Serum thyroxine, triiodothyronine, and TSH levels and TSH release after TRH in aging Male and female rats

G. H. Greeley; M. A. Lipton; J. S. Kizer

doi:10.3109/07435808209045762

Serum thyroxine, triiodothyronine, and TSH levels and TSH release after TRH in aging Male and female rats

G. H. Greeley, M. A. Lipton, J. S. Kizer

Research output: Contribution to journal › Article › peer-review

25 Scopus citations

Abstract

Serum levels of TSH, T₃ and T₄, pituitary responsiveness to TRH, and T₃-resin uptake were examined in aging male and female rats. Despite normal serum TSH levels, serum T₃ and T₄, levels were significantly reduced in old male rats (19-26 months of age) when compared to young (120-150 days of age) and middle-aged males (12-18 months of age). In old female rats, serum TSH and T₃ levels were not significantly (p >0.05) different from those of young or middle-aged females. Serum T₄ levels were significantly lower in old females when compared to younger rats. The To-resin uptake of old rats was not significantly different from the value of young rats. Serum T₄ levels, 3 hours after TRH induced TSH release, were significantly depressed in old male and female rats. Pituitary sensitivity to TRH was unaltered in old rats. These findings suggest that thyroidal release of T₄ and T₃ is depressed, and that the hypothalamic-pituitary axis is insensitive to diminished thyroid hormone feedback in old rats.

Original language	English (US)
Pages (from-to)	169-177
Number of pages	9
Journal	Endocrine Research
Volume	9
Issue number	3-4
DOIs	https://doi.org/10.3109/07435808209045762
State	Published - 1982
Externally published	Yes

ASJC Scopus subject areas

Endocrinology

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title = "Serum thyroxine, triiodothyronine, and TSH levels and TSH release after TRH in aging Male and female rats",

abstract = "Serum levels of TSH, T3 and T4, pituitary responsiveness to TRH, and T3-resin uptake were examined in aging male and female rats. Despite normal serum TSH levels, serum T3 and T4, levels were significantly reduced in old male rats (19-26 months of age) when compared to young (120-150 days of age) and middle-aged males (12-18 months of age). In old female rats, serum TSH and T3 levels were not significantly (p >0.05) different from those of young or middle-aged females. Serum T4 levels were significantly lower in old females when compared to younger rats. The To-resin uptake of old rats was not significantly different from the value of young rats. Serum T4 levels, 3 hours after TRH induced TSH release, were significantly depressed in old male and female rats. Pituitary sensitivity to TRH was unaltered in old rats. These findings suggest that thyroidal release of T4 and T3 is depressed, and that the hypothalamic-pituitary axis is insensitive to diminished thyroid hormone feedback in old rats.",

author = "Greeley, {G. H.} and Lipton, {M. A.} and Kizer, {J. S.}",

note = "Funding Information: This work was supported in part by a NICHD Grant (HD 03110)",

year = "1982",

doi = "10.3109/07435808209045762",

language = "English (US)",

volume = "9",

pages = "169--177",

journal = "Endocrine Research",

issn = "0743-5800",

publisher = "Informa Healthcare",

number = "3-4",

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AU - Greeley, G. H.

AU - Lipton, M. A.

AU - Kizer, J. S.

N1 - Funding Information: This work was supported in part by a NICHD Grant (HD 03110)

PY - 1982

Y1 - 1982

N2 - Serum levels of TSH, T3 and T4, pituitary responsiveness to TRH, and T3-resin uptake were examined in aging male and female rats. Despite normal serum TSH levels, serum T3 and T4, levels were significantly reduced in old male rats (19-26 months of age) when compared to young (120-150 days of age) and middle-aged males (12-18 months of age). In old female rats, serum TSH and T3 levels were not significantly (p >0.05) different from those of young or middle-aged females. Serum T4 levels were significantly lower in old females when compared to younger rats. The To-resin uptake of old rats was not significantly different from the value of young rats. Serum T4 levels, 3 hours after TRH induced TSH release, were significantly depressed in old male and female rats. Pituitary sensitivity to TRH was unaltered in old rats. These findings suggest that thyroidal release of T4 and T3 is depressed, and that the hypothalamic-pituitary axis is insensitive to diminished thyroid hormone feedback in old rats.

AB - Serum levels of TSH, T3 and T4, pituitary responsiveness to TRH, and T3-resin uptake were examined in aging male and female rats. Despite normal serum TSH levels, serum T3 and T4, levels were significantly reduced in old male rats (19-26 months of age) when compared to young (120-150 days of age) and middle-aged males (12-18 months of age). In old female rats, serum TSH and T3 levels were not significantly (p >0.05) different from those of young or middle-aged females. Serum T4 levels were significantly lower in old females when compared to younger rats. The To-resin uptake of old rats was not significantly different from the value of young rats. Serum T4 levels, 3 hours after TRH induced TSH release, were significantly depressed in old male and female rats. Pituitary sensitivity to TRH was unaltered in old rats. These findings suggest that thyroidal release of T4 and T3 is depressed, and that the hypothalamic-pituitary axis is insensitive to diminished thyroid hormone feedback in old rats.

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Serum thyroxine, triiodothyronine, and TSH levels and TSH release after TRH in aging Male and female rats

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