Noise-induced acetyl-histone H2B expression alteration in marginal cell of stria vascularis and spiral ganglion cell of cochlear / 中国耳鼻咽喉头颈外科

ABSTRACT

OBJECTIVE Aimed to observe the changes of acetylated histone H2B in the marginal cells of stria vascularis and spiral ganglion cells from the noise-induced hearing loss model (NIHL). METHODS Fifty guinea pigs were randomly divided into control and noise-exposure group. Auditory brainstem response threshold shift was examined before noise exposure and at 1h after noise exposure (122 dB SPL, 3 h). Immunofluorescence staining and western blot were used to observe the expression of acetyl-histone H2B both in the marginal cells of stria vascularis and spiral ganglion cells of modiolus 2 h after noise expose in two groups. RESULTS There was no significant difference in hearing threshold of 4, 8, 16, 32 kHz for the two groups before noise exposure. The hearing threshold was beyond 90dB (the maximum output) at 4,8,16 and 32 kHz 1h after noise exposure. The expression of acetylated histone H2B significantly decreased with immunofluorescence staining in the marginal cells after noise stimulation. Accordingly, the protein level of acetylated histone H2B in the lateral wall of cochlear decreased obviously in the noise group compared to the control, the ratios of H2B-AcK5/p-actin were 0. 3471 ±0. 0843 and 0. 6114 ±0. 0207 respectively(t=5. 268,P＜0. 01). There was no obvious difference for the expression of acetylated histone H2B in the modiolar tissue between two groups, the ratio of H2B-AcK5/p-actin was 0. 4993 ± 0. 0994 for the noise group and 0. 5139±0. 0132 for the controI (P＞0. 05). CONCLUSION Noise exposure significantly decreased histone acetylation expression in the nuclei of strial marginal cells, whereas the level in the spiral ganglion cells remained stable. Histone acetylation imbalance in the marginal cells of stria vascularis may contributed to the occurrence ofNIHL.