Estrogen receptors in the normal adult and developing human inner ear and in Turner's syndrome

Sexual orientation and the auditory system

The auditory system exhibits differences by sex and by sexual orientation, and the implication is that relevant auditory structures are altered during prenatal development, possibly by exposure to androgens. The otoacoustic emissions (OAEs) of newborn male infants are weaker than those of newborn females, and these sex differences persist through the lifespan. The OAEs of nonheterosexual females also are weaker than those of heterosexual females, suggesting an atypically strong exposure to androgens some time early in development. Auditory evoked potentials (AEPs) also exhibit sex differences beginning early in life. Some AEPs are different for heterosexual and nonheterosexual females, and other AEPs are different for heterosexual and nonheterosexual males. Research on non-humans treated with androgenic or anti-androgenic agents also suggests that OAEs are masculinized by prenatal exposure to androgens late in gestation. Collectively, the evidence suggests that prenatal androgens, acting globally or locally, affect both nonheterosexuality and the auditory system.

Discrepancy in improvement of hearing loss between left and right ears after postmenopausal hormone therapy

Physiological levels of estrogen would seem to have a possible protective effect on hearing function and estrogen replacement therapy may delay hearing loss in menopausal women. Treatment of healthy menopausal women with Tibolone for 6 months resulted in improvement in audiometry results at low frequencies which was more prominent on the right side. The reason of better improvement on the right side is not known. There might be some other factors modifying the condition or effect of the drug such as laterality. There might be hearing lateralization in menopausal women. Especially significant improvement on right ear might be explained by differences in distribution of estrogen receptor (ER) in the ear, in another words lateralization of ER concentration. ER-α and -β might be more dense in the right ear, so give better response to estrogen treatment. Another reason might be difference in bone mineral density of sides of body which is lower on the right side. Similarly lower bone mineral density right ear bones would cause better response to estrogen therapy and better improvement in audiometry results on that side.

Peripheral auditory processing changes seasonally in Gambel's white-crowned sparrow

Song in oscine birds is a learned behavior that plays important roles in breeding. Pronounced seasonal differences in song behavior and in the morphology and physiology of the neural circuit underlying song production are well documented in many songbird species. Androgenic and estrogenic hormones largely mediate these seasonal changes. Although much work has focused on the hormonal mechanisms underlying seasonal plasticity in songbird vocal production, relatively less work has investigated seasonal and hormonal effects on songbird auditory processing, particularly at a peripheral level. We addressed this issue in Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii), a highly seasonal breeder. Photoperiod and hormone levels were manipulated in the laboratory to simulate natural breeding and non-breeding conditions. Peripheral auditory function was assessed by measuring the auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) of males and females in both conditions. Birds exposed to breeding-like conditions demonstrated elevated thresholds and prolonged peak latencies when compared with birds housed under non-breeding-like conditions. There were no changes in DPOAEs, however, which indicates that the seasonal differences in ABRs do not arise from changes in hair cell function. These results suggest that seasons and hormones impact auditory processing as well as vocal production in wild songbirds.

Sex differences in auditory filters of brown-headed cowbirds (Molothrus ater)

Receiver sensory abilities can be influenced by a number of factors, including habitat, phylogeny and the selective pressure to acquire information about conspecifics or heterospecifics. It has been hypothesized that brood-parasitic brown-headed cowbird (Molothrus ater) females may locate or determine the quality of potential hosts by eavesdropping on their sexual signals. This is expected to produce different sex-specific pressures on the auditory system to detect conspecific and heterospecific acoustic signals. Here, we examined auditory filter shape and efficiency, which influence the ability to resolve spectral and temporal information, in males and females at center frequencies of 2, 3 and 4 kHz. We found that overall, cowbirds had relatively wide filters (lsmean +/- SE: 619.8 +/- 41.6 Hz). Moreover, females had narrower filters (females: 491.4 +/- 66.8, males: 713.8 +/- 67.3 Hz) and greater filter efficiency (females: 59.0 +/- 2.0, males: 69.8 +/- 1.9 dB) than males. Our results suggest that the filters of female cowbirds may allow them to extract spectral information from heterospecific vocalizations. The broader auditory filters of males may reflect limited spectral energy in conspecific vocalizations in this frequency range, and hence, weaker selection for high resolution of frequency in the range of 2-4 kHz.

Epidermal growth factor receptor expression in human fetal cochlea with Turner syndrome

HYPOTHESIS

Growth hormones have beneficial effects on increasing height in adults with Turner syndrome (TS) and may also affect auditory function.

BACKGROUND

Turner syndrome is the most common sex-linked chromosomal abnormality in female conceptions. Epidermal growth factor and its receptor (EGFR) affect differentiation, proliferation, and migration of epithelial cells and function as survival factors. The expression of EGFR is found in the developing and juvenile inner ear of experimental animals but is absent in adults.

METHODS

To determine whether EGFR plays a role in TS, its expression was analyzed in the cochlea of healthy fetus and fetus with TS and in healthy adults.

RESULTS

In healthy fetuses, EGFR protein expression was localized to the inner and outer hair cells and the Reissner membrane. The fetuses with TS on the 13th gestational week (GW) showed a similar pattern of immunoreactivity as the normal 16th and 20th GW cochlea. By the 23rd GW, EGFR immunoreactivity was not detectable in the TS hair cells or the Reissner membrane, and less intensive staining was found in the surrounding fibrocytes of the spiral ganglion.

CONCLUSION

This is the first demonstration of EGFR immunoreactivity in the human cochlea and illustrates how EGFR expression is altered during development in TS. These findings indicate the importance of growth hormone receptors for inner ear development in humans.

Estrogen receptors in the inner ear during different stages of pregnancy and development in the rat

CONCLUSION

ERalpha and ERbeta are present in the inner ear and are up- and down-regulated depending on the stage of maturation, development and pregnancy, suggesting that estrogen may have an effect on the cochlea during various stages of life. No estrogen receptors (ERs) were found in the cochlea of the developing fetus, which suggests that estrogen does not have an effect on the cochlea during gestation.

OBJECTIVE

To investigate the distribution of ERs in the cochlea during pregnancy, maturation and development in a female rat model.

MATERIALS AND METHODS

The cochleas of 24 rats in 4 groups in different time periods of maturation (21 and 56 days old) and pregnancy (day 8 and 18 of pregnancy) and 16 fetuses at gestational ages of 8 and 18 days were collected. All specimens were stained for ERs using standard immunohistochemical techniques.

RESULTS

ERs are present in the cochlea of the rat and vary during maturation and pregnancy. No ERs were found in the fetal cochleas. Of the non-fetal time points measured, the expression levels of ERs in the rat cochlea were highest at the postnatal age of 21 days and were lowest during late pregnancy (day 18).

Presence of aromatase and estrogen receptor alpha in the inner ear of zebra finches

Sex differences in song behavior and in the neural system controlling song in songbirds are well documented but relatively little is known about sex differences in hearing. We recently demonstrated the existence of sex differences in auditory brainstem responses in a songbird species, the zebra finch (Taeniopygia guttata). Many sex differences are regulated by sex steroid hormone action either during ontogeny or in adulthood. As a first step to test the possible implication of sex steroids in the control of sex differences in the zebra finch auditory system, we evaluated via immunocytochemistry whether estrogens are produced and act in the zebra finch inner ear. Specifically we examined the distribution of aromatase, the enzyme converting testosterone into an estrogen, and of estrogen receptors of the alpha subtype (ERalpha) in adult zebra finch inner ears. The anatomy of the basilar papillae was visualized by fluorescein-phalloidin, which delineated the actin structure of hair cells and supporting cells at their apical surface. Whole mount preparations of basilar papillae stained by immunocytochemistry revealed in both males and females an abundant aromatase distribution in the cytoplasm of hair cells, while ERalpha was identified in the nuclei of hair cells and of underlying supporting cells. Double-labeled preparations confirmed the extensive co-localization of aromatase and ERalpha in the vast majority of the hair cells. These results are consistent with studies on non-avian species, suggesting a role for estrogens in auditory function. These findings are also consistent with the notion that estrogens may contribute to a sex difference in hearing. To our knowledge, this is the first demonstration of the presence of aromatase and of the co-localization of aromatase and ERalpha in the sensory epithelium of the inner ear in any animal model.

Masculinization of the mammalian cochlea

Otoacoustic emissions (OAEs) differ between the sexes in humans, rhesus and marmoset monkeys, and sheep. OAEs also are different in a number of special populations of humans. Those basic findings are reviewed and discussed in the context of possible prenatal-androgen effects on the auditory system. A parsimonious explanation for several outcomes is that prenatal exposure to high levels of androgens can weaken the cochlear amplifiers and thereby weaken otoacoustic emissions (OAEs). Prenatal androgen exposure apparently also can alter auditory evoked potentials (AEPs). Some non-hormonal factors possibly capable of producing sex and group differences are discussed, and some speculations are offered about specific cochlear structures that might differ between the two sexes.

Surgical management of otologic disease in pediatric patients with Turner syndrome

OBJECTIVES

Previous reports suggest that patients with Turner syndrome have a predisposition for acute and chronic otitis media. However, the role of early or aggressive surgical management of otologic disease has not been explored in the pediatric population. With respect to otitis media in pediatric Turner syndrome patients, we examined (1) the impact of timing and (2) the type of surgical intervention in the treatment of disease.

METHODS

Retrospective 10-year review of patients with Turner syndrome and chronic otitis and its surgical management at a single pediatric tertiary institution.

RESULTS

One hundred and seventy-eight patients with Turner syndrome were evaluated at our institution from 1997 to 2007. Thirty-two (18.0%) were diagnosed with middle ear disease. Eighteen (10.1%) were referred to otolaryngology for evaluation. Average age at presentation was 4.7 years (range: 1 month to 12 years). The 18 patients referred to otolaryngology required a mean of 16 clinic visits each for otologic symptoms. A mean of 6.7 pressure equalization tubes (PET) were required per patient (range: 0-25). Middle ear effusions (n=14, 78%) along with tympanic membrane retractions and/or perforations (n=10, 55.6%) were the most common otoscopic findings. Patients with tympanic membrane retractions (8/18) required a higher average number of PET (9.1) and cumulatively underwent a total of five tympanoplasty-type procedures. Six ears had evidence of cholesteatoma. Two patients underwent myringoplasty, 6 patients underwent tympanoplasty (33.3%, mean age 11.6 years), and 3 patients (16.7%, mean age 9.4 years) underwent tympanomastoidectomy. Revision procedures were common. Older age at first PET placement was significantly correlated with the need for later tympanoplasty and/or tympanomastoidectomy operations (p<0.036). Tympanoplasty or tympanomastoidectomy patients had their first PET placed on average at 5.2 years as compared to 2.6 years in those not requiring tympanoplasty or tympanomastoidectomy operations.

CONCLUSIONS

Recurrent and chronic otitis media is common in patients with Turner syndrome. Once established, disease is recalcitrant and leads to multiple surgical procedures. Early PET insertion is advocated to offset the future necessity of more extensive tympanic procedures.

Estrogen and hearing from a clinical point of view; characteristics of auditory function in women with Turner syndrome

Turner syndrome is a chromosomal aberration affecting 1:2000 newborn girls, in which all or part of one X chromosome is absent. This leads to ovarial dysgenesis and little or no endogenous estrogen production. These women have, among many other syndromal features, a high occurrence of ear and hearing problems, and neurocognitive dysfunctions, including reduced visual-spatial abilities; it is assumed that estrogen deficiency is at least partially responsible for these problems. In this, study 30 Turner women aged 40-67, with mild to moderate hearing loss, performed a battery of hearing tests aimed at localizing the lesion causing the sensorineural hearing impairment and assessing central auditory function, primarily sound localization. The results of TEOAE, ABR and speech recognition scores in noise were all indicative of cochlear dysfunction as the cause of the sensorineural impairment. Phase audiometry, a test for sound localization, showed mild disturbances in the Turner women compared to the reference group, suggesting that auditory-spatial dysfunction is another facet of the recognized neurocognitive phenotype in Turner women.

Hearing loss in Turner syndrome: results of a multicentric study

The purpose of this article was to evaluate otological diseases in 173 patients (pts) with Turner syndrome (TS).

STUDY DESIGN

One hundred and seventy-three pts, mean chronological age (CA) 12+/-6.2 yr. Patients were submitted to different therapies: GH, estrogen therapy (EE), no therapy (no tx). Seventy-nine pts (CA 11 yr) had no otological diseases. Conductive hearing loss (CHL) occurred in 38.7% (CA 11 yr) and otoscopy was: persistent secretory otitis media in 55.2%, chronic otitis media in 10.4%, pars flaccida retraction pocket in 19.4%, mostly bilateral. Cholesteatoma was present in 15%. Sensorineurinal hearing loss (SNHL) occurred in 15.6% (CA 16 yr), 11 of whom were affected by high tone loss, and 15 by loss in midfrequencies (dip between 0.5-3 kHz), bilateral in 93%. Degree of hearing loss (HL) was mild [20-40 decibel hearing level (dBHL)] in 15%, moderate (45-60 dBHL) in 31%, severe (65-80 dBHL) in 8%, profound (dBHL>85) in 2%. We found a significant association between CHL and karyotype 45, X (p<0.025), congenital cranio-facial abnormalities, prevalently with low-set ears (p<0.04), narrow and/or high arched palate (p<0.018), and micrognathia (p<0.004). Our study confirms that the high prevalence of middle ear infections and CHL in TS are probably due to growth disturbances of the structures from the first and second branchial arches. We did not find any association between EE, GH, and HL. We recommend a regular audiological follow-up, especially during childhood, to prevent important middle ear anatomic sequele and to identify HL at an early stage, as the impact on social functioning may be significant.

Estrogen receptor beta protects against acoustic trauma in mice

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 ERbeta in the auditory system by investigating mice deficient in ERalpha (ERKO mice), ERbeta (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 ERalpha-selective agonist, propyl(1H) pyrazole-1,3,5-triyl-trisphenol (PPT), partially protected ARKO mice from trauma, while the ERbeta-selective agonist, 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN), protected WT and ARKO mice. Immunohistochemistry and western blotting confirmed the expression of ERbeta 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 ERbeta-mediated neuroprotection involving BDNF in the auditory system of males and females.

Ultrastructural changes in otoconia of osteoporotic rats

The etiology of benign paroxysmal positional vertigo (BPPV) remains obscure in many cases and women are affected more often than men. A recent prospective study, performed in women >50 years of age suffering from recurrent BPPV, showed associated osteopenia or osteoporosis in a large percentage of these patients. These results suggested the possible relationship between recurrent BPPV and a decreased fixation of calcium in bone in women >50 years. To test this hypothesis, an experimental study was performed in adult female rats. Utricular otoconia of female rats in which osteopenia/osteoporosis was induced by bilateral ovariectomy (OVX) were compared to those of sham-operated adult females rats (SHAM), as control group. FIRST STUDY: The morphology of theutricles of OVX and SHAM rats was analyzed with scanning electron microscopy. In osteopenic/osteoporotic rats, the density of otoconia (i.e. the number of otoconia per unit area) was decreased (p = 0.036)and their size was increased (p = 0.036) compared to the control group. SECOND STUDY: To test the role of calcium turnover in such morphological changes, utricular otoconia of 2 other groups of OVX and SHAM rats, previously injected with calcein subcutaneously, were examined by conventional and epifluorescence microscopy. In epifluorescence microscopy, labeling with calcein showed no significant fluorescence in either group. This finding was interpreted as a lack of external calcium turnover into otoconia of adult female rats. The ultrastructural modifications of otoconia in osteopenic/osteoporotic female adult rats as well as the role of estrogenic receptors in the inner ear are discussed. The possible pathophysiological mechanisms which support the relationship between recurrent BPPV in women and the disturbance of the calcium metabolism of osteopenia/osteoporosis are debated.

Experimental estrogen-induced hyperprolactinemia results in bone-related hearing loss in the guinea pig

Our group (Horner KC, Guieu R, Magnan J, Chays A, Cazals Y. Neuropsychopharmacology 26: 135-138, 2002) has earlier described hyperprolactinemia in some patients presenting inner ear dysfunction. However, in that study, it was not possible to determine whether hyperprolactinemia was a cause or an effect of the symptoms. To investigate the effect of hyperprolactinemia on inner ear function, we first developed a model of hyperprolactinemia in estrogen-primed Fischer 344 rats and then performed functional studies on pigmented guinea pigs. Hyperprolactinemia induced, after 2 mo, a hearing loss of approximately 30-40 dB across all frequencies, as indicated by the compound action potential audiogram. During the 3rd mo, the hearing loss continued to deteriorate. The threshold shifts were more substantial in males than in females. Observations under a dissection microscope revealed bone dysmorphology of the bulla and the cochlea. Light microscopy observations of cryostat sections confirmed bone-related pathology of the bony cochlear bulla and the cochlear wall and revealed morphopathology of the stria vascularis and spiral ligament. Scanning electron microscopy revealed loss of hair cells and stereocilia damage, in particular in the upper three cochlear turns and the two outermost hair cell rows. The data provide the first evidence of otic capsule and hair cell pathology associated with estrogen-induced prolonged hyperprolactinemia and suggest that conditions such as pregnancy, anti-psychotic drug treatment, aging, and/or stress might lead to similar ear dysfunctions.

Estrogen and the inner ear: megalin knockout mice suffer progressive hearing loss

Megalin, the largest member of the low-density lipoprotein receptor-related protein family, functions as an endocytic receptor for a variety of essential lipophilic metabolites, including the steroid hormone estrogen. In the cochlea, megalin is strongly expressed within the marginal cells of the stria vascularis, and previous studies demonstrated that beta-estrogen receptors are also expressed in megalin-expressing marginal cells. In the present study, we demonstrate that homozygous megalin mutant mice exhibit profound hearing loss at 3 months of age associated with features of presbycusis, enrichment of lipofuscin granules, and a reduced number of microvilli in marginal cells of the stria vascularis. FITC-labeled beta-estrogen is taken up into the strial marginal cells; however, in megalin-deficient mice the uptake of FITC-labeled beta-estrogen is reduced. This highlights beta-estrogen as a possible carrier-bound candidate ligand for megalin and supports the concept that estrogen may function via megalin within the inner ear. A crucial role of megalin in hearing should be considered and the megalin/estrogen interaction needs to be discussed in the context of early presbycusis in estrogen-deficient humans and mice.

Large scale gene expression profiles of regenerating inner ear sensory epithelia

Loss of inner ear sensory hair cells (HC) is a leading cause of human hearing loss and balance disorders. Unlike mammals, many lower vertebrates can regenerate these cells. We used cross-species microarrays to examine this process in the avian inner ear. Specifically, changes in expression of over 1700 transcription factor (TF) genes were investigated in hair cells of auditory and vestibular organs following treatment with two different damaging agents and regeneration in vitro. Multiple components of seven distinct known signaling pathways were clearly identifiable: TGFbeta, PAX, NOTCH, WNT, NFKappaB, INSULIN/IGF1 and AP1. Numerous components of apoptotic and cell cycle control pathways were differentially expressed, including p27(KIP) and TFs that regulate its expression. A comparison of expression trends across tissues and treatments revealed identical patterns of expression that occurred at identical times during regenerative proliferation. Network analysis of the patterns of gene expression in this large dataset also revealed the additional presence of many components (and possible network interactions) of estrogen receptor signaling, circadian rhythm genes and parts of the polycomb complex (among others). Equal numbers of differentially expressed genes were identified that have not yet been placed into any known pathway. Specific time points and tissues also exhibited interesting differences: For example, 45 zinc finger genes were specifically up-regulated at later stages of cochlear regeneration. These results are the first of their kind and should provide the starting point for more detailed investigations of the role of these many pathways in HC recovery, and for a description of their possible interactions.

Hearing impairment and low bone mineral density increase the risk of bone fractures in women with Turner's syndrome

AIMS

To assess factors associated with excess rates of fractures in women with Turner's syndrome (TS).

OUTCOME MEASURES

History of bone fracture and treatment with oestrogen, growth hormone (GH), oxandrolone and thyroxine, anthropometry, blood measurements of calcium, vitamin D (25-hydroxycholecalciferol), parathyroid hormone and karyotype, pure tone audiometry and spinal bone mineral density (BMD).

RESULTS

One hundred and seventy-seven consecutive women with TS, aged 19-60 years, were interviewed with respect to bone fracture history. BMD and hearing information were recorded from the medical notes. Karyotype was available in 94% of patients (55% monosomy 45X, 45% other X chromosome defects and mosaicism). Subjects had a mean (SD) height of 1.47 (0.07) m and BMI 25.8 (5.2) kg/m(2). The prevalence of fractures was 32% and hearing impairment 84% (18% conductive and 67% sensorineual, of whom 32% and 16%, respectively, used hearing aids). BMD T score was < -1 in 55% of women and < -2.5 in 9%. Fracture rates were higher in subjects with a combination of low BMD and hearing impairment (44% in conductive and 35% in sensorineural) than those with high BMD and normal hearing (25%) (P < 0.05). The duration of oestrogen deficiency was also longer in the former groups (P < 0.05). Multivariate logistic regression analysis (adjusted for age and karyotype) showed that increased risk of fracture was independently associated with low BMD (OR 3.2, 95% CI: 1.0 to10.5) and hearing impairment (conductive: OR 4.8, 95% CI: 1.2 to18.9, sensorineural: OR 3.6, 95% CI: 1.1 to11.8). Subgroup analysis showed that hearing impairment was associated with fractures only in those with low BMD (OR 9.0, 95% CI: 1.1-73.4). Further adjustments for weight, height, BMI, calcium levels, vitamin D concentrations, thyroxine use and oestrogen deficiency, previous use of oxandrolone or GH did not alter these relationships.

CONCLUSIONS

Women with TS who have low BMD and hearing impairment, particularly a conductive type, are at increased risk of bone fractures.

Hearing loss in Turner syndrome

OBJECTIVE

To address the characteristics of hearing loss in patients with Turner syndrome (TS), we evaluated hearing levels of patients with TS and analyzed causative factors.

STUDY DESIGN

Thirty-three patients with TS (8 to 40 years of age) were studied through the use of audiological measurements, and causative factors were explored.

RESULTS

Twenty cases (35 of 66 ears tested) showed high-frequency (8 kHz) sensory neural hearing loss (HFQ-SNHL). Fifteen cases (26 ears) and 15 cases (24 ears) of the impaired 20 cases were unresponsive to distortion-product otoacoustic emissions and transient-evoked otoacoustic emissions, respectively. HFQ-SNHL showed little relation to the history of middle ear infection and puberty, although middle ear infections were seen in 11 of the 20 cases. The hearing thresholds at high frequencies were correlated with age and body height (P < .001). The age-dependent increase in hearing thresholds in the high frequencies was more apparent in patients with TS with monosomic 45, X than in those with the mosaic type (P < .05).

CONCLUSIONS

More than 60% of patients with TS had HFQ-SNHL. Because the increase in hearing threshold at high frequencies was shown to depend on karyotype and aging, regular otological examination is important for the determination of proper treatment.

Progestin negatively affects hearing in aged women

Female hormone influences on auditory system aging are not completely understood. Because of widespread clinical use of hormone replacement therapy (HRT), it is critical to understand HRT effects on sensory systems. The present study retrospectively analyzed and compared hearing abilities among 124 postmenopausal women taking HRT, treated with estrogen and progestin (E+P; n = 32), estrogen alone (E; n = 30), and a third [non-hormone replacement therapy (NHRT; n = 62)] control group. Subjects were 60-86 years old and were matched for age and health status. All had relatively healthy medical histories and no significant noise exposure, middle-ear problems, or major surgeries. Hearing tests included pure-tone audiometry, tympanometry, distortion-product otoacoustic emissions (DPOAEs), transient otoacoustic emissions, and the hearing-in-noise test (HINT). The HINT tests for speech perception in background noise, the major complaint of hearing-impaired persons. Pure-tone thresholds in both ears were elevated (poorer) for the E+P relative to the E and control groups. For DPOAEs, the E+P group presented with lower (worse) levels than the E and control groups, with significant differences for both ears. For the HINT results, the E+P group had poorer speech perception than the E and control groups across all background noise speaker locations and in quiet. These findings suggest that the presence of P as a component of HRT results in poorer hearing abilities in aged women taking HRT, affecting both the peripheral (ear) and central (brain) auditory systems, and it interferes with the perception of speech in background noise.

Brain aromatase: new lessons from non-mammalian model systems

This review highlights recent studies of the anatomical and functional implications of brain aromatase (estrogen synthase) expression in two vertebrate lineages, teleost fishes and songbirds, that show remarkably high levels of adult brain aromatase activity, protein and gene expression compared to other vertebrate groups. Teleosts and birds have proven to be important neuroethological models for investigating how local estrogen synthesis leads to changes in neural phenotypes that translate into behavior. Region-specific patterns of aromatase expression, and thus estrogen synthesis, include the vocal and auditory circuits that figure prominently into the life history adaptations of vocalizing teleosts and songbirds. Thus, by targeting, for example, vocal motor circuits without inappropriate steroid exposure to other steroid-dependent circuits, such as those involved in either copulatory or spawning behaviors, the neuroendocrine system can achieve temporal and spatial specificity in its modulation of neural circuits that lead to the performance of any one behavior.

The association between short stature and sensorineural hearing loss

In order to test the Thrifty Phenotype Hypothesis on hearing, data from two cross-sectional studies on hearing were re-evaluated. The data sets comprised 500 18-year-old conscripts, and 483 noise-exposed male employees. Sensorineural hearing loss (SNHL) was over-represented among conscripts with a short stature (odds ratio=2.2) or hearing loss in the family (odds ration=4.2), but not among noise-exposed conscripts (odds ratio=0.9-1.3). Among noise-exposed short employees, hypertension and age exhibited a negative impact on high frequency hearing thresholds, while among tall employees hypertension had no effect on hearing and the influence of age was less pronounced (p<0.01 for body height; p<0.02 for age, hypertension and the interaction between body height and hypertension; p<0.05 for the interaction between body height and age). This suggests that mechanisms linked to fetal programming and growth retardation and/or insulin-like growth factor 1 levels during fetal life, such as a delayed cell cycle during the time window when the cochlea develops, may cause SNHL in adulthood.

Estrogen and hearing: a summary of recent investigations

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.

Atypical hearing loss in women with breast cancer receiving adjuvant treatment

There are no reports of adjuvant treatments for early breast cancer causing hearing loss. Yet in this exploratory study 14/16 women who had received Fluorouracil, Epirubicin and Cyclophosphamide (FEC) chemotherapy regimen, 11 of whom also received endocrine treatment, had reduced hearing sensitivity, with 9/16 being atypical. It is not clear whether this finding is related to oestrogen reduction and/or ototoxicity but a more detailed investigation in this area is warranted given the large number of women with breast cancer who receive adjuvant treatments.

Distribution of estrogen receptor alpha mRNA in the brain and inner ear of a vocal fish with comparisons to sites of aromatase expression

Among vertebrates, teleost fish have the greatest capacity for estrogen production in the brain. Previously, we characterized the distribution of the estrogen-synthesizing enzyme aromatase in the brain of the midshipman fish. Here, we investigated the distribution of estrogen receptor alpha (ERalpha). A partial cDNA of ERalpha was cloned and used to generate midshipman-specific primers for RT and real-time PCR which identified transcripts in liver and ovary, the CNS, and the sensory epithelium of the main auditory endorgan (sacculus). In situ hybridization revealed abundant expression throughout the preoptic area, a vocal-acoustic site in the hypothalamus, amygdala homologs of the dorsal pallium, the pineal organ, the inner ear, the pituitary, and the ovary. Weaker expression was found in the midbrain's nucleus of the medial longitudinal fasciculus and in the dimorphic vocal motor nucleus. ERalpha expression in the pineal, gonad, and pituitary axis may function to time seasonal abiotic cues to reproductive state, while expression in the vocal motor and auditory systems support neurophysiological evidence for estrogen as a modulator of vocal motor and auditory encoding mechanisms in midshipman fish. While ERalpha is restricted to specific nuclei, aromatase expression is abundant in glial cells throughout the entire forebrain, and high in midbrain and hindbrain - spinal vocal regions. The only site of aromatase-containing neurons is in the peripheral auditory system, where it is localized to ganglion cells in the auditory nerve. Estrogen production proximal to ERalpha-positive neurons may provide for focal sites of estrogen effects on reproductive-, vocal-, and auditory-related neurons.

Seasonal changes in frequency tuning and temporal processing in single neurons in the frog auditory midbrain

Frogs rely on acoustic signaling to detect, discriminate, and localize mates. In the temperate zone, reproduction occurs in the spring, when frogs emerge from hibernation and engage in acoustically guided behaviors. In response to the species mating call, males typically show evoked vocal responses or other territorial behaviors, and females show phonotactic responses. Because of their strong seasonal behavior, it is possible that the frog auditory system also displays seasonal variation, as evidenced in their vocal control system. This hypothesis was tested in male Northern leopard frogs by evaluating the response characteristics of single neurons in the torus semicircularis (TS; a homolog of the inferior colliculus) to a synthetic mating call at different times of the year. We found that TS neurons displayed a seasonal change in frequency tuning and temporal properties. Frequency tuning shifted from a predominance of TS units sensitive to intermediate frequencies (700-1200 Hz) in the winter, to low frequencies (100-600 Hz) in the summer. In winter and early spring, most TS neurons showed poor, or weak, time locking to the envelope of the amplitude-modulated synthetic call, whereas in late spring and early summer the majority of TS neurons showed robust time-locked responses. These seasonal differences indicate that neural coding by auditory midbrain neurons in the Northern leopard frog is subject to seasonal fluctuation.

Estrogen receptor beta and breast cancer

A second estrogen receptor, estrogen receptor-beta, was identified in 1996 and has led to an intensive re-evaluation of the role of estrogens in normal physiological and disease processes. While much has been learnt about this new receptor, there remain many outstanding questions, particularly regarding its prognostic significance and therapeutic implications.

Steroid-Dependent Auditory Plasticity Leads to Adaptive Coupling of Sender and Receiver

For seasonally breeding vertebrates, reproductive cycling is often coupled with changes in vocalizations that function in courtship and territoriality. Less is known about changes in auditory sensitivity to those vocalizations. Here, we show that nonreproductive female midshipman fish treated with either testosterone or 17beta-estradiol exhibit an increase in the degree of temporal encoding of the frequency content of male vocalizations by the inner ear that mimics the reproductive female's auditory phenotype. This sensory plasticity provides an adaptable mechanism that enhances coupling between sender and receiver in vocal communication.

Transition in Turner's syndrome

Management of the chromosomal condition Turner's syndrome requires consistent medical care, especially during the time when affected girls transition from childhood into adulthood. The medical problems that first develop during childhood of a patient with Turner's syndrome such as congenital heart disease, hearing loss, skeletal problems and dental and ophthalmological abnormalities, should be followed into adulthood. Providing the necessary continuum of care will require that medical centers develop teams with the appropriate expertise in treatment of Turner's syndrome. Now more than ever patients with Turner's syndrome have the capability of achieving their full potential, but it requires a multidisciplinary approach toward care throughout their lifetime.

Considerations for transition from paediatric to adult endocrinology: women with Turner's syndrome

Turner's syndrome (TS) is a genetic anomaly that results from complete or partial absence of one X chromosome and is the most commonly occurring chromosomal abnormality in females. While most females with TS present at birth or in early childhood, nearly one quarter present at adult services with primary or secondary amenorrhoea. It is only with the advent of clinics dedicated to adults with TS that we have realised the degree of occult pathology present in this group. Adults with TS are thought to have a reduced life expectancy, mainly due to excess cardiovascular risk, but they may also have multiple comorbidities including hypothyroidism, deafness, osteoporosis and the attendant problems of oestrogen deficiency and infertility. Many of these features may be affected by the timing of treatments in paediatrics - particularly the timing of growth hormone (GH) and oestrogen use. It is the role of adult TS services to audit the outcome of TS and to inform their paediatric colleagues of the long-term effects of childhood treatments. Thus, a multidisciplinary approach to focused adult care is needed, with consideration of how to optimise surveillance strategies in these women.

Effects of estrogen therapy on hearing in postmenopausal women

OBJECTIVE

This study was undertaken to investigate how hormone therapy affects hearing in postmenopausal women.

STUDY DESIGN

This prospective study involved 109 postmenopausal women. Twenty of the women were using estrogen therapy (ET group), 30 women were using hormone therapy (HT group), and 59 had not received hormone therapy of any kind (control group). Otoscopic examination revealed normal tympanic membranes in all 109 subjects. Each individual was tested with low- (250-2000 Hz) and high-frequency audiometry (4000-16000 Hz). Duration of hormone therapy was recorded, and patient characteristics (age, type of menopause, time since onset of menopause), body mass index (BMI), and hearing test results in the ET, HT, and control groups were compared.

RESULTS

There were no statistically significant differences between the treatment (ET and HT group) and control groups with respect to age, BMI, or time since onset of menopause. The mean time on HT and ET was 4.13+/-2.41 years and 3.35+/-2.20 years, respectively. The mean air conduction results at low frequencies (250, 500, 1000, and 2000 Hz) in the ET group were significantly higher than the corresponding findings in the control group (P<.001) and than the HT group (P<.001). When the same comparisons were made between the HT group and the control group, none of the differences was statistically significant (P>.05). The mean air-conduction results at high frequencies (4, 6, 8, 10, 12, 14, and 16 kHz) in the ET group were significantly higher than the corresponding results in the HT group (P<.008). ET versus controls and HT versus controls at high frequencies revealed no significant differences (P>.05). The mean bone conduction results in the ET group were significantly higher than the corresponding findings in the control group (P<.016). Analysis of the same comparisons between the HT-ET and HT-control groups revealed no significant differences (P>.05).

CONCLUSION

Estrogen therapy may slow down hearing loss in aging postmenopausal women; however, further studies of larger series are needed to confirm this, and the sites of hormonal action must also be explored.

The emotional ear in stress

Stress of some kind is encountered everyday and release of stress hormones is essential for adaptation to change. Stress can be physical (pain, noise exposure, etc.), psychological (apprehension to impending events, acoustic conditioning, etc.) or due to homeostatic disturbance (hunger, blood pressure, inner ear pressure, etc.). Persistent elevated levels of stress hormones can lead to disease states. The aim of the present review is to bring together data describing morphological or functional evidence for hormones of stress within the inner ear. The present review describes possible multiple interactions between the sympathetic and the complex feed-back neuroendocrine systems which interact with the immune system and so could contribute to various inner ear dysfunctions such as tinnitus, vertigo, hearing losses. Since there is a rapidly expanding list of genes specifically expressed within the inner ear this clearly allows for possible genomic and non-genomic local action of steroid hormones. Since stress can be encountered at any time throughout the life-time, the effects might be manifested starting from in-utero. These are avenues of research which remain relatively unexplored which merit further consideration. Progress in this domain could lead towards integration of stress concept into the overall clinical management of various inner ear pathologies.

Adulthood in women with Turner syndrome

Turner syndrome, resulting from a complete or partial absence of one X chromosome, is the most commonly occurring chromosomal abnormality in females. Patients have traditionally been carefully followed in paediatric practice during childhood, but were often discharged to primary care on reaching adulthood. Adults with Turner syndrome are thought to have a reduced life expectancy, mainly due to excess cardiovascular risk, but they may also have multiple comorbidities including hypothyroidism, deafness, osteoporosis and the attendant problems of oestrogen deficiency and infertility. A multidisciplinary approach to focused adult care is needed, with consideration of how to optimise surveillance strategies in these women.

Effect of estrogen and antiestrogens on the estrogen receptor content in the cochlea of ovariectomized rats

Older women in the normal population tend to develop less severe hearing loss as compared to males in the same age. In Turner syndrome (45,X), estrogen deficiency is one of the predominant problems. Ear and hearing problems are common among these patients. Does estrogen have an impact on the hearing organ? Twenty-four rats were ovariectomized and treated with vehicle (controls), estradiol or selective estrogen receptor modulators such as tamoxifen and ICI182780, in order to study the effects on the estrogen receptor levels and distribution in the inner ear. The cochleas were stained immunohistochemically using antibodies against estrogen receptor alpha and beta. No major difference in estrogen receptor content in the cochleas was observed among groups. There was however a potential down regulation of estrogen receptor alpha in the marginal cells of stria vascularis in the rats that were substituted with ICI182780 (pure antiestrogen) as compared to those given estradiol or tamoxifen. When investigating the tissues with light microscopy no change in inner ear anatomy could be observed.

The impact and management of Turner's syndrome in adult life

Turner's syndrome (TS), caused by an absent or structurally abnormal X chromosome, affects 1 in 2500 live female births. Most medical attention has focused on the attainment of final height in childhood and, when this has been achieved, many women are discharged to primary care. It has become increasingly evident that adults with Turner's syndrome are susceptible to a range of disorders such as osteoporosis, hypothyroidism and diabetes. Because of these, and because of the need for long-term oestrogen replacement, it seems most practical for adult health surveillance in TS to come under the remit of the endocrinologist. It must be accepted, however, that the reduced life expectancy in women with TS is largely accounted for by cardiovascular disease. Also, the commonly observed social isolation in adults with TS can be linked to deafness that is increasingly prevalent in an ageing group. Co-ordination of all these issues requires a dedicated multidisciplinary clinic along the lines of those in place in diabetes.

Estrogen receptors alpha and beta in the inner ear of the 'Turner mouse' and an estrogen receptor beta knockout mouse

Estrogen receptors have earlier been shown in the normal mouse, rat and human inner ear. If estrogens are important in normal hearing and development of presbyacusis in the normal population is not known. However it is known that patients with Turner syndrome, where a lack of estrogens is one of the main characteristics, commonly develop an early presbyacusis. A 'Turner mouse' has been developed, as a model for the ear problems in Turner syndrome, and it shows otitis media and a premature aging of the hearing. Estrogen receptors exist in an alpha and a beta form. In this study inner ear tissue, from the Turner mouse and an estrogen receptor beta knockout mouse (betaERKO), was investigated regarding estrogen receptor alpha and beta using immunohistochemistry. Results show that the Turner mouse has the same pattern of inner ear labeling, both concerning the estrogen receptor alpha and beta, as that of a normal CBA/Ca mouse, with positive staining in the organ of Corti and spiral ganglion. The betaERKO mice show close to normal inner ear morphology and positive estrogen receptor alpha immunostaining at the same locations as the CBA/Ca mouse.