Body's 'natural opioids' affect brain cells much differently than morphine

(University of California – San Francisco) A new study led by UC San Francisco scientists shows that brain cells, or neurons, react differently to opioid substances created inside the body — the endorphins responsible for the 'natural high' that can be produced by exercise, for example — than they do to morphine and heroin, or to purely synthetic opioid drugs, such as fentanyl. The researchers say their findings may help explain why the use of synthetic opioids can lead to addiction.