Researchers may have uncovered answers on how to create a safer opioid: Design it to bypass the part of brain that feels pleasure, but retain the analgesic properties, which make opioids one of the most effective pain relievers.
In a study published in Nature Oct. 13, researchers looked at how opioids may have become so widely abused.
“We identified a major source of how mu-opioids mediate reward,” said lead author Daniel Castro, acting instructor in anesthesiology and pain medicine at UW Medicine and part of The Bruchas Lab, which examines how neural circuits affect motivated behaviors. “We provided a blueprint of how the system works.”
They studied a part of the brain called the nucleus accumbens, a key region in the reward circuit of the brain. When we do anything that is considered rewarding, dopamine neurons project to this area of the brain and make us feel good and want more.
“Mu-Opioids, like morphine act on specific receptors in the brain, like keys in a lock”, said Michael Bruchas, UW professor of anesthesiology and pain medicine. “We isolated a new brain pathway where these receptors exert powerful effects to promote reward consumption behavior.”
They found that opioid receptors are in a part of the brain called the dorsal raphe nucleus located towards the back of the brain by the brain stem. They act to alter the communication between the raphe and nucleus accumbens, which are in the front of the brain.
“This finding was pretty unexpected,” said Castro.
