The Torpid State: Recent Advances in Metabolic Adaptations and Protective Mechanisms†

Frontiers in Physiology, Год журнала: 2021, Номер 11

Опубликована: Янв. 20, 2021

Torpor and hibernation are powerful strategies enabling animals to survive periods of low resource availability. The state torpor results from an active drastic reduction individual’s metabolic rate (MR) associated with a relatively pronounced decrease in body temperature. To date, several forms have been described all three mammalian subclasses, i.e., monotremes, marsupials, placentals, as well few avian orders. This review highlights some the characteristics, whole organism down cellular molecular aspects, phenotype. first part this focuses on specific adaptations torpor, it is used by many species temperate zones. notably includes endocrine changes involved fat- food-storing hibernating species, explaining biomedical implications MR depression. We further compare adaptive mechanisms occurring opportunistic vs. seasonal heterotherms, such tropical sub-tropical species. Such comparisons bring new insights into origins among including resistance oxidative stress. second section emphasizes heterotherms protect their key organs against potential threats, reactive oxygen torpid state. address rehabilitation protection during hibernation, emphasis brain, central organ requiring recovery. Also, special focus given role ubiquitous readily-diffusing molecule, hydrogen sulfide (H 2 S), protecting ischemia-reperfusion damage various over torpor-arousal cycle conclude that (i) flexibility use strategy enables different heterothermic substantially suppress energy needs severely reduced food availability, (ii) phenotype implies marked levels, (iii) highly efficient protective ensuring continuity proper bodily functions. Comparison monotremes marsupials warranted for understanding origin evolution torpor.

Язык: Английский

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An Expanding Role for Nonvisual Opsins in Extraocular Light Sensing Physiology

Annual Review of Vision Science, Год журнала: 2023, Номер 9(1), С. 245 - 267

Опубликована: Май 17, 2023

We live on a planet that is bathed in daily and seasonal sunlight cycles. In this context, terrestrial life forms have evolved mechanisms directly harness light energy (plants) or decode information for adaptive advantage. animals, the main sensors are family of G protein-coupled receptors called opsins. Opsin function best described visual sense. However, most animals also use opsins extraocular sensing behavior camouflage. While it has long been believed mammals do not an capacity, recent evidence suggests otherwise. Notably, encephalopsin (OPN3) neuropsin (OPN5) both known to mediate mice. Examples mediation include photoentrainment circadian clocks skin (by OPN5) acute light-dependent regulation metabolic pathways OPN3 OPN5). This review summarizes current findings expanding field photoreception their relevance human physiology.

Язык: Английский

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Circadian clock mechanism driving mammalian photoperiodism

Nature Communications, Год журнала: 2020, Номер 11(1)

Опубликована: Авг. 27, 2020

The annual photoperiod cycle provides the critical environmental cue synchronizing rhythms of life in seasonal habitats. In 1936, Bünning proposed a circadian-based coincidence timer for photoperiodic synchronization plants. Formal studies support universality this so-called timer, but we lack understanding mechanisms involved. Here show mammals that long photoperiods induce circadian transcription factor BMAL2, pars tuberalis pituitary, and triggers summer biology through eyes absent/thyrotrophin (EYA3/TSH) pathway. Conversely, long-duration melatonin signals on short repressors including DEC1, suppressing BMAL2 EYA3/TSH pathway, triggering winter biology. These actions are associated with progressive genome-wide changes chromatin state, elaborating effect timer. Hence, clock-pituitary epigenetic pathway interactions form basis mammalian mechanism. Our results constitute blueprint timekeeping vertebrates.

Язык: Английский

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GnRHand the photoperiodic control of seasonal reproduction: Delegating the task to kisspeptin andRFRP‐3

Journal of Neuroendocrinology, Год журнала: 2022, Номер 34(5)

Опубликована: Март 15, 2022

Abstract Synchronization of mammalian breeding activity to the annual change photoperiod and environmental conditions is utmost importance for individual survival species perpetuation. Subsequent early 1960s, when central role melatonin in this adaptive process was demonstrated, our comprehension mechanisms through which light regulates gonadal has increased considerably. The current model photoperiodic neuroendocrine system points pivotal roles melatonin‐sensitive pars tuberalis (PT) its seasonally‐regulated production thyroid‐stimulating hormone (TSH), as well TSH‐sensitive hypothalamic tanycytes, radial glia‐like cells located basal part third ventricle. Tanycytes respond TSH expression thyroid (TH) deiodinase 2 ( Dio2 ), leads heightened intrahypothalamic triiodothyronine (T3) during longer days spring summer. There strong evidence that local, long‐day driven, increase T3 links input at PT gonadotropin‐releasing (GnRH) output, align with seasons. mechanism(s) impinges upon GnRH remain(s) unclear. However, two distinct neuronal populations medio‐basal hypothalamus, express (Arg)(Phe)‐amide peptides kisspeptin RFamide‐related peptide‐3, appear be well‐positioned relay seasonal message towards neurons. Here, we summarize understanding cellular, molecular players, keep track ultimately govern output breeding.

Язык: Английский

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Programmed ageing: decline of stem cell renewal, immunosenescence, and Alzheimer's disease

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Год журнала: 2023, Номер 98(4), С. 1424 - 1458

Опубликована: Апрель 17, 2023

ABSTRACT The characteristic maximum lifespan varies enormously across animal species from a few hours to hundreds of years. This argues that lifespan, and the ageing process itself dictates are large extent genetically determined. Although controversial, this is supported by firm evidence semelparous display evolutionarily programmed in response reproductive environmental cues. Parabiosis experiments reveal orchestrated systemically through circulation, accompanied changes hormone levels lifetime. implies that, like circadian circannual clocks, there master ‘clock age’ (circavital clock) located limbic brain mammals modulates systemic growth factor secretion over as well alterations gene expression revealed genomic methylation analysis. Studies on accelerated mice, human longevity genes, converge conserved fibroblast factors (FGFs) their receptors, including KLOTHO, insulin‐like (IGFs) steroid hormones, key players mediating effects ageing. Age‐related these multiple other inferred cause progressive decline tissue maintenance failure stem cell replenishment. most severely affects immune system, which requires constant renewal bone marrow cells. increases risk infection whereas can be extended germfree animals. suggests major death higher organisms. Immune also associated with age‐related diseases. Taking example Alzheimer's disease (AD), we assess AD caused immunosenescence infection. signature protein brain, Aβ, now known an antimicrobial peptide, Aβ deposits may rather than disease. Because some cognitively normal elderly individuals show extensive neuropathology, argue location pathology crucial – specifically, lesions likely accentuate immunosenescence, could thus underlie vicious cycle microbial proliferation culminates AD. general model extend diseases, propose paradigm organismal senescence declining leads mortality.

Язык: Английский

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Temporal organization of pineal melatonin signaling in mammals

Molecular and Cellular Endocrinology, Год журнала: 2019, Номер 503, С. 110687 - 110687

Опубликована: Дек. 19, 2019

Язык: Английский

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Tanycytes and the Control of Thyrotropin-Releasing Hormone Flux Into Portal Capillaries

Frontiers in Endocrinology, Год журнала: 2019, Номер 10

Опубликована: Июнь 25, 2019

Central and peripheral mechanisms that modulate energy intake, partition expenditure determine homeostasis. Thyroid hormones (TH) regulate through the control of basal metabolic rate thermogenesis; they also food intake. TH concentrations are regulated by hypothalamus-pituitary-thyroid (HPT) axis, transport metabolism in blood target tissues. In mammals, hypophysiotropic thyrotropin-releasing hormone (TRH) neurons paraventricular nucleus hypothalamus integrate energy-related information. They project to external zone median eminence (ME), a brain circumventricular organ rich neuron terminal varicosities buttons, tanycytes, other glial cells capillaries. These capillary vessels form portal system links base with anterior pituitary. Tanycytes medio-basal express repertoire proteins involved transport, sensing, TH; among them is type 2 deiodinase, source 3,3',5-triiodo-L-thyronine necessary for negative feedback on TRH neurons. subtypes distinguished position phenotype. The end-feet β2-tanycytes intermingle terminals layer ME terminate close Besides TRH-degrading ectoenzyme (TRH-DE); this enzyme likely controls amount entering vessels. TRH-DE rapidly upregulated TH, contributing HPT axis. Alterations balance expression activity ME, making hub regulation axis activity. TRH-R1, which mediates positive effects size β2-tanycyte contacts lamina adjacent associations capillaries, activity, appear coordinately Thus, down-stream neuronal release action potentials arrival eminence, imbricated intercellular processes may coordinate flux into conclusion, as critical cellular element somatic post-secretory vessels, mammals.

Язык: Английский

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Hormonal regulation in male androgenetic alopecia—Sex hormones and beyond: Evidence from recent genetic studies

Experimental Dermatology, Год журнала: 2020, Номер 29(9), С. 814 - 827

Опубликована: Июнь 17, 2020

Abstract Male‐pattern hair loss, also termed androgenetic alopecia (AGA), is a highly prevalent age‐related condition that characterized by distinct pattern of loss from the frontotemporal and vertex regions scalp. The phenotype heritable hormone dependent, with androgens being recognized critical hormonal factor. Numerous molecular genetic studies have focused on variation in around gene encodes androgen receptor. More recently, however, availability high‐throughput methods, novel methods data analysis sufficiently large sample sizes rendered possible systematic investigation contribution other components receptor pathway or pathways beyond signalling pathways. Over past decade, genome‐wide association increasingly cohorts enabled identification risk factors for AGA, yielded unprecedented insights into underlying pathobiology. present review discusses some most intriguing findings relevance (sex)hormonal AGA.

Язык: Английский

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Seasonal variation in UVA light drives hormonal and behavioural changes in a marine annelid via a ciliary opsin

Nature Ecology & Evolution, Год журнала: 2021, Номер 5(2), С. 204 - 218

Опубликована: Янв. 11, 2021

Язык: Английский

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Arcuate nucleus, median eminence, and hypophysial pars tuberalis

Handbook of clinical neurology, Год журнала: 2021, Номер unknown, С. 227 - 251

Опубликована: Янв. 1, 2021

Язык: Английский

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