Effects of Estrogen on Guinea Pig Auditory Function in Simulated Spaceship Weightlessness and Noise

WANG Gang; WU Wei; HAN Hao-lun; QU Chang-bei; WANG Fang-yuan; WANG Hong-nan; LI Bao-wei; MENG Ling-zhao; YU Xue-jun; WU Da-wei; Niu Cong-min; Liu Gang

doi:10.3969/j.issn.1672-2922.2013.02.031

Abstract： Objective To investigate the effects of combined simulated weightlessness and noise on auditory brainstem response thresholds in guinea pigs and the protective effects of estrogen. Methods Forty guinea pigs were randomly divided into a simulated weightlessness only group, a weightlessness with noise group, an estrogen treatment group and an estrogen prevention group. Weightlessness was simulated by posterior limb suspension, at a-30° angle between horizon and longitudi-nal axis of the body. Except for the weightlessness only group, animals in all other groups were also exposed to simulated spaceship flying and return stages noise for 5 days.Intramuscular injection of estradiol benzoate (0.08 mg/kg/day with dou-ble dose on Day 1) was administered for 3 days before experiment in the estrogen prevention group, and from the start of the experiment to 3 days after experiment in the estrogen treatment group. Auditory brainstem response (ABR) thresholds were re-corded before, at the end of and 3 days after the experiment. Results ABR thresholds were not different among the groups be-fore the experiment. ABR thresholds were different at the end of and 3 days after the experiment, with those in the estrogen treatment group being the lowest. ABR threshold differences were also seen at different times during experiment in each group. Conclusion While both weightlessness and noise can lead to damage of auditory function in guinea pigs, their combi-nation can cause even more severe damage. Estrogen appears to have protective effects against damage of auditory function caused by compound weightlessness and noise factors in space.