Figure 1. A single dose of TCDD induces Cyp1a1 transcriptional memory.
C57BL/6J female mice (wild type) were orally treated with TCDD at a single dose of 3 μg/kg bw, and livers were collected at indicated time points post-TCDD exposure. (a) Time-course changes of Cyp1a1 mRNA expression levels in TCDD-treated animals (n = 3). (b) Lack of response in Ahr−/−animals. (c) Wild type female animals were pretreated with TCDD and repeat treated 40 days after the initial dose. Note an approximately three-fold super-induction of Cyp1a1 in TCDD pretreated animals in comparison with non-pretreated animals (n = 3). *P < 0.05, Student’s t-test.