Figure 1.

TRH is regulated by T₃ at the level of transcription in the PVH. ISH using S³⁵ radiolabeled probes. A, Representation of the two probes used for ISH. The cRNA probe labels nucleotides 307–572 of the murine prepro-TRH gene (TRH mRNA, left); the heteronuclear TRH probe labels the first intron in the TRH RNA message (TRH hnRNA, right). B, ISH was performed on brain slices from euthyroid (Euth.), hypothyroid (Hypo.), and hyperthyroid (Hyper.) WT mice. Images detail the paraventricular hypothalamus (PVH) and anterior hypothalamus (AH). n = 4 mice for each probe under each condition. Magnification, ×10; scale bars per column, 100 μm. C, Quantification of ISH via pixel density. Data are presented as sample means relative to control euthyroid mice ± sem. Significance was tested within each brain region and within each probe via one-way ANOVA. ***, P < 0.001.