Short-term hearing loss protective
medwireNews: Research shows that short-term hearing loss, such as that experienced by some music concert attendees, is actually protective rather than a sign of long-term damage.
The investigators found that this phenomenon, known as temporary threshold shift (TTS), is triggered by an increase in ATP released into the cochlea by a receptor known as P2X2.
They discovered that mice lacking a functional P2X2 receptor do not experience a TTS in response to loud sound exposure and are much more susceptible to permanent hearing damage at very high sound levels (≥95 dB) than mice with a functioning receptor.
"This explains why we lose our hearing for hours or days after we have been exposed to a rock concert, for example. The adaptation mechanism has been switched on," commented lead author Gary Housley (University of New South Wales, Sydney, Australia) in a press statement.
Notably, this research adds to previous findings from the same group linking mutations in the gene encoding the P2X2 receptor in humans with hearing loss. Two families in China with these mutations were observed to have progressive hearing loss that was accelerated by exposure to loud working environments.
Housley and co-authors of the Proceedings of the National Academy of Science paper warn that while their findings show that the cochlea is able to deal with short bursts of loud sound with no loss to hearing, constant exposure to such sound can still lead to permanent hearing damage.
"It's like sun exposure," explained Housley. "It's not the acute exposure, but the chronic exposure, that can cause problems years later."
Co-author of the study, Allen Ryan (University of California, San Diego, USA) told the press: "If the efficiency of this gene varies between individuals, as is the case for many genes, it may go some way to explaining why some people are very vulnerable to noise, or develop hearing loss with age and others don't."
Housley and team are hoping to carry out further research to find out if the pathway can be targeted to help provide better protection against sound-associated hearing loss.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Helen Albert, Senior medwireNews Reporter