Prestin gene expression in the rat cochlea following intense noise exposure.
Noise-induced permanent loss of cochlear amplification was observed previously with the majority of outer hair cells (OHCs) still surviving in the cochlea and even with a normal OHC receptor potential, indicated by CM (cochlear microphonics) recording [Chen, G.D., Fechter, L.D., 2003. The relationship between noise-induced hearing loss and hair cell loss in rats. Hear. Res. 177(1-2), 81-90; Chen, G.D., Liu, Y., 2005. Mechanisms of noise-induced hearing loss potentiation by hypoxia. Hear. Res. 200, 1-9]. This study focused on effects of an intense noise exposure (10-20 kHz at a level of 110 dB SPL for 4 h) on the OHC motor protein (prestin) and structural proteins in the OHC membrane skeleton. The noise exposure significantly disrupted CM and CAP (cochlear compound action potential). The injured CM recovered after 1-week resting period. The impaired CAP at frequencies lower than the noise band also recovered. However, the CAP recovery at frequencies of the noise band stopped at a linear line one week after the noise exposure, indicating a permanent loss of cochlear amplification. Gene expression of prestin, beta-spectrin, and beta-actin was significantly up-regulated after the noise exposure. The elevated gene expression peaked at the 3rd post-exposure day and returned to baseline 4 weeks after the noise exposure. The up-regulated gene expression may be in response to injury of the proteins, which may be responsible for the loss of cochlear amplification.
Chen
Guang-Di
GD
Center for Hearing and Deafness, 137 Cary Hall, 3435 Main Street, SUNY at Buffalo, Buffalo, NY 14214, USA. gchen7@buffalo.edu
D000200:Action Potentials; D000818:Animals; D027321:Anion Transport Proteins / Q000235:genetics*; D003051:Cochlea / Q000378:metabolism* / Q000503:physiopathology; D003055:Cochlear Microphonic Potentials; D015870:Gene Expression; D018072:Hair Cells, Auditory, Outer / Q000378:metabolism; D006317:Hearing Loss, Noise-Induced / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009622:Noise; D051381:Rats; D020318:Rats, Long-Evans; D000076988:Sulfate Transporters
D027321:Anion Transport Proteins; D009419:Nerve Tissue Proteins; C498719:SLC26A5 protein, human; D000076988:Sulfate Transporters