Dopamine may be a key to future chronic pain therapy.
Studying the pain impulse sequence occurring between the spinal cord and the brain in mice, a research team at the University of Texas Dallas studied neurons that were responsible the impact of chemical neurotransmitters on neurons that “didn’t affect acute pain, but they did have a profound effect on chronic pain.”
“These findings demonstrate a novel role for how dopamine contributes to maintaining chronic pain states,” said Dr. Ted Price, associate professor in the School of Behavioral and Brain Sciences at UT Dallas. “This may open up new opportunities to target medicines that could reverse chronic pain.”
The chemical, dopamine, is produced in the brain and sets the stage for many important brain functions, but the mechanisms that cause it to contribute to chronic pain are less well understood.
They found that chronic pain was greatly reduced when they were able to remove the collection of neurons referred to as A11. A11 contains the neurotransmitter dopamine, which is usually associated with other brain functions such as cognition, movement and reward-behavior.
Other neurotransmitters have been studied in relation to chronic pain; however, “By process of elimination, we decided to look more closely at dopamine.” said Price “We used a toxin that affected A11 neurons, and that’s when we found that acute pain signals were still normal, but chronic pain was absent.”
Pain signals travel like electricity from an injury to the spinal cord where they pass on electrical or chemical pain signals to other cells. In people with chronic pain, neurons continue to send pain signals to the brain, even in the absence of injury, but the causes of this are not known.
Studies such as these, shed light into how pain signals are transmitted to the brain, and may be an important clue to how we address chronic pain therapy. “In 2011, the Institute of Medicine estimated that more than 100 million Americans suffer from chronic pain, a condition that costs more than $600 billion each year in medical care and lost productivity.”
“In future studies, we would like to gain a better understanding of how stress interacts with A11,” Price said. “And we’d like to know more about the interaction between molecular mechanisms that promote chronic pain and dopamine.”