Changes in thyroid hormone levels in chicken liver during fasting and refeeding

Reyns, Geert; Janssens, Kristel; Buyse, Johan; Kühn, Eduard; Darras, Veerle

doi:10.1016/s1096-4959(01)00528-0

Cited by 74 publications

(47 citation statements)

References 20 publications

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“…Tissues were extracted as described in detail elsewhere (Reyns et al 2002). In short, 200 mg tissue were homogenized in methanol, and 1500-2000 c.p.m.…”

Section: Determination Of T 4 and T 3 Levels In Plasma And Tissuesmentioning

confidence: 99%

Iodothyronine deiodinases and the control of plasma and tissue thyroid hormone levels in hyperthyroid tilapia (Oreochromis niloticus)

Geyten¹,

Byamungu²,

Reyns³

et al. 2005

Journal of Endocrinology

107

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Thyroid status is one of the most potent regulators of peripheral thyroid hormone metabolism in vertebrates. Despite this, the few papers that have been published concerning the role of thyroid hormones in the regulation of thyroid function in fish often offer conflicting data. We therefore set out to investigate the effects of tetraiodothyronine (thyroxine) (T 4 ) or tri-iodothyronine (T 3 ) supplementation (48 p.p.m.) via the food on plasma and tissue thyroid hormone levels as well as iodothyronine deiodinase (D) activities in the Nile tilapia (Oreochromis niloticus). T 4 supplementation did not induce a hyperthyroid state and subsequently had no effects on the thyroid hormone parameters measured, with the liver as the sole notable exception. In T 4 -fed tilapias, the hepatic T 4 levels increased substantially, and this was accompanied by an increase in in vitro type I deiodinase (D1) activity. Although the lack of effect of T 4 supplementation could be partially explained by an inefficient uptake of T 4 from the gut, our current data suggest that also the increased conversion of T 4 into reverse (r)T 3 by the D1 present in the liver plays an important role in this respect. In addition, T 3 supplementation increased plasma T 3 and decreased plasma T 4 concentrations. T 3 levels were also increased in the liver, brain, kidney, gill and white muscle, but without affecting local T 4 concentrations. However, this increase in T 3 availability remained without effect on D1 activity in liver and kidney. This observation, together with the 6-n-propylthiouracyl (PTU) insensitivity of the D1 enzyme in fish, sets the D1 in teleost fish clearly apart from its mammalian and avian counterparts. The changes in hepatic deiodinases confirm the role of the liver as an important T 3 -regulating tissue. However, the very short plasma half-life of exogenously administered T 3 implies the existence of an efficient T 3 clearing/degradation mechanism other than deiodination.

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“…Tissues were extracted as described in detail elsewhere (Reyns et al 2002). In short, 200 mg tissue were homogenized in methanol, and 1500-2000 c.p.m.…”

Section: Determination Of T 4 and T 3 Levels In Plasma And Tissuesmentioning

confidence: 99%

Iodothyronine deiodinases and the control of plasma and tissue thyroid hormone levels in hyperthyroid tilapia (Oreochromis niloticus)

Geyten¹,

Byamungu²,

Reyns³

et al. 2005

Journal of Endocrinology

107

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“…Reduced food intake or starvation is generally associated with reduced thyroid hormones concentrations in different groups of vertebrates (Oppenheimer et al, 1987;Eales, 1988;Cokelaere et al, 1996;Van der Geyten et al, 1999;Reyns et al, 2002). Since thyroid hormones are associated with an increase in metabolic rate, these hormones are usually reduced during periods of food deprivation as a means to conserve energy (Oppenheimer et al, 1987).…”

Section: Discussionmentioning

confidence: 99%

“…Fasting and refeeding have been reported to have marked effects on the thyroid activity, circulating levels of the thyroid hormones and their metabolism in different groups of vertebrates (Eales, 1988;Wu, 1990;Cokelaere et al, 1996;Van der Geyten et al, 1999;Wright, Proctor and Alves, 1999;Kohel et al, 2001;Ortiz et al, 2001;Reyns et al, 2002;Coppola et al, 2005). In fishes, food deprivation suppresses the plasma T 4 and T 3 levels, reduces thyroid tissue sensitivity to thyroid stimulating hormone (TSH), causes a reduction in 5'-monodeiodinase and eliminates the plasma thyroid hormone daily patterns (Eales et al, 1981;Flood and Eales, 1983;Shields and Eales, 1986;Cerda-Reverter et al, 1996;Power et al, 2000;Gaylord et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Effects of Partial and Full Feed Restriction on the Plasma Levels of Thyroid Hormones and Testicular Activity in the Male Air-breathing Catfish, Clarias gariepinus during Different Phases of the Breeding Cycle

Suchiang¹,

Gupta²

2011

IJB

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The effects of partial and full feed restriction on the plasma levels of thyroxine (T 4 ), triiodothyronine (T 3 ) and testicular activity were studied in the male air-breathing catfish, Clarias gariepinus. Partial and full feed restriction for 3 weeks significantly decreased the plasma T 4 levels during the progressive and breeding phases, and decreased the plasma T 3 levels only during the breeding phase. However, full feed restriction for 3 weeks increased plasma T 3 levels and T 3 /T 4 ratio during the quiescent, progressive and regressive phases. Histologically, 3 weeks of partial and full feed restriction markedly reduced the testicular activity during the progressive and breeding phases. These results indicate that partial and full feed restriction adversely affects the thyroid hormonogenesis and testicular activity in a phase-dependent manner in C. gariepinus.

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“…Blocking deiodination activity by iopanic acid decreases the T 3 /T 4 ratio to less than 30% (Decuypere et al, 1982). Buyse et al (2002) and Reyns et al (2002) stated that the net result of fasting is a reduction of T 4 -to-T 3 conversion and a decrease in the calorigenic effect of thyroid hormones presumably due to altered T 4 to T 3 ratios. Decuypere and Kühn (1984) could halt circadian rhythmic changes of thyroid hormone blood concentrations with two days of fasting and could restore them by re-feeding.…”

Section: Discussionmentioning

confidence: 99%

“…It was shown that D1 enzyme does not react to energy restriction, while D3 activity increases significantly. It was concluded that due to energy restriction the available T 3 concentration decreases because of the increased enzymatic inactivation (Van der Geyten et al, 1999;Buyse et al, 2000;Reyns et al, 2002).…”

mentioning

confidence: 99%

Effects of energy restriction on thyroid hormone metabolism in chickens

Győrffy

Sayed-Ahmed

Zsarnovszky

et al. 2009

Acta Veterinaria Hungarica

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Energy restriction induces changes in thyroid hormone economy in the form of a complex adaptation mechanism, in order to conserve energy storage and protein reserves. In the present work, thyroid hormone serum concentrations, hepatic deiodinase enzyme activities and hepatic deiodinase mRNA expression were examined after feed restriction and fasting. We demonstrate that during energy restriction, T 3 concentration is lowered due to a decreased T 4 activation and increased T 3 inactivation. We show that hepatic type-I deiodinase (D1) is not affected by energy restriction, however, hepatic D2 is decreased on both transcriptional and enzyme activity levels. Furthermore, hepatic D3 is increased after feed restriction in the liver. We also show that the hypothalamic feedback is not involved in the changes in serum T 3 and T 4 concentrations. Our data indicate that D2 enzyme contributes to the special hormone-exporting role of the chicken liver and this enzyme can be modulated by feed restriction.

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Changes in thyroid hormone levels in chicken liver during fasting and refeeding

Cited by 74 publications

References 20 publications

Iodothyronine deiodinases and the control of plasma and tissue thyroid hormone levels in hyperthyroid tilapia (Oreochromis niloticus)

Iodothyronine deiodinases and the control of plasma and tissue thyroid hormone levels in hyperthyroid tilapia (Oreochromis niloticus)

Effects of Partial and Full Feed Restriction on the Plasma Levels of Thyroid Hormones and Testicular Activity in the Male Air-breathing Catfish, Clarias gariepinus during Different Phases of the Breeding Cycle

Effects of energy restriction on thyroid hormone metabolism in chickens

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