Regulation of Tyrosine Hydroxylase Gene Expression in the Rat Carotid Body by Hypoxia

Maria F. Czyzyk‐Krzeska, Douglas A. Bayliss, Edward E. Lawson, David E. Millhorn

Research output: Contribution to journalArticlepeer-review

168 Scopus citations


Abstract: The activity (Vmax) of tyrosine hydroxylase (TH; EC, the rate limiting enzyme in the synthesis of catecholamines, is increased in carotid body, superior cervical ganglion, and the adrenal medulla during hypoxia (i.e., reduced Pao2). The present study was undertaken to determine if the increase in TH activity in these tissues during hypoxia is regulated at the level of TH mRNA. Adult rats were exposed to hypoxia (10% O2) or room air for periods lasting from 1 to 48 h. The carotid bodies, superior cervical ganglia, and adrenals were removed and processed for in situ hybridization using 35S‐labeled oligonucleotide probes. The concentration of TH mRNA was increased by hypoxia at all time points in carotid body type I cells, but not in cells of either superior cervical ganglion or adrenal medulla. The increase in TH mRNA in carotid body during hypoxia did not require innervation of the carotid body or intact adrenal glands. In addition, hypercapnia, another physiological stimulus of carotid body activity, failed to induce an increase in TH mRNA in type I cells. Our findings suggest that hypoxia stimulates TH gene expression in the carotid body by a mechanism that is intrinsic to type I cells.

Original languageEnglish (US)
Pages (from-to)1538-1546
Number of pages9
JournalJournal of Neurochemistry
Issue number4
StatePublished - Apr 1992
Externally publishedYes


  • Carotid body
  • Gene expression
  • Hypoxia
  • In situ hybridization
  • Messenger RNA
  • Tyrosine hydroxylase

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience


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