Brain cell insulators are short-timers

Cells that sheathe the brain’s electrical wires in a protective coating called myelin have a brief career, a new study of zebrafish finds.

Specialized brain cells known as oligodendrocytes wrap myelin around axons, long fibers that carry electrical messages between nerve cells. After only five hours, the cells bow out of the myelin production business, researchers from the University of Edinburgh report in the June 24 Developmental Cell.

Myelination is crucial for brain function, and when it breaks down, so does communication among brain cells. The new results could influence treatment strategies for diseases such as multiple sclerosis, which damages myelin. Instead of coaxing existing cells to replenish myelin, doctors may need to stimulate new oligodendrocyte growth in patients’ nervous systems.

In the new study, researchers made time-lapse movies of neural development in zebrafish by tagging electricity-generating neurons and myelin-making oligodendrocytes in the fishes’ spinal cords with different colors. A protein called Fyn kinase stimulates oligodendrocytes to produce more myelin sheaths for the first five hours of the cells’ existence, but the protein can’t persuade the cells to postpone retirement, the researchers discovered.