory action upon nigral projection neurons.
Mendez
I
I
Department of Anatomy, University of Western Ontario, London, Canada.
Elisevich
K
K
Flumerfelt
B
B
D000818:Animals; D004298:Dopamine / Q000502:physiology*; D005260:Female; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009474:Neurons / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013373:Substance P / Q000494:pharmacology*; D013378:Substantia Nigra / Q000166:cytology* / Q000187:drug effects / Q000648:ultrastructure; D013569:Synapses / Q000187:drug effects*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D013373:Substance P; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase; D005968:Glutamate Decarboxylase; D004298:Dopamine