Pain-Marking Molecule

All in the Head?

Fibromyalgia is a condition which has baffled the medical community, even leading some of them to claim the disease is “all in the head.” The disease cannot be seen on clinical examination or through blood tests. Be that as it may, the disease is very real to its sufferers and is probably the most common rheumatologic complaint among women.

Now, researchers from the University of Michigan Health System have found a connection between pain and a certain molecule found in the brain. The Michigan scientists discovered that when levels of the brain molecule known as glutamate decreased, so did pain. This new finding, say the authors of the study, may prove useful in fibromyalgia drug research.

Lead author of the study, Richard E. Harris, Ph.D., research assistant professor in the Division of Rheumatology at the U-M Medical School’s Department of Internal Medicine and a researcher at the U-M Chronic Pain and Fatigue Research Center stated, “If these findings are replicated, investigators performing clinical treatment trials in fibromyalgia could potentially use glutamate as a ‘surrogate’ marker of disease response.”

Glutamate acts as a neurotransmitter, helping the neurons in the nervous system to relay information to each other. As glutamate leaves a neuron, it covers the space between the cells, then gloms onto the next neuron by way of special receptors. As glutamate binds to each receptor, the cells increase their activity. Previous studies had shown this extra activity in certain regions of the brains of fibromyalgia patients, for instance in the section of the brain known as the insula.

Overactive Neurons

Researchers had, in the past, employed functional magnetic resonance imaging (fMRI) to show that neurons are more active in the insula of fibromyalgia patients. These researchers hypothesized that this higher level of activity in the neurons of the insula may be related to levels of glutamate in this area of the brain.

In order to study the link between levels of pain and glutamate levels, the scientists used a brain imaging technique known as proton magnetic resonance spectroscopy (H-MRS). The brain imaging studies were performed both before and after a four week period of treatment with either acupuncture or sham acupuncture; the latter a type of placebo in which the skin was pricked with needles to produce sensations similar to those produced by true acupuncture.

After four weeks of this treatment, patients reported a significant reduction in pain. More important for the purposes of this study was that the greater the pain reduction, the greater the decrease in the glutamate levels in the insula.