Zebrafish research may be the key to tinnitus drugs

23 May 2008

Twenty years ago, Ernest Moore developed tinnitus after his hearing was damaged by exposure to too many M16 rifles and artillery explosions during his time in the US Army. Now an audiologist and Research Professor of Molecular Pharmacology at Northwestern University, Moore is studying zebrafish in his search for a cure.

Zebrafish, a type of tropical fish often found in aquariums, are also commonly used in scientific research. Their ears are similar enough to human ears to make them useful for investigating how a normal ear works and what can go wrong in the cases of hearing loss and tinnitus. Moore has been able to observe over-activity in zebrafish hair cells – found in the inner ear and balance system – after exposing them to certain drugs. Although it isn’t possible to know directly whether the fish can hear ringing in their ears, increased activity is an early sign of damage to the auditory system in mammals. Brain imaging studies in humans have also shown increased activity in the auditory cortex of tinnitus sufferers.

In a second stage of research, Moore has attempted to block the over-activity with drugs that return the cells to normal. His preliminary findings show that the drugs do slow down the increased activity – or tinnitus-like behaviour – of the hair cells.  Moore now aims to launch a clinical trial to test these drugs for patients. He says, "If these drugs are found to be safe – and some are already on the market for other uses – and if they are found to have efficacy in humans, then they might be used to treat an individual's tinnitus."