The glucocorticoid antagonist mifepristone attenuates sound‐induced long‐term deficits in auditory nerve response and central auditory processing in female rats

What is it about?

Glucocorticoids act as stress hormones that display an impressive diversity of actions. In a healthy body, glucocorticoids are secreted from the adrenal glands in hourly pulses and after physically or mentally demanding, stirring or even frightening experiences with the goal to maintain resilience and health. We often forget these positive actions of stress that in the population mostly carries negative connotations. Nevertheless, it is widely known and accepted that systemic corticosteroids are the mainstay of treatment for a wide range of diseases for over 30 years. Among those are also hearing disorders as e.g. sudden hearing loss, cochlear fibrosis, or hearing preservation during cochlear implantation. This may likely explain why negative effects of stress on hearing, known to reduce tone perception or hamper central synaptic plasticity in auditory brain regions are often overlooked in a clinical / scientific surrounding. In the present study, evidence is brought that corticosterone can reach the periphery of the auditory fibers and that it can worsen the sound response probabilities in auditory brain region, particularly after acoustic trauma. These consequences of corticosterone levels on auditory nerve fibers can even negatively influence the ability of the brain to adapt to reduced auditory fiber responses under healthy conditions. We thus have to keep in mind that accelerating social life with elevated risk of increasing stress levels can be very harmful for hearing, even when we would not detect it in through clinical routine measurements.

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