Diminished hepatic l-triiodothyronine nuclear receptor concentration in rats bearing the walker 256 carcinoma is not due to a generalized decrease in nonhistone protein synthesis

Zalman Starosta, Frank Gasparini, Lawrence E. Shapiro, Martin I. Surks

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Abstract

To determine whether the decrease in hepatic T3 nuclear receptors in rats bearing the Walker 256 carcinoma (T rats) is a consequence of nonthyroidal disease or related to a generalized decrease in hepatic protein synthesis, we measured hepatic T3 nuclear receptors and [3H]leucine incorporation into protein in control and T rats. Mean protein contents of liver homogenate, purified nuclei, 0.4 M NaCl extracts of nuclei, and nonhistone protein fractions were similar in control and T rats. In pooled data from three experiments, [3H]leucine incorporation into protein in these liver fractions was significantly increased (55-73%) in T rats. Since the precursor nonradioactive leucine pool, measured by a novel HPLC method, was similar in control and T rats, the increased incorporation of [3H] leucine in all liver fractions suggests an increase in protein synthesis in T rats. Additional measurements in the same rats (two experiments) indicated that hepatic nuclear receptors were decreased to 50% of the control value in T rats (P< 0.001). Our findings suggest that in the Walker tumor model of nonthyroidal disease, decreased hepatic nuclear T3 receptors appears relatively specific and is not associated with a generalized decrease in hepatic protein synthesis.

Original languageEnglish (US)
Pages (from-to)1172-1177
Number of pages6
JournalEndocrinology
Volume123
Issue number2
DOIs
Publication statusPublished - Aug 1 1988

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ASJC Scopus subject areas

  • Endocrinology

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