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Scientists Discover Mechanism to Block Heroin and Morphine Addiction (Aug. 15)

(+)-naloxone shuts down immune-addiction response in preclinical study

In a major breakthrough, a team of scientists has shown that addiction to morphine and heroin can be blocked, while at the same time increasing pain relief.

Researchers at the University of Adelaide in Australia and at the University of Colorado in the U.S. announced on August 15 that they have discovered the key mechanism in the body's immune system that amplifies addiction to opioid drugs.

Laboratory studies showed that the drug (+)-naloxone will selectively block the immune-addiction response.

The results — which could eventually lead to new co-formulated drugs that assist patients with severe pain, as well as helping heroin users to kick the habit — will be published in the Journal of Neuroscience.

The team focused its research efforts on the immune receptor known as Toll-like receptor 4 (TLR4).

"Opioid drugs such as morphine and heroin bind to TLR4 in a similar way to the normal immune response to bacteria. The problem is that TLR4 then acts as an amplifier for addiction," said Dr. Mark Hutchinson, research fellow at the University of Adelaide’s School of Medical Sciences.

"The drug (+)-naloxone automatically shuts down the addiction. It shuts down the need to take opioids; it cuts out behaviors associated with addiction; and the neurochemistry in the brain changes — dopamine, which is the chemical important for providing that sense of 'reward' from the drug, is no longer produced."

The researchers say clinical trials may be possible within the next 18 months.

For more information, visit the University of Adelaide's School of Medical Sciences Web site.

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