University of Iowa researchers say that we can learn a lot about noise-induced hearing loss by studying the common fruit fly, Drosophila Melanogaster. The reason: The molecular underpinnings to its hearing are roughly the same as in humans.
The fly uses its antenna as its ear. The researchers exposed a test group of flies to a loud, 120 decibel tone, which over-stimulated their auditory system, similar to a human ear’s exposure at a rock concert. Later, the flies’ hearing was tested by playing a series of song pulses at a naturalistic volume, and measuring the physiological response by inserting tiny electrodes into their antennae. The fruit flies receiving the loud tone were found to have their hearing impaired relative to the control group.
When the flies were tested again a week later, those exposed to noise had recovered normal hearing levels. When the structure of the flies’ ears was examined in detail, the researchers discovered that nerve cells of the noise-rattled flies showed signs of stress, including altered shapes of the mitochondria, which are responsible for generating most of a cell’s energy supply. Flies with a mutation making them susceptible to stress not only showed more severe reductions in hearing ability and more prominent changes in mitochondria shape, they still had deficits in hearing 7 days later.
With the fruit fly offering a superior model in terms of genetic flexibility, cost and ease of testing, researchers are hoping to better understand all the factors involved in noise-induced hearing loss and how it can be alleviated. They are ultimately looking to learn how genetic pathways change in response to noise-induced hearing loss.