Intestinal dysbiosis and circadian rhythm disruption are associated with similar diseases including obesity, metabolic syndrome, and inflammatory bowel disease. Despite the overlap, the potential ...relationship between circadian disorganization and dysbiosis is unknown; thus, in the present study, a model of chronic circadian disruption was used to determine the impact on the intestinal microbiome. Male C57BL/6J mice underwent once weekly phase reversals of the light:dark cycle (i.e., circadian rhythm disrupted mice) to determine the impact of circadian rhythm disruption on the intestinal microbiome and were fed either standard chow or a high-fat, high-sugar diet to determine how diet influences circadian disruption-induced effects on the microbiome. Weekly phase reversals of the light:dark (LD) cycle did not alter the microbiome in mice fed standard chow; however, mice fed a high-fat, high-sugar diet in conjunction with phase shifts in the light:dark cycle had significantly altered microbiota. While it is yet to be established if some of the adverse effects associated with circadian disorganization in humans (e.g., shift workers, travelers moving across time zones, and in individuals with social jet lag) are mediated by dysbiosis, the current study demonstrates that circadian disorganization can impact the intestinal microbiota which may have implications for inflammatory diseases.
Studies of body weight regulation have focused almost entirely on caloric intake and energy expenditure. However, a number of recent studies in animals linking energy regulation and the circadian ...clock at the molecular, physiological, and behavioral levels raise the possibility that the timing of food intake itself may play a significant role in weight gain. The present study focused on the role of the circadian phase of food consumption in weight gain. We provide evidence that nocturnal mice fed a high‐fat diet only during the 12‐h light phase gain significantly more weight than mice fed only during the 12‐h dark phase. A better understanding of the role of the circadian system for weight gain could have important implications for developing new therapeutic strategies for combating the obesity epidemic facing the human population today.
The molecular clock maintains energy constancy by producing circadian oscillations of rate-limiting enzymes involved in tissue metabolism across the day and night. During periods of feeding, ...pancreatic islets secrete insulin to maintain glucose homeostasis, and although rhythmic control of insulin release is recognized to be dysregulated in humans with diabetes, it is not known how the circadian clock may affect this process. Here we show that pancreatic islets possess self-sustained circadian gene and protein oscillations of the transcription factors CLOCK and BMAL1. The phase of oscillation of islet genes involved in growth, glucose metabolism and insulin signalling is delayed in circadian mutant mice, and both Clock and Bmal1 (also called Arntl) mutants show impaired glucose tolerance, reduced insulin secretion and defects in size and proliferation of pancreatic islets that worsen with age. Clock disruption leads to transcriptome-wide alterations in the expression of islet genes involved in growth, survival and synaptic vesicle assembly. Notably, conditional ablation of the pancreatic clock causes diabetes mellitus due to defective -cell function at the very latest stage of stimulus-secretion coupling. These results demonstrate a role for the -cell clock in coordinating insulin secretion with the sleep-wake cycle, and reveal that ablation of the pancreatic clock can trigger the onset of diabetes mellitus.
Background
Circadian rhythm disruption is a prevalent feature of modern day society that is associated with an increase in pro‐inflammatory diseases, and there is a clear need for a better ...understanding of the mechanism(s) underlying this phenomenon. We have previously demonstrated that both environmental and genetic circadian rhythm disruption causes intestinal hyperpermeability and exacerbates alcohol‐induced intestinal hyperpermeability and liver pathology. The intestinal microbiota can influence intestinal barrier integrity and impact immune system function; thus, in this study, we sought to determine whether genetic alteration of the core circadian clock gene, Clock, altered the intestinal microbiota community.
Methods
Male ClockΔ19‐mutant mice (mice homozygous for a dominant‐negative‐mutant allele) or littermate wild‐type mice were fed 1 of 3 experimental diets: (i) a standard chow diet, (ii) an alcohol‐containing diet, or (iii) an alcohol‐control diet in which the alcohol calories were replaced with dextrose. Stool microbiota was assessed with 16S ribosomal RNA gene amplicon sequencing.
Results
The fecal microbial community of Clock‐mutant mice had lower taxonomic diversity, relative to wild‐type mice, and the ClockΔ19 mutation was associated with intestinal dysbiosis when mice were fed either the alcohol‐containing or the control diet. We found that alcohol consumption significantly altered the intestinal microbiota in both wild‐type and Clock‐mutant mice.
Conclusions
Our data support a model by which circadian rhythm disruption by the ClockΔ19 mutation perturbs normal intestinal microbial communities, and this trend was exacerbated in the context of a secondary dietary intestinal stressor.
The etiology of abnormal eating behaviors, including binge-eating disorder, is poorly understood. The neural circuits modulating the activities of the neurotransmitters dopamine and serotonin are ...proposed to be dysfunctional in individuals suffering from eating disorders. Prader-Willi syndrome is a neurodevelopmental disorder that causes extreme food seeking and binge-eating behaviors together with reduced satiety. One of the genes implicated in Prader-Willi syndrome, Magel2, is highly expressed in the regions of the brain that control appetite. Our objective was to examine behaviors relevant to feeding and the neural circuits controlling feeding in a mouse model of Prader-Willi syndrome that lacks expression of the Magel2 gene. We performed behavioral tests related to dopaminergic function, measuring cocaine-induced hyperlocomotion, binge eating, and saccharin-induced anhedonia in Magel2-deficient mice. Next, we analyzed dopaminergic neurons in various brain regions and compared these findings between genotypes. Finally, we examined biochemical markers in the brain under standard diet, high-fat diet, and withdrawal from a high-fat diet conditions. We identified abnormal behaviors and biomarkers reflecting dopaminergic dysfunction in mice lacking Magel2. Our results provide a biological framework for clinical studies of dopaminergic function in children with Prader-Willi syndrome, and may also provide insight into binge-eating disorders that occur in the general population.
Affective behaviours and mental health are profoundly affected by disturbances in circadian rhythms. Casein kinase 1 epsilon (CSNK1E) is a core component of the circadian clock. Mice with tau or null ...mutation of this gene have shortened and lengthened circadian period respectively. Here, we examined anxiety‐like, fear, and despair behaviours in both male and female mice of these two different mutants. Compared with wild‐type mice, we found reductions in fear and anxiety‐like behaviours in both mutant lines and in both sexes, with the tau mutants exhibiting the greatest phenotypic changes. However, the behavioural despair had distinct phenotypic patterns, with markedly less behavioural despair in female null mutants, but not in tau mutants of either sex. To determine whether abnormal light entrainment of tau mutants to 24‐h light–dark cycles contributes to these phenotypic differences, we also examined these behaviours in tau mutants on a 20‐h light–dark cycle close to their endogenous circadian period. The normalized entrainment restored more wild‐type‐like behaviours for fear and anxiety, but it induced behavioural despair in tau mutant females. These data show that both mutations of Csnk1e broadly affect fear and anxiety‐like behaviours, while the effects on behavioural despair vary with genetics, photoperiod, and sex, suggesting that the mechanisms by which Csnk1e affects fear and anxiety‐like behaviours may be similar, but distinct from those affecting behavioural despair. Our study also provides experimental evidence in support of the hypothesis of beneficial outcomes from properly entrained circadian rhythms in terms of the anxiety‐like and fear behaviours.
Anxiety‐like, fear, and despair behaviours were examined in both male and female mice of Csnk1e wild type, null, and tau mutants. Compared with wild‐type mice, lower levels of fear and anxiety‐like behaviours were observed in both mutant lines and in both sexes. However, the behavioural despair had distinct phenotypic patterns, with markedly less behavioural despair in female null mutants, but not in tau mutants of either sex. To determine whether abnormal light entrainment of tau mutants to 24‐h light–dark cycles contributes to these phenotypic differences, these behaviours were also examined in tau mutants on a 20‐h light–dark cycle close to their endogenous circadian period. The normalized entrainment restored more wild‐type‐like behaviours for fear and anxiety, but it induced behavioural despair in tau mutant females.
Abstract
Study Objectives
Sleep deprivation induces systemic inflammation that may contribute to stress vulnerability and other pathologies. We tested the hypothesis that immunization with ...heat-killed Mycobacterium vaccae NCTC 11659 (MV), an environmental bacterium with immunoregulatory and anti-inflammatory properties, prevents the negative impacts of 5 days of sleep disruption on stress-induced changes in sleep, behavior, and physiology in mice.
Methods
In a 2 × 2 × 2 experimental design, male C57BL/6N mice were given injections of either MV or vehicle on days –17, –10, and –3. On days 1–5, mice were exposed to intermittent sleep disruption, whereby sleep was disrupted for 20 h per day. Immediately following sleep disruption, mice were exposed to 1-h social defeat stress or novel cage (control) conditions. Object location memory (OLM) testing was conducted 24 h after social defeat, and tissues were collected 6 days later to measure inflammatory markers. Sleep was recorded using electroencephalography (EEG) and electromyography (EMG) throughout the experiment.
Results
In vehicle-treated mice, only the combination of sleep disruption followed by social defeat (double hit): (1) increased brief arousals and NREM beta (15–30 Hz) EEG power in sleep immediately post-social defeat compared to baseline; (2) induced an increase in the proportion of rapid-eye-movement (REM) sleep and number of state shifts for at least 5 days post-social defeat; and (3) induced hyperlocomotion and lack of habituation in the OLM task. Immunization with MV prevented most of these sleep and behavioral changes.
Conclusions
Immunization with MV ameliorates a stress-induced sleep and behavioral phenotype that shares features with human posttraumatic stress disorder.
Mania-Like Behavior Induced by Disruption of CLOCK Roybal, Kole; Theobold, David; Graham, Ami ...
Proceedings of the National Academy of Sciences - PNAS,
04/2007, Letnik:
104, Številka:
15
Journal Article
Recenzirano
Odprti dostop
Circadian rhythms and the genes that make up the molecular clock have long been implicated in bipolar disorder. Genetic evidence in bipolar patients suggests that the central transcriptional ...activator of molecular rhythms, CLOCK, may be particularly important. However, the exact role of this gene in the development of this disorder remains unclear. Here we show that mice carrying a mutation in the Clock gene display an overall behavioral profile that is strikingly similar to human mania, including hyperactivity, decreased sleep, lowered depression-like behavior, lower anxiety, and an increase in the reward value for cocaine, sucrose, and medial forebrain bundle stimulation. Chronic administration of the mood stabilizer lithium returns many of these behavioral responses to wild-type levels. In addition, the Clock mutant mice have an increase in dopaminergic activity in the ventral tegmental area, and their behavioral abnormalities are rescued by expressing a functional CLOCK protein via viral-mediated gene transfer specifically in the ventral tegmental area. These findings establish the Clock mutant mice as a previously unrecognized model of human mania and reveal an important role for CLOCK in the dopaminergic system in regulating behavior and mood.
In addition to the characteristic motor symptoms, Parkinson's disease (PD) often involves a constellation of sleep and mood symptoms. However, the mechanisms underlying these comorbidities are ...largely unknown. We have previously reconstructed gene networks in the striatum of a population of (C57BL/6J x A/J) F2 mice and associated the networks to sleep and affective phenotypes, providing a resource for integrated analyses to investigate perturbed sleep and affective functions at the gene network level. Combining this resource with PD-relevant transcriptomic datasets from humans and mice, we identified four networks that showed elevated gene expression in PD patients, including a circadian clock and mitotic network that was altered similarly in mouse models of PD. We then utilized multiple types of omics data from public databases and linked this gene network to postsynaptic dopamine signaling in the striatum, CDK1-modulated transcriptional regulation, and the genetic susceptibility of PD. These findings suggest that dopamine deficiency, a key aspect of PD pathology, perturbs a circadian/mitotic gene network in striatal neurons. Since the normal functions of this network were relevant to sleep and affective behaviors, these findings implicate that dysregulation of functional gene networks may be involved in the emergence of non-motor symptoms in PD. Our analyses present a framework for integrating multi-omics data from diverse sources in mice and humans to reveal insights into comorbid symptoms of complex diseases.
The inbred mouse C57BL/6J is the reference strain for genome sequence and for most behavioral and physiological phenotypes. However, the International Knockout Mouse Consortium uses an embryonic stem ...cell line derived from a related C57BL/6N substrain. We found that C57BL/6N has a lower acute and sensitized response to cocaine and methamphetamine. We mapped a single causative locus and identified a nonsynonymous mutation of serine to phenylalanine (S968F) in Cytoplasmic FMRP interacting protein 2 (Cyfip2) as the causative variant. The S968F mutation destabilizes CYFIP2, and deletion of the C57BL/6N mutant alíele leads to acute and sensitized cocaine-response phenotypes. We propose that CYFIP2 is a key regulator of cocaine response in mammals and present a framework to use mouse substrains to identify previously unknown genes and alíeles regulating behavior.
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