of TH action by a number of industrial chemicals is critical to
identify. Several chemicals including polychlorinated biphenyls are
metabolized by the dioxin-inducible enzyme CYP1A1; some of their
metabolites can interact with the TH receptor. In animals, this
mechanism is reflected by a strong correlation between the expression of
CYP1A1 mRNA and TH-regulated mRNAs. If this mechanism occurs in humans,
we expect that CYP1A1 expression will be positively correlated with the
expression of genes regulated by TH.
expression is correlated with TH-regulated mRNAs in human placenta.
disease were obtained from the GESTE study (Sherbrooke, Qéubec, Canada).
Maternal and cord blood TH levels were measured at birth. The mRNA
levels of CYP1A1 and placental TH receptor targets [placental lactogen
(PL) and GH-V] were quantitated by quantitative PCR.
detectable CYP1A1 mRNA. CYP1A1 mRNA was positively correlated with PL (r = 0.64; P < .0001) and GH-V (P < .0001, r = 0.62) mRNA. PL and GH-V mRNA were correlated with each other (r = 0.95; P < .0001), suggesting a common activator. The mRNAs not regulated by TH were not correlated with CYP1A1 expression.