title: Cannabidiol Counteracts Amphetamine-Induced Neuronal and Behavioral Sensitization of the Mesolimbic Dopamine Pathway through a Novel mTOR/p70S6 Kinase Signaling Pathway.
abstract: Schizophrenia-related psychosis is associated with disturbances in mesolimbic dopamine (DA) transmission, characterized by hyperdopaminergic activity in the mesolimbic pathway. Currently, the only clinically effective treatment for schizophrenia involves the use of antipsychotic medications that block DA receptor transmission. However, these medications produce serious side effects leading to poor compliance and treatment outcomes. Emerging evidence points to the involvement of a specific phytochemical component of marijuana called cannabidiol (CBD), which possesses promising therapeutic properties for the treatment of schizophrenia-related psychoses. However, the neuronal and molecular mechanisms through which CBD may exert these effects are entirely unknown. We used amphetamine (AMPH)-induced sensitization and sensorimotor gating in rats, two preclinical procedures relevant to schizophrenia-related psychopathology, combined with in vivo single-unit neuronal electrophysiology recordings in the ventral tegmental area, and molecular analyses to characterize the actions of CBD directly in the nucleus accumbens shell (NASh), a brain region that is the current target of most effective antipsychotics. We demonstrate that Intra-NASh CBD attenuates AMPH-induced sensitization, both in terms of DAergic neuronal activity measured in the ventral tegmental area and psychotomimetic behavioral analyses. We further report that CBD controls downstream phosphorylation of the mTOR/p70S6 kinase signaling pathways directly within the NASh. Our findings demonstrate a novel mechanism for the putative antipsychotic-like properties of CBD in the mesolimbic circuitry. We identify the molecular signaling pathways through which CBD may functionally reduce schizophrenia-like neuropsychopathology.
  
  
  
  The cannabis-derived phytochemical, cannabidiol (CBD), has been shown to have pharmacotherapeutic efficacy for the treatment of schizophrenia. However, the mechanisms by which CBD may produce antipsychotic effects are entirely unknown. Using preclinical behavioral procedures combined with molecular analyses and in vivo neuronal electrophysiology, our findings identify a functional role for the nucleus accumbens as a critical brain region whereby CBD can produce effects similar to antipsychotic medications by triggering molecular signaling pathways associated with the effects of classic antipsychotic medications. Specifically, we report that CBD can attenuate both behavioral and dopaminergic neuronal correlates of mesolimbic dopaminergic sensitization, via a direct interaction with mTOR/p70S6 kinase signaling within the mesolimbic pathway.
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and.
authors.forename: Justine
authors.initials: J
authors.lastname: Renard
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and.
authors.forename: Michael
authors.initials: M
authors.lastname: Loureiro
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and.
authors.forename: Laura G
authors.identifier: 0000-0002-9168-2531
authors.initials: LG
authors.lastname: Rosen
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and.
authors.forename: Jordan
authors.initials: J
authors.lastname: Zunder
authors.affiliation: Department of Anatomy and Cell Biology, and.
authors.forename: Cleusa
authors.initials: C
authors.lastname: de Oliveira
authors.affiliation: Department of Anatomy and Cell Biology, and.
authors.forename: Susanne
authors.initials: S
authors.lastname: Schmid
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Rushlow
authors.affiliation: Addiction Research Group, Department of Anatomy and Cell Biology, and Department of Psychiatry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada Steven.Laviolette@schulich.uwo.ca.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Laviolette
mesh_terms: D000661:Amphetamine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D002185:Cannabidiol / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D018765:Dopamine Uptake Inhibitors / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D059290:Dopaminergic Neurons / Q000187:drug effects*; D008032:Limbic System / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009434:Neural Pathways / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D009714:Nucleus Accumbens / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013216:Reflex, Startle / Q000187:drug effects; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D018765:Dopamine Uptake Inhibitors; D002185:Cannabidiol; D000661:Amphetamine; C546843:mTOR protein, mouse; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases
keywords: cannabidiol; dopamine; mesolimbic system; nucleus accumbens; schizophrenia; ventral tegmental area