THYROTROPIN-RELEASING-HORMONE GENE-EXPRESSION IN THE HUMAN HYPOTHALAMUS

We studied the distribution of mRNA coding for thyrotropin-releasing h ormone (TRH) in the human hypothalamus by means of in situ hybridizati on. In 10% formalin-fixed paraffin-embedded tissue sections of five hy pothalami, TRH mRNA-containing cells were found in several nuclei and areas. Numerous TRH mRNA-containing cells were detected in the medial region of the caudal part of the paraventricular nucleus. These neuron s were heavily labeled and mainly small to medium-sized. Few, lightly- and medium-labeled, small cells were detected in the suprachiasmatic nucleus. In addition, heavily labeled single cells were found in the p erifornical area and the anterior- and lateral hypothalamic regions. I n the latter region, occasional heavily labeled cells were found just dorsal to the supraoptic nucleus. Neither in the supraoptic nucleus no r in the sexually dimorphic nucleus of the preoptic area were TRH mRNA -containing cells found. This is the first description of TRH mRNA con taining cells in the human hypothalamus.