A Little Myelin Goes a Long Way to Restore Nervous System Function


Source: University of Wisconsin-Madison

Summary: Scientists have discovered that renewed thin myelin sheaths can restore impaired nervous system function.


The nerve fibers of the central nervous system (CNS) in humans and other mammals are wrapped by an insulating sheath made up of lipids and proteins which help in the transmission of nerve impulses or electrical signals and direct our bodies to walk, talk, breathe or perform routine physical acts. This insulation is known as the myelin sheath. In some diseases such as multiple sclerosis, the myelin sheath is degraded which disrupts the flow of information between the brain and the body. Scientists for a long time have puzzled over how myelin repairs itself naturally and also the myelin sheath thinning is a hallmark of the healing nervous system enough for restoring brain’s circuitry. The findings were published in the journal Proceedings of the National Academy of Sciences.

Insulating Sheath

The normal mature dog spinal cord (A) has many axons surrounded by thick myelin sheaths (blue). In contrast, in the recovered dog with the genetic abnormality (B), there are many axons with thin myelin sheaths, identical to that seen in remyelination. Credit: University of Wisconsin-Madison

Researchers at the University of Wisconsin-Madison found in long-lived animals, that renewed myelin sheaths are enough to restore the impaired nervous system and can do it for years even after the disease onset. Duncan and his team analyzed a rare genetic disorder in Weimaraners breed of dog which develops a severe tremor and loss of coordination in 12-14 day old pups. The condition occurs as a result of the delayed development of myelin sheath in parts of the dog’s CNS. These symptoms gradually disappear in most cases altogether by 3-4 months of age. Researchers say that the purpose of the study was to confirm, thin myelin sheaths persisted and supported normal neurologic function.

That element of the study, looking at remyelination two years after the onset of the condition, Duncan notes, is an example of “true demyelination and remyelination. We found that nearly every optic nerve fiber was remyelinated with a thin myelin sheath, which is important for understanding human disease because in multiple sclerosis, the optic nerve is often the first to be demyelinated.”


More Information: Ian D. Duncan et al. “Thin myelin sheaths as the hallmark of remyelination persist over time and preserve axon function,” PNAS (2017).

 www.pnas.org/cgi/doi/10.1073/pnas.1714183114


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