title: Distribution of SMI-32-immunoreactive neurons in the central auditory system of the rat.
abstract: SMI-32 antibody recognizes a non-phosphorylated epitope of neurofilament proteins, which are thought to be necessary for the maintenance of large neurons with highly myelinated processes. We investigated the distribution and quantity of SMI-32-immunoreactive(-ir) neurons in individual parts of the rat auditory system. SMI-32-ir neurons were present in all auditory structures; however, in most regions they constituted only a minority of all neurons (10-30%). In the cochlear nuclei, a higher occurrence of SMI-32-ir neurons was found in the ventral cochlear nucleus. Within the superior olivary complex, SMI-32-ir cells were particularly abundant in the medial nucleus of the trapezoid body (MNTB), the only auditory region where SMI-32-ir neurons constituted an absolute majority of all neurons. In the inferior colliculus, a region with the highest total number of neurons among the rat auditory subcortical structures, the percentage of SMI-32-ir cells was, in contrast to the MNTB, very low. In the medial geniculate body, SMI-32-ir neurons were prevalent in the ventral division. At the cortical level, SMI-32-ir neurons were found mainly in layers III, V and VI. Within the auditory cortex, it was possible to distinguish the Te1, Te2 and Te3 areas on the basis of the variable numerical density and volumes of SMI-32-ir neurons, especially when the pyramidal cells of layer V were taken into account. SMI-32-ir neurons apparently form a representative subpopulation of neurons in all parts of the rat central auditory system and may belong to both the inhibitory and excitatory systems, depending on the particular brain region.
authors.affiliation: Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Vídeňská 1083, 142 20 Prague, Czech Republic. ouda@biomed.cas.cz
authors.forename: Ladislav
authors.initials: L
authors.lastname: Ouda
authors.forename: Rastislav
authors.initials: R
authors.lastname: Druga
authors.forename: Josef
authors.initials: J
authors.lastname: Syka
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism*; D001303:Auditory Cortex / Q000166:cytology / Q000378:metabolism; D001306:Auditory Pathways / Q000166:cytology*; D017626:Cochlear Nucleus / Q000166:cytology / Q000378:metabolism; D005829:Geniculate Bodies / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D007245:Inferior Colliculi / Q000166:cytology / Q000378:metabolism; D008853:Microscopy; D016900:Neurofilament Proteins / Q000378:metabolism*; D009475:Neurons, Afferent / Q000378:metabolism*; D016548:Prosencephalon / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D000911:Antibodies, Monoclonal; D016900:Neurofilament Proteins