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Understanding how estrogen affects sound transducing cells

As humans we don’t typically associate changes of season with changes in our ability to detect sound. Instead we usually associate age with changes in sound detection, as human hearing depletes as we age. But for other animals sound detection does not necessarily change with age. In some species there are seasonal shifts in sound detection, which we call “seasonal auditory plasticity”. An example of season auditory plasticity can be observed in a species of toadfish known as plainfin midshipman. During the breeding season male midshipman make nests under rocks and “sing” to attract females. Interestingly, the female midshipman’s ability to detect these male calls increases during the breeding season. It turns out that fluctuations in estrogen are what stimulates this seasonal auditory plasticity within female midshipman. Although we know that estrogen can stimulate auditory plasticity, we don’t understand exactly how. Recently it was found that the answer may lie in hair cells, cells which transduce sound into electrical signals the brain can interpret. Within the inner ear of female midshipman there is an increase in hair cells during the breeding season, but we don’t know if estradiol is responsible for this change. My thesis focuses on how estradiol interacts with hair cells to produce seasonal auditory plasticity via changes in hair cell density within the female midshipman inner ear. It is possible that estrogen is causing more hair cells to be added to the inner ear, or is increasing hair cell survival, or maybe even both! Research in humans has suggested that estrogen protects against age related hearing loss, but this is still not well understood. By understanding how estrogen interacts with hair cells to produce seasonal changes in their density we can build a strong foundation for future research that can translate to humans such as hearing loss prevention and maybe even hearing restoration.