Journal of Nuclear Medicine
September 29, 2022
Tudor M. Ionescu, Mario Amend, Tadashi Watabe et al.
19 citations
MDMA triggers neuronal activation in limbic projection areas involved in emotional processing, shown by localized increases in glucose metabolism measured with 18F-FDG fPET. Simultaneously, it causes global cerebral and extracerebral hemodynamic decreases detected by BOLD fMRI. The hemodynamic reductions strongly correlate with serotonin transporter occupancy and are of a nonneuronal, peripheral origin. Increased serotonin from SERT blockage leads to neurovascular uncoupling via direct vascular effects. These findings challenge interpretations of previous fMRI studies that suggested MDMA mainly inhibits brain activity, and recommend 18F-FDG fPET as a more robust measure for pharmacological research on psychedelics.
European Journal of Nuclear Medicine and Molecular Imaging
July 1, 1986
Kazuhiko Yanai, Tatsuo Ido, Kiichi Ishiwata et al.
2 citations
The endogenous hallucinogen N,N-dimethyltryptamine (DMT), labeled with carbon-11, accumulates preferentially in the cerebral cortex, caudate putamen, and amygdaloid nuclei of rat brain. Subcellular distribution studies show specific localization in fractions enriched with serotonin receptors only when a very low dose is injected. Pretreatment with the monoamine oxidase inhibitor pargyline greatly enhances the proportion of radioactivity in receptor-rich fractions. In dog brain, positron emission tomography demonstrates specific binding of [11C]DMT to serotonin receptors, with 5-methoxy-N,N-dimethyltryptamine causing approximately 20% displacement of the radioligand from receptors.
bioRxiv Preprint Server
February 14, 2022
Tudor M. Ionescu, Mario Amend, Tadashi Watabe et al.
1 citation
preprint
MDMA, a psychedelic compound being tested for treating post-traumatic stress disorder, inhibits brain activity rather than exciting it, according to fMRI studies. However, interpreting these hemodynamic changes is complicated by MDMA's potent vascular effects. This study used simultaneous PET/fMRI in rats to relate BOLD-fMRI hemodynamic changes to glucose utilization and serotonin transporter occupancy measured by [18F]FDG fPET and [11C]DASB PET. The findings help clarify how MDMA affects brain function, challenging earlier assumptions of mainly excitatory effects.