CNR1 and schizophrenia: Cannabinoid 1 receptors are G-protein–coupled receptors expressed on presynaptic nerve terminals of excitatory and inhibitory neurons throughout the cortex, thalamus, hippocampus, and striatum.12 Ex vivo studies in schizophrenia have reported lower CB1R messenger RNA and protein levels13,14,15 but higher CB1R density.16,17,18,19 In vivo studies in schizophrenia have also reported higher20,21 and lower22 CB1R availability.