Fig. 1: An overview of the experimental design to study associations between brain CB1R availability and circulating endocannabinoids.
a CB1R availability was investigated in vivo in male patients with, first episode psychosis (FEP) and healthy controls (HC) using a CB1R-selective radiotracer using positron emission tomography (PET), with arterial blood sampling. This study was performed at two study sites using two independent samples in the city of Turku, Finland, and an inner-city area of London, United Kingdom. A [18F]FMPEP-d2 PET tracer was used in Turku, while [11C]MePPEP tracer was used in London. b Quantification of circulating endocannabinoids was performed in matched FEP and HC subjects using a quantitative liquid chromatography–triple quadrupole mass spectrometry assay. c Peripheral differences in endocannabinoids between FEP and HCs were evaluated by univariate statistics. In order to assess if circulatory endocannabinoids associated with CB1R availability in the brain, we performed statistical correlation analysis between six endogenous endocannabinoids and 17 CB1R tracer distribution volumes. The correlation analysis was performed separately between FEP and HC for the two study sites.
