This multifaceted project provides new knowledge of how the cochlear nucleus processes the information that it received from the inner ear through the auditory nerve. Neurotransmitters, neuromodulators, related enzymes and receptors active at major synapses in auditory nuclei in the brainstem are identified and characterized. It is determined how the auditory nerve and the cochlear nucleus may change after lesions in the cochlea. Small mammals have been used in these studies. I. Our results show, in immunocytochemical studies, with light and electron microscopy, using monoclonal antibodies against the glycine receptor and polyclonal antibodies against GABA and against glycine, that putative GABAergic and glycinergic innervation is widespread in the auditory brainstem. In double labeling studies, cells in the superficial dorsal cochlear nucleus showed immunoreaction to both anti-GABA and anti-glycine antibodies. II. We have begun to biochemically characterize excitatory amino acid receptors by studying how the binding of radioactively labeled glutamate and kainate changes with various detergent treatments of rat brain membrane. III. In collaboration with the Laboratory of Molecular Biology, NINCDS, we used our two affinity purified anti-glutamate dehydrogenase (anti-GDH) polyclonal antibodies to detect a bacteriophage expressing an immunoreactive recombinant protein. A comparison of peptides from this protein and from bovine GDH strongly suggested that the bacteriophage clone encoded part of the GDH gene. IV. We have begun to use neurofilament proteins of auditory nerve components (spiral ganglion cells, central and peripheral processes) as parameters to follow nerve changes after lesions of auditory sensory cells in the organ of hearing.
