Researchers Might Have Found a Cure to Drug Addiction

Canadian scientists have developed some clever molecular trickery that is helping to reduce the drug cravings of addicted rats.

One of the problems in addiction is that neurons in some parts of the brain lose glutamate receptors from the cell surface, and those receptors are important for communication between neurons.

The researchers have sidestepped this problem by crafting a peptide that mimics a portion of the tail of the glutamate receptor and, once inside a neuron, serves as a decoy to prevent the loss of glutamate receptors.

Yu Tian Wang, an HHMI international research scholar, and colleagues at the University of British Columbia in Vancouver report their findings in the November 25, 2005, issue of the journal Science.

"We think this is a good candidate for a drug against addiction that has very few side effects", said Wang, a neuroscientist. Although the initial studies are promising, Wang cautioned that the drug is in the early stages of development and is years away from testing in humans.

Wang and colleagues tested the peptide in rats that had been given amphetamine once every other day for 20 days. During this period, the animals displayed stereotypical behavior such as repeated sniffing, licking and grooming, indicating a craving for the drug.

Such behavior parallels the compulsive thought patterns that people addicted to drugs experience, said Anthony Phillips, Wang's colleague at the University of British Columbia and a co-author of the article.

After keeping the rats drug-free for 21 days, the researchers gave the animals a small amount of drug again. The rats immediately displayed intense stereotypical behavior, a sign of behavioral sensitization. The behavior meant that the glutamate receptors in the animals' neurons were rapidly internalized, said Wang. "It's the trigger that leads to sustained motivation to seek a drug."

In contrast, addicted animals who received an intravenous injection of the artificial peptide displayed no sensitized behavior. "The effect was immediate and very noticeable", said Wang.