Neuron ‘messages’ take longer without key cells

"The delay was several milliseconds," says Steven Mennerick. "That may sound like a small amount of time, but in electrical communication in the central nervous system, a few milliseconds is a very big deal. Such a delay could interfere with neuronal development and contribute to problems seen in conditions such as autism and schizophrenia." (Credit: Death to the Stock Photo)

Without cells called astrocytes, the ability of neurons to send certain signals slows down. Such a slowdown could interfere with neuronal development and contribute to conditions linked to communication between neurons.

The findings, from cell cultures, shed light on possible contributors to autism, schizophrenia, and other neuro-psychiatric disorders.

“This work highlights that although neurons are the focus of considerable research, the brain is composed of other types of cells that also are very important,” says first author Courtney Sobieski of Washington University School of Medicine in St. Louis.

“Astrocytes are support cells that appear to play a key role in the development of healthy neurons. The neurons have trouble communicating without the support of astrocytes.”

Senior author Steven Mennerick, professor of psychiatry, explains that glutamate, a neurotransmitter, plays a key role in carrying messages around the brain.

“It’s the main transmitter at about 90 percent of the points of communication in the brain,” he says. “And we found that when we take away astrocytes, glutamate signaling is compromised.”

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Sobieski, a graduate student in Mennerick’s lab, developed a way to grow individual neurons either with or without astrocytes. As they compared the neurons in culture, they found that when there was no astrocyte, a neuron’s ability to send glutamate signals slowed down and became disjointed.

“The delay was several milliseconds,” explains Mennerick, also an investigator with the Taylor Family Institute for Innovative Psychiatric Research. “That may sound like a small amount of time, but in electrical communication in the central nervous system, a few milliseconds is a very big deal. Such a delay could interfere with neuronal development and contribute to problems seen in conditions such as autism and schizophrenia.”

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The disruptions in glutamate signaling linked to astrocytes also may be related to seizure disorders, such as epilepsy, that are characterized by interrupted electrical signaling.

Mennerick says that more research is needed but that it is important for researchers to look beyond neurons.

“It may be that the root of a problem is related to a nearby astrocyte,” he says. “So broadening our perspective and keeping those connections in mind when there are disruptions in signaling between neurons is an important implication of this work.”

The study is available in the Journal of Neuroscience.

Funding for this research comes from the National Institute of Mental Health, the National Institute of General Medical Sciences, and the National Institute of Neurological Disorders and Stroke of the National Institutes of Health (NIH). The Taylor Family Institute for Innovative Psychiatric Research also funded the research.

Source: Washington University in St. Louis