Melatonin as a Hormone: New Physiological and Clinical Insights

Endocrine Reviews, Journal Year: 2018, Volume and Issue: 39(6), P. 990 - 1028

Published: Sept. 12, 2018

Melatonin is a ubiquitous molecule present in almost every live being from bacteria to humans. In vertebrates, besides produced peripheral tissues and acting as an autocrine paracrine signal, melatonin centrally synthetized by neuroendocrine organ, the pineal gland. Independently of considered species, hormone always during night its production secretory episode duration are directly dependent on length night. As tightly linked light/dark cycle, main hormonal systemic integrative action coordinate behavioral physiological adaptations environmental geophysical day season. The circadian signal daily regularity, contrast between concentrations, specially developed ways action. During episode, coordinates adaptive physiology through immediate effects primes responses prospective that will only appear at daytime, when absent. Similarly, annual history central nervous/endocrine system seasons come. Remarkably, maternal programs fetuses' behavior cope with cycle season after birth. These unique turn into biological time-domain–acting molecule. review focuses above considerations, proposes putative classification clinical dysfunctions, discusses general guidelines therapeutic use melatonin.

Language: Английский

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The Versatile Tanycyte: A Hypothalamic Integrator of Reproduction and Energy Metabolism

Endocrine Reviews, Journal Year: 2018, Volume and Issue: 39(3), P. 333 - 368

Published: Jan. 17, 2018

The fertility and survival of an individual rely on the ability periphery to promptly, effectively, reproducibly communicate with brain neural networks that control reproduction, food intake, energy homeostasis. Tanycytes, a specialized glial cell type lining wall third ventricle in median eminence hypothalamus, appear act as linchpin these processes by dynamically controlling secretion neuropeptides into portal vasculature hypothalamic neurons regulating blood-brain blood–cerebrospinal fluid exchanges, both depend cells adapt their morphology physiological state individual. In addition barrier properties, tanycytes possess sense blood glucose levels, play fundamental active role shuttling circulating metabolic signals intake. Moreover, accumulating data suggest that, keeping putative descent from radial cells, are endowed stem properties may respond dietary or reproductive cues modulating neurogenesis. Tanycytes could thus constitute missing link loop connecting behavior, hormonal changes, signal transduction, central neuronal activation and, finally, behavior again. this article, we will examine recent advances understanding tanycytic plasticity function hypothalamus underlying molecular mechanisms. We also discuss involvement therapeutic potential disorders.

Language: Английский

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The role of thyroglobulin in thyroid hormonogenesis

Nature Reviews Endocrinology, Journal Year: 2019, Volume and Issue: 15(6), P. 323 - 338

Published: March 18, 2019

Language: Английский

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The ecological function of thyroid hormones

Philosophical Transactions of the Royal Society B Biological Sciences, Journal Year: 2024, Volume and Issue: 379(1898)

Published: Feb. 5, 2024

Thyroid hormones (TH) are central hormonal regulators, orchestrating gene expression and complex biological processes vital for growth reproduction in variable environments by triggering specific developmental response to external cues. TH serve distinct roles different species: inducing metamorphosis amphibians or teleost fishes, governing metabolic mammals, acting as effectors of seasonality. These multifaceted raise questions about the underlying mechanisms action. Recent evidence suggests a shared ecological role across vertebrates, potentially extending significant portion bilaterian species. According this model, ensure that ontogenetic transitions align with environmental conditions, particularly terms energy expenditure, helping animals match their transition available resources. This alignment spans post-embryonic common all vertebrates more subtle adjustments during seasonal changes. The logic function is synchronize environment. review briefly outlines fundamental thyroid signalling shows various ways which use system natural environments. Lastly, we propose model linking signalling, trajectory metabolism. article part theme issue ‘Endocrine responses variation: conceptual approaches recent developments’.

Language: Английский

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Clocks for all seasons: unwinding the roles and mechanisms of circadian and interval timers in the hypothalamus and pituitary

Journal of Endocrinology, Journal Year: 2014, Volume and Issue: 222(2), P. R39 - R59

Published: June 2, 2014

Adaptation to the environment is essential for survival, in all wild animal species seasonal variation temperature and food availability needs be anticipated. This has led evolution of deep-rooted physiological cycles, driven by internal clocks, which can track time with remarkable precision. Evidence now accumulated that a change thyroid hormone (TH) within brain crucial element. mediated local control TH-metabolising enzymes specialised ependymal cells lining third ventricle hypothalamus. Within these cells, deiodinase type 2 enzyme activated response summer day lengths, converting metabolically inactive thyroxine (T 4 ) tri-iodothyronine 3 ). The TH hypothalamus appears an important factor driving changes occur season. Remarkably, both birds mammals, pars tuberalis (PT) pituitary gland plays role. A endocrine thyrotroph cell ( TSH -expressing) regulated changing day-length signal, leading activation long days. acts on adjacent TSH-receptors expressed hypothalamic causing regulation conversion active T . In PT nocturnal melatonin signal. Summer-like signals activate PT-expressed clock-regulated transcription regulator EYA3 ), turn drives expression TSHβ sub-unit, sustained increase expression. this manner, timer, melatonin, initiates cascade molecular events, , translates neuroendocrine activity There are parallels between circuit photoperiodic timing system used plants, while plants use different (constans vs it widely divergent organisms probably obey common set design principles.

Language: Английский

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An integrative view of mammalian seasonal neuroendocrinology

Journal of Neuroendocrinology, Journal Year: 2019, Volume and Issue: 31(5)

Published: May 1, 2019

Abstract Seasonal neuroendocrine cycles that govern annual changes in reproductive activity, energy metabolism and hair growth are almost ubiquitous mammals have evolved at temperate polar latitudes. Changes nocturnal melatonin secretion regulating gene expression the pars tuberalis (PT) of pituitary stalk a critical common feature seasonal mammals. The PT sends signal(s) to distalis regulate prolactin thus moult cycle. also signals retrograde manner via thyroid‐stimulating hormone tanycytes, which line ventral wall third ventricle hypothalamus. Tanycytes show plasticity play pivotal role local thyroid (TH) availability. Within mediobasal hypothalamus, cellular molecular targets TH remain elusive. However, two populations hypothalamic neurones, produce RF‐amide neuropeptides kisspeptin RFRP3 (RF‐amide related peptide 3), plausible relays between gonadotrophin‐releasing hormone‐pituitary‐gonadal axis. By contrast, ways by impinges on systems intake expenditure unknown. Here, we review underpinnings seasonality identify several areas warrant further research.

Language: Английский

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Binary Switching of Calendar Cells in the Pituitary Defines the Phase of the Circannual Cycle in Mammals

Current Biology, Journal Year: 2015, Volume and Issue: 25(20), P. 2651 - 2662

Published: Sept. 24, 2015

Highlights•A circannual timer may reside in the pituitary pars tuberalis thyrotroph•This is defined by a digital switching mechanism controlling EYA3 expression•The clockwork drives morphogenic cycle PT and hypothalamus•This involves recapitulation of developmental programSummaryPersistent free-running (approximately year-long) rhythms have evolved animals to regulate hormone cycles, drive metabolic (including hibernation), time annual reproduction. Recent studies photoperiodic input this rhythm, wherein melatonin acts on thyrotroph cells (PT), leading seasonal changes control thyroid metabolism hypothalamus. However, persist constant conditions many species absence changing photoperiod signal, generation cycles. It not known which cells, tissues, pathways generate these remarkable long-term rhythmic processes. We show that individual thyrotrophs can be one two binary states reflecting either long (EYA3+) or short (CHGA+) photoperiod, with relative proportion each state defining phase cycle. also driven leads extensive re-modeling hypothalamus over propose employ recapitulated pathway morphology tissues cells. Our data are consistent hypothesis within encoded switch timing mechanism, neuroendocrine rhythms, dynamic hypothalamic interface. In summary, PT-ventral now appears prime structure involved rhythm generation.Graphical abstract

Language: Английский

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A unifying, eco‐physiological framework for animal dormancy

Functional Ecology, Journal Year: 2020, Volume and Issue: 35(1), P. 11 - 31

Published: Nov. 12, 2020

Abstract Various animals across the tree of life express some form programmed dormancy (e.g. hibernation, diapause) to maximize fitness in highly seasonal environments. The integrated phenotype undergoing is strikingly similar among diverse groups; however, research on has historically been phylogenetically siloed. A broad comparative approach could clarify new angles for answering fundamental questions about evolution. To advance this approach, we present a cross‐taxonomic framework describing dimensions that distinguish animal dormancies and provide set core traits regulate as they progress through eco‐physiological phases deep, dormancy. We use universal explore ultimate drivers evolutionary consequences life. Deep, appears be predictable repeated adaptation environments draws conserved suite ancestral traits. highlight evidence molecular convergence signalling pathways coordinating environmental sensing energy metabolism insect mammal lineages, separated by 700 million years evolution representing independent colonizations Lastly, discuss utility opportunities challenges researchers continue advancing our understanding broad, lens. free Plain Language Summary can found within Supporting Information article.

Language: Английский

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Sea cucumber genome provides insights into saponin biosynthesis and aestivation regulation

Cell Discovery, Journal Year: 2018, Volume and Issue: 4(1)

Published: May 28, 2018

Echinoderms exhibit several fascinating evolutionary innovations that are rarely seen in the animal kingdom, but how these animals attained such features is not well understood. Here we report sequencing and analysis of genome extensive transcriptomes sea cucumber

Language: Английский

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Cellular, Molecular, and Physiological Adaptations of Hibernation: The Solution to Environmental Challenges

Annual Review of Cell and Developmental Biology, Journal Year: 2020, Volume and Issue: 36(1), P. 315 - 338

Published: Sept. 8, 2020

Thriving in times of resource scarcity requires an incredible flexibility behavioral, physiological, cellular, and molecular functions that must change within a relatively short time. Hibernation is collection physiological strategies allows animals to inhabit inhospitable environments, where they experience extreme thermal challenges food water. Many different kinds employ hibernation, there spectrum hibernation phenotypes. Here, we focus on obligatory mammalian hibernators identify the unique face adaptations allow overcome them. This includes cellular used combat low environmental body temperatures lack We discuss metabolic, neuronal, hormonal cues regulate how are thought be coordinated by internal clocks. Last, touch questions left addressed field research. Studies from last century more recent work reveal not simply passive reduction temperature vital parameters but rather active process seasonally regulated at molecular, organismal levels.

Language: Английский

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