[Protective effects of N-acetylcysteine on cochlear damage occur in guinea pigs exposed to irradiation].
OBJECTIVE
To explore the protective effects of N-acetylcysteine (NAC) on cochlear damage occurring in irradiated guinea pigs.


METHODS
Seventy-two guinea pigs were randomly divided into 4 groups (n = 18 each). Control group received neither NAC nor irradiation, irradiation group received total cranium irradiation of 70 Gy, irradiation & saline group cranium irradiation of 70 Gy and saline solution through a round window and NAC group cranium irradiation of 70 Gy and NAC through a round window. The right ear received radiation. The animals were sacrificed at Day 14 post-irradiation. The specimens were dehydrated, embeded in paraffin and serially cut into 5-µm slices. Sections were stained with immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). The cochlear basal membranes were observed for malondialdehyde (MDA) and superoxide dismutase (SOD) with scanning electron microscope.


RESULTS
The cilium of hair cells had no clear loss and apoptotic number of spiral ganglion cells decreased in NAC group. The average optical density value of Caspase 3 in spiral ganglion in NAC group significantly decreased versus the irradiation group (0.08 ± 0.02 vs 0.10 ± 0.01, P < 0.01). The level of MDA of NAC group also decreased versus the irradiation group (0.33 ± 0.05 vs 0.84 ± 0.13, P < 0.05). The level of SOD in the NAC group increased versus the irradiation group (10.7 ± 3.0 vs 8.7 ± 1.3, P < 0.05). The ratio of apoptotic cell in SGC in the NAC group at Day 14 (7.8% ± 1.8%) decreased versus the irradiation group (32.0% ± 8.7%) at Day 14.


CONCLUSIONS
MDA and SOD may be involved in the pathogenesis of cochlear cell damage. And NAC protects the irradiated cochlear cell.
Department of Otorhinolaryngology & Head and Neck, First Affiliated Hospital, Guangxi Medical University, Nanning 530021, China.
Li-hong
LH
Xie
An-zhou
AZ
Tang
Shi-hua
SH
Yin
Song-hua
SH
Tan
D000111:Acetylcysteine / Q000494:pharmacology*; D000818:Animals; D003051:Cochlea / Q000187:drug effects* / Q000378:metabolism* / Q000528:radiation effects; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000166:cytology; D008315:Malondialdehyde / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism
D008315:Malondialdehyde; D013482:Superoxide Dismutase; D000111:Acetylcysteine