Opioid system within brain activated by dummy medication to alleviate pain.
Researchers at RIKEN have discovered the neural mechanisms behind the placebo effect in rats, offering insights into how belief in pain relief can act as an analgesic. Through conditioning, the researchers managed to induce the placebo effect in the animals, demonstrating a correlation between opioid signaling in the medial prefrontal cortex and the activation of the brain's pain-inhibition network.
Approximately one-third of the rats displayed a full placebo response, enabling the scientists to examine their brain activity more closely using advanced neuroimaging techniques. The placebo effect was found to initiate as a result of opioid-related signals within the medial prefrontal cortex, which in turn stimulated the brain's descending pain inhibitory system.
The researchers' findings could potentially lead to innovative therapies that harness the power of the placebo effect to reduce the need for painkillers and their associated side effects. While it is easier to induce and monitor the placebo effect in humans, the challenge lies in understanding its underlying neural circuits with non-invasive techniques.
"Ethical concerns and technical limitations make it virtually impossible to determine what neurons and circuits are involved in the placebo effect in people," remarks Yilong Cui of the RIKEN Center for Integrative Medical Sciences. In an effort to overcome these obstacles, Cui and his team conditioned rats with real painkillers over four days. Afterwards, the animals exhibited reduced pain responses when injected with a saline solution, demonstrating the power of the placebo effect.
"Many researchers didn't believe that animals could experience the placebo effect," says Cui. "But we succeeded in inducing it in rodents by using Pavlovian conditioning." The discovered mechanism shares similarities with how pain relief occurs in humans, suggesting a potentially translatable approach to pain management.
The scientists are currently investigating the trigger for the observed opioid signals in the medial prefrontal cortex, with the aim of further elucidating the neural circuits involved in the placebo effect.
This groundbreaking research provides a foundation for future studies on the placebo effect in humans and animals, potentially paving the way for innovative approaches to pain management and reducing the reliance on strong painkillers.
Sources:
- RIKEN
- Yilong Cui - RIKEN
- Science Advances
- Link to the original research paper
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- The neuroimaging techniques revealed that approximately one-third of the rats, which had exhibited a full placebo response, displayed distinct opioid-related brain activity in the medial prefrontal cortex and the activation of the brain's pain-inhibition network.
- The placebo effect in rats, as shown by the researchers, was found to initiate through opioid signaling in the medial prefrontal cortex, subsequently stimulating the brain's descending pain inhibitory system.
- The scientists are now delving deeper into understanding the trigger for the observed opioid signals in the medial prefrontal cortex, aiming to further elucidate the neural circuits involved in the placebo effect.
- The novel therapies emerging from this research could potentially minimize the need for painkillers and their associated side effects by leveraging the power of the placebo effect.
- This significant research in the field of neuroscience news offers a groundbreaking foundation for future studies about the placebo effect in humans and animals, potentially paving the way for innovative health-and-wellness therapies and treatments.
