Vivian M. Rakoff Positron
Emission Tomography
Centre
Dr. Sylvain
Houle, Director
 Research at the vivian m. rakoff positron Emission
Tomography (PET) Centre concentrates in the following areas: PET Methodology
(Radiochemistry and PET Instrumentation); Schizophrenia; Mood and Anxiety
Disorders; and Addiction. In addition to our own research, we maintain
active collaboration with other scientists within CAMH and with researchers
at the University of Toronto.PET Radioligands Development
The radiochemistry group, led by Dr. Alan Wilson,
continues its innovative work in radioligand development. Our new radio-ligand
for the serotonin transporter [C-11]-DASB has generated worldwide interest.
This serotonin transporter is the target of the selective serotonin
reuptake inhibitors, medication widely used for the treatment of depression.
For the first time, we can measure accurately the effects of these antidepressants
on the serotonin transporters.
New projects currently under way are attempting
to develop a pet radioligand for the norepinephrine transporter as well
as one to image amyloid plaques in Alzheimer's disease.
PET Instrumentation
The construction of our new scanner is nearly
complete. This will be the most sophisticated pet scanner in existence
for brain research and will strengthen our international leadership
in psychiatric pet research. Funding for the new scanner was secured
by a grant from the Canada Foundation for Innovation and the Ontario
Innovation Trust Fund.
An internationally renowned pet physicist, Peter
Bloomfield, has joined the pet Centre scientific team. His work will
focus on maximizing the potential of the new scanner. He will be assisted
by pet physicist Dr. Nathalie Ginovart. Dr. Ginovert has recently initiated
a new series of pharmacological experiments in rodents using a stereotactic
positron probe that provides temporal and spatial resolution superior
to those of existing small-animal pet scans.
Investigation of the Mechanism of Action of Antipsychotics
The pet Schizophrenia research program, under
the leadership of Dr. Shitij Kapur, continues to explore the role of
the dopamine system in schizophrenia. This work attempts to understand
anti-psychotic medications' mechanism of action in the brain. We continue
to link human findings obtained with pet with those obtained from animal
research to give us insights in the role of the dopamine system.
We continue to find clinical benefits in the
treatment of schizophrenia, such as by optimizing existing treatments
and by offering new avenues for developing more effective drugs.
The Neurochemistry of Depression
Headed by Dr. Jeffrey Meyer, this program aims
to investigate the neurochemical basis of symptoms for mood disorders
and the neurochemical effects of antidepressant treatment.
Recent work has focused on the relationship between
changes in serotonin and dopamine receptors and the specific cognitive
and neuropsychological abnormalities that are observed during depressive
episodes.
We are also investigating dopamine and serotonin
transporter regulation. This year, we discovered that the regulation
of these transporters has an important role as a vulnerability factor
for low monoamines and accompanying symptoms. Treatment studies examine
the mechanism of selective serotonin reuptake inhibitors (SSRIs). We
are trying to establish the percentage of serotonin reuptake sites occupied
during ssri treatment and the effects of SSRIs upon post-synaptic serotonin
receptors.
The Role of Serotonin in Parkinson's Disease
Dr. Stephen Kish, in collaboration with Dr.
Mark Guttman, continues to apply the pet Centre's serotonin transporter
radio-ligand
to Parkinson's disease. Abnormalities of the serotonin system may explain
the onset of depression often experienced by patients with this
disease. This research may help elucidate the non-motor aspects
of Parkinson's disease.
Investigation of the Neurochemical Sequelae of
Ecstasy Use
The effects on the brain of MDMA, better known
as ecstasy, remain controversial. Dr. Stephen Kish is using [C-11]-DASB
to find definite evidence about the presence or absence of ecstasy's
effects on the serotonin transporter.
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