Effects of Catechol Estrogens1 and Catecholamines on Hypothalamic and Corpus Striatal Tyrosine Hydroxylase Activity

M. M. Foreman, J. C. Porter

Research output: Contribution to journalArticlepeer-review

75 Scopus citations

Abstract

Abstract: The effects of catechol estrogens on tyrosine hydroxylase activity in hypothalamic and corpus striatal extracts were evaluated. When assayed in the presence of subsaturating concentrations of pterin cofactor, tyrosine hydroxylase activity was depressed by 2‐hydroxyestrone, 2‐hydroxyestradiol, Lnorepinephrine, or dopamine. However, estrone, 17β‐estradiol, 2‐ methoxyestrone, or 2‐methoxyestradiol had no consistent inhibitory effect on tyrosine hydroxylase activity under in vitro conditions. Moreover, a decrease in pterin binding affinity (elevated Km) in the presence of either catecholamines or 2‐hydroxyestrogens was found. These findings were suggestive of a competitive interaction between catechols and pterin. Catechol estrogens and catecholamines were shown to inhibit both membrane‐bound and soluble forms of tyrosine hydroxylase. The membrane‐bound form of tyrosine hydroxylase, however, was found to have a greater binding affinity (lower Kl) for 2hydroxyestradiol and norepinephrine than did the soluble form. The results of the present study are suggestive of a cytoplasmic effect of estrogen that may be mediated by 2‐hydroxyestrogen and terminated by O‐methylation.

Original languageEnglish (US)
Pages (from-to)1175-1183
Number of pages9
JournalJournal of Neurochemistry
Volume34
Issue number5
DOIs
StatePublished - May 1980

Keywords

  • 2‐Methox yestrogens
  • Catechol estrogens
  • Catecholamines
  • Estrogens
  • Pterin
  • Tyrosine hydroxylase

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

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