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- Title
Dopamine Response to Psychosocial Stress in Chronic Cannabis Users: A PET Study With [<sup>11</sup>C]-(+)-PHNO.
- Authors
Mizrahi, Romina; Suridjan, Ivonne; Kenk, Miran; George, Tony P; Wilson, Alan; Houle, Sylvain; Rusjan, Pablo
- Abstract
A number of addictions have been linked with decreased striatal dopamine (DA) receptor availability and DA release. Stress has a key role in cannabis craving, as well as in modulation of dopaminergic signaling. The present study aimed to assess DA release in response to a laboratory stress task with [11C]-(+)-PHNO positron emission tomography in cannabis users (CU). Thirteen healthy CU and 12 healthy volunteers (HV) were scanned during a sensorimotor control task (SMCT) and under a stress condition using the validated Montreal imaging stress task (MIST). The simplified reference tissue model (SRTM) was used to obtain binding potential (BPND) in striatal subdivisions: limbic striatum (LST), associative striatum (AST), and sensorimotor striatum (SMST). Stress-induced DA release (indexed as a percentage of reduction in [11C]-(+)-PHNO BP ND) between CU and HV was tested with analysis of variance. SMCT BPND was significantly higher in CU compared with HV in the AST (F=10.38, p=0.003), LST (F=4.95, p=0.036), SMST (F=4.33, p=0.048), and whole striatum (F=9.02, p=0.006). Percentage of displacement (change in BPND between SMCT and MIST PET scans) was not significantly different across groups in any brain region, except in the GP (−5.03±14.6 in CU, compared with 6.15±12.1 in HV; F=4.39, p=0.049). Duration of cannabis use was significantly associated with stress-induced [11C]-(+)-PHNO displacement by endogenous DA in the LST (r=0.566, p=0.044), with no effect in any other brain region. In conclusion, despite an increase in striatal BPND observed during the control task, chronic cannabis use is not associated with alterations in stress-induced DA release.
- Subjects
DOPAMINE; CANNABIS (Genus); POSITRON emission tomography; DOPAMINERGIC mechanisms; ANALYSIS of variance; PSYCHOSOCIAL factors; SENSORIMOTOR integration; PSYCHOLOGICAL stress
- Publication
Neuropsychopharmacology, 2013, Vol 38, Issue 4, p673
- ISSN
0893-133X
- Publication type
Article
- DOI
10.1038/npp.2012.232