Effects of Noise Exposure on the Auditory Function of Ovariectomized Rats with Estrogen Deficiency

Abstract

OBJECTIVE:The benefits of estrogen for the auditory function of women depend on a number of factors. In this study, we aimed to examine the impact of noise trauma on the auditory function of ovariectomized rats with estrogen deficiency. MATERIALS and METHODS:Twenty-eight young, female Sprague-Dawley rats were assigned to three groups (OVX+N, OVX-N, Sham+N). Rats in the OVX+N group and the OVX-N group underwent bilateral ovariectomy (OVX); the OVX+N group alone was also exposed to white noise (N) of 115 dB SPL for 8 hours a day over 14 days. The Sham+N group consisted of rats with intact ovaries that were exposed to the same noise. The auditory function of all rats was measured before treatment and after noise exposure by the signal-to-noise ratio (SNR) of distortion-product otoacoustic emissions (DPOAE) and the threshold of auditory-evoked brainstem response (ABR). RESULTS:The Sham+N group (intact ovaries, noise-exposed) had worse auditory function than the OVX-N group (ovariectomy, no noise). The OVX+N group had decreased SNRs of DPOAE and increased ABR thresholds relative to the Sham+N group. CONCLUSION:Noise exposure may cause greater damage to auditory function when estrogen levels are low in females.

Effects of Noise Pollution on Sex Hormone Levels in Rats

“…The results show that the noise pollution is not only directly damage the auditory organs [4], and stimulate the signal through the auditory system cause the hypothalamus-pituitary-adrenal axis excited [5], the adrenal glands secrete hormones in the body increases [6], heart rate increases, blood pressure rises, leading to cardiovascular damage [7], memory loss, attention deficit disorder, and other mental syndrome [8]. At the same time, noise pollution can also cause the inhibition of hypothalamic-pituitary-gonad axis , which can decrease male gonadal function [9], women estrogen abnormal secretion [10]. Noise pollution makes experimental rat testis and epididymis, seminal vesicle gland weight were significantly lower, and the number of sperm movement ability markedly reduced [11], the main reason is because of the noise pollution promoted the process of cell apoptosis, inhibit the occurrence of the sperm dynamics [12], make sperm and agglutination of sperm death increases [13], the male hormones (testosterone) level significantly lower [9].…”

Central conduction time in auditory brainstem response and ear advantage in dichotic listening across menstrual cycle

“…The participants had no history of abortion, pregnancy and use of contraceptives during the last 6 months prior to the study [ 2 , 5 ]. They also had no history of mental and neurological illnesses, tinnitus, central auditory processing disorder [ 5 ], ototoxic drug [ 28 ] and noise exposure [ 29 ]. Their otoscopic examination was normal and their hearing thresholds measured with an audiometer (AC40, Interacoustics, Middelfart, Denmark) were better than 25 dBHL bilaterally between 250Hz and 8000Hz.…”

Sex Differences in the Triad of Acquired Sensorineural Hearing Loss

“…In addition, the ERβ agonist treatment could reduce the temporary threshold shift. In female rats after ovariectomy, noise exposure can also cause more significant damage [ 121 ]. These results may partially explain the better hearing in females in response to noise observed in the clinic but the direct effect of estrogen on the auditory system in NIHL needs further elucidation.…”