Opioid drugs and natural (or endogenous) opioids run along different paths inside neurons, which could explain why the “runner’s high” that results from exercise differs from the unnatural high produced by morphine, heroin, or synthetic opioids. Whereas opioid drugs and natural opioids both activate opioid receptors on the surface of neurons, opioid drugs take a detour after neurons internalize them. By tracking the path taken by opioid drugs, researchers based at the University of California, San Francisco (UCSF), hope to better understand opioid addiction. The researchers, led by Mark von Zastrow, M.D., Ph.D., a professor of psychiatry at UCSF, also hope that their findings will lead to less addictive pain-killing drug designs. "There has been no evidence so far that opioid drugs do anything other than what natural opioids do, so it's been hard to reconcile the experiences that drug users describe—that opioid drugs are more intensely ...
Original Article: Opioid Drugs Rush In Where Natural Opioids Fail to Activate