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Cocaine Addiction Blocked

An international collaboration has discovered a mechanism in the body’s immune system that amplifies addiction to cocaine.

Published in Molecular Psychiatry, the research shows that cocaine’s rewarding properties can be blocked by a drug that prevents the immune system’s response.

The team has focused its research efforts on the role of the immune receptor Toll-Like receptor 4 (TLR4). “Our previous studies have shown that TLR4 is responsible for amplifying addiction to opioid drugs such as heroin, but this is the first time we’ve discovered it has a key role to play in cocaine addiction,” says Prof Mark Hutchinson of The University of Adelaide.

Lead author Alexis Northcutt of the University of Colorado Boulder adds: “We’ve demonstrated conclusively that cocaine interacts with TLR4 to produce a pro-inflammatory effect in the brain. The effect is necessary to convey the drug’s rewarding effects. Without it, reward is greatly reduced.

“This suggests that the immune signalling may be a key mechanism underlying the rewarding and reinforcing effects of drugs such as opioids, cocaine, and potentially other abused substances like methamphetamine and alcohol,” she says.

The researchers have previously demonstrated that opioid addiction can be blocked by using the drug (+)-naloxone to prevent opioids from binding to TLR4.

“The cocaine study has had the same result, which is unique in itself,” Hutchinson says. “We now have two major drugs of addiction that are both being amplified by TLR4, which we can stop through the use of (+)-naloxone.

“These are very exciting and encouraging results. It means that we could potentially see a single intervention for a wide range of addictions in the future.”