title: Endocannabinoids modulate human blood-brain barrier permeability in vitro.
abstract: OBJECTIVE
  Endocannabinoids alter permeability at various epithelial barriers, and cannabinoid receptors and endocannabinoid levels are elevated by stroke, with potential neuroprotective effects. We therefore explored the role of endocannabinoids in modulating blood-brain barrier (BBB) permeability in normal conditions and in an ischaemia/reperfusion model.
  
  
  METHODS
  Human brain microvascular endothelial cell and astrocyte co-cultures modelled the BBB. Ischaemia was modelled by oxygen-glucose deprivation (OGD) and permeability was measured by transepithelial electrical resistance. Endocannabinoids or endocannabinoid-like compounds were assessed for their ability to modulate baseline permeability or OGD-induced hyperpermeability. Target sites of action were investigated using receptor antagonists and subsequently identified with real-time PCR.
  
  
  RESULTS
  Anandamide (10 μM) and oleoylethanolamide (OEA, 10 μM) decreased BBB permeability (i.e. increased resistance). This was mediated by cannabinoid CB2 receptors, transient receptor potential vanilloid 1 (TRPV1) channels, calcitonin gene-regulated peptide (CGRP) receptor (anandamide only) and PPARα (OEA only). Application of OEA, palmitoylethanolamide (both PPARα mediated) or virodhamine (all 10 μM) decreased the OGD-induced increase in permeability during reperfusion. 2-Arachidonoyl glycerol, noladin ether and oleamide did not affect BBB permeability in normal or OGD conditions. N-arachidonoyl-dopamine increased permeability through a cytotoxic mechanism. PPARα and γ, CB1 receptors, TRPV1 channels and CGRP receptors were expressed in both cell types, but mRNA for CB2 receptors was only present in astrocytes.
  
  
  CONCLUSIONS
  The endocannabinoids may play an important modulatory role in normal BBB physiology, and also afford protection to the BBB during ischaemic stroke, through a number of target sites.
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: William H
authors: WH
authors: Hind
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: Cristina
authors: C
authors: Tufarelli
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: Maria
authors: M
authors: Neophytou
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: Susan I
authors: SI
authors: Anderson
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: Timothy J
authors: TJ
authors: England
authors: School of Medicine, University of Nottingham, Royal Derby Hospital, Derby, UK.
authors: Saoirse E
authors: SE
authors: O'Sullivan
mesh_terms: D001095:Arachidonic Acids / Q000008:administration & dosage / Q000378:metabolism; D001253:Astrocytes / Q000378:metabolism; D001812:Blood-Brain Barrier / Q000378:metabolism*; D002478:Cells, Cultured; D018920:Coculture Techniques; D017097:Electric Impedance; D063388:Endocannabinoids / Q000008:administration & dosage / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism; D006801:Humans; D009829:Oleic Acids / Q000008:administration & dosage / Q000378:metabolism; D010539:Permeability; D053284:Polyunsaturated Alkamides / Q000008:administration & dosage / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D015427:Reperfusion Injury / Q000378:metabolism*
chemical_list: D001095:Arachidonic Acids; D063388:Endocannabinoids; D009829:Oleic Acids; D053284:Polyunsaturated Alkamides; D012333:RNA, Messenger; D043885:Receptor, Cannabinoid, CB2; C488250:oleoylethanolamide; C078814:anandamide
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