Fig. 6.

The HPT axis of NCoRΔID mice responds normally to changes in serum TH level. A, Serum TSH was measured by high-affinity RIA in hypothyroid (PTU) and low T₃ replacement dose groups (n = 3–7 animals per group). B, TSH subunit mRNA levels were quantified by quantitative PCR in hypothyroid and physiological T₃ replacement dose groups. mRNA levels are expressed relative to WT euthyroid animals (set to 1) (n = 5–7 animals per group). C, Expression of known TH targets in the pituitary of NCoRΔID mice at different circulating T₃ levels. mRNA expression levels were quantified by quantitative PCR and presented relative to euthyroid WT group (set to 1) (n = 5–7 animals per group). D, Feedback suppression of thyroid function by exogenous T₃. WT and NCoRΔID mice were given injections of two indicated incremental doses of T₃ for 4 d each. Total serum T₄ levels were measured at the end of each treatment period, and the decrease was expressed as a percentage of the baseline obtained in the same animals before the treatment (n = 7–9 animals per group). Data are presented as mean ± sem; * P < 0.05; **P < 0.01.