Opiates produce a sense of euphoria that is highly addictive. If addicts stop taking the drugs, they are faced with opiate withdrawal, which can feel like the worst imaginable stomach flu with symptoms that include muscle aches, sweating, nausea, vomiting, diarrhea and a runny nose.
Stanford researchers have identified and suppressed the neural pathway responsible for these withdrawal symptoms in opiate-addicted mice, as reported in Nature.
Most research that studies drug addiction is focused on the reward pathway because that is the reason you start to take drugs, but people who really get addicted also take drugs to get rid of the withdrawal effect. This is especially important in opiate addiction.
Chen’s team studied the nucleus accumbens, a group of neurons that plays a key role in addiction through its response to rewarding and aversive stimuli. They used fluorescent proteins to identify a clear link between the nucleus accumbens and another brain center associated with drug-seeking behavior called the paraventricular nucleus of the thalamus (PVT).
Next, the researchers used optogenetics to turn neurons in this nucleus accumbens-PVT pathway off, by introducing light-sensitive molecules and then hitting them with light from an optical fiber. The news release explains:
Using optogenetic tools, the scientists were then able to revert the pathway to its original strength, effectively erasing the effects of the drug. Although the research was conducted in mice, Chen said that it suggests that reprogramming the circuit holds promise for treating opiate addiction in humans.
Chen’s research may also guide the development of treatments for many people with exaggerated aversive response to stimuli, including those with drug addiction, anxiety and depression.
Jennifer Huber, PhD, is a science writer with extensive technical communications experience as an academic research scientist, freelance science journalist, and writing instructor.
Previously: New painkiller could tackle pain, without risk of addiction, Inside the brain of optogenetics pioneer Karl Deisseroth, Blocking addiction risks of morphine without reducing its pain-killing effects, and Could a vaccine be used to treat addiction? One expert’s perspective
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