title: Endocannabinoid CB1 receptor activation upon global ischemia adversely impact recovery of reward and stress signaling molecules, neuronal survival and behavioral impulsivity.
abstract: Global cerebral ischemia in rodents, which mimics cardiac arrest in humans, is associated with a surge in endocannabinoids and increased transmission of dopamine and glutamate leading to excitotoxic cell death. The current study assessed the role of CB1 receptor activation at the moment of an ischemic insult on ensuing regulation of stress and reward signaling molecules, neuronal injury and anxiety-like behavior. Male Wistar rats were separated into 4 groups (n=10/group); sham and ischemic rats administered the CB1 endocannabinoid receptor antagonist AM251 (2mg/kg, i.p.) 30min prior to global cerebral ischemia, and vehicle-treated counterparts. The effects of CB1 receptor blockade on corticotropin-releasing hormone (CRH), vesicular glutamate transporter 2 (vGluT2), tyrosine hydroxylase (TH) and dopamine receptor 1 (DRD1) signaling expression, together with CA1 neuronal damage and anxiety-like behaviors were assessed. Our findings show attenuated CA1 injury and behavioral deficits in AM251-treated ischemic rats. AM251-pretreatment also partially or completely reversed ischemia-induced alterations in TH-ir expression at the hippocampus, ventral tegmental area (VTA), nucleus accumbens (NAc) and basolateral amygdala (BLA), normalized DRD1-ir at the medial forebrain bundle, and diminished BLA and PVN-CRH expression. All groups showed comparable vGluT2 expression at the BLA and PVN-parvocellular subdivision. These findings support a determinant role of CB1 receptor activation at time of ischemia on functional recovery. They also support "state-dependent" effects of endocannabinoids, raising considerations in the development of effective molecules to regulate HPA axis function and mood disorders following cardiac arrest and stroke.
authors.affiliation: Department of Psychology, University of Ottawa, Behavioural Neuroscience Group, 136 Jean-Jacques Lussier, Ottawa, ON, Canada.
authors.forename: Megan Dunbar
authors.initials: MD
authors.lastname: Knowles
authors.affiliation: Department of Psychology, University of Ottawa, Behavioural Neuroscience Group, 136 Jean-Jacques Lussier, Ottawa, ON, Canada.
authors.forename: Patricia Barra
authors.initials: PB
authors.lastname: de la Tremblaye
authors.affiliation: Department of Psychology, University of Ottawa, Behavioural Neuroscience Group, 136 Jean-Jacques Lussier, Ottawa, ON, Canada.
authors.forename: Idu
authors.initials: I
authors.lastname: Azogu
authors.affiliation: Department of Psychology, University of Ottawa, Behavioural Neuroscience Group, 136 Jean-Jacques Lussier, Ottawa, ON, Canada. Electronic address: hplamond@uottawa.ca.
authors.forename: Hélène
authors.initials: H
authors.lastname: Plamondon
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D002545:Brain Ischemia / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology*; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism; D007175:Impulsive Behavior / Q000502:physiology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors*; D017447:Receptors, Dopamine D1 / Q000378:metabolism; D012201:Reward; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D050599:Vesicular Glutamate Transport Protein 2 / Q000378:metabolism
chemical_list: D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D017447:Receptors, Dopamine D1; D050599:Vesicular Glutamate Transport Protein 2; C103505:AM 251; D003346:Corticotropin-Releasing Hormone; D014446:Tyrosine 3-Monooxygenase
keywords: Corticotropin-releasing hormone; Dopamine; Emotional behavior; Endocannabinoids; Global cerebral ischemia; Mesolimbic system; Neuroprotection