Ultrastructural relationships between choline acetyltransferase- and neuropeptide y-containing neurons in the rat striatum.
The relationships between cholinergic and neuropeptide Y-containing neuronal systems in the rat striatum were examined using a dual immunoperoxidase labelling method. These neurons were identified by their immunoreactivity to choline acetyltransferase and neuropeptide Y, respectively, and were visualized on the same sections using 3,3'-diaminobenzidine and benzidine dihydrochloride as distinct chromogens under two conditions: (i) neuropeptide Y detection by the 3,3'-diaminobenzidine diffuse brown reaction product and choline acetyltransferase detection by the benzidine dihydrochloride blue, granular reaction product; (ii) choline acetyltransferase detection by 3,3'-diaminobenzidine and neuropeptide Y detection by benzidine dihydrochloride. Although both neuropeptide Y- and choline acetyltransferase-immunoreactive cell bodies were simultaneously detected and were easily distinguishable whatever the conditions used, neuropeptide Y- and choline acetyltransferase-immunoreactive dendrites and axons could not be visualized on the same sections, since only the diaminobenzidine-labelled processes were detectable. Light microscopic observations on sections dual labelled with either method confirmed that choline acetyltransferase and neuropeptide Y immunoreactivities were localized in morphologically different populations of striatal neurons scattered throughout the striatum, choline acetyltransferase immunoreactivity being associated with large neurons and neuropeptide Y immunoreactivity with medium-sized neurons. In addition, the choline acetyltransferase-immunoreactive neurons were found to be more numerous than the neuropeptide Y-immunoreactive neurons and to be prevalent in the dorsolateral areas of the striatum, whereas neuropeptide Y-immunoreactive neurons were preferentially found in the ventromedial areas of this structure. Electron microscopic observations on sections processed under either condition revealed that choline acetyltransferase-positive terminals form synaptic contacts of the symmetrical type with neuropeptide Y-positive somata and proximal dendrites and that choline acetyltransferase-positive neurons are contacted by neuropeptide Y-positive terminals. These data show that the striatal neuropeptide Y- and choline acetyltransferase-containing neuronal systems have reciprocal synaptic interactions and provide morphological support for the hypothesis that striatal cholinergic and neuropeptide Y interneuron activities may be functionally linked.
Vuillet
J
J
Centre de Microscopie Electronique, Faculté de Médecine, 13385 Marseille, France.
Dimova
R
R
Nieoullon
A
A
Kerkerian-Le Goff
L
L
D015100:3,3'-Diaminobenzidine; D000818:Animals; D001560:Benzidines; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D003342:Corpus Striatum / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*; D007124:Immunoenzyme Techniques; D009411:Nerve Endings / Q000187:drug effects / Q000201:enzymology; D009474:Neurons / Q000201:enzymology / Q000378:metabolism / Q000648:ultrastructure*; D009478:Neuropeptide Y / Q000378:metabolism*; D010275:Parasympathetic Nervous System / Q000187:drug effects / Q000201:enzymology; D051381:Rats; D011919:Rats, Inbred Strains
D001560:Benzidines; D009478:Neuropeptide Y; D015100:3,3'-Diaminobenzidine; C029876:benzidine; D002795:Choline O-Acetyltransferase