Tags

Type your tag names separated by a space and hit enter

Thyrotropin-releasing hormone and thyroid hormone interactions on thyrotropin secretion in the rat: lack of inhibiting effects of small doses of triiodo-L-thyronine in the hypothyroid rat.
Endocrinology. 1976 Jan; 98(1):203-13.E

Abstract

Rats were thyroidectomized (T) and injected once daily with thyroxine (T4) or triiodothyronine (T3) ip; circulating thyrotropin (TSH) levels and TSH response to 100 ng of thyrotropin releasing hormone (TRH) iv, were measured in different groups of rats at several intervals after the last dose of T4 or T3. It was found that T rats on 1.8 mug T4 or 0.4 mug T3/100 g BW/day, response to TRH decreased after the injection of the hormone, maximum suppressive effect being found about 7-8 h after T4, or 4 h after T3. The response increased as T4 or T3 levels reached a nadir, in agreement with present views on TRH, T4, and T3 interactions at the pituitary level. The degree of TSH response to TRH appears as a sensitive parameter of T4 or T3 activity in this experimental model. However, in T rats on 0.2 mug T3/100 g BW/day, TSH response to TRH did not decrease, but actually increased, after the daily injection of T3. These animals appeared to be in a state of continuous thyroid hormone deficiency. The same 0.2 mug T3 dose effectively suppresses the elevated basal TSH levels of these animals. It is also capable of decreasing TSH response to 100 ng TRH in animals under more "euthyroid" conditions. These results in the T rats on 0.2 mug T3 are not easily fitted into the relatively simple model frequently described to explain TRH-T3 interactions and TSH secretion.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

813987

Citation

García, M D., et al. "Thyrotropin-releasing Hormone and Thyroid Hormone Interactions On Thyrotropin Secretion in the Rat: Lack of Inhibiting Effects of Small Doses of triiodo-L-thyronine in the Hypothyroid Rat." Endocrinology, vol. 98, no. 1, 1976, pp. 203-13.
García MD, Escobar del Rey F, Morreale de Escobar G. Thyrotropin-releasing hormone and thyroid hormone interactions on thyrotropin secretion in the rat: lack of inhibiting effects of small doses of triiodo-L-thyronine in the hypothyroid rat. Endocrinology. 1976;98(1):203-13.
García, M. D., Escobar del Rey, F., & Morreale de Escobar, G. (1976). Thyrotropin-releasing hormone and thyroid hormone interactions on thyrotropin secretion in the rat: lack of inhibiting effects of small doses of triiodo-L-thyronine in the hypothyroid rat. Endocrinology, 98(1), 203-13.
García MD, Escobar del Rey F, Morreale de Escobar G. Thyrotropin-releasing Hormone and Thyroid Hormone Interactions On Thyrotropin Secretion in the Rat: Lack of Inhibiting Effects of Small Doses of triiodo-L-thyronine in the Hypothyroid Rat. Endocrinology. 1976;98(1):203-13. PubMed PMID: 813987.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Thyrotropin-releasing hormone and thyroid hormone interactions on thyrotropin secretion in the rat: lack of inhibiting effects of small doses of triiodo-L-thyronine in the hypothyroid rat. AU - García,M D, AU - Escobar del Rey,F, AU - Morreale de Escobar,G, PY - 1976/1/1/pubmed PY - 1976/1/1/medline PY - 1976/1/1/entrez SP - 203 EP - 13 JF - Endocrinology JO - Endocrinology VL - 98 IS - 1 N2 - Rats were thyroidectomized (T) and injected once daily with thyroxine (T4) or triiodothyronine (T3) ip; circulating thyrotropin (TSH) levels and TSH response to 100 ng of thyrotropin releasing hormone (TRH) iv, were measured in different groups of rats at several intervals after the last dose of T4 or T3. It was found that T rats on 1.8 mug T4 or 0.4 mug T3/100 g BW/day, response to TRH decreased after the injection of the hormone, maximum suppressive effect being found about 7-8 h after T4, or 4 h after T3. The response increased as T4 or T3 levels reached a nadir, in agreement with present views on TRH, T4, and T3 interactions at the pituitary level. The degree of TSH response to TRH appears as a sensitive parameter of T4 or T3 activity in this experimental model. However, in T rats on 0.2 mug T3/100 g BW/day, TSH response to TRH did not decrease, but actually increased, after the daily injection of T3. These animals appeared to be in a state of continuous thyroid hormone deficiency. The same 0.2 mug T3 dose effectively suppresses the elevated basal TSH levels of these animals. It is also capable of decreasing TSH response to 100 ng TRH in animals under more "euthyroid" conditions. These results in the T rats on 0.2 mug T3 are not easily fitted into the relatively simple model frequently described to explain TRH-T3 interactions and TSH secretion. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/813987/Thyrotropin_releasing_hormone_and_thyroid_hormone_interactions_on_thyrotropin_secretion_in_the_rat:_lack_of_inhibiting_effects_of_small_doses_of_triiodo_L_thyronine_in_the_hypothyroid_rat_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo-98-1-203 DB - PRIME DP - Unbound Medicine ER -