Cannabis induced dopamine release: an in-vivo SPECT study.
In a research study aimed at examining the alterations in dopaminergic function in schizophrenia, the authors identified a surreptitious case scenario which provided new insights into the subjective and neurochemical effects of cannabis. A 38-year-old drug-free schizophrenic patient took part in a single photon emission computerized tomographic (SPECT) study of the brain, and smoked cannabis secretively during a pause in the course of an imaging session. Cannabis had an immediate calming effect, followed by a worsening of psychotic symptoms a few hours later. A comparison of the two sets of images, obtained before and immediately after smoking cannabis, indicated a 20% decrease in the striatal dopamine D2 receptor binding ratio, suggestive of increased synaptic dopaminergic activity. This observation offers a plausible biological explanation for the psychotogenic effects of cannabis in vulnerable individuals, and also raises speculations about an interaction between cannabinoid and dopaminergic systems in the brain reward pathways.
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Institute of Medical Science, University of Toronto, Toronto, ON, Canada. lvorugan@julian.uwo.ca
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D000328:Adult; D002188:Cannabis / Q000187:drug effects*; D003342:Corpus Striatum / Q000000981:diagnostic imaging*; D004298:Dopamine / Q000378:metabolism*; D006801:Humans; D008297:Male; D011605:Psychoses, Substance-Induced / Q000000981:diagnostic imaging*; D015899:Tomography, Emission-Computed, Single-Photon
D004298:Dopamine