Hypothalamic control of the thyroidal axis in the chicken: Over the boundaries of the classical hormonal axes

Groef, Bert De; Vandenborne, Kristien; As, Pieter Van; Darras, Veerle; Kühn, Eduard; Decuypere, Eddy; Geris, Kris

doi:10.1016/j.domaniend.2005.02.008

Cited by 31 publications

(18 citation statements)

References 26 publications

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“…These results are consistent with the statement that TRH increases the plasma concentration of T4 only in chicken embryos and growing chicks, but in adults TRH does not induce the release of thyrotroph hormone, challenging the subsequent increase in T4 and T3 levels (Kühn et al, 1988). In adults, TRH exerts a stimulatory effect on the somatotropic axis, resulting in elevated growth hormone (GH) level which provokes increased hepatic T4 to T3 conversion (De Groef et al, 2005).…”

Section: Discussionsupporting

confidence: 89%

Effects of environmental temperature on thyroid hormones in the barn owl (Tyto alba)

Klein

Kulcsár

Krízsik

et al. 2006

Acta Veterinaria Hungarica

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The basic patterns of thyroid hormones [thyroxine (T4) and 3,3',5-triiodothyronine (T3)] and the T4 and T3 responses induced by thyrotropin releasing hormone (TRH) are reported in captive female barn owls (Tyto alba) during the non-breeding period. The main findings of the study, conducted on a total of 10 owls, are as follow: (1) The thyroid gland of barn owl can be stimulated by the classical TRH stimulation test. (2) T3 response was much more pronounced both under cold (around 10 °C) and warm (around 20 °C) conditions, whereas T4 response ranged so widely that we could not point out any significant change in it. (3) Basal T3 plasma level was significantly (p = 0.036) higher in birds exposed to cold temperature, and they responded to TRH treatment with a lower plasma T3 elevation than the birds kept in a warm chamber. This pattern, however, cannot be explained by increased food intake, but is in agreement with the fact that enhanced T3 level may account for higher avUCP mRNA expression, which results in higher heat production on the cell level. From the results it is concluded that altering T3 plasma level plays a significant role in cold-induced thermoregulation.

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Section: Discussionsupporting

confidence: 89%

Effects of environmental temperature on thyroid hormones in the barn owl (Tyto alba)

Klein

Kulcsár

Krízsik

et al. 2006

Acta Veterinaria Hungarica

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“…Our finding is consistent with the previous reports in chickens (9,14). Interestingly, it is reported that TRH can stimulate cTSH secretion and consequently elevate the plasma T 4 levels in chicken embryos, or in growing chickens, but this action seems to be diminished in adult chickens (14,15).…”

Section: 2 or 4 H) Failed To Stimulate Their Secretion From Cultusupporting

confidence: 95%

“…Despite the full conservation of TRH structure across vertebrates, TRH action on the pituitary in nonmammalian vertebrates seems to be nonidentical to that in mammals (9,10). In chicken embryos or growing chicks, injection of TRH stimulates TSH secretion and elevates plasma T 4 levels (9,(11)(12)(13). However, this thyrotropic activity seems to be diminished in adult chickens (14,15).…”

mentioning

confidence: 86%

“…In nonmammalian vertebrates, a hypothalamic releasing factor specific for TSH secretion, however, remains elusive. Despite the full conservation of TRH structure across vertebrates, TRH action on the pituitary in nonmammalian vertebrates seems to be nonidentical to that in mammals (9,10). In chicken embryos or growing chicks, injection of TRH stimulates TSH secretion and elevates plasma T 4 levels (9,(11)(12)(13).…”

mentioning

confidence: 96%

“…In amphibians, TRH stimulates pituitary TSH release moderately in adult frogs but not in tadpoles, and it also induces PRL and GH secretion effectively (10,(21)(22)(23). Interestingly, CRH, a well-known ACTH-releasing factor in mammals (24,25), has been demonstrated to act as a TSH-releasing factor (TRF) in chickens, amphibians, and teleosts (16, 21, 26 -30), in addition to its classic action on pituitary ACTH secretion (9,16,29,(31)(32)(33)(34)(35). In view of the fact that TRH and CRH can stimulate the secretion of multiple pituitary hormones in chickens and other lower vertebrates, it raises an intriguing, but fundamental, question, whether a hypothalamic releasing factor specific for TSH secretion exists and functions in nonmammalian vertebrates, such as in chickens.…”

mentioning

confidence: 96%

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Glucagon-Like Peptide (GCGL) Is a Novel Potential TSH-Releasing Factor (TRF) in Chickens: I) Evidence for Its Potent and Specific Action on Stimulating TSH mRNA Expression and Secretion in the Pituitary

Huang

Meng

et al. 2014

Endocrinology

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Our recent study proposed that the novel glucagon-like peptide (GCGL), encoded by a glucagon-like gene identified in chickens and other lower vertebrates, is likely a hypophysiotropic factor in nonmammalian vertebrates. To test this hypothesis, in this study, we investigated the GCGL action on chicken pituitaries. The results showed that: 1) GCGL, but not TRH, potently and specifically stimulates TSH secretion in intact pituitaries incubated in vitro or in cultured pituitary cells monitored by Western blotting or a cell-based luciferase reporter assay; 2) GCGL (0.1nM-10nM) dose dependently induces the mRNA expression of TSHβ but not 5 other hormone genes in cultured pituitary cells examined by quantitative real-time RT-PCR, an action likely mediated by intracellular adenylate cyclase/cAMP/protein kinase A and phospholipase C/inositol 1,4,5-trisphosphate/Ca(2+) signaling pathways coupled to GCGL receptor (GCGLR); 3) GCGLR mRNA is mainly localized in pituitary cephalic lobe demonstrated by in situ hybridization, where TSH-cells reside, further supporting a direct action of GCGL on thyrotrophs. The potent and specific action of GCGL on pituitary TSH expression and secretion, together with the partial accordance shown among the temporal expression profiles of GCGL in the hypothalamus and GCGLR and TSHβ in the pituitary, provides the first collective evidence that hypothalamic GCGL is most likely to be a novel TSH-releasing factor functioning in chickens. The discovery of this novel potential TSH-releasing factor (GCGL) in a nonmammalian vertebrate species, ie, chickens, would facilitate our comprehensive understanding of the hypothalamic control of pituitary-thyroid axis across vertebrates.

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Immunohistochemical and Morphometric Study of Pituitary Pars Distalis Thyrotrophs of Male Viscacha (Lagostomus maximus maximus): Seasonal Variations and Effect of Melatonin and Castration

Filippa¹,

Mohamed²

2008

The Anatomical Record

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The physiology and behavior of viscacha vary along the year according to the modifications of environmental signals such as the photoperiod length, temperature, rainfall pattern, food composition, and social interactions. The pituitary pars distalis thyrotrophs (TSH cells) of male viscacha were immunohistochemically identified, and the morphometric parameters: percentage of immunopositive area (% IA), cell percentage in pars distalis (% PDC), number of cells per reference area (no. cells/RA), and major cellular and nuclear diameters were analyzed. Three different groups of adult male viscachas were used: (1) captured in their natural habitat during the year, (2) melatonin-administered, and (3) castrated. The thyrotrophs were localized in the ventromedial sector, mainly in the pars distalis cephalic extreme. They were oval or pyramidal in shape, and their immunostaining intensity was heterogeneous. The % IA, % PDC, and no. cells/RA exhibited a significant decrease in June-July (winter, gonadal regression period) in relation to February-March (summer-early autumn, reproductive period), and they were recovered in August-September (later winter-early spring, gonadal recovery period). No morphometric variations of TSH cells were observed in melatonin-treated animals, whereas a decrease of the % IA, % PDC, and no. cells/RA was observed in castrated animals in relation to the intact animals. Our results show TSH cell morphometric variations during the year in agreement with the animal's different physiological conditions during the reproductive cycle, and probably in response to the environmental signals changes. Melatonin does not have a direct effect on the TSH cells. However, castration modifies some thyrotroph morphometric parameters, reinforcing the hypothesis that androgens affect the cells activity.

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Hypothalamic control of the thyroidal axis in the chicken: Over the boundaries of the classical hormonal axes

Cited by 31 publications

References 26 publications

Effects of environmental temperature on thyroid hormones in the barn owl (Tyto alba)

Effects of environmental temperature on thyroid hormones in the barn owl (Tyto alba)

Glucagon-Like Peptide (GCGL) Is a Novel Potential TSH-Releasing Factor (TRF) in Chickens: I) Evidence for Its Potent and Specific Action on Stimulating TSH mRNA Expression and Secretion in the Pituitary

Immunohistochemical and Morphometric Study of Pituitary Pars Distalis Thyrotrophs of Male Viscacha (Lagostomus maximus maximus): Seasonal Variations and Effect of Melatonin and Castration

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