Researchers at the Indiana University School of Medicine have discovered a new way to deal with chronic pain. And it’s not medical marijuana.
The IU scientists found a peptide that avoids a pathway for chronic pain. And unlike contemporary treatments, this peptide does not have harmful side effects like reduced motor coordination, memory loss, or depression. The research is detailed in the journal Nature Medicine in an article that was posted online.
The peptide, CBD3, has displayed in mice its ability to interfere with the signals that direct calcium channels to generate pain. Dissimilar from other substances that block pain signals, CBD3 does not directly prevent the influx of calcium. This is significant because influx of calcium regulates heart rhythm and vital functions in other organs.
Rajesh Khanna, Ph.D., assistant professor of pharmacology and toxicology at the Indiana University School of Medicine, said the peptide discovered by him and his coworkers is hypothetically safer to use than addictive opioids or cone snail toxin–an acknowledged analgesic that is shot up into the spinal column. Both can cause respiratory distress, cardiac irregularities and other difficulties.
"After opioids–the gold standard for pain control -- the next target is calcium channels," said Dr. Khanna. "Along the pain pathway in the spinal cord, there are pain-sensing neurons called nociceptors that have an abundance of calcium channels."
International research conducted earlier has shown that the calcium conduit is a big-time player within the pathway for pain indicators. Thanks to work from Dr. Khanna's laboratory, it is also believed that an axonal protein, CRMP-2, binds to the calcium channel "acting like a remote control" to control transmission of excitability and pain signals, Dr. Khanna explained.
Khanna and his colleagues discovered the CBD3 peptide, a portion of the CRMP-2 protein, recognizing that its smaller size would be useful in making a synthetic version for drug development.
CBD3 can be given systemically and it blocks pain in an assortment of acute as well as chronic pain models, he said. The novel peptide binds to the calcium channel and reduces the number of excitability signals without disturbing the beneficial global calcium flow. Upon reaching the brain, these signals are interpreted as the sensation of pain.
"Since our approach does not directly inhibit calcium entry through voltage-gated channels, we expect that this molecule will be more specific and have fewer side effects than currently available analgesics," said Dr. Khanna. "We anticipate that this peptide will serve as a novel pharmacological therapeutic for the relief of chronic pain."