Up-regulation of prestin mRNA expression in the organs of Corti of guinea pigs and rats following unilateral impulse noise exposure.
Prestin is the motor protein of the outer hair cells (OHCs) and is required for both their electromotility and for cochlear amplification. We investigated the prestin mRNA expression in guinea pigs and rats in relation to the degree of noise-induced hearing loss (NIHL) induced by unilateral impulse noise exposure (167dB peak SPL) for 2.5-5 min. Distortion product otoacoustic emissions (DPOAE) and auditory brainstem responses were recorded before and one week post exposure. Prestin mRNA was examined by quantitative reverse transcription-polymerase chain reaction. Either the whole organs of Corti or the apical, middle and basal parts were examined separately. The specimens were pooled and grouped according to the degree of NIHL measured in the exposed ears. In rats, the number of hair cells was counted. A clear base-to-apex gradient in the prestin mRNA expression was found to exist in guinea pig and rat controls. In both species, there was an increase in the number of prestin RNA transcripts at a mean NIHL of about 15-25 dB indicating an up-regulation in the remaining intact cells. In rats, this degree of NIHL corresponded to an OHC loss of about 40%. Interestingly, the contralateral ears also revealed an up-regulation of prestin mRNA accompanied by significant DPOAE improvements.
Mazurek
Birgit
B
Charité-Universitätsmedizin Berlin, Campus Charité Mitte, Department of Otorhinolaryngology, Molecular Biological Research Laboratory, Charitéplatz 1, 10117 Berlin, Germany. birgit.mazurek@charite.de
Haupt
Heidemarie
H
Amarjargal
Nyamaa
N
Yarin
Yuri M
YM
Machulik
Astrid
A
Gross
Johann
J
D000818:Animals; D001933:Brain Stem / Q000378:metabolism; D005260:Female; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000378:metabolism; D034381:Hearing Loss; D008297:Male; D009622:Noise; D017084:Otoacoustic Emissions, Spontaneous; D011312:Pressure; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015854:Up-Regulation
C498722:Pres protein, Cavia porcellus; D011506:Proteins; D012333:RNA, Messenger