Oxidative stress, inflammation, and autophagic stress as the key mechanisms of premature age-related hearing loss in SAMP8 mouse Cochlea.

Aims: In our aging society, age-related hearing loss (ARHL) or presbycusis is increasingly important. Here, we study the mechanism of ARHL using the senescence-accelerated mouse prone 8 (SAMP8) which is a useful model to probe the effects of aging on biological processes.

Results: We found that the SAMP8 strain displays premature hearing loss and cochlear degeneration recapitulating the processes observed in human presbycusis (i.

Tmprss3, a transmembrane serine protease deficient in human DFNB8/10 deafness, is critical for cochlear hair cell survival at the onset of hearing.

Mutations in the type II transmembrane serine protease 3 (TMPRSS3) gene cause non-syndromic autosomal recessive deafness (DFNB8/10), characterized by congenital or childhood onset bilateral profound hearing loss. In order to explore the physiopathology of TMPRSS3 related deafness, we have generated an ethyl-nitrosourea-induced mutant mouse carrying a protein-truncating nonsense mutation in Tmprss3 (Y260X) and characterized the functional and histological consequences of Tmprss3 deficiency. Auditory brainstem response revealed that wild type and heterozygous mice have normal hearing thresholds up to 5 months of age, whereas Tmprss3(Y260X) homozygous mutant mice exhibit severe deafness.

Wayfinding through an unfamiliar environment.

Strategies for finding one's way through an unfamiliar environment may be helped by 2D maps, 3D virtual environments, or other navigation aids. The relative effectiveness of aids was investigated. Experiments were conducted in a large, park-like environment.

Impairment of SLC17A8 encoding vesicular glutamate transporter-3, VGLUT3, underlies nonsyndromic deafness DFNA25 and inner hair cell dysfunction in null mice.

Autosomal-dominant sensorineural hearing loss is genetically heterogeneous, with a phenotype closely resembling presbycusis, the most common sensory defect associated with aging in humans. We have identified SLC17A8, which encodes the vesicular glutamate transporter-3 (VGLUT3), as the gene responsible for DFNA25, an autosomal-dominant form of progressive, high-frequency nonsyndromic deafness. In two unrelated families, a heterozygous missense mutation, c.

Characteristics of tinnitus in a population of 555 patients: specificities of tinnitus induced by noise trauma.

Tinnitus is often associated with hearing loss of a known etiology. In this study, we compared tinnitus that appeared to be induced by noise trauma with that perceived to start in other circumstances in a population of 555 patients attending the specialist tinnitus clinic at the University Hospital in Montpellier, France. Patients had consulted for persistent tinnitus for 7 years from the onset of their symptoms.

Physiology, pharmacology and plasticity at the inner hair cell synaptic complex.

This report summarizes recent neuropharmacological data at the IHC afferent/efferent synaptic complex: the type of Glu receptors and transporter involved and the modulation of this fast synaptic transmission by the lateral efferents. Neuropharmacological data were obtained by coupling the recording of cochlear potentials and single unit of the auditory nerve with intra-cochlear applications of drugs (multi-barrel pipette). We also describe the IHC afferent/efferent functioning in pathological conditions.

Dopamine transporter is essential for the maintenance of spontaneous activity of auditory nerve neurones and their responsiveness to sound stimulation.

Dopamine, a neurotransmitter released by the lateral olivocochlear efferents, has been shown tonically to inhibit the spontaneous and sound-evoked activity of auditory nerve fibres. This permanent inhibition probably requires the presence of an efficient transporter to remove dopamine from the synaptic cleft. Here, we report that the dopamine transporter is located in the lateral efferent fibres both below the inner hair cells and in the inner spiral bundle.

Expression of members of Wnt and Frizzled gene families in the postnatal rat cochlea.

The functioning of the mammalian cochlea is entirely based on its mechanical properties, which are supported by a highly complex tissue architecture resulting from the precise arrangement of sensory hair cells and non-sensory supporting cells. Growing evidence indicates that evolutionary conserved signaling pathways are involved in inner ear development and in the differentiation of its diverse cell types. We investigated whether members of the Wnt and Frizzled gene families, which play key roles in a wide variety of cellular and developmental processes, are expressed in the postnatal rat cochlea.