An Australian-led team of researchers have found that stimulating nerve cells in the brain promotes the laying down of myelin around these nerve cells. Their laboratory discovery may lead to new interventions to promote myelin repair in MS.
Nerve cells, or neurons, send signals along axons to and from the body in order to move muscles and allow us to sense, interpret and engage with the world around us. Many axons are protected by an insulating layer known as myelin, which allows the nerve signals to travel at great speed and provides nourishment for the neurons.
In MS, this myelin layer gets damaged and depleted, impairing the ability of neurons to communicate with one another and disrupting signal transmission between the brain and the body. This disruption leads to the symptoms of MS. Eventually, without the protection and nourishment of the myelin layer, the nerve cell dies, leading to irreversible damage.
In MS research, considerable effort is being invested in developing ways to replenish myelin after it becomes depleted in MS. One approach is to uncover how nerve cells become coated with myelin during normal brain development. Understanding these mechanisms could hold important clues to help develop therapies to promote myelin regeneration, which could stop some of the symptoms of MS and potentially reverse disability.
Now, for the first time, a group of scientists has discovered that the level of electrical activity of a nerve cell determines the degree to which it is myelinated.
In this study, published in Nature Communications, Dr Tobias Merson (ARMI at Monash University) and his team showed that stimulating individual axons in the brains of mice increased the production of myelin-forming cells, formally known as oligodendrocytes. These oligodendrocytes were found to preferentially lay down myelin on the activated axons and the myelin on the activated axons also formed a thicker layer. Conversely, lowering the activity of neurons reduced their level of myelination.
For some time, it has been known that training for specific tasks, such as juggling or playing musical instruments, increases the degree to which parts of the brain are myelinated. This study, which indicates that the amount of myelin around a nerve cell is affected by its level of activity, may explain how this occurs. This fundamental discovery could help us unlock ways of encouraging the natural repair of myelin in the brains of people with MS.
Whilst this research is still in its early stages, this is an important step forward, which may pave the way for us to manipulate myelin repair. Therapeutic approaches that increase the activation of certain nerve cells may be coupled with medications that promote remyelination, reducing or potentially reversing disability in a person with MS.
Image L-R; Dr Lulu Xing, Dr Stanislaw Mitew, Dr Laura Dumas, Dr Tobia Merson, Mr Bernard Chaung and Mr Kaveh Moradi.
With thanks to MS Research Australia – the lead provider of research summaries on our website.