Pain-Alleviating Centre in Brain, May Help Unravel Opioid Alternatives
An international collaboration has now identified a region in the brain responsible for the control of pain alleviation, suggesting new pathways toward non-opioid painkillers.
Opioid drugs such as oxycodone, hydrocodone and fentanyl hijack the endogenous analgesia system, which is what makes them such effective painkillers. However, they are also highly addictive, which has led to the opioid crisis in the United States, where drug overdose is now the leading cause of death for those under 50, with opioid overdoses representing two-thirds of those deaths.
“We’re trying to understand exactly what the endogenous analgesia system is: why we have it, how it works and where it is controlled in the brain,” said Dr Ben Seymour of Cambridge’s Department of Engineering, who led the research. “If we can figure this out, it could lead to treatments that are much more selective in terms of how they treat pain.”
The new results “build a picture of why and how the brain decides to turn off pain in certain circumstances,” lead study author Ben Seymour, a neuroscientist at the University of Cambridge in the United Kingdom, said in a statement. The study identifies a brain region
called the pregenual cingulate cortex “as a critical ‘decision center’ controlling pain in the brain,” Seymour said.“Pain can actually help us recover by removing our drive to do unnecessary things – in a sense, this can be considered ‘healthy pain’,” said Seymour. “So why might the brain want to turn down the pain signal sometimes?”
The team hypothesized that sometimes this ‘healthy pain’ could be a problem, especially if we could actively do something that might help – such as try and find a way to cool a burn. In these situations, the brain might activate the pain-killing system to actively look for relief. To prove this, and to try and identify where in the brain this system was activated, the team designed a pair of experiments using brain scanning technology.
The scientists, in the course of their study, attached a metal probe to the arm of a series of healthy volunteers – and heated it up to a level that was painful, but not enough to physically burn them.
The volunteers then played a type of gambling game where they had to find which button on a small keypad cooled down the probe. The level of difficulty was varied over the course of the experiments – sometimes it was easy to turn the probe off, and sometimes it was difficult. Throughout the task, the volunteers frequently rated their pain, and the researchers constantly monitored their brain activity.
Using a computer model, the researchers were able to pinpoint this brain activity to the area of the brain called the pregenual cingulate cortex.
“These results build a picture of why and how the brain decides to turn off pain in certain circumstances, and identify the pregenual cingulate cortex as a critical ‘decision centre’ controlling pain in the brain,” said Seymour.
