Feb. 4, 2010
Jeremy Craig, 404-413-1357
ATLANTA — Georgia State University scientists have found that the gas nitric oxide – an air pollutant found in cigarette smoke and automobile exhaust – is also produced in cells of the nervous system and serves physiological functions. This discovery has implications for better understanding the nervous system’s development and its diseases.
The findings, published Feb. 3 in the Journal of Neuroscience, show that nitric oxide, which is produced by neurons, changes the electrical properties of nerve cells.
When nitric oxide is generated by one neuron, that nitric oxide helps to modulate electrical activity in nearby neurons. Normally, a junction called a synapse is necessary to transmit a signal from one neuron to another, but nitric oxide can move freely through the wall of the cells.
Neurons, the basic unit of the nervous system, work by firing signals to one another. Synapses are the junctions of neurons across which signals are transmitted through neurotransmitters.
But unlike typical neurotransmitters, such as dopamine and serotonin, which are released from one neuron and activate receptors on other synaptically connected neurons, nitric oxide can freely diffuse through the walls of the cells and affect other cells in its path.
“The study provides the first direct evidence that a single neuron can produce enough of this gas to effectively alter both the electrical properties and the morphology of neurons at the distance, and thus can modulate a network of neurons without synaptic connections,” said Liana Artinian, a research scientist in the Department of Biology at GSU.
The research team also included graduate students Karine Tornieri and Lei Zhong; Deborah Baro, associate professor of biology; and Vincent Rehder, professor of biology and associate faculty member at Georgia State’s Neuroscience Institute, who led this research project.
The researchers found that nitric oxide changes the firing activity of neurons by blocking specific potassium channels, acting like a switch that moves neurons from spontaneously firing to being silent. Nitric oxide, acting as what is called a “volume messenger,” is ideal for coordinating global neuronal activity.
In the end, the amount of nitric oxide does not only affect the firing activity in neuronal networks, but also affects the cells’ growth. Too much and too little of it has adverse affects, so it is important that the production of nitric oxide is tightly controlled: if there’s too much of the gas, it can cause the death of the neurons. Neuronal death can lead to symptoms of neurodegenerative diseases as found in stroke and dementia.
The article, “Nitric Oxide Acts as a Volume Transmitter to Modulate Electrical Properties of Spontaneously Firing Neurons via Apamin-Sensitive Potassium Channels,” is available online at www.jneurosci.org/cgi/content/full/30/5/i.
For more information about the Department of Biology at Georgia State, visit http://biology.gsu.edu.