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The suprachiasmatic nuclei (SCN) of the hypothalamus harbor the central clock of the circadian system, which gradually matures during the perinatal period. In this study, time-resolved transcriptomic and proteomic approaches were used to describe fetal SCN tissue-level rhythms before rhythms in clock gene expression develop. Pregnant rats were maintained in constant darkness and had intact SCN, or their SCN were lesioned and behavioral rhythm was imposed by temporal restriction of food availability. Model-selecting tools dryR and CompareRhythms identified sets of genes in the fetal SCN that were rhythmic in the absence of the fetal canonical clock. Subsets of rhythmically expressed genes were assigned to groups of fetuses from mothers with either intact or lesioned SCN, or both groups. Enrichment analysis for GO terms and signaling pathways revealed that neurodevelopment and cell-to-cell signaling were significantly enriched within the subsets of genes that were rhythmic in response to distinct maternal signals. The findings discovered a previously unexpected breadth of rhythmicity in the fetal SCN at a developmental stage when the canonical clock has not yet developed at the tissue level and thus likely represents responses to rhythmic maternal signals.
Assuntos
Ritmo Circadiano , Proteômica , Animais , Ritmo Circadiano/genética , Feminino , Feto/fisiologia , Hipotálamo , Gravidez , Ratos , Núcleo Supraquiasmático/metabolismoRESUMO
The choroid plexus (ChP) in the brain ventricles has a major influence on brain homeostasis. In this study, we aimed to determine whether the circadian clock located in ChP is affected by chronodisruption caused by misalignment with the external light/dark cycle and/or inflammation. Adult mPer2Luc mice were maintained in the LD12:12 cycle or exposed to one of two models of chronic chronodisruption - constant light for 22-25 weeks (cLL) or 6-hour phase advances of the LD12:12 cycle repeated weekly for 12 weeks (cLD-shifts). Locomotor activity was monitored before the 4th ventricle ChP and suprachiasmatic nuclei (SCN) explants were recorded in real time for PER2-driven population and single-cell bioluminescence rhythms. In addition, plasma immune marker concentrations and gene expression in ChP, prefrontal cortex, hippocampus and cerebellum were analyzed. cLL dampened the SCN clock but did not shorten the inactivity interval (sleep). cLD-shifts had no effect on the SCN clock, but transiently affected sleep duration and fragmentation. Both chronodisruption protocols dampened the ChP clock. Although immune markers were elevated in plasma and hippocampus, levels in ChP were unaffected, and unlike the liver clock, the ChP clock was resistant to lipopolysaccharide treatment. Importantly, both chronodisruption protocols reduced glucocorticoid signaling in ChP. The data demonstrate the high resistance of the ChP clock to inflammation, highlighting its role in protecting the brain from neuroinflammation, and on the other hand its high sensitivity to chronodisruption. Our results provide a novel link between human lifestyle-induced chronodisruption and the impairment of ChP-dependent brain homeostasis.
Assuntos
Relógios Circadianos , Leucemia Linfocítica Crônica de Células B , Humanos , Camundongos , Animais , Ritmo Circadiano/fisiologia , Plexo Corióideo/metabolismo , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , InflamaçãoRESUMO
Misaligned feeding may lead to pancreatic insufficiency, however, whether and how it affects circadian clock in the exocrine pancreas is not known. We exposed rats to a reversed restricted feeding regimen (rRF) for 10 or 20 days and analyzed locomotor activity, daily profiles of hormone levels (insulin, glucagon, and corticosterone) in plasma, and clock gene expression in the liver and endocrine and exocrine pancreas. In addition, we monitored responses of the exocrine pancreatic clock in organotypic explants of mPer2Luc mice in real time to acetylcholine, insulin, and glucocorticoids. rRF phase-reversed the clock in the endocrine pancreas, similar to the clock in the liver, but completely abolished clock gene rhythmicity and significantly downregulated the expression of Cpb1 and Cel in the exocrine pancreas. rRF desynchronized the rhythms of plasma insulin and corticosterone. Daily profiles of their receptor expression differed in the two parts of the pancreas and responded differently to rRF. Additionally, the pancreatic exocrine clock responded differently to treatments with insulin and the glucocorticoid analog dexamethasone in vitro. Mathematical simulation confirmed that the long-term misalignment between these two hormonal signals, as occurred under rRF, may lead to dampening of the exocrine pancreatic clock. In summary, our data suggest that misaligned meals impair the clock in the exocrine part of the pancreas by uncoupling insulin and corticosterone rhythms. These findings suggest a new mechanism by which adverse dietary habits, often associated with shift work in humans, may impair the clock in the exocrine pancreas and potentially contribute to exocrine pancreatic insufficiency.
Assuntos
Relógios Circadianos , Pâncreas Exócrino , Animais , Relógios Circadianos/fisiologia , Ritmo Circadiano/fisiologia , Corticosterona/metabolismo , Corticosterona/farmacologia , Glucocorticoides , Insulina/metabolismo , Camundongos , Pâncreas Exócrino/metabolismo , RatosRESUMO
AIMS: Circadian clocks in the hippocampus (HPC) align memory processing with appropriate time of day. Our study was aimed at ascertaining the specificity of glycogen synthase kinase 3-beta (GSK3ß)- and glucocorticoid (GC)-dependent pathways in the entrainment of clocks in individual HPC regions, CA1-3, and dentate gyrus (DG). METHODS: The role of GCs was addressed in vivo by comparing the effects of adrenalectomy (ADX) and subsequent dexamethasone (DEX) supplementation on clock gene expression profiles (Per1, Per2, Nr1d1, and Bmal1). In vitro the effects of DEX and the GSK3ß inhibitor, CHIR-99021, were assessed from recordings of bioluminescence rhythms in HPC organotypic explants of mPER2Luc mice. RESULTS: Circadian rhythms of clock gene expression in all HPC regions were abolished by ADX, and DEX injections to the rats rescued those rhythms in DG. The DEX treatment of the HPC explants significantly lengthened periods of the bioluminescence rhythms in all HPC regions with the most significant effect in DG. In contrast to DEX, CHIR-99021 significantly shortened the period of bioluminescence rhythm. Again, the effect was most significant in DG which lacks the endogenously inactivated (phosphorylated) form of GSK3ß. Co-treatment of the explants with CHIR-99021 and DEX produced the CHIR-99021 response. Therefore, the GSK3ß-mediated pathway had dominant effect on the clocks. CONCLUSION: GSK3ß- and GC-dependent pathways entrain the clock in individual HPC regions by modulating their periods in an opposite manner. The results provide novel insights into the mechanisms connecting the arousal state-relevant signals with temporal control of HPC-dependent memory and cognitive functions.
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Relógios Circadianos , Animais , Relógios Circadianos/genética , Ritmo Circadiano , Giro Denteado/metabolismo , Glucocorticoides/metabolismo , Glucocorticoides/farmacologia , Quinase 3 da Glicogênio Sintase/metabolismo , Quinase 3 da Glicogênio Sintase/farmacologia , Glicogênio Sintase Quinase 3 beta/metabolismo , Hipocampo/metabolismo , Camundongos , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , RatosRESUMO
Modification of the Per2 clock gene in mPer2Luc reporter mice significantly alters circadian function. Behavioral period in constant dark is lengthened, and dissociates into two distinct components in constant light. Rhythms exhibit increased bimodality, enhanced phase resetting to light pulses, and altered entrainment to scheduled feeding. Mechanistic mathematical modelling predicts that enhanced protein interactions with the modified mPER2 C-terminus, combined with differential clock regulation among SCN subregions, can account for effects on circadian behavior via increased Per2 transcript and protein stability. PER2::LUC produces greater suppression of CLOCK:BMAL1 E-box activity than PER2. mPer2Luc carries a 72 bp deletion in exon 23 of Per2, and retains a neomycin resistance cassette that affects rhythm amplitude but not period. The results show that mPer2Luc acts as a circadian clock mutation illustrating a need for detailed assessment of potential impacts of c-terminal tags in genetically modified animal models.
Assuntos
Ritmo Circadiano , Luciferases/genética , Proteínas Circadianas Period/genética , Animais , Comportamento Animal , Comportamento Alimentar , Locomoção , Camundongos , Camundongos Endogâmicos C57BL , MutaçãoRESUMO
KEY POINTS: In mammals, the mother-offspring interaction is essential for health later in adulthood. The impact of altered timing and quality of maternal care on the offspring's circadian system was assessed using a cross-strain fostering approach. Better maternal care facilitated the development of amplitudes of Bmal1 clock gene expression in the central clock, as well as the clock-driven activity/rest rhythm, and also its entrainment to the external light/dark cycle. Worse maternal care impaired entrainment of the central clock parameters in the Wistar rat during the early developmental stages. Better maternal care remedied the dampened amplitudes of the colonic clock, as well as cardiovascular functions. The results provide compelling evidence that the circadian phenotype of a foster mother may affect the pathological symptoms of the offspring, even if they are genetically programmed. ABSTRACT: In mammals, the mother-offspring interaction is essential for health later in adulthood. Maternal care is determined by the circadian phenotype of the mother. The impact of altered timing and quality of maternal care on the circadian system was assessed using a cross-strain fostering approach, with 'abnormal' (i.e. circadian misaligned) care being represented by spontaneously hypertensive rats (SHR) and 'normal' care by Wistar rats. The SHR mothers worsened synchrony of the central clock in the suprachiasmatic nuclei with the light/dark cycle in Wistar rat pups, although this effect disappeared after weaning. The maternal care provided by Wistar rat mothers to SHR pups facilitated the development of amplitudes of the Bmal1 expression rhythm in the suprachiasmatic nuclei of the hypothalamus, as well as the clock-driven activity/rest rhythm and its entrainment to the external light/dark cycle. The peripheral clocks in the liver and colon responded robustly to cross-strain fostering; the circadian phenotype of the Wistar rat foster mother remedied the dampened amplitudes of the colonic clock in SHR pups and improved their cardiovascular functions. In general, the more intensive maternal care of the Wistar rat mothers improved most of the parameters of the abnormal SHR circadian phenotype in adulthood; conversely, the less frequent maternal care of the SHR mothers worsened these parameters in the Wistar rat during the early developmental stages. Altogether, our data provide compelling evidence that the circadian phenotype of a foster mother may positively and negatively affect the regulatory mechanisms of various physiological parameters, even if the pathological symptoms are genetically programmed.
Assuntos
Comportamento Animal/fisiologia , Relógios Circadianos/fisiologia , Comportamento Materno/fisiologia , Núcleo Supraquiasmático/fisiologia , Animais , Animais Recém-Nascidos , Feminino , Masculino , Fenótipo , Ratos Endogâmicos SHR , Ratos Wistar , Especificidade da EspécieRESUMO
The role of melatonin in maintaining proper function of the circadian system has been proposed but very little evidence for such an effect has been provided. To ascertain the role, the aim of the study was to investigate impact of long-term melatonin absence on regulation of circadian system. The parameters of behavior and circadian clocks of rats which were devoid of the melatonin signal due to pinealectomy (PINX) for more than one year were compared with those of intact age-matched controls. PINX led to a decrease in spontaneous locomotor activity and a shortening of the free-running period of the activity rhythm driven by the central clock in the suprachiasmatic nuclei (SCN) in constant darkness. However, the SCN-driven rhythms in activity and feeding were not affected and remained well entrained in the light/dark cycle. In contrast, in these conditions PINX had a significant effect on amplitudes of the clock gene expression rhythms in the duodenum and also partially in the liver. These results demonstrate the significant impact of long-term melatonin absence on period of the central clock in the SCN and the amplitudes of the peripheral clocks in duodenum and liver and suggest that melatonin might be a redundant but effective endocrine signal for these clocks.
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Ritmo Circadiano , Melatonina/fisiologia , Animais , Ritmo Circadiano/efeitos dos fármacos , Ritmo Circadiano/fisiologia , Escuridão , Feminino , Luz , Locomoção/fisiologia , Melatonina/metabolismo , Fotoperíodo , Glândula Pineal/metabolismo , Glândula Pineal/cirurgia , Ratos , Ratos Wistar , Transdução de Sinais/fisiologia , Núcleo Supraquiasmático/metabolismoRESUMO
OBJECTIVES: Bipolar disorder is a common psychiatric disease characterized by mood disturbances with alternating episodes of mania and depression. Moreover, disturbances in the sleep/wake cycle are prevalent. We tested a hypothesis that the function of the circadian system, which drives the sleep/wake cycle, may differ in patients with bipolar disorder depending on whether they are experiencing an episode of mania or depression. METHODS: To assess the functional state of the central circadian clock, daily profiles of melatonin levels in saliva were determined. The functional state of the peripheral clocks was assessed by determining daily profiles of Per1 and Nr1d1 clock gene expression in buccal mucosa cells. Sixteen patients with bipolar disorder in a manic episode, 22 patients in a depressive episode, and 19 healthy control subjects provided samples at regular intervals during a 24-hour cycle. RESULTS: During episodes of mania, the daily profiles of melatonin differed compared with healthy controls and patients in an episode of depression, mainly due to elevated melatonin levels during the daytime. No difference was found between melatonin profiles of control subjects and patients in depression. The Per1 and Nr1d1 profiles were advanced in patients in mania compared with those in depression. Compared with controls, a trend toward an advance was apparent in the profiles of patients during an episode of mania but not depression. The amplitude of the Nr1d1 expression profile was higher in mania than in depression. CONCLUSIONS: The data revealed differences in the functional state of the circadian system in patients with bipolar disorder depending on whether they were experiencing a manic or a depressive episode.
Assuntos
Transtorno Bipolar/genética , Transtornos Cronobiológicos/genética , Ritmo Circadiano/genética , Melatonina/metabolismo , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/genética , Proteínas Circadianas Period/genética , RNA Mensageiro/metabolismo , Adulto , Transtorno Bipolar/fisiopatologia , Transtorno Bipolar/psicologia , Estudos de Casos e Controles , Transtornos Cronobiológicos/fisiopatologia , Transtornos Cronobiológicos/psicologia , Relógios Circadianos/genética , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mucosa Bucal/metabolismo , Prevalência , Saliva/química , TranscriptomaRESUMO
Colonic morphology and function change significantly during ontogenesis. In mammals, many colonic physiological functions are temporally controlled by the circadian clock in the colon, which is entrained by the central circadian clock in the suprachiasmatic nuclei (SCN). The aim of this present study was to ascertain when and how the circadian clock in the colon develops during the perinatal period and whether maternal cues and/or the developing pup SCN may influence the ontogenesis of the colonic clock. Daily profiles of clock genes Per1, Per2, Cry1, Cry2, Rev-erbα, Bmal1, and Clock expression in the colon underwent significant modifications since embryonic day 20 (E20) through postnatal days (P) 2, 10, 20, and 30 via changes in the mutual phasing among the individual clock gene expression rhythms, their relative phasing to the light-dark regime, and their amplitudes. An adult-like state was achieved around P20. The foster study revealed that during the prenatal period, the maternal circadian phase may partially modulate development of the colonic clock. Postnatally, the absence and/or presence of rhythmic maternal care affected the phasing of the clock gene expression profiles in pups at P10 and P20. A reversal in the colonic clock phase between P10 and P20 occurred in the absence of rhythmic signals from the pup SCN. The data demonstrate ontogenetic maturation of the colonic clock and stress the importance of prenatal and postnatal maternal rhythmic signals for its development. These data may contribute to the understanding of colonic function-related diseases in newborn children.
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Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/metabolismo , Ritmo Circadiano , Colo/metabolismo , Animais , Animais Recém-Nascidos , Restrição Calórica , Ritmo Circadiano/genética , Peptídeos e Proteínas de Sinalização do Ritmo Circadiano/genética , Colo/embriologia , Comportamento Alimentar , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Idade Gestacional , Masculino , Comportamento Materno , Morfogênese , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Ratos , Ratos Wistar , Transdução de Sinais , Núcleo Supraquiasmático/embriologia , Núcleo Supraquiasmático/metabolismo , Fatores de TempoRESUMO
The topic of human circadian rhythms is not only attracting the attention of clinical researchers from various fields but also sparking a growing public interest. The circadian system comprises the central clock, located in the suprachiasmatic nucleus of the hypothalamus, and the peripheral clocks in various tissues that are interconnected; together they coordinate many daily activities, including sleep and wakefulness, physical activity, food intake, glucose sensitivity and cardiovascular functions. Disruption of circadian regulation seems to be associated with metabolic disorders (particularly impaired glucose tolerance) and cardiovascular disease. Previous clinical trials revealed that disturbance of the circadian system, specifically due to shift work, is associated with an increased risk of type 2 diabetes mellitus. This review is intended to provide clinicians who wish to implement knowledge of circadian disruption in diagnosis and strategies to avoid cardio-metabolic disease with a general overview of this topic.
Assuntos
Doenças Cardiovasculares , Ritmo Circadiano , Doenças Metabólicas , Humanos , Ritmo Circadiano/fisiologia , Doenças Cardiovasculares/etiologia , Doenças Cardiovasculares/fisiopatologia , Doenças Metabólicas/fisiopatologia , Doenças Metabólicas/metabolismo , Doenças Metabólicas/etiologia , Diabetes Mellitus Tipo 2/fisiopatologia , Diabetes Mellitus Tipo 2/metabolismo , Transtornos Cronobiológicos/fisiopatologia , Transtornos Cronobiológicos/complicaçõesRESUMO
Choroid plexus (ChP), the brain structure primarily responsible for cerebrospinal fluid production, contains a robust circadian clock, whose role remains to be elucidated. The aim of our study was to [1] identify rhythmically controlled cellular processes in the mouse ChP and [2] assess the role and nature of signals derived from the master clock in the suprachiasmatic nuclei (SCN) that control ChP rhythms. To accomplish this goal, we used various mouse models (WT, mPer2Luc, ChP-specific Bmal1 knockout) and combined multiple experimental approaches, including surgical lesion of the SCN (SCNx), time-resolved transcriptomics, and single cell luminescence microscopy. In ChP of control (Ctrl) mice collected every 4 h over 2 circadian cycles in darkness, we found that the ChP clock regulates many processes, including the cerebrospinal fluid circadian secretome, precisely times endoplasmic reticulum stress response, and controls genes involved in neurodegenerative diseases (Alzheimer's disease, Huntington's disease, and frontotemporal dementia). In ChP of SCNx mice, the rhythmicity detected in vivo and ex vivo was severely dampened to a comparable extent as in mice with ChP-specific Bmal1 knockout, and the dampened cellular rhythms were restored by daily injections of dexamethasone in mice. Our data demonstrate that the ChP clock controls tissue-specific gene expression and is strongly dependent on the presence of a functional connection with the SCN. The results may contribute to the search for a novel link between ChP clock disruption and impaired brain health.
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Plexo Corióideo , Relógios Circadianos , Núcleo Supraquiasmático , Animais , Núcleo Supraquiasmático/metabolismo , Núcleo Supraquiasmático/fisiologia , Plexo Corióideo/metabolismo , Plexo Corióideo/fisiologia , Relógios Circadianos/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Ritmo Circadiano/fisiologia , Masculino , Camundongos Knockout , Fatores de Transcrição ARNTL/metabolismo , Fatores de Transcrição ARNTL/genéticaRESUMO
STUDY OBJECTIVES: Social jetlag manifests as a difference in sleep timing on workdays and free days. Social jetlag is often associated with shorter, lower-quality sleep, so it is unclear how much the chronic circadian misalignment contributes to observed negative health outcomes. We aimed to (1) investigate associations between social jetlag, chronotype (one of its determinants), and the levels of health markers, (2) describe factors associated with social jetlag, and (3) examine whether working from home can reduce social jetlag. METHODS: Adult respondents participated in a nationally representative longitudinal survey of Czech households (individuals in each wave: n2018/19/20â =â 5132/1957/1533), which included Munich ChronoType Questionnaire to evaluate chronotype and social jetlag. A subset provided blood samples (n2019â =â 1957) for detection of nine biomarkers and was surveyed in three successive years (social jetlag calculated for n2018/19/20â =â 3930/1601/1237). Data were analyzed by nonparametric univariate tests and mixed effects multivariate regression with social jetlag, chronotype, sex, age, body-mass index, and reported diseases as predictors and biomarker levels as outcomes. RESULTS: Higher social jetlag (≥0.65 h) was significantly associated with increased levels of total cholesterol and low-density lipoprotein cholesterol, particularly in participants older than 50 years (Mann-Whitney, men: pCHLâ =â 0.0005, pLDLâ =â 0.0009; women: pCHLâ =â 0.0079, pLDLâ =â 0.0068). Extreme chronotypes were associated with cardiovascular disease risk markers regardless of social jetlag (Kruskal-Wallis, pâ <â 0.0001). Commuting to work and time stress were identified as important contributors to social jetlag. Individual longitudinal data showed that working from home decreased social jetlag and prolonged sleep. CONCLUSIONS: We report significant associations between sleep phase preference, social jetlag, and cardio-metabolic biomarkers.
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Ritmo Circadiano , Doenças Metabólicas , Adulto , Masculino , Humanos , Feminino , Sono , Síndrome do Jet Lag , Doenças Metabólicas/complicações , Inquéritos e Questionários , Biomarcadores , ColesterolRESUMO
Lithium is an effective mood stabilizer, but the mechanism of its therapeutic action is not well understood. We investigated the effect of lithium on the circadian clock located in the ventricle barrier complex containing the choroid plexus (CP), a part of the glymphatic system that influences gross brain function via the production of cerebrospinal fluid. The mPer2Luc mice were injected with lithium chloride (LiCl) or vehicle, and their effects on the clock gene Nr1d1 in CP were detected by RT qPCR. CP organotypic explants were prepared to monitor bioluminescence rhythms in real time and examine the responses of the CP clock to LiCl and inhibitors of glycogen synthase kinase-3 (CHIR-99021) and protein kinase C (chelerythrine). LiCl affected Nr1d1 expression levels in CP in vivo and dose-dependently delayed the phase and prolonged the period of the CP clock in vitro. LiCl and CHIR-99021 had different effects on 1] CP clock parameters (amplitude, period, phase), 2] dexamethasone-induced phase shifts of the CP clock, and 3] dynamics of PER2 degradation and de novo accumulation. LiCl-induced phase delays were significantly reduced by chelerythrine, suggesting the involvement of PKC activity. The effects on the CP clock may be involved in the therapeutic effects of lithium and hypothetically improve brain function in psychiatric patients by aligning the function of the CP clock-related glymphatic system with the sleep-wake cycle. Importantly, our data argue for personalized timing of lithium treatment in BD patients.
Assuntos
Relógios Circadianos , Camundongos , Animais , Lítio/farmacologia , Ritmo Circadiano/genética , Plexo Corióideo/metabolismo , Proteínas Circadianas Period/genéticaRESUMO
Background: The MTNR1B gene encodes a receptor for melatonin, a hormone regulating biorhythms. Disruptions in biorhythms contribute to the development of type 2 diabetes mellitus (T2DM). Genetic studies suggest that variability in the MTNR1B gene affects T2DM development. Our aim was to compare the distribution of the genetic variant rs10830963 between persons differing in glucose tolerance in a sample of the Czech population (N=1206). We also evaluated possible associations of the polymorphism with insulin sensitivity, beta cell function, with the shape of glucose, insulin and C-peptide trajectories measured 7 times during a 3-hour oral glucose tolerance test (OGTT) and with glucagon response. In a subgroup of 268 volunteers we also evaluated sleep patterns and biorhythm. Results: 13 persons were diagnosed with T2DM, 119 had impaired fasting blood glucose (IFG) and/or impaired glucose tolerance (IGT). 1074 participants showed normal results and formed a control group. A higher frequency of minor allele G was found in the IFG/IGT group in comparison with controls. The GG constellation was present in 23% of diabetics, in 17% of IFG/IGT probands and in 11% of controls. Compared to CC and CG genotypes, GG homozygotes showed higher stimulated glycemia levels during the OGTT. Homozygous as well as heterozygous carriers of the G allele showed lower very early phase of insulin and C-peptide secretion with unchanged insulin sensitivity. These differences remained significant after excluding diabetics and the IFG/IGT group from the analysis. No associations of the genotype with the shape of OGTT-based trajectories, with glucagon or with chronobiological patterns were observed. However, the shape of the trajectories differed significantly between men and women. Conclusion: In a representative sample of the Czech population, the G allele of the rs10830963 polymorphism is associated with impaired early phase of beta cell function, and this is evident even in healthy individuals.
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Diabetes Mellitus Tipo 2 , Intolerância à Glucose , Resistência à Insulina , Estado Pré-Diabético , Receptor MT2 de Melatonina , Glicemia , Peptídeo C , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/genética , Feminino , Glucagon , Glucose , Intolerância à Glucose/epidemiologia , Intolerância à Glucose/genética , Humanos , Insulina , Resistência à Insulina/genética , Cinética , Masculino , Receptor MT2 de Melatonina/genéticaRESUMO
INTRODUCTION: The maternal part of the rodent placenta harbors a circadian clock which robustly responds to glucocorticoids, however, its sensitivity to other hormones has not been elucidated. In this study, we tested five selected hormones (dopamine, melatonin, insulin, leptin and ghrelin) for their effectiveness to affect the clock in decidual region of mouse placenta in vitro. METHODS: We administered the hormones or corresponding vehicles at various time points over 24 h to organotypic placental explants of mPer2Luc mice containing the decidua basalis (DB) region and monitored their effects on amplitude, period, median expression level (mesor) and phase of PER2-driven bioluminescence rhythms. RESULTS: Dopamine significantly increased the amplitude, robustly dampened the mesor, and during a narrow time interval (corresponding to daytime) induced phase delays of the rhythms. In contrast, melatonin had no effect on amplitude, but induced phase advances of the rhythms at the opposite time window than dopamine (corresponding to nighttime). Leptin and ghrelin, but not insulin, slightly increased amplitudes and moderately modulated phase delays of the clock, suggesting that the DB clock, in contrast to other peripheral clocks, is rather resilient to abrupt changes in levels of feeding- and metabolism-related hormones. DISCUSSION: The results demonstrate for the first time that dopamine and melatonin exhibit delicate yet specific effects on parameters of the DB clock and may thus potentially contribute to fine-tuning of its phase under in vivo conditions. It also implies that dysregulation of their levels, which accompany various pathologies, may account for malfunction of the clock in DB.
Assuntos
Relógios Circadianos , Ritmo Circadiano , Dopamina/fisiologia , Hormônios/fisiologia , Placenta/metabolismo , Animais , Feminino , Masculino , Camundongos , GravidezRESUMO
The epithelial cells of choroid plexus (CP) in brain ventricles produce cerebrospinal fluid and act as the blood-cerebrospinal fluid barrier. In this study, we confirmed that CP in the 4th ventricle is composed of cellular oscillators that all harbor glucocorticoid receptors and are mutually synchronized to produce a robust clock gene expression rhythm detectable at the tissue level in vivo and in vitro. Animals lacking glucocorticoids (GCs) due to surgical removal of adrenal glands had Per1, Per2, Nr1d1 and Bmal1 clock gene rhythmicity in their CP significantly dampened, whereas subjecting them to daily bouts of synthetic GC analog, dexamethasone (DEX), reinforced those rhythms. We verified these in vivo effects using an in vitro model of organotypic CP explants; depending on the time of its application, DEX significantly increased the amplitude and efficiently reset the phase of the CP clock. The results are the first description of a PRC for a non-neuronal clock in the brain, demonstrating that CP clock shares some properties with the non-neuronal clocks elsewhere in the body. Finally, we found that DEX exhibited multiple synergic effects on the CP clock, including acute activation of Per1 expression and change of PER2 protein turnover rate. The DEX-induced shifts of the CP clock were partially mediated via PKA-ERK1/2 pathway. The results provide the first evidence that the GC rhythm strengthens and entrains the clock in the CP helping thus fine-tune the brain environment according to time of day.
Assuntos
Glândulas Suprarrenais/metabolismo , Plexo Corióideo/metabolismo , Relógios Circadianos , Glucocorticoides/metabolismo , Núcleo Supraquiasmático/metabolismo , Animais , Dexametasona , Sistema de Sinalização das MAP Quinases , Masculino , Proteínas Circadianas Period/genética , Proteínas Circadianas Period/metabolismo , Ratos WistarRESUMO
Suprachiasmatic nucleus (SCN) of the hypothalamus is the master clock that drives circadian rhythms in physiology and behavior and adjusts their timing to external cues. Neurotransmitter glutamate and glutamatergic receptors sensitive to N-methyl-d-aspartate (NMDA) play a dual role in the SCN by coupling astrocytic and neuronal single cell oscillators and by resetting their phase in response to light. Recent reports suggested that signaling by endogenous cannabinoids (ECs) participates in both of these functions. We have previously shown that ECs, such as 2-arachidonoylglycerol (2-AG), act via CB1 receptors to affect the SCN response to light-mimicking NMDA stimulus in a time-dependent manner. We hypothesized that this ability is linked to the circadian regulation of EC signaling. We demonstrate that circadian clock in the rat SCN regulates expression of 2-AG transport, synthesis and degradation enzymes as well as its receptors. Inhibition of the major 2-AG synthesis enzyme, diacylglycerol lipase, enhanced the phase delay and lowered the amplitude of explanted SCN rhythm in response to NMDAR activation. Using microscopic PER2 bioluminescence imaging, we visualized how individual single cell oscillators in different parts of the SCN respond to the DAGL inhibition/NMDAR activation and shape response of the whole pacemaker. Additionally, we present strong evidence that the zero amplitude behavior of the SCN in response to single NMDA stimulus in the middle of subjective night is the result of a loss of rhythm in individual SCN cells. The paper provides new insights into the modulatory role of endocannabinoid signaling during the light entrainment of the SCN.
Assuntos
Ritmo Circadiano/fisiologia , Endocanabinoides/fisiologia , Agonistas de Aminoácidos Excitatórios/farmacologia , Lipase Lipoproteica/antagonistas & inibidores , N-Metilaspartato/farmacologia , Núcleo Supraquiasmático/fisiologia , Animais , Ritmo Circadiano/efeitos dos fármacos , Feminino , Lipase Lipoproteica/metabolismo , Masculino , Camundongos , Camundongos Transgênicos , Ratos , Ratos Wistar , Núcleo Supraquiasmático/citologia , Núcleo Supraquiasmático/efeitos dos fármacosRESUMO
Changes in photoperiod modulate the circadian system, affecting the function of the central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus. The aim of the present study was to elucidate the dynamics of adjustment to a change of a long photoperiod with 18 h of light to a short photoperiod with 6 h of light of clock gene expression rhythms in the mouse SCN and in the peripheral clock in the liver, as well as of the locomotor activity rhythm. Three, five, and thirteen days after the photoperiod change, daily profiles of Per1, Per2, and Rev-erbalpha expression in the rostral, middle, and caudal parts of the SCN and of Per2 and Rev-erbalpha in the liver were determined by in situ hybridization and real-time RT-PCR, respectively. The clock gene expression rhythms in the different SCN regions, desynchronized under the long photoperiod, attained synchrony gradually following the transition from long to short days, mostly via advancing the expression decline. The photoperiodic modulation of the SCN was due not only to the degree of synchrony among the SCN regions but also to different waveforms of the rhythms in the individual SCN parts. The locomotor activity rhythm adjusted gradually to short days by advancing the activity onset, and the liver rhythms adjusted by advancing the Rev-erbalpha expression rise and Per2 decline. These data indicate different mechanisms of adjustment to a change of the photoperiod in the central SCN clock and the peripheral liver clock.
Assuntos
Ritmo Circadiano/fisiologia , Fígado/fisiologia , Atividade Motora/fisiologia , Fotoperíodo , Núcleo Supraquiasmático/fisiologia , Fatores de Transcrição ARNTL/genética , Animais , Relógios Biológicos , DNA Complementar/genética , Escuridão , Regulação da Expressão Gênica , Luz , Camundongos , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/genética , Especificidade de Órgãos , Proteínas Circadianas Period/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ajustamento SocialRESUMO
Abandoning daylight saving time in Europe raises the topical issue of proper setting of yearlong social time, which needs mapping of various socio-demographic factors, including chronotype, in specific geographic regions. This study represents the first detailed large scale chronotyping in the Czech Republic based on data collected in the complex panel socio-demographic survey in households (total 8760 respondents) and the socio-physiological survey, in which chronotyped participants also provided blood samples (n = 1107). Chronotype assessment based on sleep phase (MCTQ questions and/or time-use diary) correlated with a self-assessed interval of best alertness. The mean chronotype of the Czech population defined as mid sleep phase (MSFsc) was 3.13 ± 0.02 h. Chronotype exhibited significant east-to-westward, north-to-southward, and settlement size-dependent gradients and was associated with age, sex, partnership, and time spent outdoors as previously demonstrated. Moreover, for subjects younger than 40 years, childcare was highly associated with earlier chronotype, while dog care was associated with later chronotype. Body mass index correlated with later chronotype in women whose extreme chronotype was also associated with lower plasma levels of protective HDL cholesterol. Based on the chronotype prevalence the results favour yearlong Standard Time as the best choice for this geographic region.
Assuntos
Relógios Circadianos/fisiologia , Fotoperíodo , Sono/fisiologia , Inquéritos e Questionários/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Criança , Cronobiologia/estatística & dados numéricos , República Tcheca , Demografia/estatística & dados numéricos , Feminino , Humanos , Masculino , Fatores Sexuais , Fatores de Tempo , Adulto JovemRESUMO
The above article from British Journal of Pharmacology, published online as an Accepted Article on 19 August 2019 in Wiley Online Library (wileyonlinelibrary.com), has been withdrawn by agreement between the authors, the journal Editor-in-Chief Professor Amrita Ahluwalia, and John Wiley & Sons Limited. The withdrawal has been agreed owing to new findings that necessitate re-interpretation of the results.