Protective Effects of Estrogen on Cochlea during Mid-Long Term Simulated Manned Spacecraft Environment
ZHANG Chi
WU Wei
HAN Haolun
WANG Gang
ZHOU Libin
WANG Hongnan
LI Baowei
DING Ruiying
Abstract：Objective To study the effects of compound factors of weightlessness and noise in spaceship on rat hearing and cochlear morphology, as well as protection against auditory damage by estrogen. Methods Thirty two SD rats were ran-domly divided into groups A and B (n=12 each) and group C (n=8) Animals in groups A and B were subjected to glued tail suspension to simulate weightlessness, and exposed to simulated spaceship noise for 8 weeks. Additionally, animals in group B were injected with 0.02 mg benzoate twice a week (first dose=0.04 mg) until the end of the experiment. Auditory brain-stem response (ABR) thresholds were tested bilaterally before and at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks after noise exposure. The cochlea was harvested and processed for scanning electron microscopy (SEM) studies at the end. Re-sults ABR thresholds were significantly higher in group A than other groups (P<0.01). The longer the exposure, the higher the thresholds. ABR thresholds in group B were also increased along with noise exposure (P< 0.05). ABR thresholds in group C increased along with noise exposure from week 1 to week 2 (P<0.05), but not significantly at other time points (P>0.05). ABR thresholds in group A were higher than in group C at all times (P<0.01). ABR thresholds in group B were not significantly different than in group C from day 3 to 8 weeks. (P>0.05). ABR thresholds in group A were not significant-ly different from group B during the 1st week, but higher than group B at other time points (P< 0.05). SEM showed the most severe cochlear damage in group A, followed by group B. Only mild cochlear change was observed in group C. Con-clusions Simulated weightlessness and noise exposure can cause damage to hearing and changes of cochlear morphology in SD rats. Estrogen appears to protect against such damages.
Keywords：Simulated weightlessnessNoiseAuditory brainstem responseEstrogen
Publication Date：2015-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：4( 738-741 )