Vitamin A Repletion in rats with concurrent vitamin A and iodine deficiency affects pituitary THS {beta} gene expression and reduces thyroid hyperstimulation and thyroid size

R. Biebinger, M. Arnold, W. Langhans, R.F. Hurrell, M.B. Zimmermann

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Abstract

Concurrent vitamin A (VA) deficiency (VAD) and iodine deficiency (ID) are common in developing countries. VAD has effects on thyroid metabolism that may be dependent on iodine status. The aim of this study was to investigate the effect of VA supplementation (VAS) and/or dietary iodine repletion, alone and in combination, on the thyroid-pituitary axis in rats with concurrent VAD and ID. Weanling rats (n = 96) were fed diets deficient in VA and iodine or sufficient in both (control), for 30 d. Subsequently, deficient rats were repleted with iodine and/or single VAS or remained deficient for 10 d. Serum retinol (SR), thyroid hormones, serum thyrotropin (TSH), pituitary TSHß mRNA expression level, and thyroid weight were measured. High-dose VAS restored SR concentrations to normal in both iodine-deficient and iodine-sufficient rats. Despite continuing VAD, provision of the iodine-sufficient diet entirely reversed the abnormalities of the pituitary-thyroid axis produced by VAD and ID. In iodine-sufficient rats, VAS had no discernible effects on the pituitary-thyroid axis; in iodine-deficient rats, VAS reduced pituitary production of TSH and thyroid stimulation but had no discernible effects on circulating thyroid hormone concentrations. Primary hypothyroidism in rats with concurrent VAD and ID does not reduce the efficacy of VAS, nor does VAD reduce the efficacy of dietary iodine to correct pituitary-thyroid axis dysfunction due to ID. In concurrent VAD and ID, VAS, independent of iodine repletion, reduces thyroid hyperstimulation and size, an effect likely mediated through the effects of VA on pituitary TSHß gene expression.
Original languageEnglish
Pages (from-to)573-577
JournalThe Journal of Nutrition
Volume137
Issue number3
DOIs
Publication statusPublished - 2007

Fingerprint

Vitamin A Deficiency
Vitamin A
Iodine
Thyroid Gland
Gene Expression
Thyroid Hormones
Serum
Diet

Keywords

  • liquid-chromatography
  • stimulating hormone
  • 9-cis-retinoic acid
  • goitrous children
  • alpha-tocopherol
  • retinol
  • plasma
  • supplementation
  • metabolism
  • thyroxine

Cite this

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title = "Vitamin A Repletion in rats with concurrent vitamin A and iodine deficiency affects pituitary THS {beta} gene expression and reduces thyroid hyperstimulation and thyroid size",
abstract = "Concurrent vitamin A (VA) deficiency (VAD) and iodine deficiency (ID) are common in developing countries. VAD has effects on thyroid metabolism that may be dependent on iodine status. The aim of this study was to investigate the effect of VA supplementation (VAS) and/or dietary iodine repletion, alone and in combination, on the thyroid-pituitary axis in rats with concurrent VAD and ID. Weanling rats (n = 96) were fed diets deficient in VA and iodine or sufficient in both (control), for 30 d. Subsequently, deficient rats were repleted with iodine and/or single VAS or remained deficient for 10 d. Serum retinol (SR), thyroid hormones, serum thyrotropin (TSH), pituitary TSH{\ss} mRNA expression level, and thyroid weight were measured. High-dose VAS restored SR concentrations to normal in both iodine-deficient and iodine-sufficient rats. Despite continuing VAD, provision of the iodine-sufficient diet entirely reversed the abnormalities of the pituitary-thyroid axis produced by VAD and ID. In iodine-sufficient rats, VAS had no discernible effects on the pituitary-thyroid axis; in iodine-deficient rats, VAS reduced pituitary production of TSH and thyroid stimulation but had no discernible effects on circulating thyroid hormone concentrations. Primary hypothyroidism in rats with concurrent VAD and ID does not reduce the efficacy of VAS, nor does VAD reduce the efficacy of dietary iodine to correct pituitary-thyroid axis dysfunction due to ID. In concurrent VAD and ID, VAS, independent of iodine repletion, reduces thyroid hyperstimulation and size, an effect likely mediated through the effects of VA on pituitary TSH{\ss} gene expression.",
keywords = "liquid-chromatography, stimulating hormone, 9-cis-retinoic acid, goitrous children, alpha-tocopherol, retinol, plasma, supplementation, metabolism, thyroxine",
author = "R. Biebinger and M. Arnold and W. Langhans and R.F. Hurrell and M.B. Zimmermann",
year = "2007",
doi = "10.1093/jn/137.3.573",
language = "English",
volume = "137",
pages = "573--577",
journal = "The Journal of Nutrition",
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Vitamin A Repletion in rats with concurrent vitamin A and iodine deficiency affects pituitary THS {beta} gene expression and reduces thyroid hyperstimulation and thyroid size. / Biebinger, R.; Arnold, M.; Langhans, W.; Hurrell, R.F.; Zimmermann, M.B.

In: The Journal of Nutrition, Vol. 137, No. 3, 2007, p. 573-577.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Vitamin A Repletion in rats with concurrent vitamin A and iodine deficiency affects pituitary THS {beta} gene expression and reduces thyroid hyperstimulation and thyroid size

AU - Biebinger, R.

AU - Arnold, M.

AU - Langhans, W.

AU - Hurrell, R.F.

AU - Zimmermann, M.B.

PY - 2007

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N2 - Concurrent vitamin A (VA) deficiency (VAD) and iodine deficiency (ID) are common in developing countries. VAD has effects on thyroid metabolism that may be dependent on iodine status. The aim of this study was to investigate the effect of VA supplementation (VAS) and/or dietary iodine repletion, alone and in combination, on the thyroid-pituitary axis in rats with concurrent VAD and ID. Weanling rats (n = 96) were fed diets deficient in VA and iodine or sufficient in both (control), for 30 d. Subsequently, deficient rats were repleted with iodine and/or single VAS or remained deficient for 10 d. Serum retinol (SR), thyroid hormones, serum thyrotropin (TSH), pituitary TSHß mRNA expression level, and thyroid weight were measured. High-dose VAS restored SR concentrations to normal in both iodine-deficient and iodine-sufficient rats. Despite continuing VAD, provision of the iodine-sufficient diet entirely reversed the abnormalities of the pituitary-thyroid axis produced by VAD and ID. In iodine-sufficient rats, VAS had no discernible effects on the pituitary-thyroid axis; in iodine-deficient rats, VAS reduced pituitary production of TSH and thyroid stimulation but had no discernible effects on circulating thyroid hormone concentrations. Primary hypothyroidism in rats with concurrent VAD and ID does not reduce the efficacy of VAS, nor does VAD reduce the efficacy of dietary iodine to correct pituitary-thyroid axis dysfunction due to ID. In concurrent VAD and ID, VAS, independent of iodine repletion, reduces thyroid hyperstimulation and size, an effect likely mediated through the effects of VA on pituitary TSHß gene expression.

AB - Concurrent vitamin A (VA) deficiency (VAD) and iodine deficiency (ID) are common in developing countries. VAD has effects on thyroid metabolism that may be dependent on iodine status. The aim of this study was to investigate the effect of VA supplementation (VAS) and/or dietary iodine repletion, alone and in combination, on the thyroid-pituitary axis in rats with concurrent VAD and ID. Weanling rats (n = 96) were fed diets deficient in VA and iodine or sufficient in both (control), for 30 d. Subsequently, deficient rats were repleted with iodine and/or single VAS or remained deficient for 10 d. Serum retinol (SR), thyroid hormones, serum thyrotropin (TSH), pituitary TSHß mRNA expression level, and thyroid weight were measured. High-dose VAS restored SR concentrations to normal in both iodine-deficient and iodine-sufficient rats. Despite continuing VAD, provision of the iodine-sufficient diet entirely reversed the abnormalities of the pituitary-thyroid axis produced by VAD and ID. In iodine-sufficient rats, VAS had no discernible effects on the pituitary-thyroid axis; in iodine-deficient rats, VAS reduced pituitary production of TSH and thyroid stimulation but had no discernible effects on circulating thyroid hormone concentrations. Primary hypothyroidism in rats with concurrent VAD and ID does not reduce the efficacy of VAS, nor does VAD reduce the efficacy of dietary iodine to correct pituitary-thyroid axis dysfunction due to ID. In concurrent VAD and ID, VAS, independent of iodine repletion, reduces thyroid hyperstimulation and size, an effect likely mediated through the effects of VA on pituitary TSHß gene expression.

KW - liquid-chromatography

KW - stimulating hormone

KW - 9-cis-retinoic acid

KW - goitrous children

KW - alpha-tocopherol

KW - retinol

KW - plasma

KW - supplementation

KW - metabolism

KW - thyroxine

U2 - 10.1093/jn/137.3.573

DO - 10.1093/jn/137.3.573

M3 - Article

VL - 137

SP - 573

EP - 577

JO - The Journal of Nutrition

JF - The Journal of Nutrition

SN - 0022-3166

IS - 3

ER -