DETECTION OF TYROSINE-HYDROXYLASE AND PHENYLETHANOLAMINE-N-METHYLTRANSFERASE MESSENGER-RNAS IN THE MOUSE ADRENAL-GLAND AND THE BRAIN BY INSITU HYBRIDIZATION

To study the expression of tyrosine hydroxylase (TH) and phenylethanol amine-N-methyltransferase (PNMT) genes in the mouse adrenal gland and the brain, we performed in situ hybridization studies by using several types of complementary DNA probes recognizing coding regions of human TH (THc), the 3'-end of the human region of TH (TH3'), and the coding region of the human PNMT (PNMTc). THc mRNA was detected in the chroma ffin cells of the mouse adrenal medulla and brain catecholaminergic ne urons including the substantia nigra and ventral tegmental area. TH-im munopositive neurons were located in a similar pattern in adjacent sec tions. However no positive signals were detected by the TH3' probe. Us ing the PNMTc probe, the majority of cells in the adrenal medulla demo nstrated positive labelling. Although the mouse TH and PNMT genes have not been fully isolated and sequenced, the present study strongly sug gests that the sequence of the coding regions of TH and PNMT are simil ar in human and mouse. The THc and PNMTc probes are particularly usefu l in investigating the loci of gene transcription in mouse tissues.