Glial Cells: More than What Meets the Afferent Neuron of the Eye?

Author:  Falishia Sloan

Institution:  Eastern Virginia Medical School
Date:  August 2007

Scientists at the Department of Neuroscience and Center for Neuroscience Research (CNR) at Tufts University School of Medicine recently showed that glial cells of the nervous system may have a more active role in neuronal activity than previously thought. In their research, published in the August 2 edition of Neuron, the scientists found that a specific group of glial cells is required to control Drosophilia circadian behavior, the flies' internal 24-hour clock.

"Our results suggest that an autonomous glial mechanism may drive circadian rhythms in the activity of a Drosophila protein known as Ebony," explained F. Rob Jackson, director of the CNR, professor of neuroscience at TUSM and co-author of the paper with Joowon Suh. "Ebony activity and the glia containing that activity function independently of, or in concert with, other brain cells (neurons to control circadian behavior)."

Ebony, which occurs only in glial cells, was shown to have a role in locomotor activity, which is one of the most observed rhythmic behaviors of the Drosophila fly. Previous research with the protein showed that Ebony can act as an enzyme by promoting the conjugation of dopamine, a neurotransmitter in the brain.

"Glia may communicate with neurons of the circadian system and help to coordinate their outputs, which are critical for the temporal control of behavior," Jackson said. The study suggests that Ebony may influence locomotor activity by modifying the transmission of dopamine between brain cells.

Jackson explained that it would be a priority to first identify glial populations in organisms that do have a significant effect on neuronal activity and therefore behavioral process.

"Our work is the first to identify a defined glial population in any organism that is critical for a behavioral process,in this case, circadian timing," he said. "Research has not yet demonstrated that glia regulate circadian rhythms in mammals, including humans, but those studies are currently underway in other labs. Everything we know about circadian mechanisms in Drosophila and mammals says that they are quite similar."

Glial cells were previously thought to function primarily in supporting and protecting the neurons involved in signal transmission throughout the nervous system.

Written by Falishia Sloan