In Vivo Stimulation of Rat Pineal Type II Thyroxine 5′-Deiodinase Activity by Either Norepinephrine or Isoproterenol

J. M. Guerrero, C. Santana, R. J. Retter

Research output: Contribution to journalArticle

9 Scopus citations

Abstract

Herein we show, for the first time, a very marked increase in thyroxine 5′-deiodinase (5′-D) activity in rats injected with norepinephrine (NE) and desmethylimipramine, a drug which inhibits NE uptake by nerve terminals. The response to NE was greater in pineals collected from hypothyroid animals than in glands from euthyroid animals. NE was more effective in stimulating pineal 5′-D than was isoproterenol, suggesting that, in addition to β-adrenergic receptors, α-adrenergic receptors might be involved in the 5′-D activation. However, phenylephrine, an α-adrenergic agonist, did not potentiate the effect of isoproterenol on pineal 5′-D activity. The nocturnal increase in pineal 5′-D activity was completely abolished by propranolol, a β-adrenergic receptor blocker, while prazosin, an α-adrenergic receptor blocker, had minimal effect. These results show that the role of α-receptors in promoting the NE-mediated rise in rat pineal 5′-D activity is minor in contrast to the role of β-adrenergic receptors.

Original languageEnglish (US)
Pages (from-to)327-331
Number of pages5
JournalProceedings of the Society for Experimental Biology and Medicine
Volume194
Issue number4
DOIs
StatePublished - Sep 1990

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

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