Effects of long-term exposure to DEHP on the mRNA expression levels of TRHr, TSHβ, TPO, D1, TSHr, NIS, TG and TTf-1 at 3 M and 6 M respectively. All rats were treated with DEHP (0, 150, 300, 600 mg/kg/day) by gavage for 3 M and 6 M, and the effect of this treatment on the expression of above-mentioned thyroid-related genes were examined by QPCR. Groups of different doses of DEHP: 0 mg/kg/day, control group; 150 mg/kg/day, low-dose group; 300 mg/kg/day, middle-dose group; 600 mg/kg/day, high-dose group. Data are presented as the mean ± S.E.M (6/group). a Significantly different from the control (p < 0.05); b Significantly different from the control (p < 0.01). (A) TRHr; (B) TSHβ; (C) TPO; (D) D1; (E) TSHr; (F) NIS; (G) TG; (H) TTf-1; (I) D1. Hypothalamus: (A); Pituitary: (B); Thyroid: (C–H); Liver: (I).