No abstract

No abstract

Is the female sex steroid estrogen the key to preserved hearing in the aging human? This question remains unanswered, but hearing loss is more profound in elderly males than females. There are also well-known sex differences in the auditory brainstem response (ABR), i.e. women have shorter latencies than men. Moreover, menopausal women who are administered hormone replacement therapy have slightly better hearing than those who are not, and women with Turner's syndrome (45,X), who are biologically estrogen-deficient, show longer ABR latencies and early presbyacusis. These findings are also supported by animal experiments. When boosted with estrogen or testosterone the non-reproductive female midshipman fish alters its inner ear auditory mechanism so that it can hear the male's hum-like call. If estrogen receptor beta is knocked out in mice, severe progressive hearing loss occurs, leading to early deafness. In apparent contradiction to these findings, there have been case reports suggesting that hormone replacement therapy and oral contraceptive use can lead to hearing loss, but of another type, namely acute sudden deafness. Such contradictory aspects of the action of estrogen are commonly found and may spring from the fact that there are two estrogen receptors, alpha and beta, both of which are present in the inner ear of mice, rats and humans. Knowing how sex steroids can alter hearing ability may give important clues as to how estrogen can preserve hearing in humans. In this review we present a summary of current knowledge about hearing and estrogen.

The test group exhibited good preservation of the tissue, no increasing skin reactions and no adverse events. The time required for this surgery was reduced, as was their healing time. These patients also experienced less numbness and pain in the surrounding area and had an improved cosmetic outcome. MAIN OUTCOME AND CONCLUSION: This clinical trial indicates that introduction of the abutment to the osseointegrated screw directly through the skin, without skin thinning, could be beneficial. This approach had fewer negative effects than the conventional procedure during the 12- month follow-up period.

The hormone estradiol affects the auditory system both by itself and by its interaction with neuroprotective factors. In this study, we examined the role of estrogen receptors (ERs) in response to auditory trauma. We found a ligand-dependent protective role for ERβ in the auditory system by investigating mice deficient in ERα (ERKO mice), ERβ (BERKO mice), and aromatase (ARKO mice). Basal auditory brainstem response (ABR) thresholds were similar in all animals. An acoustic trauma causing a temporary hearing loss raised ABR thresholds in male and female BERKO and ARKO mice compared with WT and ERKO mice. The ERα-selective agonist, propyl(1H) pyrazole-1,3,5-triyl-trisphenol (PPT), partially protected ARKO mice from trauma, while the ERβ-selective agonist, 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN), protected WT and ARKO mice. Immunohistochemistry and western blotting confirmed the expression of ERβ in cochlea of WT males and females. Levels of brain-derived neurotrophic factor (BDNF), a neuroprotective peptide that can be induced by estrogen, was lower in BERKO and ARKO mice compared with WT. DPN treatment increased BDNF expression in ARKO mice. These data indicate ERβ-mediated neuroprotection involving BDNF in the auditory system of males and females.