A potential new treatment for cocaine addiction could also have implications for all types of drug addictions, according to research released on February 3rd.
A team led by the University of Adelaide in South Australia and the University of Colorado in the United States has discovered a mechanism in the body's immune system that amplifies addiction to cocaine.
They found that cocaine's rewarding properties can be blocked, thanks to a drug that prevents the immune system's response.
The team, lead by Alexis Northcutt, from the Center for Neuroscience at the University of Colorado Boulder, focused its research efforts on the role of the immune receptor known as Toll-Like receptor 4 (TLR4).
"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.
"Combined with our previous work, 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," Northcutt says.
"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 Professor Mark Hutchinson, ARC Research Fellow in the University of Adelaide's School of Medical Sciences.
The researchers had previously demonstrated in laboratory studies that opioid addiction could 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. We now have two major drugs of addiction that are both being amplified by TLR4, which we can stop through the use of (+)-naloxone," says Professor Hutchinson, who is also Director of the ARC Centre of Excellence for Nanoscale BioPhotonics at the University of Adelaide.
"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."
The results of their research were published in the Nature journal Molecular Psychiatry.