Noise-induced Alteration In Expression Patterns Of Cystathionine-γ-lyase In Rat Cochleae

OBJECTIVEWith the progress of Urbanization and Industrialization, the impairment brought by noise to the human body is gradually perceivable. Many of the organs in our body could be affected by long-term exposure to noise, and hearing organs are of the most vulnerability. Massive evidences have identified microcirculation disturbance in the cochlea as a major cause of noise-induced hearing loss, thus making cochlear microcirculation a heat point of the otologists'interest in scientific research. Recent studies have implicated that hydrogen sulfide (H2S), one of the aseous signaling molecules, plays an important role in vascular microcirculation. Based on the distribution of H2S in the cochlea and its effect on angiotasis regulation, plus the pivotal role that microcirculation played in noise-induced hearing loss, we observed the expression and distribution of cystathionine-γ-lyase (CSE), a H2S synthetase in mammalian, in adult rat cochlea before and after noise exposure.Our findings set the basis for further investigations of the effects that H2S has on inner ear microcirculation, and shed light on a new way about the prevention and treatment of microcirculation disturbance associated inner ear disorders, including noise induced hearing loss.METHODSAn immunohistochemistry method was used to detect the locations of CSE in the normal cochlea tissue of adult Sprague Dawley rat. Thrity-two adult SD rats were divided into 4 groups: group 1 was normal animals, and group 2, 3 and 4 were the animals examined at 1 day ,1 week and 3 weeks after exposed to a broadband white noise of 110 dB SPL, respectively. The differential expressions of CSE before and after the noise exposure were examined using a RT-PCR technique.RESULTSWe found that CSE was expressed in the stria vascularis, microvascular and vascular endothelium of the modiolar artery. However, no immumoreativity was observed in the organ of Corti and spiral ganglion cells. The expression level of CSE mRNA was increased in the day-1 and week-1 groups,but decreased in the week-3 group.CONCLUSIONThese findings showed that CSE is expressed in the normal rat cochlea, and the differential expression after noise exposure is likely to contribute to the regulation of the cochlea blood flow.