Summer 1996 Volume 5, Number 3

A new "factor" for multiple sclerosis

In multiple sclerosis (MS) destruction of the myelin sheath which acts as an insulator for nerve cells axons, results in impaired conduction of impulses in the brain and spinal cord. MS is the most common demyelinating disease of the central nervous system; it unpredictably affects different regions of the nervous system at unpredictable times, leaving patients with deficits in vision, speech, strength, sensation, and coordination. Sometimes the deficits are reversible, but many times they are not.

In MS, there is not only demyelination of nerves, but also destruction of cells (called oligodendrocytes) that form myelin and conspicuous interference with repair or remyelination. Yet, axons are able to induce some remaining oligodendrocytes to remyelinate the areas injured in MS, and Tim Vartanian and his colleagues are seeking the "factors" on axons responsible for this.

One such factor, they have found, is a molecule called neuregulin, which causes oligodendrocytes to make membranes resembling large sheets that can then go on to make myelin. Neuregulin is present on axons, oligodendrocytes possess the receptors for neuregulin, and neuregulin is present in regions of MS lesions where remyelination takes place. Thus neuregulin could prove to be a factor which could promote repair of demylenation in MS, offering a long term development potential for new treatments for the disease.

Schematic of a neuron and an oligodendrocyte with formed, and forming, myelin. Neuregulin on the axonal surface induces formation of myelin through neuregulin on oligodendrocytes. (By Leigh Coriale Design and Illustration, from drawing by T. Vartanian.)

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