For many years, researchers have explained the effects of drugs on the brain by saying that they activate the same receptors in the brain that react to natural chemicals called endorphins, which produce a sense of well-being or euphoria. Endorphins are brain hormones and chemicals that are released to cope with pain or stress, but make the body feel good.
The brain releases endorphins during pleasurable activities, such as exercising, eating foods you like, having sex or laughing with friends. The endorphins then activate receptors in the brain that make you feel less pain or feel good.
A new study from UC San Francisco has shown that, contrary to previous thought, there are differences in the way the brain responds to drug use compared to natural endorphins. A “drug high” is different in the brain than a natural one, which may help to explain high rates of opioid addiction.
Study researchers created a biosensor that could detect and record the activity of both natural endorphins and the ones produced by opioids. The biosensors showed that opioid drugs pass through cells different and bind to a different area of the brain than endorphins that are made inside the body.
Opioid drugs activated receptors in a part of the brain called the Golgi apparatus, which natural endorphins could not activate. This activation of sensors in the Golgi apparatus could explain why opioid drugs create so much stronger sensations in the body than other activities or substances that create endorphins.
It also might explain why opioid drugs are effective in relieving pain when natural endorphins have only a limited pain-relieving effect. The study also found that opioid drugs reach the Golgi apparatus at least three times faster than endorphins took to bind to their receptors, which could explain why oxycodone is so much more addictive than chocolate, for example.
Now that scientists know about the Golgi apparatus and the differences between the effects of opioid drugs and endorphins, they plan to use this information to develop drugs that can target different receptors and that avoid the addictive effect of current drugs.
UC San Francisco professor and senior study author Mark von Zastrow said:
“We’re very excited about the possibility of leveraging these principles to develop better or more selective drugs that have the ability to get into the brain, but then differ in their activities at internal locations within individual neurons. This is an area that hasn’t been explored in drug development because people haven’t been thinking about it, but the potential is there.”
In the meantime, doctors have become more careful when prescribing opioids to avoid the addictive effects that can so often accompany their use. Alternative pain treatments like acupuncture, meditation and yoga can release natural endorphins that relieve pain and may reduce or eliminate the need for opioid use, which could help prevent a substance use disorder from developing.