Abstract
Glutamate is used in the cochlear nucleus as a neurotransmitter by cochlear nerve synapses and by local circuits of granule cell axons. In the present study, immunocytochemistry and in situ hybridization were used to identify different types of neurons expressing N-methyl- d-aspartate receptor subunit 1 (NMDAR1) in the mouse cochlear nucleus. N-Methyl- d-aspartate receptor subunit 1 was expressed in most neuronal types, but granule cells in the dorsal cochlear nucleus had little, if any, expression, unlike their heavily labeled counterparts in the small cell shell and cerebellum. The findings do not support an analogy between the dorsal cochlear nucleus and the cerebellar cortex. In the cochlear nucleus the most heavily labeled structures were dendrites in the small cell shell and superficial dorsal cochlear nucleus, including the fusiform cell apical dendrites, which are targets of granule cell axons. However, fusiform cell basal dendrites, which are the synaptic sites of cochlear nerve fibers, did not express N-methyl- d-aspartate receptor subunit 1. Thus different parts of the fusiform cells can have different subunits in their glutamte receptors. Also branches of the same cochlear nerve axons projecting to the octopus, stellate, and bushy cells of the ventral cochlear nucleus can use N-methyl- d-aspartate receptor, while their branches to fusiform cells cannot. Each cochlear nucleus neuron type has a characteristic level of N-methyl- d-aspartate receptor subunit 1 expression. Each type differs in its auditory response properties, which may depend on synaptic activities requiring different glutamate subunit patterns.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call