Induction of TH gene by TCDD exposure inN2a-Rβ cells. (A) AhR protein (96 kDa) in N2a-Rβ cells was detected by Western blotting using an anti-AhR antibody. No signal was detected in N2a-Vc cells. (B) The expression of TH and CYP1A1 mRNAs in N2a-Rβ cells was detected by RT-PCR. TH mRNA expression was induced in addition to CYP1A1 mRNA in TCDD-exposed N2a-Rβ cells. CYP1A1, a typical XRE-mediated gene, was used as a marker of AhR activation. TH and CYP1A1 mRNAs were not detected in N2a-Vc cells. Data represent triplicate experiments.