TORONTO, Jan. 25, 2012 /CNW/ - Scientists at the Centre for Addiction
and Mental Health (CAMH) have identified a potential target for the
development of anti-craving medications for people with addictions to
stimulants such as methamphetamine.
The discovery centres on a brain receptor related to the chemical
dopamine, which has a complex role in addictive behaviours.
Using brain scans and a novel chemical probe developed in CAMH's Research Imaging Centre, CAMH scientists found that the probe had high levels of binding to the
dopamine D3 receptor in some people with methamphetamine addiction,
compared with those who had no addiction. Higher levels of D3 were also
linked to participants' reported motivation to take drugs.
"This is the first time, to our knowledge, that anyone has shown that D3
receptor levels are high in people with an active addiction to
methamphetamine," says Dr. Isabelle Boileau, a scientist in the Research Imaging Centre, part of the new Campbell
Family Research Institute at CAMH. Boileau led the study that appears
in the January 25, 2012 issue of The Journal of Neuroscience.
Using positron emission tomography (PET), Boileau's team looked at D3
levels in 16 people who were dependent on methamphetamine. Participants
abstained from methamphetamine use for 14 days prior to brain scans.
Their results were compared with scans from 16 participants with no
addiction. On a separate day after scanning, participants were given a
low dose of amphetamine, and they had to report how much they wanted to
D3 receptors appear to have a role in craving, but it is not fully
established how they are related to drug-related behaviours. The new
chemical probe developed at CAMH, called 11C-(+)-PHNO, binds to dopamine D3 receptors. This probe allows
researchers to study D3 in people for the first time, using PET scans,
in order to answer questions about its role in stimulant addiction.
Understanding the role of brain receptors in addiction has enabled
researchers to develop treatment medications, such as nicotine
replacement therapy for smoking. So far, therapeutic strategies for
stimulant addiction have focused on increasing activity with D2
receptors, where binding levels have been low.
"We can now suggest that any therapeutic approach aimed at increasing
activity with D2 receptors should consider being selective at targeting
D2, and not increasing D3 levels," says Boileau. "Our finding also
supports the idea that D3 should be considered another target for
Boileau is also looking at the role of D3 in different types of
addictions, including cocaine and gambling.
Building on CAMH's record of innovation and discovery, the Campbell
Family Mental Health Research Institute will be accelerating
discoveries in the areas of mood disorders, addictions, schizophrenia
and cognitive impairment.
CAMH's Research Imaging Centre is the first of its kind in Canada where
positron emission tomography (PET), magnetic resonance imaging (MRI),
and imaging-genetics are dedicated to the study of mental illness and
The Centre for Addiction and Mental Health (CAMH) is Canada's largest
mental health and addiction teaching hospital, as well as one of the
world's leading research centres in the area of addiction and mental
health. CAMH combines clinical care, research, education, policy
development and health promotion to help transform the lives of people
affected by mental health and addiction issues.
CAMH is fully affiliated with the University of Toronto, and is a Pan
American Health Organization/World Health Organization Collaborating
SOURCE Centre for Addiction and Mental Health
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