title: GABA-immunopositive neurons in rat neocortex with contralateral projections to S-I.
abstract: The callosal projection is traditionally believed to be exclusively excitatory in function. A new method combining lectin-conjugated colloidal gold for retrograde tracing with immunofluorescence for GABA was used to investigate this question. The large majority of neurons retrogradely labeled after injections of tracer into contralateral S-I were GABA-negative cells in layers II-VI. However, GABA-positive neurons projecting to contralateral S-I were also seen. The majority of double-labeled cells were only weakly labeled with tracer; they were located both in superficial and deep cortical layers and represented at least 1% of all retrogradely labeled neurons. Neurons double-labeled for both tracer and GABA in upper layers were found mainly within the central patch of callosally projecting neurons, whereas those in deep layers were scattered throughout contralateral cortex.
authors.affiliation: Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill 27599, USA.
authors.forename: Y A
authors.initials: YA
authors.lastname: Gonchar
authors.forename: P B
authors.initials: PB
authors.lastname: Johnson
authors.forename: R J
authors.initials: RJ
authors.lastname: Weinberg
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology*; D002772:Cholera Toxin; D003337:Corpus Callosum / Q000166:cytology*; D017979:Gold Colloid; D007150:Immunohistochemistry; D037102:Lectins; D008297:Male; D009434:Neural Pathways; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D010446:Peptide Fragments; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D017979:Gold Colloid; D037102:Lectins; D010446:Peptide Fragments; D005680:gamma-Aminobutyric Acid; D002772:Cholera Toxin