In a study published today in the Journal, Proceedings of the National Academy of Sciences, an international team of researchers based in the U.S. and UK revealed that they were able to halt the potentially lethal, breath holding episodes associated with the neurological disease Rett syndrome.
Rett syndrome is a disorder of the brain that affects around 1 in 10,000 young girls. On October 4, 1999, a groundbreaking study was published showing that the disease is caused by a spontaneous mutation in the gene methyl-CpG-binding protein 2 (MeCP2). The gene encodes a protein which acts as a "master switch" that is critical for controlling the expression of many other genes regulating the production of specific proteins in brain cells.
One of the more serious consequences of the disease is the intermittent episodes of breath holding, which can put individuals at risk for brain damage due to oxygen deprivation. The team led by Professor John Bissonnette, M.D., of Oregon Health and Science University, Portland OR and Professor Julian FR Paton, PhD, at the University of Bristol in the UK discovered a way to prevent the frequent episodes of breath holding in a mouse model of Rett syndrome using a unique combination of drugs.
Initially, the investigators' earlier work found that an area of the brain that allows breathing to persist throughout life, without interruption, has reduced levels of a vital transmitter substance called gamma-aminobutyric acid (GABA). The researchers took a two-pronged approach, using one set of drugs to increase the amount of GABA, and others to target a specific type of serotonin receptor to reduce activity in brain cells that normally depress inhalation. Both of these approaches halted the life threatening episodes of breathing arrests in Rett syndrome mice and confirmed the investigators' initial theory.
Dr. Bissonnette, co-principal investigator on the IRSF funded study commented, "When the phrenic nerve going to the diaphragm is silent, nerves going to muscles for expiration are excessively active. Building on our earlier studies that showed a defect in inhibition within the brain's respiratory areas, we reasoned that expiratory neurons were not receiving enough inhibition. When we boosted inhibition, or separately used a drug known to silence expiratory neurons, the pattern of breath holding was markedly improved." Dr. Bissonnette added, "While the specific drugs used in this mouse study are not available for human use, drugs with similar modes of action have been used in other conditions."
On Friday, the International Rett Syndrome Foundation (IRSF) announced $1.5M in funding for new research grants in 2010. IRSF announced continuing support for Drs. Bissonnette and Paton who will conduct follow-up studies to further investigate the pharmacological treatment of respiratory dysfunction in mouse models of Rett syndrome.
Commenting on the study, IRSF Chief Scientific Officer Dr. Antony Horton said, "The work of Drs. Bissonnette and Paton presents a powerful proof of concept which allows us to think of new ways to potentially treat this life-threatening complication of Rett syndrome. Their newly-funded studies, demonstrate our continued commitment towards advancing new therapeutic strategies to treat and ultimately reverse this devastating disease."
About Rett Syndrome Rett syndrome (RTT), a developmental neurological disorder, occurs almost exclusively in females. RTT results in severe movement and communication problems following apparently normal development for the first six to 18 months of life. Characteristic features of the disease include loss of speech and purposeful hand use, repetitive hand movements, abnormal walking, abnormal breathing, slowing in the rate of head growth and increased risk of seizures. Current treatment for girls with RTT includes physical and occupational therapy, speech therapy, and medication for seizures. There is no known cure for RTT. In 2007, researchers heralded a major breakthrough by reversing RTT symptoms in mouse models. RTT is considered a "Rosetta Stone" that is helping scientists understand multiple developmental neurological disorders, and shares genetic links with other conditions such as autism and schizophrenia.
About the International Rett Syndrome Foundation
IRSF is the world's leading private funder of basic, translational and clinical Rett syndrome research, funding over $23M in high-quality, peer-reviewed research grants and programs to date. Annually, IRSF hosts the world's largest gathering of global Rett researchers and clinicians to establish research direction and priorities while exchanging ideas and the most recent information. IRSF is the most comprehensive non-profit organization dedicated to providing thorough and accurate information about Rett syndrome, offering informational and emotional family support, and stimulating research aimed at accelerating treatments and a cure for Rett syndrome and related disorders. IRSF has earned Charity Navigator's most prestigious 4 star rating. To learn more about IRSF and Rett syndrome, visit www.rettsyndrome.org or call IRSF at 1-800-818-RETT (7388).
About Oregon Health and Science University
In 1887, the inaugural class of the University of Oregon Medical School met in the school's lone building - a two-room converted grocery store in northwest Portland. From that small school we have grown into a world-class teaching hospital and research center that draws in students, scientists, and patients from across the country and around the world. At the same time, we retain our strong commitment to serving our local community, and to treating each patient as a unique individual. With a rich diversity of activities happening across our campuses in and around Portland, we know that you can find what you are looking for - whether it is preparing yourself for a future as a health care provider, delving into critical research questions, or looking for a place where you can feel completely confident in the high quality of care you or a loved one receives. http://www.ohsu.edu
About the University of Bristol's Research and Enterprise Strategy
The University of Bristol's mission is "to pursue and share knowledge and understanding, both for their own sake and to help individuals and society fulfill their potential." This is underpinned by a vision where the University of Bristol is an international powerhouse of learning, discovery and enterprise, whose excellence is acknowledged locally, nationally and globally that is dedicated to academic achievement across a broad range of disciplines, and to continuous innovation and improvement. http://www.bris.ac.uk
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