Study identifies key cellular mechanisms behind the onset of tinnitus

May 10, 2012

Researchers in the University of Leicester's Department of Cell Physiology and Pharmacology have identified a cellular mechanism that could underlie the development of tinnitus following exposure to loud noises. The discovery could lead to novel tinnitus treatments, and investigations into potential drugs to prevent tinnitus are currently underway.

Tinnitus is a sensation of phantom sounds, usually ringing or buzzing, heard in the ears when no external noise is present. It commonly develops after exposure to loud noises (acoustic over-exposure), and scientists have speculated that it results from damage to nerve cells connected to the ears.

Although and affect around ten percent of the population, there are currently no drugs available to treat or prevent tinnitus.

University of Leicester researcher Dr Martine Hamann, who led the study published in the journal Hearing Research, said: "We need to know the implications of acoustic over exposure, not only in terms of hearing loss but also what's happening in the brain and . It's believed that tinnitus results from changes in excitability in cells in the brain - cells become more reactive, in this case more reactive to an unknown sound."

Dr Hamann and her team, including PhD student Nadia Pilati, looked at cells in an area of the brain called the dorsal cochlear nucleus - the relay carrying signals from nerve cells in the ear to the that decode and make sense of sounds. Following exposure to loud noises, some of the (neurons) in the dorsal cochlear nucleus start to fire erratically, and this uncontrolled activity eventually leads to tinnitus.

Dr Hamann said "We showed that exposure to loud sound triggers hearing loss a few days after the exposure to the sound. It also triggers this uncontrolled activity in the neurons of the dorsal cochlear nucleus. This is all happening very quickly, in a matter of days"

In a key breakthrough in collaboration with who sponsored Dr Pilati's PhD, the team also discovered the specific that leads to the neurons' over-activity. Malfunctions in specific potassium channels that help regulate the nerve cell's electrical activity mean the neurons cannot return to an equilibrium resting state.

Ordinarily, these cells only fire regularly and therefore regularly return to a rest state. However, if the potassium channels are not working properly, the cells cannot return to a rest state and instead fire continuously in random bursts, creating the of constant noise when none exists.

Dr Hamann explained: "In normal conditions the channel helps to drag down the cellular electrical activity to its resting state and this allows the cell to function with a regular pattern. After exposure to loud sound, the channel is functioning less and therefore the cell is constantly active, being unable to reach its resting state and displaying those irregular bursts."

Although many researchers have investigated the mechanisms underlying tinnitus, this is the first time that cellular bursting activity has been characterised and linked to specific potassium channels. Identifying the involved in the early stages of tinnitus opens up new possibilities for preventing tinnitus with early drug treatments.

Dr Hamann's team is currently investigating potential drugs that could regulate the damaged cells, preventing their erratic firing and returning them to a resting state. If suitable drug compounds are discovered, they could be given to patients who have been exposed to loud noises to protect them against the onset of tinnitus.

These investigations are still in the preliminary stages, and any drug treatment would still be years away.

The research was funded by a Research Councils UK fellowship to Dr Hamann, a grant from the Wellcome Trust and a PhD studentship from GlaxoSmithKline, with follow-up investigations funded by a three-month grant from Deafness Research UK. Further pharmaceutical research will be carried out by the University of Leicester in collaboration with Autifony Therapeutics Ltd via a Medical Research Council Case studentship due to start in October 2012.

Vivienne Michael, Chief Executive of Deafness Research UK, said "We're pleased to hear about this progress in such a debilitating hearing impairment. The charity continues to fund research into better treatments for tinnitus, with the ultimate aim of a cure. Our free information leaflets offer immediate help to sufferers and our national helpline provides additional support. Regularly tinnitus generates the most requests for help."

Explore further: New evidence touch-sensing nerve cells may fuel 'ringing in the ears'

Related Stories

New evidence touch-sensing nerve cells may fuel 'ringing in the ears'

February 1, 2012
We all know that it can take a little while for our hearing to bounce back after listening to our iPods too loud or attending a raucous concert. But new research at the University of Michigan Health System suggests over-exposure ...

Study to test new tinnitus 'treatment'

March 20, 2012
A new clinical trial is to test whether a pocket-sized device that uses sound simulation to reboot faulty 'wiring' in the brain could cure people with the debilitating hearing disorder tinnitus.

Tinnitus discovery could lead to new ways to stop the ringing

September 12, 2011
Neuroscientists at the University of California, Berkeley, are offering hope to the 10 percent of the population who suffer from tinnitus – a constant, often high-pitched ringing or buzzing in the ears that can be annoying ...

Recommended for you

Google searches can be used to track dengue in underdeveloped countries

July 20, 2017
An analytical tool that combines Google search data with government-provided clinical data can quickly and accurately track dengue fever in less-developed countries, according to new research published in PLOS Computational ...

MRSA emerged years before methicillin was even discovered

July 19, 2017
Methicillin resistant Staphylococcus aureus (MRSA) emerged long before the introduction of the antibiotic methicillin into clinical practice, according to a study published in the open access journal Genome Biology. It was ...

New test distinguishes Zika from similar viral infections

July 18, 2017
A new test is the best-to-date in differentiating Zika virus infections from infections caused by similar viruses. The antibody-based assay, developed by researchers at UC Berkeley and Humabs BioMed, a private biotechnology ...

'Superbugs' study reveals complex picture of E. coli bloodstream infections

July 18, 2017
The first large-scale genetic study of Escherichia coli (E. coli) cultured from patients with bloodstream infections in England showed that drug resistant 'superbugs' are not always out-competing other strains. Research by ...

Ebola virus can persist in monkeys that survived disease, even after symptoms disappear

July 17, 2017
Ebola virus infection can be detected in rhesus monkeys that survive the disease and no longer show symptoms, according to research published by Army scientists in today's online edition of the journal Nature Microbiology. ...

Mountain gorillas have herpes virus similar to that found in humans

July 13, 2017
Scientists from the University of California, Davis, have detected a herpes virus in wild mountain gorillas that is very similar to the Epstein-Barr virus in humans, according to a study published today in the journal Scientific ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.