Two different types of dynorphin-A-immunoreactive terminals in rat substantia nigra.
The opioid peptide dynorphin A (1-17) is the third transmitter identified in the striatonigral projection, the other two being gamma-aminobutyric acid (GABA) and substance P. The ultrastructural features of the dynorphinergic terminals in substantia nigra/pars reticulata were studied using pre-embedding immunocytochemistry with the classical peroxidase-antiperoxidase-diaminobenzidine-method; these features were compared with GABAergic boutons visualized with an immunogold method. Two distinct types of dynorphin-A-immunoreactive boutons could be identified: (1) type A (81%) possessing characteristics similar to the GABAergic nerve endings in this region, i.e., large pleomorphic vesicles and symmetric synaptic contacts; (2) type B (19%) displaying asymmetric synaptic zones and small, mostly round vesicles. These results are in agreement with physiological studies suggesting a dual action of dynorphin A in substantia nigra.
Riesenberg
R
R
Anatomische Anstalt, Universität München, Federal Republic of Germany.
Nitsch
C
C
D000818:Animals; D004399:Dynorphins / Q000276:immunology* / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000276:immunology / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D013378:Substantia Nigra / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
D004399:Dynorphins; D005968:Glutamate Decarboxylase