Alpha amanitin administration results in a temporary inhibition of hepatic enzyme induction by triiodothyronine: further evidence favoring a long lived mediator of thyroid hormone action

W. H. Dillmann, H. L. Schwartz, E. Silva, Martin I. Surks, J. H. Oppenheimer

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Alpha-amanitin was shown to inhibit triiodothyronine (T 3)-induced increases in mitochondrial alpha-glycerophosphate dehydrogenase (α-GPD) and cytoplasmic malic enzyme activity in the livers of male Sprague-Dawley rats. A 3-fold increase in α-GPD observed 24 h after the iv injection of 3 μg T 3/100 g BW was completely inhibited by administration of alpha-amanitin at 0 and 8 h. Similarly, alpha-amanitin blocked a two- to four-fold increase in malic enzyme 24 h following iv injection of 3 mg T 3/100 g BW into euthyroid rats. After the initial inhibition of enzyme induction by alpha-amanitin was dissipated, however, a delayed but striking increase in enzyme activity occurred. In hypothyroid animals, α-GPD activity rose after the initial 24 h inhibition and reached levels at 72 h equal to those observed in hypothyroid rats treated with T 3 only. In euthyroid animals treated with T 3 and alpha-amanitin, a delayed increase in malic enzyme activity was observed at 72 h and attained values at 96 h similar to those in euthyroid animals injected with T 3 only. The delayed rise in enzyme response is most easily explained by the formation of a long-lived intermediate during the exposure of the nuclear sites to T 3.

Original languageEnglish (US)
Pages (from-to)1621-1627
Number of pages7
JournalEndocrinology
Volume100
Issue number6
StatePublished - 1977

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Alpha-Amanitin
Enzyme Induction
Triiodothyronine
Thyroid Hormones
Liver
Enzymes
Glycerolphosphate Dehydrogenase
Injections
Sprague Dawley Rats

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Alpha amanitin administration results in a temporary inhibition of hepatic enzyme induction by triiodothyronine : further evidence favoring a long lived mediator of thyroid hormone action. / Dillmann, W. H.; Schwartz, H. L.; Silva, E.; Surks, Martin I.; Oppenheimer, J. H.

In: Endocrinology, Vol. 100, No. 6, 1977, p. 1621-1627.

Research output: Contribution to journalArticle

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