Studies on [H-3]CP-55940 binding in the human central nervous system: Regional specific changes in density of cannabinoid-1 receptors associated withschizophrenia and cannabis use

A number of studies suggested that cannabis use can cause or exacerbate psy choses and may increase the risk of developing schizophrenia, These finding s suggest that changes in the cannabinoid system of the brain may be involv ed in the pathology of schizophrenia. To determine whether changes in the c annabinoid system were present in the brains of subjects with schizophrenia , we used in situ radioligand binding and autoradiography to measure the bi nding of [H-3]CP-55940 to the cannabinoid-1 receptor in the dorsolateral pr efrontal cortex (Brodmann's area 9), caudate-putamen and areas of the tempo ral lobe from schizophrenic and control subjects, some of whom had ingested cannabis close to death. There was an increase in the density of [H-3]CP-5 5940 binding to cannabinoid-1 receptors in the dorsolateral prefrontal cort ex from subjects with schizophrenia (mean +/- S.E.M.: 142 +/- 9.9 vs 119 +/ - 6.6 fmol/mg estimated tissue equivalents: P < 0.05) that was independent of recent cannabis ingestion. There was an increase in the density of canna binoid-1 receptors in the caudate-putamen from subjects who had recently in gested cannabis (151 +/- 9.0 vs 123 +/- 7.2 fmol/mg estimated tissue equiva lents: P < 0.05) that was independent of diagnoses. These data indicate that there are changes in cannabinoid-1 receptors in th e dorsolateral prefrontal cortex that may prove to he associated with the p athology of schizophrenia. By contrast. changes in the density of cannabino id-1 receptors may occur in the caudate-putamen in response to cannabis ing estion. (C) 2001 IBRO. Published by Elsevier Science Ltd. All rights reserv ed.