Tuesday, December 05, 2017 by Janine Acero
A team of researchers from the University of Wisconsin-Madison reports that thin myelin sheaths are able to restore the impaired nervous system of animals with long life spans and can support its function for years after the onset of a disease.
Myelin is a vital insulating sheet or layer wrapping the nerve fibers found in the central nervous systems of humans and all other mammals. It is made up of proteins and fatty substances around nerve fibers in the brain and spinal chord that helps speed the electrical signals or nerve impulses that direct our bodies to perform any routine physical act like breathing, walking, talking, or swallowing.
Myelin deteriorates when demyelinating diseases such as multiple sclerosis (MS) target the nervous system, disrupting the flow of information between the brain and the body, and impairing the overall ability of the nervous system to function properly. Despite this, myelin can repair itself naturally when a disease damages it, known as remyelination. The process however, creates a thinner myelin sheath than normal. Scientists have puzzled over whether the thinned protective covering is adequate for restoring brain circuitry in the long run.
The research team, led by senior author and demyelinating diseases expert Ian Duncan at the UW-Madison School of Veterinary Medicine looked at a unique genetic disorder that naturally afflicts a particular breed of dog, Weimaraners. The condition occurs when the development of the myelin sheath in the dog’s nervous system is delayed, causing severe tremors and loss of coordination in 12- to 14-day old pups. The symptoms gradually diminish and in most cases disappear altogether by three to four months of age.
A precursor to this study was a case of two Weimaraner pups who were once patients at the School of Veterinary Medicine 13 years ago. Duncan was able to retrieve samples of the dogs’ spinal tissue after the dogs lived out their lives. The samples revealed that the dogs exhibited few signs of tremors and were deemed “neurologically normal” up to 13 years of age.
The study showed that the thinned myelin sheets were a persistent marker of remyelination, or the regeneration of myelin. However, the thinned layer was the only sign of myelin repair available, which made it difficult for the researchers to identify or quantify myelin repair, according to Duncan.
Duncan also looked at a condition in cats, another long-lived species that has been shown to fully recover nervous system function after demyelination, particularly in the optic nerves. The findings revealed that nearly every optic nerve fiber was renewed with a thin myelin sheath two years after the onset of the condition. Duncan noted that it is “important for understanding human disease because in multiple sclerosis, the optic nerve is often the first to be demyelinated.”
The research confirms that the basis for evaluating remyelination is the long-term persistence of thin myelin layers, which support nerve fiber function and survival. This could be a helpful tool in designing new therapies for diseases like MS to promote myelin repair that can be evaluated and quantified based on the presence of the thin myelin sheaths.
The study was published in the Proceedings of the National Academy of Sciences.
MS is a debilitating disease that strikes the central nervous system. Besides sticking to your MS treatment plan, here are some lifestyle adjustments whereby you can manage your symptoms to make each day easier:
Read more about disease prevention at Prevention.news.