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  • Small Arms Fire-like noise:...
    Altschuler, Richard A.; Halsey, Karin; Kanicki, Ariane; Martin, Cathy; Prieskorn, Diane; DeRemer, Susan; Dolan, David F.

    Neuroscience, 05/2019, Letnik: 407
    Journal Article

    •Small arms fire-like noise induced loss of inner hair cell synaptic ribbons in rat cochleae.•Small arms fire-like noise also reduced Gap Detection many noise-induced rats, this can be associated with Tinnitus.•Noise-exposed rats with reduced Gap Detection had greater loss of hair cell ribbons than those with normal Gap Detection.•Piribedil, memantine, and ACEMg treatment significantly reduced the noise-induced loss of ribbons.•A treatment induced reduction in incidence of noise-induced reduced Gap Detection did not reach significance. A noise-induced loss of inner hair cell (IHC) – auditory nerve synaptic connections has been suggested as a factor that can trigger the progression of maladaptive plastic changes leading to noise-induced tinnitus. The present study used a military relevant small arms fire (SAF)-like noise (50 biphasic impulses over 2.5 min at 152 dB SPL given unilaterally to the right ear) to induce loss (∼1/3) of IHC synaptic ribbons (associated with synapse loss) in rat cochleae with only minor (less than 10%) loss of outer hair cells. Approximately half of the noise-exposed rats showed poorer Gap Detection post-noise, a behavioral indication suggesting the presence of tinnitus. There was significantly greater loss of IHC ribbons in noise-exposed rats with reduced Gap Detection compared to noise-exposed rats retaining normal Gap Detection. We have previously shown systemic administration of piribedil, memantine, and/or ACEMg significantly reduced loss of IHC ribbons induced by a 3 h 4 kHz octave band 117 dB (SPL) noise. The present study examined if this treatment would also reduce ribbon loss from the SAF-like noise exposure and if this would prevent the reduced Gap Detection. As in the previous study, piribedil, memantine, and ACEMg treatment significantly reduced the noise-induced loss of ribbons, such that it was no longer significantly different from normal. However, it did not prevent development of the reduced Gap Detection indication of tinnitus in all treated noise-exposed rats, reducing the incidence but not reaching significance.