title: Coexpression of the cannabinoid receptor type 1 with dopamine and serotonin receptors in distinct neuronal subpopulations of the adult mouse forebrain.
abstract: The cannabinoid receptor type 1 (CB1) displays unusual properties, including the dual capacity to inhibit or stimulate adenylate cyclase and a brain density considerably higher than the majority of G protein-coupled receptors. Together with overlapping expression patterns of dopamine and serotonin receptors this suggests a potential of CB1 to modulate the function of the dopamine and serotonin system. Indeed, pharmacological studies provide evidence for cross-talks between CB1 and receptors of these neurotransmitter systems. In trying to obtain further insights into possible functional and/or structural interactions between CB1 and the dopamine receptors and the serotonin receptors, we performed double-label in situ hybridization at the cellular level on mouse forebrain sections by combining a digoxigenin-labelled riboprobe for CB1 with 35S-labelled riboprobes for dopamine receptors D1 and D2, and for serotonin receptors 5-HT1B and 5-HT3, respectively. As a general rule, we found that CB1 colocalizes with D1, D2 and 5-HT1B only in low-CB1-expressing cells which are principal projecting neurons, whereas CB1 coexpression with 5-HT3 was also observed in high-CB1-expressing cells which are considered to be mostly GABAergic. In striatum and olfactory tubercle, CB1 is coexpressed to a high extent with D1, D2 and 5-HT1B. Throughout the hippocampal formation, CB1 is coexpressed with D2, 5-HT1B and 5-HT3. In the neocortex, coexpression was detected only with 5-HT1B and 5-HT3. In summary a distinct pattern is emerging for the cannabinoid system with regard to its colocalization with dopamine and serotonin receptors and, therefore, it is likely that different mechanisms underlie its cross-talk with these neurotransmitter systems.
authors.affiliation: Group Molecular Genetics of Behavior, Max-Planck-Institute of Psychiatry, Kraepelinstrasse 2-10, D-80804, Munich, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Hermann
authors.forename: G
authors.initials: G
authors.lastname: Marsicano
authors.forename: B
authors.initials: B
authors.lastname: Lutz
mesh_terms: D000818:Animals; D002186:Cannabinoids / Q000378:metabolism* / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism; D017403:In Situ Hybridization; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D016548:Prosencephalon / Q000166:cytology / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D044302:Receptor, Serotonin, 5-HT1B; D043882:Receptors, Cannabinoid; D011954:Receptors, Dopamine / Q000235:genetics*; D017447:Receptors, Dopamine D1 / Q000235:genetics; D017448:Receptors, Dopamine D2 / Q000235:genetics; D011955:Receptors, Drug / Q000235:genetics*; D011985:Receptors, Serotonin / Q000235:genetics*; D044406:Receptors, Serotonin, 5-HT3; D012701:Serotonin / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*
chemical_list: D002186:Cannabinoids; D012333:RNA, Messenger; D044302:Receptor, Serotonin, 5-HT1B; D043882:Receptors, Cannabinoid; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D011955:Receptors, Drug; D011985:Receptors, Serotonin; D044406:Receptors, Serotonin, 5-HT3; D012701:Serotonin; D004298:Dopamine