Lighting conditions affect serum and pituitary TSH in male rats

It has been reported that periodicity of lighting plays a role in the regulation of the function of the hypothalamus-anterior pituitary-thyroid axis in the rat. We studied whether other properties of lighting influence the levels of pituitary and serum thyrotropin (TSH) in adult male rats. The animals were reared 7 days under various lighting conditions, then trunk blood and adenohypophyses were collected at different times of the day, and TSH was measured radioimmunologically. In natural lighting conditions the diurnal variation of plasma and pituitary TSH levels was abolished, and the overall levels of plasma TSH were higher and those of pituitary TSH lower than in ordinary laboratory lighting conditions. The intensity of lighting affected the serum TSH levels; daytime serum TSH decreased in the rats under low daytime illuminances and in those under nighttime twilight instead of darkness. Changing the rate of the lighting transition at dawn and dusk had no influence on the TSH patterns. We conclude that, in addition to periodicity, other features of lighting affect the daily secretion patterns of TSH.

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Serum concentrations of thyrotropin, thyroxine, triiodothyronine and thyroxine binding globulin in female endurance runners and joggers

Acta Endocrinologica ◽

10.1530/acta.0.1140041 ◽

1987 ◽

Vol 114 (1) ◽

pp. 41-46 ◽

Cited By ~ 10

Author(s):

H. Hohtari ◽

A. Pakarinen ◽

A. Kauppila

Keyword(s):

Endurance Training ◽

Anterior Pituitary ◽

Luteal Phase ◽

Serum Concentrations ◽

Endurance Running ◽

Thyroxine Binding Globulin ◽

Trh Stimulation ◽

Pituitary Thyroid Axis ◽

Thyroid Axis ◽

Serum Tsh

Abstract. The effects of endurance training and season on the function of the anterior pituitary-thyroid axis were studied in 18 female runners and their 12 controls, and in 13 joggers and their 11 controls in Northern Finland, with a large seasonal difference in environmental factors. The serum concentrations of thyrotropin (TSH), thyroxine (T4), free thyroxine (fT4), triiodothyronine (T3), thyroxine binding globulin (TBG) and oestradiol (E2) were measured during one menstrual cycle in the light training season (autumn) and in the hard training season (spring). The responses of TSH to intravenous TRH stimulation were also measured in the luteal phase of the cycle during the hard training season. Endurance running did not affect the basal or TRH-stimulated serum TSH concentrations, while those of T4 and fT4 in runners were lowered in both seasons and that of T3 in the light training season in relation to control subjects. The serum concentrations of TBG were also significantly lower in runners than their controls in the luteal phase in both seasons. The effect of jogging on thyroid hormones was less pronounced. Serum concentrations of TSH, T4, fT4, T3 and TBG were generally slightly higher in spring than in autumn. Strenuous endurance training seems to have minor changes on the function of the thyroid gland. Depressed T4 levels in runners may rather be due to lowered TBG levels than due to direct effect of training. In spring the function of anterior pituitary-thyroid axis is more active than in autumn.

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Low-Dose Effects of Ammonium Perchlorate on the Hypothalamic-Pituitary-Thyroid Axis of Adult Male Rats Pretreated with PCB126

Toxicological Sciences ◽

10.1093/toxsci/kfm063 ◽

2007 ◽

Vol 97 (2) ◽

pp. 308-317 ◽

Cited By ~ 22

Author(s):

Eva D. McLanahan ◽

Jerry L. Campbell ◽

Duncan C. Ferguson ◽

Barry Harmon ◽

Joan M. Hedge ◽

...

Keyword(s):

Ammonium Perchlorate ◽

Adult Male ◽

Low Dose ◽

Male Rats ◽

Dose Effects ◽

Pituitary Thyroid Axis ◽

Thyroid Axis ◽

Low Dose Effects

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Effects of neonatal exposure to TRH on development of the pituitary-thyroid axis in rats

Acta Endocrinologica ◽

10.1530/acta.0.1040201 ◽

1983 ◽

Vol 104 (2) ◽

pp. 201-205 ◽

Cited By ~ 1

Author(s):

Yoshiaki Kawai ◽

Mizuo Azukizawa ◽

Nobuyuki Ashida ◽

Yuichi Kumahara ◽

Kiyoshi Miyai

Keyword(s):

Body Weight ◽

Hormone Level ◽

Neonatal Period ◽

Neonatal Exposure ◽

Neonatal Rats ◽

Neonatal Life ◽

Pituitary Thyroid Axis ◽

Thyroid Axis ◽

Serum Tsh ◽

Tsh Levels

Abstract. TRH (10 and 1000 μg/kg body weight) was administered ip daily to neonatal rats from day 0 to 9 after birth (Neo-TRH rats) and their pituitary-thyroid axis was examined on days 4, 10, 21 and 90. The pituitary TSH content in Neo-TRH rats was significantly smaller than in controls on days 4 and 10. The serum TSH levels in Neo-TRH rats were significantly lower than those in controls on days 4 (male group only), 10 and 21 (only 10 μg/kg group). The serum T4 levels in Neo-TRH rats were lower than in controls on day 10. The reduced pituitary TSH content and serum TSH and T4 were restored to control levels on day 90. However, the response of serum TSH to exogenous TRH (10 μg/kg/ip) was blunted in Neo-TRH rats on days 10, 21 and 90. It is concluded that repetitive administration of TRH during the neonatal period suppresses the pituitary-thyroid axis in neonatal life, even after the basal hormone level has been restored to normal.

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The influence of equol on the hypothalamic–pituitary–thyroid axis and hepatic lipid metabolic parameters in adult male rats

Life Sciences ◽

10.1016/j.lfs.2015.02.002 ◽

2015 ◽

Vol 128 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Panida Loutchanwoot ◽

Prayook Srivilai ◽

Hubertus Jarry

Keyword(s):

Adult Male ◽

Metabolic Parameters ◽

Male Rats ◽

Hepatic Lipid ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

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Postnatal Low Protein Diet Programs Leptin Signaling in the Hypothalamic-Pituitary-Thyroid Axis and Pituitary TSH Response to Leptin in Adult Male Rats

Hormone and Metabolic Research ◽

10.1055/s-0031-1299747 ◽

2012 ◽

Vol 44 (02) ◽

pp. 114-122 ◽

Cited By ~ 9

Author(s):

P. Lisboa ◽

E. Oliveira ◽

A.T. Fagundes ◽

A. Santos-Silva ◽

E.P. Conceição ◽

...

Keyword(s):

Adult Male ◽

Protein Diet ◽

Male Rats ◽

Low Protein Diet ◽

Leptin Signaling ◽

Low Protein ◽

Pituitary Thyroid Axis ◽

Thyroid Axis

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Distinct Roles of Deiodinases on the Phenotype of Mct8 Defect: A Comparison of Eight Different Mouse Genotypes

Endocrinology ◽

10.1210/en.2010-0900 ◽

2011 ◽

Vol 152 (3) ◽

pp. 1180-1191 ◽

Cited By ~ 51

Author(s):

Xiao-Hui Liao ◽

Caterina Di Cosmo ◽

Alexandra M. Dumitrescu ◽

Arturo Hernandez ◽

Jacqueline Van Sande ◽

...

Keyword(s):

Growth Response ◽

Pituitary Thyroid Axis ◽

Severe Impairment ◽

Serum T3 ◽

Serum T4 ◽

Thyroid Axis ◽

Mct8 Deficiency ◽

The Brain ◽

Insight Into ◽

Serum Tsh

Mice deficient in the thyroid hormone (TH) transporter Mct8 (Mct8KO) have increased 5′-deiodination and impaired TH secretion and excretion. These and other unknown mechanisms result in the low-serum T4, high T3, and low rT3 levels characteristic of Mct8 defects. We investigated to what extent each of the 5′-deiodinases (D1, D2) contributes to the serum TH abnormalities of the Mct8KO by generating mice with all combinations of Mct8 and D1 and/or D2 deficiencies and comparing the resulting eight genotypes. Adding D1 deficiency to that of Mct8 corrected the serum TH abnormalities of Mct8KO mice, normalized brain T3 content, and reduced the impaired expression of TH-responsive genes. In contrast, Mct8D2KO mice maintained the serum TH abnormalities of Mct8KO mice. However, the serum TSH level increased 27-fold, suggesting a severely impaired hypothalamo-pituitary-thyroid axis. The brain of Mct8D2KO manifested a pattern of more severe impairment of TH action than Mct8KO alone. In triple Mct8D1D2KO mice, the markedly increased serum TH levels produced milder brain defect than that of Mct8D2KO at the expense of more severe liver thyrotoxicosis. Additionally, we observed that mice deficient in D2 had an unexplained marked reduction in the thyroid growth response to TSH. Our studies on these eight genotypes provide a unique insight into the complex interplay of the deiodinases in the Mct8 defect and suggest that D1 contributes to the increased serum T3 in Mct8 deficiency, whereas D2 mainly functions locally, converting T4 to T3 to compensate for distinct cellular TH depletion in Mct8KO mice.

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Influence of meal composition on the postprandial response of the pituitary–thyroid axis

Acta Endocrinologica ◽

10.1530/eje.0.1330075 ◽

1995 ◽

Vol 133 (1) ◽

pp. 75-79 ◽

Cited By ~ 7

Author(s):

Vinay Kamat ◽

Wendy L Hecht ◽

Robert T Rubin

Keyword(s):

Significant Decline ◽

Randomized Design ◽

Postprandial Response ◽

Pituitary Thyroid Axis ◽

Tsh Secretion ◽

Thyroid Axis ◽

Normal Men ◽

Allegheny General Hospital ◽

Serum Tsh ◽

Meal Composition

Kamat V, Hecht WL, Rubin RT. Influence of meal composition on the postprandial response of the pituitary–thyroid axis. Eur J Endocrinol 1995;133:75–9. ISSN 0804–4643 Ingestion of food can result in an acute decline of serum thyrotropin (TSH) concentrations, but it is not known whether meal composition and/or stomach distension are influential. Normal men and women were given a normocaloric or hypocaloric, isobulk meal at lunch and at dinner in a randomized design. The normocaloric, but not the isobulk, meal resulted in a significant decline in serum TSH at both lunch and dinner; thyroid hormones and cortisol were not affected significantly. These findings suggest that meal composition is influential in the acute postprandial decline of serum TSH in man. A possible mechanism is food-induced elevation of somatostatin and consequent suppression of TSH secretion. Robert T Rubin, Neurosciences Research Center, Allegheny General Hospital, 320 E North Ave. Pittsburgh, PA 15212-4772, USA

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Prolactin release, oestrogens and proliferation of prolactin-secreting cells in the anterior pituitary gland of adult male rats

Journal of Endocrinology ◽

10.1677/joe.0.1080399 ◽

1986 ◽

Vol 108 (3) ◽

pp. 399-403 ◽

Cited By ~ 29

Author(s):

R. L. Pérez ◽

G. A. Machiavelli ◽

M. I. Romano ◽

J. A. Burdman

Keyword(s):

Cell Proliferation ◽

Pituitary Gland ◽

Adult Male ◽

Anterior Pituitary ◽

Pituitary Hormones ◽

Anterior Pituitary Gland ◽

Male Rats ◽

Serum Prolactin ◽

Prolactin Release ◽

Experimental Conditions

ABSTRACT Relationships among the release of prolactin, the effect of oestrogens and the proliferation of prolactin-secreting cells were studied under several experimental conditions. Administration of sulpiride or oestradiol released prolactin and stimulated cell proliferation in the anterior pituitary gland of adult male rats. Clomiphene completely abolished the rise in cell proliferation, but did not interfere with the sulpiride-induced release of prolactin. Treatment with oestradiol plus sulpiride significantly increased serum prolactin concentrations and the mitotic index compared with the sum of the stimulation produced by both drugs separately. Bromocriptine abolished the stimulatory effect of oestradiol on the serum prolactin concentration and on cell proliferation. In oestradiol- and/or sulpiride-treated rats, 80% of the cells in mitoses were lactotrophs. The remaining 20% did not stain with antisera against any of the pituitary hormones. The number of prolactin-secreting cells in the anterior pituitary gland significantly increased after the administration of oestradiol or sulpiride. The results demonstrate that treatment with sulpiride and/or oestradiol increases the proliferation and the number of lactotrophs in the anterior pituitary gland of the rat. J. Endocr. (1986) 108, 399–403

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