Was Kate Moss on to something? In 2006 the BBC reported that the supermodel and sometimes drug user was getting acupuncture to combat her cravings. "People say it seems to work," says Kenneth Kwong, at Massachusetts General Hospital (MGH). Now, Kwong and his colleagues think they might know why.
Acupuncture is thought to release beta-endorphins, which have analgesic effects - something that anyone, not just a person experiencing withdrawal, could benefit from, says Thomas Kosten at Baylor College of Medicine in Houston. What Kwong has found is that, in addiction, acupuncture might help regulate an out-of-whack dopamine system, a hallmark of drug dependence.
At the most recent Society for Neuroscience meeting in San Diego, Kwong and his colleagues presented a poster on their experiments in applying electroacupuncture (a variation on the traditional method) to rats that they had given amphetamine. The drug produces a flood of dopamine release (see "Addictive research," The Scientist, 21:48-55, 2006). Following a dose of amphetamine, the researchers inserted a fine needle into an acupuncture point on the paw of the animal. Using fMRI, they saw less blood flow activity in numerous areas of the brain, which they say could represent a decrease in dopamine release, which could, in turn, reduce cravings.
In a related study, they also inserted a microdialysis tube into the rat's striatum to measure dopamine directly. The striatum includes the nucleus accumbens, the area of the brain that receives dopamine when a drug is taken. After the rats received amphetamine, the acupuncture returned the elevated dopamine levels to normal in about half the time it would take without acupuncture. "We were very skeptical," says Kwong, but "when we saw our data we were very happy. It's something concrete."
Kwong's team isn't the first to look at the neural mechanisms of acupuncture in drug use. A South Korean group also used microdialysis to measure dopamine in the nucleus accumbens of rats given morphine or ethanol, and it saw the same thing - a drop in dopamine levels following acupuncture (Neurosci Lett, 387:17-21, 2005; Neurosci Lett, 395:28-32, 2006).
One hypothesis of Kwong and his colleagues states that acupuncture leads to the release of other neurotransmitters that antagonize dopamine release, but they don't agree on how this happens. One author says that acupuncture releases glutamate, which then leads to GABA release, which then reduces dopamine. "My interpretation is a little bit different," says Kwong's colleague, Kathleen Hui, also at MGH. She thinks the GABA release can occur independent of glutamate in interneurons. The involvement of interneurons, she says, helps explain the long-lasting effects of acupuncture that she and her colleagues see in their experiments. The time it takes for dopamine to return to normal after amphetamine administration, according to their results, is more than one hour after acupuncture and twice as long without it.
Therapeutically, it's not clear how these data might fit into a treatment regimen. Returning dopamine to normal faster after drug use is "akin to tolerance," says Eric Nestler at the University of Texas Southwestern. "This might prompt an addict to take more amphetamine." However, because cravings are also associated with dopamine release, "If acupuncture also decreased dopamine release to a cue or stress, it might be therapeutic," Nestler wrote in an e-mail.
There's also some debate about whether acupuncture even works for drug addiction, Nestler notes. Kosten says the greatest efficacy has been seen with opiate addicts, but for stimulants, he's found that cocaine addicts did no better with acupuncture than with needles inserted into the wrong places (JAMA, 287:55-63, 2002).
To perhaps resolve this issue, David Lee at Harvard's McLean Hospital is in the midst of clinical trials on the effects of acupuncture in treating people addicted to heroin. In one study, he imaged people's brains with fMRI following a heroin cue with and without acupuncture, and he expects to publish data on those trials later this year. But Kwong says that, for now, he prefers to work with rats, especially when his experiments rely on subjective responses. "It's an animal, so there's no psychology involved," Kwong says. "The animal doesn't know what I'm doing to it; it just responds."