Unilateral Activation of Caudate Tyrosine Hydroxylase During Voluntary Circling Behavior

Michael E. Morgan, Bryan K. Yamamoto, Curt R. Freed

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


Abstract: We trained rats to circle for a sucrose water reward and found that this behavior is associated with a unilateral increase in the activity of caudate tyrosine hydroxylase, the rate‐limiting enzyme for dopamine synthesis. The increase in tyrosine hydroxylase activity occurs in caudate contralateral to the circling direction and the change is transient, increasing during the first 20 min of circling but then plateauing and falling as turning slows. Enhanced synthetic capacity is followed by increases in the contents of dopamine and dihydroxyphenylacetic acid in the contralateral caudate nucleus. These observations are the first evidence for specific activation of a neurotransmitter synthetic enzyme during voluntary motor behavior.

Original languageEnglish (US)
Pages (from-to)737-741
Number of pages5
JournalJournal of Neurochemistry
Issue number3
StatePublished - Sep 1984


  • 6‐Methyltetrahydropterin
  • Caudate
  • Rats
  • Trained circling rat
  • Tyrosine hydroxylase

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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