Neural circuit basis of placebo pain relief

https://www.nature.com/articles/s41586-024-07816-z?utm_campaign=morning_rounds&utm_medium=email&_hsenc=p2ANqtz-8q1heDIAc7E5_oItSd9U6M8YQExSlSxgDWf6A2OX1Tv9uvJoRzDZaLfNMPOtONkkf4yYg4mQO1kxhjuQLtZjwKJpuuIA&_hsmi=317386118&utm_content=317386118&utm_source=hs_email Hot mice unlock the brain's secret to pain placebos The placebo effect is mysterious and often pesky in clinical trials, but new research in Nature offers new evidence for which brain circuit is responsible for the placebo effect in treating pain. A team led by researchers from the University of North Carolina conditioned mice to expect pain relief by putting them in a chamber with two rooms: one with a hot floor and one with a comfortably warm floor. They induced the placebo effect by making both chambers hot, but mice kept crossing into the one they had been conditioned to expect to be less hot. By studying their brains, researchers pinned down which specific neurons seemed to be responsible for convincing the mice that they were experiencing pain relief. Injecting the mice with naloxone, an opioid receptor antagonist, got rid of the placebo effect, suggesting the brain’s natural opioid system is involved with modulating those neurons. Though there’s still more work to be done, researchers noted that their results indicate that the pathway they identified could be tackled by new pain-relieving interventions like drugs or cognitive behavioral therapies.