Tokyo, 2 January, /AJMEDIA/
A team of researchers have designed a new opioid to bypass the part of the brain that feels pleasure, but retain the analgesic properties, which make opioids one of the most effective pain relievers.
The study has been published in the ‘Nature Journal’.
“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 behaviours.
“We provided a blueprint of how the system works,” he added.
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.
“We isolated a new brain pathway where these receptors exert powerful effects to promote reward consumption behaviour,” he added.
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 acted 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.
Bruchas said prior work had focused solely on how mu-opioid receptors alter dopamine transmission.
To create safer opioids, pharmaceutical companies would need to either bypass or create ways to bias the drug’s effect away from the dorsal raphe to nucleus accumbens pathway, Castro said.
The researchers focused on the opioid peptide receptor MOPR. When stimulated, MOPR altered respiration; analgesia, reward behaviourd, and can induce substance abuse and overdose. This is the most common opioid peptide receptor engaged by opioid