Opiate drugs—such as morphine, codeine, heroin and opium—are potent pain killers used to manage severe pain. These drugs work by binding to opiate receptors in the body that control the amount of “pain messages” sent to the brain. Despite their potential for abuse, dependence and other side effects, these drugs remain the best option for helping patients deal with extreme pain. However, a group of neuroscientists at Washington University of Medicine in Missouri have tested a new way of setting off these opioid receptors using light.
Research neurobiologists and anesthesiologists have created new brain receptors in rodents that fused natural opioid receptors with rhodopsin, a protein in the eye’s retina that responds to light. Once injected into the laboratory mice’s brain, the opioid receptors, which are found in most mammal brains and play a key role in pain management, affected the way the laboratory mice responded to light.
The rodents exhibited the same reward response to light stimulation as they normally would opioid drugs. In the drug reward models, light caused their brains to release more of the body’s “feel-good” chemical dopamine, which reinforced the rodents’ lever-pressing. Researchers also discovered that they were able to manipulate the mice’s response depending on the type of light used. They found factors such as different light colors, exposure duration and pulsating produced varying effects.
Theoretically, during pain control trials, the light would bind to the brain receptors resulting in the release of natural painkilling chemicals in the body. These chemicals would then block the neural pathways associated with the sensation of pain.
Researchers believe that these findings may pave the way for future developments in activating and deactivating the brain’s natural pain receptors with light instead of drugs. However, there’s still a long way to go and much more testing that’s needed before this method can be used on humans.
 Siuda ER, Copits BA, Schmidt MJ, Baird MA, Al-Hasani R, Planer WJ, Funderburk SC, McCall JG, Gereau RW, Bruchas M. (2015, April 30). Spatiotemporal control of opioid signaling and behavior. Retrieved August 6, 2015 from http://www.ncbi.nlm.nih.gov/pubmed/25937173.