Polynesian compound may revolutionalize alcoholism treatment


In 1964, a team of Canadian researchers were digging in the soil of Easter Island, famous for its mysterious statues. Among the samples, they discovered a unique compound, which they dubbed rapamycin, after the island's true name of Rapa Nui. Decades later it's commonly used in organ transplants to prevent rejection.

Dr. Dorit Ron explores addictions at UCSF's Gallo Clinic and Research Center in Emeryville. She and her team were interested in rapamycin's effect on a signaling pathway that's part of the brain's reward system. Their test subjects were binge drinking rodents.

"They reached a blood alcohol level that is defined as binge drinking in humans," she said.

But she says when the same rodents were given rapamycin, the change in their behavior was striking.

"They drank alcohol in the same rate as mice and rats who were consuming only water," Ron said.

They went from binging to merely sipping the alcohol. Rapamycin works in all mammals, by blocking a specific enzyme that's part of a cellular communication system -- an enzyme that influences several processes in the body, including cell growth.

Rapamycin's effect on cell behavior has been the target of intense research in recent years. Some scientists have tried to use it to slow the growth of tumors while others use it to expand longevity.

Last year, we reported on studies at the Buck Institute for Age Research in Marin County, where scientists are using rapamycin to extend the lifespan of fruit flies by slowing the metabolism of their cells.

"So there is a lot of buzz in the field about understanding how this might work," Pankaj Kapahi, PhD said.

In the Gallo study, the drug apparently interrupted only a very specific reward pathway in the brain. The rodents who were no longer binging on alcohol, were still attracted to other substances, like sweets.

"Which suggests that whatever we observed, the benefits of rapamycines were signals for alcohol. But it did not reduce rewards for anything else," Ron said.

Ron cautions that while rapamycin is given to human transplant patients, it's powerful effect on the immune system would make it too dangerous for immediate use as an alcohol therapy.

"But I do think there will be a new generation of drugs that will be able to. I think that it's very promising," she said.

For now, researchers are focused on unlocking the mysterious workings of a compound plucked from an exotic home, so many decades ago.

Ron says that unlike the targeted effect observed with rapamycin, many of the drugs currently used to treat alcoholism can effect multiple reward responses in the body, making them difficult for some patients to tolerate.

Written and produced by Tim Didion

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