The Stanford University School of Medicine researchers who conducted the work, led by Ben Barres, MD, PhD, professor of neurobiology, also discovered two of the proteins made by glial cells that signal synapse formation. This study, published in the Feb. 11 issue of Cell, could help researchers understand diseases such as epilepsy and addiction in which too many synapses form.
"We knew glia had a close relationship with neurons," Barres said. "We never thought the synapses would entirely fail to form without the glia." In fact, that relationship was considered so unlikely that the grant application was turned down six times because the work was considered too risky. The research was eventually funded by the National Institute on Drug Abuse, whose interest in the work stems from the possibility that new synapses are what keep recovered addicts craving drugs.
Barres said the relationship remained hidden in past research because of the neuron's complete dependence on glial cells for survival in a lab dish. Nobody had ever succeeded in maintaining neurons without glial cells, so little was known about what the glial cells did, exactly.
However, in past work, Barres and his team devised a way of keeping the neurons alive without glial cells. In this environment the neurons formed one-seventh the number of synapses compared to cells grown with glia. He added that the glia probably have many additional roles, also unknown. "Ninety percent of human brain cells are glia and it's completely a mystery what they do," he said.