DISTRIBUTION OF GLYCINE-IMMUNOREACTIVE CELL-BODIES AND FIBERS IN THE RAT-BRAIN

To localize glycinergic cell bodies and fibers in the rat brain, we de veloped a sensitive immunohistochemical method combining the use of sp ecific glycine antibodies (Campistron G. et al. (1986) Brain Res. 376, 400-405; Wenthold R. J. et al. (1987) Neuroscience 22, 897-912) with the streptavidin-horseradish peroxidase technique and 3,3'-diaminobenz idine . 4HCl-nickel intensification. We confirmed the presence of nume rous glycine-immunoreactive cell bodies and fibers in the cochlear nuc lei, superior olivary complex, nucleus of the trapezoid body, cerebell ar cortex, deep cerebellar nuclei and area postrema. For the first tim e in rats, we described a large to very large number of cell bodies in the medial vestibular ventral part, prepositus hypoglossal gracile, r aphe magnus and sensory trigeminal nuclei. A large number of cells was also observed in the oral and caudal pontine, parvocellular, parvocel lular pars alpha, gigantocellular and gigantocellular pars alpha retic ular nuclei. In addition, glycine-immunoreactive cells were seen in th e ambiguus and subtrigeminal nuclei, the lateral habenula and the subf ornical organ. We also provide the first evidence in rats for a very l arge number of fibers in the trigeminal, facial, ambiguus and hypoglos sal motor nuclei, all nuclei of the medullary and pontine reticular fo rmation, and the raphe and trigeminal sensory nuclei. We further revea led the presence of a substantial number of fibers in regions where gl ycine was not considered as a main inhibitory neurotransmitter, such a s the pontine nuclei, the periaqueductal gray, the mesencephalic retic ular formation, the anterior pretectal nucleus, the intralaminar thala mic nuclei, the zona incerta, the fields of Forel, the parvocellular p arts of the paraventricular nucleus, the posterior hypothalamic areas, the anterior hypothalamic area, and the lateral and medial preoptic a reas. These results indicate that, in contrast to previous statements, glycine may be an essential inhibitory neurotransmitter not only in t he lower brainstem and spinal cord, but also in the upper brainstem an d the forebrain. Copyright (C) 1996 IBRO.