Ear injections could reverse 'permanent' hearing loss caused by loud noise
Posted Jul 05 2010 8:00am
A new drug could reverse hearing loss caused by prolonged exposure to loud noise, scientists have revealed.
Hearing loss caused by loud noise is one of the leading occupational hazards in industrialised countries, especially for those working in the military of construction industry. The RNID also estimates that four million young people are at risk of noise induced hearing loss from amplified music.
Hazardous levels of noise can cause the build up of free radicals, which can overwhelm the defensive systems of sensory hair cells in the inner ear causing cell damage and permanent hearing loss.
At present, sufferers can only resort to wearing a hearing aid or having a cochlear implant.
But now researchers from the University of Auckland, New Zealand, have found injecting a chemical agent called 'ADAC' into the inner ear can repair damage caused by noise stress.
The scientists found that a five day treatment of daily injections through the skin starting six hours after noise exposure were most effective. Single treatments were less effective but also resulted in some hearing recovery.
The ear has a sensitive lining that can be easily damaged by noise
They targeted molecules known as A1 adenosine receptors, which are found in the inner hair cells.
The drug is thought to work by increasing the sensory hair cell’s ability to break down the damaging waste products, which build up during noise exposure.
Lead researcher Dr Srdjan Vlajkovic and his team injected the chemical adenosine amine congener (ADAC) into rats who had been exposed to loud noise.
They measured the hearing in the rats before and after the treatments by measuring the response to a series of clicking noise via electrodes placed on the skin.
The team found both cochlear injury and hearing loss in rats was substantially restored.
Dr Vlajkovic said: 'To our knowledge, this study presents the most effective pharmacological strategy to date for reducing noise-induced hearing loss after exposure to damaging noise. We now hope to test its effectiveness in humans and are currently seeking industry partners to move this to clinical trials.'