title: Aryl hydrocarbon receptor-dependent upregulation of Cyp1b1 by TCDD and diesel exhaust particles in rat brain microvessels.
abstract: BACKGROUND
  AhR activates the transcription of several target genes including CYP1B1. Recently, we showed CYP1B1 as the major cytochrome P450 (CYP) enzyme expressed in human brain microvessels. Here, we studied the effect of AhR activation by environmental pollutants on the expression of Cyp1b1 in rat brain microvessels.
  
  
  METHODS
  Expression of AhR and Cyp1b1 was detected in isolated rat brain microvessels. AhR was immunovisualised in brain microvessel endothelial cells. The effect of AhR ligands on Cyp1b1 expression was studied using isolated brain microvessels after ex vivo and/or in vivo exposure to TCDD, heavy hydrocarbons containing diesel exhaust particles (DEP) or Δ9-tetrahydrocannabinol (Δ9-THC).
  
  
  RESULTS
  After ex vivo exposure to TCDD (a highly potent AhR ligand) for 3 h, Cyp1b1 expression was significantly increased by 2.3-fold in brain microvessels. A single i.p. dose of TCDD also increased Cyp1b1 transcripts (22-fold) and Cyp1b1 protein (2-fold) in rat brain microvessels at 72 h after TCDD. Likewise, DEP treatment (in vivo and ex vivo) strongly induced Cyp1b1 protein in brain microvessels. DEP-mediated Cyp1b1 induction was inhibited by actinomycin D, cycloheximide, or by an AhR antagonist. In contrast, a sub-chronic in vivo treatment with Δ9-THC once daily for 7 seven days had no effect on Cyp1b1 expression
  
  
  CONCLUSIONS
  Our results show that TCDD and DEP strongly induced Cyp1b1 in rat brain microvessels, likely through AhR activation.
authors.affiliation: Neuropsychopharmacologie des addictions (CNRS UMR 8206), Université Paris Descartes, Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France. xavier.decleves@parisdescartes.fr.
authors.forename: Aude
authors.initials: A
authors.lastname: Jacob
authors.forename: Anika Ms
authors.initials: AM
authors.lastname: Hartz
authors.forename: Sophie
authors.initials: S
authors.lastname: Potin
authors.forename: Xavier
authors.initials: X
authors.lastname: Coumoul
authors.forename: Salah
authors.initials: S
authors.lastname: Yousif
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Scherrmann
authors.forename: Björn
authors.initials: B
authors.lastname: Bauer
authors.forename: Xavier
authors.initials: X
authors.lastname: Declèves