"A protein acts as a switch for chronic pain, and researchers have applied for a patent to develop a new class of drugs that will block chronic pain by turning this switch off."
Chronic pain affects approximately 48 million people in the U.S. and current medications are either largely ineffective or have serious side effects. But researchers from Columbia University Medical Center have discovered a protein in nerve cells that acts as a switch for chronic pain, and have applied for a patent to develop a new class of drugs that will block chronic pain by turning this switch off. The discovery is published on the website of the journal Neuroscience, and will appear in the publication's August issue.
Most prior attempts at alleviating chronic pain have focused on the "second order" neurons in the spinal cord that relay pain messages to the brain. It's difficult to inhibit the activity of these neurons with drugs, though, because the drugs need to overcome the blood-brain barrier. Instead, the CUMC researchers have focused on the more accessible "first order" neurons in the periphery of our body that send messages to the spinal cord.
Pain becomes chronic when the activity of first and second order neurons persists after damaged neuron heals or the tissue inflammation subsides. It's been known for years that for chronic pain to persist, a master switch must be turned on inside the peripheral neurons, though until now the identity of this switch remained a mystery. Richard Ambron, Ph.D., professor of cell biology, and Ying-Ju Sung, Ph.D., assistant professor, both in the department of Anatomy and Cell Biology, have now discovered that the switch is an enzyme called protein kinase G (PKG).
The researchers found that upon injury or inflammation, the PKG is turned on and activated. Once activated, these molecules set off other processes that generate the pain messages. As long as the PKG remains on, the pain persists. Conversely, turning the PKG off relieves the pain, making PKG an excellent target for therapy.