oligonucleotidemicroarray. This study may also provide basic information to candidate genes associated with hearing loss and/or tinnitus or recovery after salicylate-induced cochlear dysfunction. Objectives: Salicylate ototoxicity is accompanied by temporary hearing loss and tinnitus. The purpose of the present study is to evaluate the gene expression profiles in the mouse cochlea with salicylate ototoxi- city using DNA microarray. Materials and Methods: The subject mice were injected intraperitoneally with 400 mg/kg of sodium salicylate, and an approximate 30 dB threshold shift that was observed by auditory brainstem response was achieved 3 hours after an injection of sodium salicylate and the hearing threshold returned to within normal range at 3 days. Differential gene expression profiles at 3 hours after salicylate injection in com- parison to the normal cochlea were analyzed with DNA microarray technology. Results: The analysis of the ontogenic distribution was performed in up-regulated or down-regulated genes with the Gene Ontology Database system and GFINDer. Microarray revealed that 87 genes were up-regulated two-fold or more in the mouse cochlea with salicylate ototoxicity in comparison to the nor- mal cochlea. Among these genes, increased expression levels of 30 functional genes were confirmed by semi-quantitative RT-PCR.
The dorsal cochlear nucleus as a contributor to auditory and non-auditory components of tinnitus. (Abstract of ARO Meeting Denver, Colorado) James Kaltenbach Waynes State University
The dorsal cochlear nucleus (DCN) has been modeled in numerous studies as a possible source of tinni- tus-generating signals. This hypothesis was originally developed on the basis of evidence that the DCN becomes hyperactive following exposure to intense noise. Since these early observations, evidence that the DCN is an important contributor to tinnitus has grown considerably. In this paper, the available evidence to date will be summarized. In addition, the DCN hypothesis of tinnitus can now be expanded to include possible involvement in other, non-auditory components of tinnitus. It will be shown by way of literature review that the DCN has direct connections with non-auditory brainstem structures, such as the locus coeruleus, reticular formation and raphe nuclei, that are implicated in the control of attention and emotional responses. The hypothesis will be presented that attentional and emotional disorders, such as anxiety and depression, which are commonly associated with tinnitus, may result from an interplay bet- ween these non-auditory brainstem structures and the DCN. Implicit in this hypothesis is that attempts to develop effective anti-tinnitus therapies are likely to benefit from a greater understanding of how the levels of activity in the DCN are influenced by different states of activation of these non-auditory brains- tem structures and vice versa.
Effects of salicylate on spontaneous activity in brain slices of different central auditory structures. (Abstract of ARO Meeting Denver, Colorado) Dietmar Basta1,2, Romy Goetze2, Magdalena Sliwowska2, Arne Ernst1 1Dept. of ENT at ukb, University of Berlin, Germany, 2Institute of Biology Humboldt-University of Berlin, Germany
Salicylate is well known to produce tinnitus in humans and animals as well. It has been shown that sys- temic application of salicylate primarily changes outer hair cell electromotility and can influence neuronal activity in several parts of the auditory system. A direct action of salicylate on neurons of the inferior colliclus has been shown earlier in brain slice preparations. However, such an effect cannot be excluded for other parts of the central auditory pathway. The present study therefore investigated the in-vitro-effect
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