Tracing specific transmitter pathways in the rat CNS: combination of [3H]serotonin retrograde labelling with immunocytochemical detection of endogenous transmitters.
Selective retrograde labelling with [3H]serotonin ([3H]5-HT) can be used to identify serotonergic cell bodies after specific [3H]5-HT uptake by the corresponding nerve terminals. In the present study, we demonstrate that autoradiography of this [3H]5-HT radiolabelling can be combined with immunocytochemical detection of endogenous serotonin, GABA or substance P on the same tissue section. The midbrain raphe serotonergic projections to the olfactory bulb and the spinal projections of medullary serotonergic nuclei were investigated. The specificity of retrograde labelling with [3H]5-HT was confirmed by immunoreactivity of the radiolabelled cells for serotonin, using an antiserum specific for formaldehyde-fixed serotonin. After spinal injections of [3H]5-HT, many retrogradely labelled cells in the medullary raphe were immunopositive for substance P, and a few for GABA. These results are in agreement with the available information on the co-existence of putative transmitters in the spinal projections of caudal raphe neurons. Therefore, autoradiography of [3H]5-HT retrograde labelling combined with immunocytochemistry offers a possibility to test the specificity of transmitter-selective retrograde labelling, to identify transmitter-defined neuronal interactions and to investigate the projection fields of multitransmitter containing neurons.
Araneda
S
S
Laboratoire de Cytologie, Institut des Neurosciences CNRS, Universite de Paris VI, France.
Magoul
R
R
Calas
A
A
D000818:Animals; D002490:Central Nervous System / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D012701:Serotonin; D013373:Substance P; D005680:gamma-Aminobutyric Acid