Thyroid hormones and seasonal reproductive neuroendocrine interactions

Nakao, Nobuhiro; Ono, Hiroko; Yoshimura, Takashi

doi:10.1530/rep-08-0041

Cited by 101 publications

(72 citation statements)

References 59 publications

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“…The influence of breeding status on TH could also be the result of TH and reproductive endocrine systems being intimately intricated (Nakao et al, 2008). For example, decreases in T3 serum levels were reported in lactating Crioula Lanada Serrana ewes compared to non-lactating females (Colodel et al, 2010).…”

Section: Effects Of Breeding Status and Season On Thyroid Hormone Levelsmentioning

confidence: 99%

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

Bourgeon

Riemer

Tartu

et al. 2017

Environmental Research

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As apex predators, polar bears (Ursus maritimus) are among the most heavily polluted organisms in the Arctic. In addition to this anthropogenic stressor, climate warming has been shown to negatively affect their body condition, reproductive output and survival. Among potential underlying physiological mechanisms, thyroid hormones (THs), which control thermoregulation, metabolism and reproduction, can be affected by a variety of both natural and anthropogenic factors. While THs have been extensively used as proxies for pollution exposure in mammals, including polar bears, there is a lack of knowledge of their natural variations. In this context, we examined seasonal variations in body condition and circulating TH concentrations in free-ranging female polar bears. Females with variable reproductive status (i.e., solitary, with cubs of the year or with yearlings) were sampled from locations with contrasted sea ice conditions. Furthermore, we studied THs in relation to levels of organohalogenated contaminants. As predicted, solitary females were in better condition than females caring for offspring, especially in spring. In addition, TH levels were lower in autumn compared to spring, although this seasonal effect was mainly observed in solitary females.Finally, the negative relationships between organochlorine and perfluoroalkyl substances and some THs suggest a possible alteration of homeostasis of THs. Since the latter relationships were only observed during spring, we emphasize the importance of considering the ecological factors when using THs as proxies for pollution exposure. Yet, the combined effects of natural and anthropogenic stressors on THs might impair the ability of polar bears to adapt to ongoing climate changes.

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Section: Effects Of Breeding Status and Season On Thyroid Hormone Levelsmentioning

confidence: 99%

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

Bourgeon

Riemer

Tartu

et al. 2017

Environmental Research

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“…This reciprocal switching between induction of DIO2 and DIO3 seems to fine-tune the thyroid hormone concentration within the MBH. Photoperiodic changes in DIO2 and DIO3 expression and T 3 concentration within the MBH have been confirmed in various vertebrate species, including quail (3, 4), sparrows (5), rats (6), hamsters (5, 7-11), goats (12), and sheep (13), and are understood to play a critical role in the control of seasonal reproduction (2,14). Although the responses of DIO2 and DIO3 to photoperiodic changes appear conserved among various species, the signal transduction pathway regulating DIO2 and DIO3 appears to differ between birds and mammals.…”

mentioning

confidence: 96%

Involvement of thyrotropin in photoperiodic signal transduction in mice

Ono¹,

Hoshino²,

Yasuo

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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254

241

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Local thyroid hormone catabolism within the mediobasal hypothalamus (MBH) by thyroid hormone-activating (DIO2) and -inactivating (DIO3) enzymes regulates seasonal reproduction in birds and mammals. Recent functional genomics analysis in birds has shown that long days induce thyroid-stimulating hormone production in the pars tuberalis (PT) of the pituitary gland, which triggers DIO2 expression in the ependymal cells (EC) of the MBH. In mammals, nocturnal melatonin secretion provides an endocrine signal of the photoperiod to the PT that contains melatonin receptors in high density, but the interface between the melatonin signal perceived in the PT and the thyroid hormone levels in the MBH remains unclear. Here we provide evidence in mice that TSH participates in this photoperiodic signal transduction. Although most mouse strains are considered to be nonseasonal, a robust photoperiodic response comprising induced expression of TSHB (TSH ␤ subunit), CGA (TSH ␣ subunit), and DIO2, and reduced expression of DIO3, was observed in melatonin-proficient CBA/N mice. These responses could not be elicited in melatonin-deficient C57BL/6J, but treatment of C57BL/6J mice with exogenous melatonin elicited similar effects on the expression of the abovementioned genes as observed in CBA/N after transfer to short-day conditions. The EC was found to express TSH receptor (TSHR), and ICV injection of TSH induced DIO2 expression. Finally, we show that melatonin administration did not affect the expression of TSHB, DIO2, and DIO3 in TSHR-null mice. Taken together, our findings suggest that melatonin-dependent regulation of thyroid hormone levels in the MBH appears to involve TSH in mammals.circadian rhythm ͉ melatonin ͉ pars tuberalis ͉ photoperiodism ͉ type 2 and 3 iodothyronine deiodinases O rganisms living outside the tropics detect and predict seasonal changes in day length (photoperiod) to adapt various metabolic and behavioral functions to the environment. This mechanism, called photoperiodism, allows animals to control the timing of reproduction so that they can raise their offspring in spring and summer when food is most abundant. Among vertebrates, birds possess a highly sophisticated photoperiodic mechanism and show robust responses to photoperiodic changes. Taking advantage of the elaborate avian photoperiodic system, we have recently revealed the gene cascade regulating the photoperiodic response of reproduction in Japanese quail (Coturnix japonica) by using a functional genomics approach (1, 2). Exposure to long days induced thyroid-stimulating hormone (TSH), a heterodimer of the TSH ␤ subunit (TSHB), and the common glycoprotein ␣ subunit (CGA, also called TSH ␣ subunit), in the pars tuberalis (PT) of the pituitary gland. TSH triggers the expression of type 2 iodothyronine deiodinase (DIO2) in the ependymal cells (EC) lining the ventrolateral walls of the third ventricle (i.e., the infundibular recess) within the mediobasal hypothalamus (MBH). DIO2 is a thyroid hormoneactivating enzyme that converts the prohormone thyroxine...

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“…The main hormone involved in the regulation of the beginning of the rutting season is melatonin, while iodothyronines like thyroxine are considered in the mechanisms controlling entrance into the seasonal anestrus (Nakao et al 2008, Yoshimura 2010). The results obtained in this work confirm that thyroxine secretion shows circannual rhythms, characterized by higher concentrations in winter/spring than in the summer/autumn period (Webster et al 1991, Abecia et al 2005).…”

Section: Discussionmentioning

confidence: 99%

“…Various reports have implied the impact of hormones produced in the thyroid on seasonal regulation of sexual activity in red deer, but in this area, their role remains not fully explained (Nakao et al 2008, Ashkar et al 2010, Yoshimura 2010, Dittrich et al 2011, Khan et al 2011, Chu et al 2012, Ikegami and Yoshimura 2012, Mutinati et al 2013, Sechman 2013. Moreover, there are no reports indicating the circannual secretion profile of parathormone, produced in the parathyroid glands, in accordance to seasonality of breeding in red deer.…”

Section: Introductionmentioning

confidence: 99%

Circannual changes in serum concentrations of thyroxine, calcitonin and parathormone in immature and mature red deer females (Cervus elaphus)

Kuba¹,

B²,

Stankiewicz³

et al. 2015

Polish Journal of Veterinary Sciences

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The aim of this study was to determine circannual changes in the serum concentrations of thyroxine, calcitonin and parathormone in mature and immature red deer females. Blood samples from 8 hinds were collected monthly for 26 months. Secretions of thyroxine and calcitonin showed circannual rhythms with significantly higher levels in the immature hinds compared to the mature animals (p<0.05). For thyroxine, the concentration was higher in the winter/spring period than in summer/autumn (p<0.05), while for calcitonin the concentration profile was the opposite (p<0.05). The concentration of parathormone was significantly higher in summer/autumn that in the other months of the experiment (p<0.01). These results may indicate that the hormones investigated may be involved in the regulation of seasonal reproductive activity and in processes contributing to entering puberty in red deer females.

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Thyroid hormones and seasonal reproductive neuroendocrine interactions

Cited by 101 publications

References 59 publications

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

Potentiation of ecological factors on the disruption of thyroid hormones by organo-halogenated contaminants in female polar bears (Ursus maritimus) from the Barents Sea

Involvement of thyrotropin in photoperiodic signal transduction in mice

Circannual changes in serum concentrations of thyroxine, calcitonin and parathormone in immature and mature red deer females (Cervus elaphus)

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