Now, Douglas Fields of the National Institute of Child Health and Human Development and his colleagues have reported in the March 16, 2006, issue of Neuron that supporting cells called astrocytes in the central nervous system (CNS) promote myelination by releasing an immune system molecule that triggers myelin-forming cells to action. The finding, they say, "may offer new approaches to treating demyelinating diseases."
Astrocytes, so named because of their star-like shape, are the most prominent supporting cells in the nervous system. They provide critical regulatory molecules that enable nerve cells to develop and connect properly.
In their studies, Fields and his colleagues sought to understand other research findings indicating that the electrical activity of nerve cells somehow triggers myelin-producing cells, called oligodendrocytes, to form the myelin membrane surrounding the nerve cells.
In their studies, the researchers cultured rat and mice neurons together with oligodendrocytes and conducted experiments to understand the mechanism of myelin formation. They found that electrical stimulation of the neurons caused production of the energy molecule ATP, and this ATP increases myelination.
Drawing on other researchers' findings that an immune signaling molecule called leukemia inhibitory factor (LIF) might be involved, they explored whether LIF was a key molecule in the ATP-triggered myelination machinery. Their experiments revealed LIF's central role in the machinery, and further studies showed that astrocytes were the source of that LIF.