Navigation Links
Pitt team finds mechanism that causes noise-induced tinnitus and drug that can prevent it
Date:5/27/2013

PITTSBURGH, May 27, 2013 An epilepsy drug shows promise in an animal model at preventing tinnitus from developing after exposure to loud noise, according to a new study by researchers at the University of Pittsburgh School of Medicine. The findings, reported this week in the early online version of the Proceedings of the National Academy of Sciences, reveal for the first time the reason the chronic and sometimes debilitating condition occurs.

An estimated 5 to 15 percent of Americans hear whistling, clicking, roaring and other phantom sounds of tinnitus, which typically is induced by exposure to very loud noise, said senior investigator Thanos Tzounopoulos, Ph.D., associate professor and member of the auditory research group in the Department of Otolaryngology, Pitt School of Medicine.

"There is no cure for it, and current therapies such as hearing aids don't provide relief for many patients," he said. "We hope that by identifying the underlying cause, we can develop effective interventions."

The team focused on an area of the brain that is home to an important auditory center called the dorsal cochlear nucleus (DCN). From previous research in a mouse model, they knew that tinnitus is associated with hyperactivity of DCN cells they fire impulses even when there is no actual sound to perceive. For the new experiments, they took a close look at the biophysical properties of tiny channels, called KCNQ channels, through which potassium ions travel in and out of the cell.

"We found that mice with tinnitus have hyperactive DCN cells because of a reduction in KCNQ potassium channel activity," Dr. Tzounopoulos said. "These KCNQ channels act as effective "brakes" that reduce excitability or activity of neuronal cells."

In the model, sedated mice are exposed in one ear to a 116-decibel sound, about the loudness of an ambulance siren, for 45 minutes, which was shown in previous work to lead to the development of tinnitus in 50 percent of exposed mice. Dr. Tzounopoulos and his team tested whether an FDA-approved epilepsy drug called retigabine, which specifically enhances KCNQ channel activity, could prevent the development of tinnitus. Thirty minutes into the noise exposure and twice daily for the next five days, half of the exposed group was given injections of retigabine.

Seven days after noise exposure, the team determined whether the mice had developed tinnitus by conducting startle experiments, in which a continuous, 70 dB tone is played for a period, then stopped briefly and then resumed before being interrupted with a much louder pulse. Mice with normal hearing perceive the gap in sounds and are aware something had changed, so they are less startled by the loud pulse than mice with tinnitus, which hear phantom noise that masks the moment of silence in between the background tones.

The researchers found that mice that were treated with retigabine immediately after noise exposure did not develop tinnitus. Consistent with previous studies, 50 percent of noise-exposed mice that were not treated with the drug exhibited behavioral signs of the condition.

"This is an important finding that links the biophysical properties of a potassium channel with the perception of a phantom sound," Dr. Tzounopoulos said. "Tinnitus is a channelopathy, and these KCNQ channels represent a novel target for developing drugs that block the induction of tinnitus in humans."

The KCNQ family is comprised of five different subunits, four of which are sensitive to retigabine. He and his collaborators aim to develop a drug that is specific for the two KCNQ subunits involved in tinnitus to minimize the potential for side effects.

"Such a medication could be a very helpful preventive strategy for soldiers and other people who work in situations where exposure to very loud noise is likely," Dr. Tzounopoulos said. "It might also be useful for other conditions of phantom perceptions, such as pain in a limb that has been amputated."


'/>"/>

Contact: Anita Srikameswaran
SrikamAV@upmc.edu
412-578-9193
University of Pittsburgh Schools of the Health Sciences
Source:Eurekalert

Related biology news :

1. MIT research: Study finds room to store CO2 underground
2. Study finds circle hooks lower catch rate for offshore anglers
3. LSUHSC research finds HPV-related head & neck cancers rising, highest in middle-aged white men
4. Head and body lice appear to be the same species, genetic study finds
5. Study finds peoples niceness may reside in their genes
6. Large international study finds memory in adults impacted by versions of 4 genes
7. Improved loblolly pines better for the environment, study finds
8. NIST/UMass study finds evidence nanoparticles may increase plant DNA damage
9. As deadly cat disease spreads nationally, MU veterinarian finds effective treatment
10. Study finds cancer-fighting goodness in cholesterol
11. Study finds soda consumption increases overall stroke risk
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/3/2017)... WASHINGTON , April 3, 2017 /PRNewswire-USNewswire/ ... single-cell precision engineering platform, detected a statistically ... cell product prior to treatment and objective ... highlight the potential to predict whether cancer ... prior to treatment, as well as to ...
(Date:3/30/2017)... -- The research team of The Hong Kong Polytechnic ... by adopting ground breaking 3D fingerprint minutiae recovery and matching technology, ... accuracy for use in identification, crime investigation, immigration control, security of ... ... A research team led by Dr ...
(Date:3/29/2017)... 29, 2017  higi, the health IT company that ... North America , today announced a Series B ... of EveryMove. The new investment and acquisition accelerates higi,s ... to transform population health activities through the collection and ... higi collects and secures data today on behalf ...
Breaking Biology News(10 mins):
(Date:4/21/2017)... ... April 21, 2017 , ... ... to nourishing a range of emerging bio and technology start-ups, is hosting “Celebration ... 2017. This double event will start with libations and networking at 3:30 p.m. ...
(Date:4/20/2017)... ... April 20, 2017 , ... ... new webinar will explore challenging patient cases when screening for direct oral anticoagulant. ... may be a need for bridging parental anticoagulation especially for those at high ...
(Date:4/20/2017)... 2017  Eli Lilly and Company (NYSE: ... for the prevention of migraine at the American Academy ... April 22-28, 2017, in Boston . ... AAN, including safety and patient outcomes data for galcanezumab ... reduction in monthly migraine headache days among patients with ...
(Date:4/20/2017)... ... April 20, 2017 , ... ... scientific and clinical research community’s growing body of knowledge during its Eighth ... Gracie Theatre and the adjacent Darling Atrium. During the event, undergraduates, graduate students, ...
Breaking Biology Technology: