Reduced production of myelin, a type of protective nerve fiber that is lost in diseases like multiple sclerosis, may also play a role in the development of mental illness, according to researchers at the Graduate School of Biomedical Sciences at Mount Sinai School of Medicine. The study is published in the journal Nature Neuroscience.
Myelin is an insulating material that wraps around the axon, the threadlike part of a nerve cell through which the cell sends impulses to other nerve cells. New myelin is produced by nerve cells called oligodendrocytes both during development and in adulthood to repair damage in the brain of people with diseases such as multiple sclerosis (MS).
A new study led by Patrizia Casaccia, MD, PhD, Professor of Neuroscience, Genetics and Genomics; and Neurology at Mount Sinai, determined that depriving mice of social contact reduced myelin production, demonstrating that the formation of new oligodendrocytes is affected by environmental changes. This research provides further support to earlier evidence of abnormal myelin in a wide range of psychiatric disorders, including autism, anxiety, schizophrenia and depression.
"We knew that a lack of social interaction early in life impacted myelination in young animals but were unsure if these changes would persist in adulthood," said Dr. Casaccia, who is also Chief of the Center of Excellence for Myelin Repair at the Friedman Brain Institute at Mount Sinai School of Medicine. "Social isolation of adult mice causes behavioral and structural changes in neurons, but this is the first study to show that it causes myelin dysfunction as well."
Dr. Casaccia's team isolated adult mice to determine whether new myelin formation was compromised. After eight weeks, they found that the isolated mice showed signs of social withdrawal. Subsequent brain tissue analyses indicated that the socially isolated mice had lower-than-normal levels of myelin-forming oligodendrocytes in the prefrontal cortex, but not in other areas of the brain. The prefrontal cortex controls complex emotional and cognitive behavior.
The researchers also found changes in chromatin, the packing material for DNA. As a result, the DNA from the new oligodendrocytes was unavailable for gene expression.
After observing the reduction in myelin production in socially-isolated mice, Dr. Casaccia's team then re-introduced these mice into a social group. After four weeks, the social withdrawal symptoms and the gene expression changes were reversed.
"Our study demonstrates that oligodendrocytes generate new myelin as a way to respond to environmental stimuli, and that myelin production is significantly reduced in social isolation," said Dr. Casaccia. "Abnormalities occur in people with psychiatric conditions characterized by social withdrawal. Other disorders characterized by myelin loss, such as MS, often are associated with depression. Our research emphasizes the importance of maintaining a socially stimulating environment in these instances."
At Mount Sinai, Dr. Casaccia's laboratory is studying oligodendrocyte formation to identify therapeutic targets for myelin repair. They are screening newly-developed pharmacological compounds in brain cells from rodents and humans for their ability to form new myelin.
Dr. Casaccia is the recipient of the Neuroscience Javits Award by the National Institute of Neurological Disorders and Stroke, a division of the National Institutes of Health, who also funded this research (R37-NS42925-10) along with the National Multiple Sclerosis Society.
The Mount Sinai Hospital / Mount Sinai School of Medicine: http://www.mountsinai.org
This press release was posted to serve as a topic for discussion. Please comment below. We try our best to only post press releases that are associated with peer reviewed scientific literature. Critical discussions of the research are appreciated. If you need help finding a link to the original article, please contact us on twitter or via e-mail.
The Nikon Small World photomicrography competition was expanded to include video three years ago, and the result has been an incredible look into living things on the microscopic scale. This year's winning video is a three-dimensional look through a 10-day-old quail embryo growing inside its egg.
On a foggy night in 1888, the passenger steamer City of Chester was headed out of San Francisco Bay when disaster struck. The 202-foot boat was rammed by a much larger steamer, the Oceanic, coming into the bay from Asia. Sixteen people died in the accident, and the City of Chester quickly sank to the bottom. This multibeam sonar image from NOAA is the first look at the steamer in well over a century.
People who have lost their hearing will be injected with a harmless virus carrying a gene that should trigger the regrowth of their ears' sensory receptors
She lived to 115, but a study of Hendrikje van Andel-Schipper's blood hints at factors limiting lifespan
Most of us aren't as maleficent as the fairy in "Sleeping Beauty," but we're still apt to spite others, even at risk of harming ourselves. Psychologists are trying to figure out why.
PTSD treatments could soon extend beyond therapy
Areas where Czechoslovakia had three electrified fences now avoided by generation of deer who never encountered them
The mystery of a bizarre quacking sound often heard in the Southern Ocean has finally been solved, scientists report.
Why the connections between brain cells in depressed people are often shrivelled was a mystery – but a single protein could be to blame
The threat of mutually assured destruction, military or economic, promotes peace in many places. If war has ultimately forged a safer world, what's next?