Highlights d A cell-type-specific transcriptomic map of the cochlear response to noise d Noise-resilient type 1A auditory neurons upregulate the ATF3/4 pathway d Monocytes significantly alter their gene expression in response to noise exposure d STAT3/IRF7 are probable regulators of a general cochlear transcriptomic response to noise
Hearing loss is the most common form of sensory impairment in humans, with an anticipated rise in incidence as the result of recreational noise exposures. Hearing loss is also the second most common health issue afflicting military veterans. Currently, there are no approved therapeutics to treat sensorineural hearing loss in humans. While hearing loss affects both men and women, sexual dimorphism is documented with respect to peripheral and central auditory physiology, as well as susceptibility to age-related and noise-induced hearing loss. Physiological differences between the sexes are often hormone-driven, and an increasing body of literature demonstrates that the hormone estrogen and its related signaling pathways may in part, modulate the aforementioned differences in hearing. From a mechanistic perspective, understanding the underpinnings of the hormonal modulation of hearing may lead to the development of therapeutics for age related and noise induced hearing loss. Here the authors review a number of studies that range from human populations to animal models, which have begun to provide a framework for understanding the functional role of estrogen signaling in hearing, particularly in normal and aberrant peripheral auditory physiology.
Recent studies have identified sex-differences in auditory physiology and in the susceptibility to noise-induced hearing loss (NIHL). We hypothesize that 17β-estradiol (E2), a known modulator of auditory physiology, may underpin sex-differences in the response to noise trauma. Here, we gonadectomized B6CBAF1/J mice and used a combination of electrophysiological and histological techniques to study the effects of estrogen replacement on peripheral auditory physiology in the absence of noise exposure and on protection from NIHL. Functional analysis of auditory physiology in gonadectomized female mice revealed that E2-treatment modulated the peripheral response to sound in the absence of changes to the endocochlear potential compared to vehicle-treatment. E2-replacement in gonadectomized female mice protected against hearing loss following permanent threshold shift (PTS)- and temporary threshold shift (TTS)-inducing noise exposures. Histological analysis of the cochlear tissue revealed that E2-replacement mitigated outer hair cell loss and cochlear synaptopathy following noise exposure compared to vehicle-treatment. Lastly, using fluorescent in situ hybridization, we demonstrate co-localization of estrogen receptor-2 with type-1C, high threshold spiral ganglion neurons, suggesting that the observed protection from cochlear synaptopathy may occur through E2-mediated preservation of these neurons. Taken together, these data indicate the estrogen signaling pathways may be harnessed for the prevention and treatment of NIHL.
There is robust evidence that sex (biological) and gender (behavioral/social) differences influence hearing loss risk and outcomes. These differences are noted for animals and humans—in the occurrence of hearing loss, hearing loss progression, and response to interventions. Nevertheless, many studies have not reported or disaggregated data by sex or gender. This article describes the influence of sex-linked biology (specifically sex-linked hormones) and gender on hearing and hearing interventions, including the role of sex-linked biology and gender in modifying the association between risk factors and hearing loss, and the effects of hearing loss on quality of life and functioning. Most prevalence studies indicate that hearing loss begins earlier and is more common and severe among men than women. Intrinsic sex-linked biological differences in the auditory system may account, in part, for the predominance of hearing loss in males. Sex- and gender-related differences in the effects of noise exposure or cardiovascular disease on the auditory system may help explain some of these differences in the prevalence of hearing loss. Further still, differences in hearing aid use and uptake, and the effects of hearing loss on health may also vary by sex and gender. Recognizing that sex-linked biology and gender are key determinants of hearing health, the present review concludes by emphasizing the importance of a well-developed research platform that proactively measures and assesses sex- and gender-related differences in hearing, including in understudied populations. Such research focus is necessary to advance the field of hearing science and benefit all members of society.
<p> </p> <p>In March of 2020 the CDC confirmed cases of COVID-19 in the state of Maryland, after which major metropolitan areas observed an increase in violent crime, including homicide. Homicides in the United States disproportionately affect minorities, and previous research also indicates that increased economic deprivation and social disorganization correlates with increased rates of homicide. The COVID-19 pandemic has exacerbated economic disparities and may have magnified existing disparities in homicide rates. Few studies have examined the incidence of teenage homicides throughout the United States, especially during COVID-19 pandemic. </p> <p>We conducted a retrospective case review of homicides involving youth between the ages 13-19 from 2018 to 2021 with the aim of assessing if COVID-19 affected rates of youth homicide.</p> <p>A total of 230 teenage homicides occurred in Maryland from 2018 to 2021 with 113 cases during the pre-COVID-19 pandemic period (2018/2019) and 117 cases during the COVID-19 pandemic (2020/2021). The majority of teenage homicide victims were African American male. More than 83% and 79% of victims were African American in 2018/2019 and 2020/2021, respectively. Victims were also predominantly male (90% in 2018/2019, and 88% in 2020/2021). Maryland has a population of approximately 6 million people and is made up of 23 counties and Baltimore City. More than 64% teenage homicides occurred in Baltimore city (N=108) and Prince George's County (N=44). While the average victim age did not vary considerably between 2018/2019 (17.8 years) and 2020/2021 (17.5 years), the percentage of cases involving victims ages 13-15 more than doubled from 5.3% of cases in 2018/2019 to 12% of cases in 2020/2021. The majority of teenage homicide cases were due to firearm injuries, but during the Covid-19 pandemic we saw a rise in violence involving sharp objects such as knives. The incidence of teenage homicide did not change considerably during the COVID-19 pandemic, although we did observe a trend toward younger males who were African American. Individuals of every stratum—be it age, race, gender, or socioeconomic status—can be involved in incidents of homicide, but those who fall within certain criteria tend to be more at risk of being involved in these violent crimes. Strategies in identifying these at-risk groups can shed light on the root cause of youth violence and aid in possible prevention tactics. </p>
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