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University of Adelaide news release
In a major breakthrough, an international team of scientists from the University of Adelaide and University of Colorado Boulder has proven that addiction to morphine and heroin can be blocked, while at the same time increasing pain relief.
The team has discovered the key mechanism in the body鈥檚 immune system that amplifies addiction to opioid drugs. Laboratory studies involving rats have shown that the drug (+)-naloxone will selectively block the immune-addiction response.
鈥淥ur studies have shown conclusively that we can block addiction via the immune system of the brain, without targeting the brain鈥檚 wiring,鈥� said lead author Dr. Mark Hutchinson, ARC Research Fellow in the University of Adelaide鈥檚 School of Medical Sciences.
鈥淏oth the central nervous system and the immune system play important roles in creating addiction, but our studies have shown we only need to block the immune response in the brain to prevent cravings for opioid drugs.鈥�
The results 鈥� 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 鈥� will be published in the Aug. 15 edition of the Journal of Neuroscience.
The team has focused its research efforts on the immune receptor known as Toll-Like receptor 4, or TLR4.
鈥淥pioid 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,鈥� Hutchinson said.
鈥淭he drug (+)-naloxone automatically shuts down the addiction,鈥� he said. 鈥淚t shuts down the need to take opioids, it cuts out behaviors associated with addiction, and the neurochemistry in the brain changes 鈥� dopamine, which is the chemical important for providing that sense of 鈥榬eward鈥� from the drug, is no longer produced.鈥�
Senior author Professor Linda Watkins, from the Center for Neuroscience at CU-Boulder, said: 鈥淭his work fundamentally changes what we understand about opioids, reward and addiction. We鈥檝e suspected for some years that TLR4 may be the key to blocking opioid addiction, but now we have the proof.
鈥淭he drug that we鈥檝e used to block addiction, (+)-naloxone, is a non-opioid mirror-image drug that was created by Dr. Kenner Rice in the 1970s,鈥� she said. 鈥淲e believe this will prove extremely useful as a co-formulated drug with morphine, so that patients who require relief for severe pain will not become addicted but still receive pain relief.听 This has the potential to lead to major advances in patient and palliative care,鈥� Watkins said.
The researchers say clinical trials may be possible within the next 18 months.
The study has been funded by the National Institute on Drug Abuse in the United States and the Australian Research Council, or ARC.
Contact:
Linda Watkins, CU-Boulder, 303-492-7034
linda.watkins@colorado.edu
Mark Hutchinson, University of Adelaide
mark.hutchinson@adelaide.edu.au
Greg Swenson, CU media relations, 303-492-3113
