Western University researchers make discovery that could end opiate addiction 0
Western University neuroscience graduate students Jordan Zunder and Laura Rosen were part of a team that discovered a pathway in the brain that controls addiction memories. (DEREK RUTTAN, The London Free Press)
Western University scientists say they’ve made a discovery that could some day stem the scourge of opiate addiction in Canada by “essentially switching an addicted brain back to a non-addicted brain.”
A team from the Schulich School of Medicine and Dentistry has identified the molecular pathway in the brain that’s switched on during addiction and controls the memories of euphoria that can send people back to drug use.
That raises the possibility someday of blocking the pathway and the memories, and, as a result, preventing relapses.
“This is an important step forward,” research team leader Steven Laviolette said.
“Addiction is obviously a huge social issue. It’s a very important issue that touches most of our lives in one way or another. Reversing the effects of what opiates do to the brain that lead to this compulsive addiction behaviour . . . that is the ultimate target of these experiments.”
The findings of the school’s addiction research team are to be published Wednesday in the Journal of Neuroscience.
Researchers are increasingly viewing addiction as a learning or memory disorder, Laviolette said in an interview.
“One of the biggest problems preventing someone addicted to opiates from successfully breaking the habit is the problem of relapse. Someone addicted to opiates will often encounter some stimulus in their environment that triggers these memories that have been associated with the euphoric effects of opiates, be it heroin or prescription narcotics.”
In common usage, opiates describe a range of drugs both natural and synthetic that are highly addictive, including heroin, oxycodone, morphine and hydromorphone.
Canada has seen an increase in abuse of and addiction to painkillers, especially oxycodone-based drugs.
Even after an addict has been clean for years, a single cue — a person, or place or even a picture of a needle — can trigger those “reward memories,” Laviolette said.
“One of the critical questions for opiate addiction is understanding what are the molecular switches in the brain that take individual from non-addictive state to addicted state,” Laviolette said.
“We’re very interested in trying to unravel these molecular memory switches that control . . . these very powerful addiction memories that are increasing the likelihood of compulsive opiate use.”
The research team exposed rats to heroin and then put them into a state of withdrawal.
Over the course of two years, the team discovered two molecular pathways in the brain’s amygdala, which process memory and emotion, associated with opiate addiction.
When the rats were not yet dependent on heroin, one pathway with the molecule ERK (extracellular signal-related kinase) controlled the memories of addiction.
But once the opiate addiction took hold, another pathway with the molecule CaMKII (calmodulin-dependent kinase II) controlled the memories.
The next step is to isolate the pathway further and dig into the cellular level to learn more about how the process works, Laviolette said.
Ultimately, the research could lead to a drug that could target the pathway and prevent or reverse the addiction memories, basically switching the brain back, he said.
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-- commonly, but incorrectly used to describe range of drugs
-- include heroin, oxycodone, morphine, hydromorphone, codeine
-- a specific molecular pathway in brain was switched on in rats addicted to heroin
-- the molecular pathway controls “reward memories” of euphoria connected to addiction
-- cues such as people, places, even photo of a needle, can trigger memories of euphoria and relapse
-- opiate addiction involves physical and psychological dependence
-- blocking the molecular, memory pathway might prevent relapse
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