Gene Expression after Cochlear Removal in Cochlear Nucleus at P7 and P21

Deprivation of peripheral nerve input by cochlear removal in young mice results in dramatic neuron death in the cochlear nucleus (CN). The same manipulation in older mice does not result in significant loss. The molecular basis of this critical period of vulnerability remains largely unknown. Here we identified genes regulated at early time points after cochlear removal at ages when neurons are vulnerable (postnatal day (P)7) or invulnerable (P21) to this challenge. Afferent deprivation regulated very different sets of genes at P7 and P21. These genes showed a variety of functions at both ages, but surprisingly there was no net increase in pro-apoptotic genes at P7. A large set of upregulated immune-related genes was identified at P21. Keywords: Time Course after Cochlear Removal, Age Comparison Mice received unilateral cochlear removals. At 6, 12, 24, and 48 hours after surgery, the CN ipsilateral and contralateral were removed, and RNA isolated from separate pools of tissue for each replicate. Deafferented CN were compared to age-matched and time-matched contralateral, control CN to identify genes regulated by cochlear removal at age P7 and P21.