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Identification of miRNAs that regulate tinnitus development

ABSTRACT: To investigate which miRNAs regulate the development of tinnitus, we have performed microarray for miRNAs as a discovery platform. The changes in dorsal cochlear nucleus after noise exposure have been suggested to play an important role in the development of tinnitus. This study was performed using 12 week-old-male Sprague-Dawley rats. Based on our previous experiment about the development of tinnitus, we set a time point for harvesting dorsal cochlear nuclei: 3 weeks after the exposure of 6-8 kHz narrow-band noise (110 dB SPL for 2 h) at right side. Eight animals were divided into two experimental groups: tinnitus group showing evidence of tinnitus (n = 5); and non-tinnitus group showing no evidence of tinnitus (n = 3) in the gap pre-pulse inhibition of acoustic startle reflex (GPIAS) recordings. Three animals of each group were anesthetized deeply and euthanized at 3 weeks post noise exposure. Dorsal cochlear nucleus at right side was harvested. Microarray for miRNAs was performed using the Affymetrix miRNA 4.0 microarray. Considering the fold change of normalized signal intensities between tinnitus and non-tinnitus groups, miR-375-3p was selected as the candidate miRNA. This result was validated by quantitative reverse transcription-PCR.

ORGANISM(S): synthetic construct Rattus norvegicus

PROVIDER: GSE172259 | GEO | 2021/06/02

REPOSITORIES: GEO

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Project description:The molecular mechanisms underlying the great differences in susceptibility to noise-induced hearing loss (NIHL) exhibited by both humans and laboratory animals are unknown. Using microarray technology, the present study demonstrates that the effects of noise overexposure on the expression of molecules likely to be important to the development of NIHL differ among inbred mice that have distinctive susceptibilities to NIHL including B6.CAST, 129X1/SvJ, and 129S1/SvImJ. The noise-exposure protocol produced, on average, a permanent loss of about 40 dB in sensitivity for auditory brainstem responses in susceptible B6.CAST mice, but no threshold elevations for the two resistant 129S1/SvImJ and 129X1/SvJ substrains. Measurements of noise-induced gene expression changes 6 h after the noise exposure revealed significant alterations in the expression levels of 48 genes in the resistant mice, while by these same criteria, there were seven differentially expressed genes in the susceptible B6.CAST mice. Differentially expressed genes in both groups of mice included subsets of transcription factors. However, only in the resistant mice was there a significant induction of proteins involved in cell-survival pathways such as HSP70, HSP40, p21, GADD45ï¢, Ier3, and Nfï«ï¢iïº. Moreover, increased expression of three of these factors after noise was confirmed at the protein level. Drastically enhanced HSP70, GADD45ï¢, and p21 immunostaining were detected 6 h after the noise exposure in subsets of cells of the lateral wall, spiral limbus, and organ of Corti as well as in cochlear nerve fibers. Upregulation of these proteins after noise exposure likely contributes to the prevalence of survival cellular pathways and thus to the resistance to NIHL that is characteristic of the 129X1/SvJ mice. Experiment Overall Design: Female 10-wk-old mice of the B6.CAST and 129X1/SvJ strains were divided randomly into non-noise control and noise-exposure groups. The non-noise mice served as controls in the gene-profiling experiments to control for the stress induced by experimenter handling and/or confinement of the mice in the noise-exposure chamber that was not directly related to the noise. This mice were in the noise chamber for a sham exposure. In contrast, the ânoiseâ groups were exposed to a 105-dB SPL, 10-kHz octave band of noise for 1 h and sacrificed 6 h after the exposure. Of each of these major groups, eight mice were used for each of three 129X1/SvJ control and three noise-exposed 129X1/SvJ arrays and two B6.CAST control and two noise-exposed B6.CAST arrays. Consequently within each subgroup the arrays are biological replicates.

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Identification of miRNAs that regulate tinnitus development

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