Effect of decreased hepatic nuclear l-triiodothyronine receptors on the response of hepatic enzymes to l-triiodothyronine in tumor-bearing rats

M. M. Grajower, Martin I. Surks

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

The activity of hepatic α-glycerophosphate dehydrogenase (α-GPD) and malic enzyme (ME) was measured in rats bearing the Walker 256 carcinoma to assess the relationship between the reduction in the nuclear L-T3 (T3) receptor concentration which occurs in tumor-bearing (T) rats and the biological effects of thyroid hormones. T3 receptor concentration was uniformly decreased when tumors exceeded 9.5% of body weight. No change in basal α-GPD activity was observed, but ME activity was decreased to between 29-61% of control. The decrease in ME activity did not appear to be related to decreased nuclear T3 receptor concentration since ME was also decreased in T rats with tumors that were too small to effect a decrease in the concentration of nuclear T3 receptors or plasma T4 and T3. The response of both ME and α-GPD to T 3 administration in T rats was comparable to that of control despite reduced nuclear T3 receptor and plasma hormone concentrations. When non-T rats were subjected to food restriction to simulate the attenuated growth curves of T rats, no changes were observed in nuclear T3 receptor concentration, plasma T4 and T3 concentration, or basal activity of α-GPD or ME. The induction of two thyroid hormone sensitive hepatic enzymes in rats with reduced nuclear T3 receptor and plasma T3 concentrations suggests that nuclear receptor and plasma T3 concentration suggests that nuclear receptors are lost from sites which are not involved with the regulation of α-GPD or ME. Thus, unchanged receptor levels at sites which control α-GPD and ME may lead to normal biological responses of these enzymes despite reduced total receptor concentration.

Original languageEnglish (US)
Pages (from-to)697-703
Number of pages7
JournalEndocrinology
Volume104
Issue number3
StatePublished - 1979

Fingerprint

Thyroid Hormone Receptors
Triiodothyronine
Cytoplasmic and Nuclear Receptors
Liver
Enzymes
Neoplasms
Thyroid Hormones
Walker Carcinoma 256
Glycerolphosphate Dehydrogenase
Body Weight
Hormones
Food

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

@article{ef85b0709aa34093b68ad2becc61fb74,
title = "Effect of decreased hepatic nuclear l-triiodothyronine receptors on the response of hepatic enzymes to l-triiodothyronine in tumor-bearing rats",
abstract = "The activity of hepatic α-glycerophosphate dehydrogenase (α-GPD) and malic enzyme (ME) was measured in rats bearing the Walker 256 carcinoma to assess the relationship between the reduction in the nuclear L-T3 (T3) receptor concentration which occurs in tumor-bearing (T) rats and the biological effects of thyroid hormones. T3 receptor concentration was uniformly decreased when tumors exceeded 9.5{\%} of body weight. No change in basal α-GPD activity was observed, but ME activity was decreased to between 29-61{\%} of control. The decrease in ME activity did not appear to be related to decreased nuclear T3 receptor concentration since ME was also decreased in T rats with tumors that were too small to effect a decrease in the concentration of nuclear T3 receptors or plasma T4 and T3. The response of both ME and α-GPD to T 3 administration in T rats was comparable to that of control despite reduced nuclear T3 receptor and plasma hormone concentrations. When non-T rats were subjected to food restriction to simulate the attenuated growth curves of T rats, no changes were observed in nuclear T3 receptor concentration, plasma T4 and T3 concentration, or basal activity of α-GPD or ME. The induction of two thyroid hormone sensitive hepatic enzymes in rats with reduced nuclear T3 receptor and plasma T3 concentrations suggests that nuclear receptor and plasma T3 concentration suggests that nuclear receptors are lost from sites which are not involved with the regulation of α-GPD or ME. Thus, unchanged receptor levels at sites which control α-GPD and ME may lead to normal biological responses of these enzymes despite reduced total receptor concentration.",
author = "Grajower, {M. M.} and Surks, {Martin I.}",
year = "1979",
language = "English (US)",
volume = "104",
pages = "697--703",
journal = "Endocrinology",
issn = "0013-7227",
publisher = "The Endocrine Society",
number = "3",

}

TY - JOUR

T1 - Effect of decreased hepatic nuclear l-triiodothyronine receptors on the response of hepatic enzymes to l-triiodothyronine in tumor-bearing rats

AU - Grajower, M. M.

AU - Surks, Martin I.

PY - 1979

Y1 - 1979

N2 - The activity of hepatic α-glycerophosphate dehydrogenase (α-GPD) and malic enzyme (ME) was measured in rats bearing the Walker 256 carcinoma to assess the relationship between the reduction in the nuclear L-T3 (T3) receptor concentration which occurs in tumor-bearing (T) rats and the biological effects of thyroid hormones. T3 receptor concentration was uniformly decreased when tumors exceeded 9.5% of body weight. No change in basal α-GPD activity was observed, but ME activity was decreased to between 29-61% of control. The decrease in ME activity did not appear to be related to decreased nuclear T3 receptor concentration since ME was also decreased in T rats with tumors that were too small to effect a decrease in the concentration of nuclear T3 receptors or plasma T4 and T3. The response of both ME and α-GPD to T 3 administration in T rats was comparable to that of control despite reduced nuclear T3 receptor and plasma hormone concentrations. When non-T rats were subjected to food restriction to simulate the attenuated growth curves of T rats, no changes were observed in nuclear T3 receptor concentration, plasma T4 and T3 concentration, or basal activity of α-GPD or ME. The induction of two thyroid hormone sensitive hepatic enzymes in rats with reduced nuclear T3 receptor and plasma T3 concentrations suggests that nuclear receptor and plasma T3 concentration suggests that nuclear receptors are lost from sites which are not involved with the regulation of α-GPD or ME. Thus, unchanged receptor levels at sites which control α-GPD and ME may lead to normal biological responses of these enzymes despite reduced total receptor concentration.

AB - The activity of hepatic α-glycerophosphate dehydrogenase (α-GPD) and malic enzyme (ME) was measured in rats bearing the Walker 256 carcinoma to assess the relationship between the reduction in the nuclear L-T3 (T3) receptor concentration which occurs in tumor-bearing (T) rats and the biological effects of thyroid hormones. T3 receptor concentration was uniformly decreased when tumors exceeded 9.5% of body weight. No change in basal α-GPD activity was observed, but ME activity was decreased to between 29-61% of control. The decrease in ME activity did not appear to be related to decreased nuclear T3 receptor concentration since ME was also decreased in T rats with tumors that were too small to effect a decrease in the concentration of nuclear T3 receptors or plasma T4 and T3. The response of both ME and α-GPD to T 3 administration in T rats was comparable to that of control despite reduced nuclear T3 receptor and plasma hormone concentrations. When non-T rats were subjected to food restriction to simulate the attenuated growth curves of T rats, no changes were observed in nuclear T3 receptor concentration, plasma T4 and T3 concentration, or basal activity of α-GPD or ME. The induction of two thyroid hormone sensitive hepatic enzymes in rats with reduced nuclear T3 receptor and plasma T3 concentrations suggests that nuclear receptor and plasma T3 concentration suggests that nuclear receptors are lost from sites which are not involved with the regulation of α-GPD or ME. Thus, unchanged receptor levels at sites which control α-GPD and ME may lead to normal biological responses of these enzymes despite reduced total receptor concentration.

UR - http://www.scopus.com/inward/record.url?scp=0018770006&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0018770006&partnerID=8YFLogxK

M3 - Article

C2 - 220018

AN - SCOPUS:0018770006

VL - 104

SP - 697

EP - 703

JO - Endocrinology

JF - Endocrinology

SN - 0013-7227

IS - 3

ER -