Featured Research

from universities, journals, and other organizations

Inner-ear disorders may cause hyperactivity

Date:
September 5, 2013
Source:
Albert Einstein College of Medicine
Summary:
Behavioral abnormalities are traditionally thought to originate in the brain. But a new study has found that inner-ear dysfunction can directly cause neurological changes that increase hyperactivity. The study, conducted in mice, also implicated two brain proteins in this process, providing potential targets for intervention.

Ear examination. For years, scientists have observed that many children and adolescents with severe inner-ear disorders -- particularly disorders affecting both hearing and balance -- also have behavioral problems, such as hyperactivity.
Credit: © corepics / Fotolia

Behavioral abnormalities are traditionally thought to originate in the brain. But a new study by researchers at Albert Einstein College of Medicine of Yeshiva University has found that inner-ear dysfunction can directly cause neurological changes that increase hyperactivity. The study, conducted in mice, also implicated two brain proteins in this process, providing potential targets for intervention.

The findings were published today in the online edition of Science.

For years, scientists have observed that many children and adolescents with severe inner-ear disorders -- particularly disorders affecting both hearing and balance -- also have behavioral problems, such as hyperactivity. Until now, no one has been able to determine whether the ear disorders and behavioral problems are actually linked.

"Our study provides the first evidence that a sensory impairment, such as inner-ear dysfunction, can induce specific molecular changes in the brain that cause maladaptive behaviors traditionally considered to originate exclusively in the brain," said study leader Jean M. Hébert, Ph.D., professor in the Dominick P. Purpura Department of Neuroscience and of genetics at Einstein.

The inner ear consists of two structures, the cochlea (responsible for hearing) and the vestibular system (responsible for balance). Inner-ear disorders are typically caused by genetic defects but can also result from infection or injury.

The idea for the study arose when Michelle W. Antoine, a Ph.D. student at Einstein at the time, noticed that some mice in Dr. Hébert's laboratory were unusually active -- in a state of near-continual movement, chasing their tails in a circular pattern. Further investigation revealed that the mice had severe cochlear and vestibular defects and were profoundly deaf. "We then realized that these mice provided a good opportunity to study the relationship between inner-ear dysfunction and behavior," said Dr. Hébert.

The researchers established that the animals' inner-ear problems were due to a mutation in a gene called Slc12a2, which mediates the transport of sodium, potassium, and chloride molecules in various tissues, including the inner ear and central nervous system (CNS). The gene is also found in humans.

To determine whether the gene mutation was linked to the animals' hyperactivity, the researchers took healthy mice and selectively deleted Slc12a2 from either the inner ear, various parts of the brain that control movement or the entire CNS. "To our surprise, it was only when we deleted the gene from the inner ear that we observed increased locomotor activity," said Dr. Hébert.

The researchers hypothesized that inner-ear defects cause abnormal functioning of the striatum, a central brain area that controls movement. Tests revealed increased levels of two proteins involved in a signaling pathway that controls the action of neurotransmitters: pERK (phosphorylated extracellular signal-regulated kinase) and pCREB (phospho-cAMP response-element binding protein), which is further down the signaling pathway from pERK. Increases in levels of the two proteins were seen only in the striatum and not in other forebrain regions.

To discover whether increased pERK levels caused the abnormal increase in locomotor activity, Slc12a2-deficient mice were given injections of SL327, a pERK inhibitor. Administering SL327 restored locomotor activity to normal, without affecting activity levels in controls. The SL327 injections did not affect grooming, suggesting that increased pERK in the striatum selectively elevates locomotor activity and not general activity. According to the researchers, the findings suggest that hyperactivity in children with inner-ear disorders might be controllable with medications that directly or indirectly inhibit the pERK pathway in the striatum.

"Our study also raises the intriguing possibility that other sensory impairments not associated with inner-ear defects could cause or contribute to psychiatric or motor disorders that are now considered exclusively of cerebral origin," said Dr. Hébert. "This is an area that has not been well studied."


Story Source:

The above story is based on materials provided by Albert Einstein College of Medicine. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. W. Antoine, C. A. Hubner, J. C. Arezzo, J. M. Hebert. A Causative Link Between Inner Ear Defects and Long-Term Striatal Dysfunction. Science, 2013; 341 (6150): 1120 DOI: 10.1126/science.1240405

Cite This Page:

Albert Einstein College of Medicine. "Inner-ear disorders may cause hyperactivity." ScienceDaily. ScienceDaily, 5 September 2013. <www.sciencedaily.com/releases/2013/09/130905142808.htm>.
Albert Einstein College of Medicine. (2013, September 5). Inner-ear disorders may cause hyperactivity. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2013/09/130905142808.htm
Albert Einstein College of Medicine. "Inner-ear disorders may cause hyperactivity." ScienceDaily. www.sciencedaily.com/releases/2013/09/130905142808.htm (accessed July 22, 2014).

Share This




More Health & Medicine News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

Gilead's $1000-a-Pill Drug Could Cure Hep C in HIV-Positive People

TheStreet (July 21, 2014) — New research shows Gilead Science's drug Sovaldi helps in curing hepatitis C in those who suffer from HIV. In a medical study, the combination of Gilead's Hep C drug with anti-viral drug Ribavirin cured 76% of HIV-positive patients suffering from the most common hepatitis C strain. Hepatitis C and related complications have been a top cause of death in HIV-positive patients. Typical medication used to treat the disease, including interferon proteins, tended to react badly with HIV drugs. However, Sovaldi's %1,000-a-pill price tag could limit the number of patients able to access the treatment. TheStreet's Keris Lahiff reports from New York. Video provided by TheStreet
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) — Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) — Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
Contaminated Water Kills 3 Babies in South African Town

Contaminated Water Kills 3 Babies in South African Town

AFP (July 18, 2014) — Contaminated water in South Africa's northwestern town of Bloemhof kills three babies and hospitalises over 500 people. The incident highlights growing fears over water safety in South Africa. Duration: 02:22 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins