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AIMS: Circadian syndrome (CircS) is considered a better predictor for cardiovascular disease than the metabolic syndrome (MetS). We aim to examine the associations between CircS and MetS with cognition in Chinese adults. METHOD: We used the data of 8546 Chinese adults aged ≥40 years from the 2011 China Health and Retirement Longitudinal Study. MetS was defined using harmonised criteria. CircS included the components of MetS plus short sleep and depression. The cut-off for CircS was set as ≥4. Global cognitive function was assessed during the face-to-face interview. RESULTS: CircS and MetS had opposite associations with the global cognition score and self-reported poor memory. Compared with individuals without the CircS and MetS, the regression coefficients (95%CI) for global cognition score were -1.02 (-1.71 to -0.34) for CircS alone and 0.52 (0.09 to 0.96) for MetS alone in men; -1.36 (-2.00 to -0.72) for CircS alone and 0.60 (0.15 to 1.06) for MetS alone in women. Having CircS alone was 2.53 times more likely to report poor memory in men (95%CI 1.80-3.55) and 2.08 times more likely in women (95%CI 1.54-2.81). In contrast, having MetS alone was less likely to report poor memory (OR 0.64 (0.49-0.84) in men and 0.65 (0.52-0.81) in women). People with CircS and MetS combined were more likely to have self-reported poor memory. CONCLUSIONS: CircS is a strong and better predictor for cognition impairment than MetS in Chinese middle-aged adults. MetS without short sleep and depression is associated with better cognition.
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Disfunção Cognitiva , Síndrome Metabólica , Humanos , Síndrome Metabólica/epidemiologia , Síndrome Metabólica/psicologia , Masculino , Feminino , Pessoa de Meia-Idade , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/epidemiologia , China/epidemiologia , Estudos Longitudinais , Idoso , Adulto , Prognóstico , Transtornos Cronobiológicos/complicações , Transtornos Cronobiológicos/epidemiologia , Fatores de Risco , Seguimentos , Ritmo Circadiano/fisiologiaRESUMO
Circadian disruption causes glucose intolerance, cardiac fibrosis, and adipocyte dysfunction in sand rats (Psammomys obesus). Exercise intervention can improve glucose metabolism, insulin sensitivity, adipose tissue function and protect against inflammation. We investigated the influence of exercise on male P. obesus exposed to a short photoperiod (5 h light:19 h dark) and high-energy diet. Exercise reduced glucose intolerance. Exercise reduced cardiac expression of inflammatory marker Ccl2 and Bax:Bcl2 apoptosis ratio. Exercise increased heart:body weight ratio and hypertrophy marker Myh7:Myh6, yet reduced Gata4 expression. No phenotypic changes were observed in perivascular fibrosis and myocyte area. Exercise reduced visceral adipose expression of inflammatory transcription factor Rela, adipogenesis marker Ppard and browning marker Ppargc1a, but visceral adipocyte size was unaffected. Conversely, exercise reduced subcutaneous adipocyte size but did not affect any molecular mediators. Exercise increased ZT7 Bmal1 and Per2 in the suprachiasmatic nucleus and subcutaneous Per2. Our study provides new molecular insights and histological assessments on the effect of exercise on cardiac inflammation, adipose tissue dysfunction and circadian gene expression in P. obesus exposed to short photoperiod and high-energy diet. These findings have implications for the protective benefits of exercise for shift workers in order to reduce the risk of diabetes and cardiovascular disease.
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Tecido Adiposo , Gerbillinae , Intolerância à Glucose , Fotoperíodo , Condicionamento Físico Animal , Animais , Masculino , Intolerância à Glucose/metabolismo , Tecido Adiposo/metabolismo , Inflamação/metabolismo , Inflamação/patologia , Dieta Hiperlipídica/efeitos adversos , Miocárdio/metabolismo , Miocárdio/patologiaRESUMO
Circadian disruption increases the development of cardiovascular disease and diabetes. We found that circadian disruption causes glucose intolerance, cardiac fibrosis and adipocyte tissue dysfunction in male sand rats, Psammomys obesus. Whether these effects occur in female P. obesus is unknown. Male and female P. obesus were fed a high energy diet and exposed to a neutral (12 light:12 dark, control) or short (5 light:19 dark, circadian disruption) photoperiod for 20 weeks. Circadian disruption impaired glucose tolerance in males but not females. It also increased cardiac perivascular fibrosis and cardiac expression of inflammatory marker Ccl2 in males, with no effect in females. Females had reduced proapoptotic Bax mRNA and cardiac Myh7:Myh6 hypertrophy ratio. Cardiac protection in females occurred despite reductions in the clock gene Per2. Circadian disruption increased adipocyte hypertrophy in both males and females. This was concomitant with a reduction in adipocyte differentiation markers Pparg and Cebpa in males and females, respectively. Circadian disruption increased visceral adipose expression of inflammatory mediators Ccl2, Tgfb1 and Cd68 and reduced browning marker Ucp1 in males. However, these changes were not observed in females. Collectively, our study show that sex differentially influences the effects of circadian disruption on glucose tolerance, cardiac function and adipose tissue dysfunction.
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Adipócitos , Fibrose , Gerbillinae , Intolerância à Glucose , Animais , Feminino , Adipócitos/metabolismo , Adipócitos/patologia , Masculino , Intolerância à Glucose/metabolismo , Miocárdio/metabolismo , Miocárdio/patologia , Ritmo CircadianoRESUMO
COVID-19 related lockdowns changed our life. Studies report that young women are more susceptible to lockdown-induced adverse effects and stress. As stress and menstrual cycle are associated, we hypothesized that menstrual cycle length might change during lockdown. We examined menstrual cycle length, and sleep-wake behaviors during lockdown in Israel. Participants were 97 women in their fertile years who used Tempdrop fertility sensor™ to track cycles. Data were collected before, during and after lockdown in Israel. Our main finding is that lockdown was associated with changes in menstrual cycle length of most participants, with either increased of decreased length. Changes were reversed when lockdown was terminated. Sleep duration increased during lockdown but we found no relationship between sleep and menstrual cycle. We suggest these findings contribute to the understanding of the relationship between stress, sleep, and menstrual cycle. Further studies should explore the sources for differential effects in sub-groups of women.
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COVID-19 , Ciclo Menstrual , Feminino , Humanos , COVID-19/epidemiologia , COVID-19/psicologia , Israel/epidemiologia , Sono , Transtornos do Sono do Ritmo Circadiano , Ritmo CircadianoRESUMO
Dysfunctional adipose tissue phenotype underpins type 2 diabetes mellitus (T2DM) development. The disruption of circadian rhythms contributes to T2DM development. We investigated the effects of high-energy diet and photoperiod length on visceral and subcutaneous adipose tissue phenotype. Psammomys obesus sand rats exposed to neutral (12 light:12 dark) or short (5 light:19 dark) photoperiod were fed a low- (LE) or high- (HE) energy diet. The HE diet and/or short photoperiod reduced subcutaneous expression of adipocyte differentiation/function markers C/ebpα, Pparδ, Pparγ and Adipoq. Visceral Pparα levels were elevated in the 5:19HE group; however, the HE diet and/or short photoperiod decreased visceral Pparγ and Adipoq expression. 5:19HE animals had elevated Ucp1 yet lower Pgc-1α levels. The HE diet increased visceral Tgf-ß1, Ccl2 and Cd68 levels, suggestive of a pro-inflammatory state. Daily visceral rhythms of these genes were affected by a short photoperiod and/or HE diet. The 12:12HE, 5:19LE or 5:19HE animals had a higher proportion of larger adipocytes, indicating increased adipocyte hypertrophy. Collectively, the HE diet and/or shorter light exposure drives a dysfunctional adipose tissue phenotype. Daily rhythms are affected by a short photoperiod and HE diet in a site-specific manner. These findings provide mechanistic insight on the influence of disrupted circadian rhythms and HE diet on adipose tissue phenotype.
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Adipócitos , Antígenos de Diferenciação/metabolismo , Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Dieta Hiperlipídica/efeitos adversos , Gordura Intra-Abdominal , Luz , Gordura Subcutânea , Adipócitos/metabolismo , Adipócitos/patologia , Animais , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/induzido quimicamente , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Gerbillinae , Gordura Intra-Abdominal/metabolismo , Gordura Intra-Abdominal/patologia , Obesidade/induzido quimicamente , Obesidade/metabolismo , Obesidade/patologia , Fotoperíodo , Gordura Subcutânea/metabolismo , Gordura Subcutânea/patologiaRESUMO
Although animals fine-tune their activity to avoid excess heat, we still lack a mechanistic understanding of such behaviors. As the global climate changes, such understanding is particularly important for projecting shifts in the activity patterns of populations and communities. We studied how foraging decisions vary with biotic and abiotic pressures. By tracking the foraging behavior of diurnal desert spiny mice in their natural habitat and estimating the energy and water costs and benefits of foraging, we asked how risk management and thermoregulatory requirements affect foraging decisions. We found that water requirements had the strongest effect on the observed foraging decisions. In their arid environment, mice often lose water while foraging for seeds and cease foraging even at high energetic returns when water loss is high. Mice also foraged more often when energy expenditure was high and for longer times under high seed densities and low predation risks. Gaining insight into both energy and water balance will be crucial to understanding the forces exerted by changing climatic conditions on animal energetics, behavior, and ecology.
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Comportamento Apetitivo/fisiologia , Murinae/fisiologia , Perda Insensível de Água/fisiologia , Animais , Temperatura Corporal/fisiologia , Clima Desértico , Ecossistema , Israel , Comportamento Predatório , SementesRESUMO
Preclinical Research Most neuropsychiatric research, including that related to the circadian system, is performed using nocturnal animals, mainly laboratory mice and rats. Mood disorders are known to be associated with circadian rhythm abnormalities, but the mechanisms by which circadian rhythm disruptions interact with depression remain unclear. As the circadian system of diurnal and nocturnal mammals differs, we previously suggested that the utilization of diurnal animal models may be advantageous for understanding these relations. During the last 10 years, we and others established the validity of several diurnal rodent species as a model for the interactions between circadian rhythms and depression. Diurnal rodents respond to photoperiod manipulation in a similar way to humans, the behavioral outcome is directly related to the circadian system, and treatment that is effective in patients is also effective in the model. Moreover, less effective treatments in patients are also less effective in the model. We, therefore, suggest that using diurnal animal models to study circadian rhythms-related affective disorders, such as depression, will provide new insights that will hopefully lead to the development of more effective treatments. Drug Dev Res 77 : 347-356, 2016. © 2016 Wiley Periodicals, Inc.
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Transtornos Cronobiológicos/fisiopatologia , Depressão/fisiopatologia , Transtornos do Humor/fisiopatologia , Animais , Transtornos Cronobiológicos/terapia , Ritmo Circadiano/fisiologia , Depressão/terapia , Modelos Animais de Doenças , Humanos , Camundongos , Transtornos do Humor/terapia , Fotoperíodo , Ratos , Especificidade da EspécieRESUMO
We report that two species of mouse-tailed bats (Rhinopoma microphyllum and R. cystops) hibernate for five months during winter in geothermally heated caves with stable high temperature (20°C). While hibernating, these bats do not feed or drink, even on warm nights when other bat species are active. We used thermo-sensitive transmitters to measure the bats' skin temperature in the natural hibernacula and open flow respirometry to measure torpid metabolic rate at different ambient temperatures (Ta, 16-35°C) and evaporative water loss (EWL) in the laboratory. Bats average skin temperature at the natural hibernacula was 21.7 ± 0.8°C, and no arousals were recorded. Both species reached the lowest metabolic rates around natural hibernacula temperatures (20°C, average of 0.14 ± 0.01 and 0.16 ± 0.04 ml O2 g(-1) h(-1) for R. microphyllum and R. cystops, respectively) and aroused from torpor when Ta fell below 16°C. During torpor the bats performed long apnoeas (14 ± 1.6 and 16 ± 1.5 min, respectively) and had a very low EWL. We hypothesize that the particular diet of these bats is an adaptation to hibernation at high temperatures and that caves featuring high temperature and humidity during winter enable these species to survive this season on the northern edge of their world distribution.
Assuntos
Cavernas , Quirópteros/fisiologia , Metabolismo Energético , Hibernação , Temperatura Alta , Perda Insensível de Água , AnimaisRESUMO
Circadian rhythms are strongly associated with affective disorders and recent studies have suggested utilization of diurnal rodents as model animal for circadian rhythms-related domains of these disorders. Previous work with the diurnal fat sand rat and Nile grass rat demonstrated that short photoperiod conditions result in behavioral changes including anxiety- and depression-like behavior. The present study examined the effect of manipulating day length on activity rhythms and behavior of the diurnal degu. Animals were housed for 3 weeks under either a short photoperiod (5-h:19-h LD) or a neutral photoperiod (12-h:12-h LD) and then evaluated by sweet solution test and the forced swim test for depression-like behavior, and in the light/dark box and open field for anxiety-like behavior. Results indicate that short photoperiod induced depression-like behavior in the forced swim test and the sweet solution preference test and anxiety-like behavior in the open field compared with animals maintained in a neutral photoperiod. No effects were shown in the light/dark box. Short photoperiod-acclimated degu showed reduced total activity duration and activity was not restricted to the light phase. The present study further supports the utilization of diurnal rodents to model circadian rhythms-related affective change. Beyond the possible diversity in the mechanisms underlying diurnality in different animals, there are now evidences that in three different diurnal species, the fat sand rat, the grass Nile rat and the degu, shortening of photoperiod results in the appearance of anxiety- and depression-like behaviors.
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Ritmo Circadiano/fisiologia , Modelos Animais de Doenças , Transtornos do Humor , Adaptação Ocular/fisiologia , Análise de Variância , Animais , Comportamento Exploratório/fisiologia , Preferências Alimentares , Masculino , Transtornos do Humor/fisiopatologia , Atividade Motora/fisiologia , Octodon , Natação/psicologiaRESUMO
Type 2 diabetes mellitus (T2DM) and its ocular complications, such as cataract and diabetic retinopathy (DR) have been linked to circadian rhythm-disturbances. Using a unique diurnal animal model, the sand rat (Psammomys obesus) we examined the effect of circadian disruption by short photoperiod acclimation on the development of T2DM and related ocular pathologies. We experimented with 48 male sand rats. Variables were day length (short photoperiod, SP, vs. neutral photoperiod NP) and diet (standard rodent diet vs. low-energy diet). Blood glucose, the presence of cataract and retinal pathology were monitored. Histological slides were examined for lens opacity, retinal cell count and thickness. Animals under SP and fed standard rodent diet (SPSR) for 20 weeks had higher baseline blood glucose levels and lower glucose tolerance compared with animals kept under NP regardless of diet, and under SP with low energy diet (SPLE). Animals under SPSR had less cells in the outer nuclear layer, a lower total number of cells in the retina, and a thickened retina. Higher blood glucose levels correlated with lower number of cells in all cellular layers of the retina and thicker retina. Animals under SPSR had higher occurrence of cataract, and a higher degree of cataract, which correlated with higher blood glucose levels. Sand rats kept under SPSR develop cataract and retinal abnormalities indicative of DR, whereas sand rats kept under NP regardless of diet, or under SPLE, do not. These ocular abnormalities significantly correlate with hyperglycemia.
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Catarata , Diabetes Mellitus Tipo 2 , Retinopatia Diabética , Intolerância à Glucose , Hiperglicemia , Animais , Masculino , Diabetes Mellitus Tipo 2/complicações , Fotoperíodo , Gerbillinae , Glicemia , Intolerância à Glucose/complicações , Retinopatia Diabética/complicações , Hiperglicemia/complicações , Catarata/patologiaRESUMO
Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian 'clock'), with the alternation of environmental light and darkness synchronizing (entraining) these rhythms to the natural day-night cycle. Our knowledge of the circadian system of animals at the molecular, cellular, tissue and organismal levels is remarkable, and we are beginning to understand how each of these levels contributes to the emergent properties and increased complexity of the system as a whole. For the most part, these analyses have been carried out using model organisms in standard laboratory housing, but to begin to understand the adaptive significance of the clock, we must expand our scope to study diverse animal species from different taxonomic groups, showing diverse activity patterns, in their natural environments. The seven papers in this Special Feature of Proceedings of the Royal Society B take on this challenge, reviewing the influences of moonlight, latitudinal clines, evolutionary history, social interactions, specialized temporal niches, annual variation and recently appreciated post-transcriptional molecular mechanisms. The papers emphasize that the complexity and diversity of the natural world represent a powerful experimental resource.
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Comportamento Animal/fisiologia , Relógios Circadianos/fisiologia , Modelos Biológicos , Animais , Relógios Circadianos/genética , Ritmo Circadiano/genética , Ritmo Circadiano/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MutaçãoRESUMO
Most studies in chronobiology focus on solar cycles (daily and annual). Moonlight and the lunar cycle received considerably less attention by chronobiologists. An exception are rhythms in intertidal species. Terrestrial ecologists long ago acknowledged the effects of moonlight on predation success, and consequently on predation risk, foraging behaviour and habitat use, while marine biologists have focused more on the behaviour and mainly on reproduction synchronization with relation to the Moon phase. Lately, several studies in different animal taxa addressed the role of moonlight in determining activity and studied the underlying mechanisms. In this paper, we review the ecological and behavioural evidence showing the effect of moonlight on activity, discuss the adaptive value of these changes, and describe possible mechanisms underlying this effect. We will also refer to other sources of night-time light ('light pollution') and highlight open questions that demand further studies.
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Comportamento Alimentar/fisiologia , Invertebrados/fisiologia , Luz , Lua , Animais , Comportamento Animal/fisiologia , Ritmo Circadiano/fisiologia , Comportamento Predatório/fisiologia , Reprodução/fisiologia , Vertebrados/fisiologiaRESUMO
The Israeli population of Eurasian otter (Lutra lutra) marks the Palearctic southern boundary of the species' distribution in the Levant. During the 20th century, the otter population in Israel experienced a dramatic decline due to anthropogenic habitat alterations. Currently, the otter population in Israel is estimated at about 100 individuals and defined as "Critically Endangered". The aim of this research was to characterize the Israeli otter population in order to determine its genetic diversity and fragmentation state for conservation purposes. Monitoring spraint sites during 2000-2011 along active and historic otter distribution regions indicate both stable and unstable otter subpopulations, mainly along the Jordan River. Four otter subpopulations, representing 57 individuals, were characterized by 12 microsatellites, previously used to characterize the European otter populations. The genetic results indicated three subpopulations correlating with three geographical regions: the Hula Valley, Sea of Galilee, and the Harod Valley. A moderate genetic diversity (F (st) = 0.087-0.123) was found among the subpopulations, suggesting sporadic interactions between individuals from distinct geographical locations along the Jordan Rift Valley. The Israeli otter population was found to be very small, demographically remote and genetically distinct, harboring unique alleles absent from the studied European populations. Therefore, immediate conservation actions are recommended to prevent the deterioration of the isolated, unique, and critically endangered otter population in Israel.
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Variação Genética , Lontras/genética , Alelos , Animais , Análise por Conglomerados , Feminino , Marcadores Genéticos , Genética Populacional , Geografia , Israel , Masculino , Repetições de MicrossatélitesRESUMO
BACKGROUND: Modern wars have a catastrophic effect on the wellbeing of civilians. However, the nature of this effect remains unclear, with most insights gleaned from subjective, retrospective studies. METHODS: We prospectively monitored 954 Israelis (>40 years) from two weeks before the May 2021 Israel-Gaza war until four weeks after the ceasefire using smartwatches and a dedicated mobile application with daily questionnaires on wellbeing. This war severely affected civilians on both sides, where over 4300 rockets and missiles were launched towards Israeli cities, and 1500 aerial, land, and sea strikes were launched towards 16,500 targets in the Gaza Strip. RESULTS: We identify considerable changes in all the examined wellbeing indicators during missile attacks and throughout the war, including spikes in heart rate levels, excessive screen-on time, and a reduction in sleep duration and quality. These changes, however, fade shortly after the war, with all affected measures returning to baseline in nearly all the participants. Greater changes are observed in individuals living closer to the battlefield, women, and younger individuals. CONCLUSIONS: The demonstrated ability to monitor objective and subjective wellbeing indicators during crises in real-time is pivotal for the early detection of and prompt assistance to populations in need.
This study investigated the impact of the May 2021 Israel-Gaza war on the wellbeing of Israeli civilians. To do so, 954 Israelis over the age of 40 were monitored for six weeks before and after the war using smartwatches and a mobile application that asked daily wellbeing questions. The researchers found that during the war, people experienced spikes in heart rate, decreased sleep quality and duration, and increased screen time. These changes were more significant in people living closer to the battlefield, women, and younger individuals. However, after the ceasefire, wellbeing indicators returned to baseline levels. The study shows that monitoring wellbeing in real-time during crises can help identify and assist populations in need.
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Chronotype reflects the morningness-eveningness preference over a 24-h period. Significant data indicates meaningful differences between evening types (ET) and morning types (MT) in behavior, personality traits, health and well-being. The aim of this study was to investigate cortisol response and subjective perceived stress of MT and ET individuals in response to an acute natural stressor. Twenty six definite MT (mean age 23.4 ± 1.7) and twenty six definite ET (mean age 23.8 ± 1.3) college students were recruited for this study. Participants were instructed to evaluate their perceived subjective stress and to provide saliva samples for cortisol levels at four different time points: Morning of regular school day, morning immediately before a final exam, afternoon of a regular school day and afternoon immediately before a final exam. For general mood assessment, the participants were also asked to fill out the Positive and Negative Affect Schedule (PANAS) questionnaire. The most outstanding finding of this study was the blunting of cortisol increase in response to acute stress in the morning in the ET group: Salivary cortisol was higher before a final exam only in MT but not in ET. However, no differences between the groups were found in the subjective stress measure. In the PANAS scale, ET showed lower positive affect, and a trend towards a higher negative affect. Overall, our results suggest dysregulation of cortisol response in ET individuals, possibly due to their daily struggle to function in a morning-oriented society. These results further highlight the challenges faced by ET individuals and raise the question of possible interventions to assist them.
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Ritmo Circadiano , Sono , Humanos , Adulto Jovem , Adulto , Sono/fisiologia , Ritmo Circadiano/fisiologia , Hidrocortisona , Cronotipo , Inquéritos e Questionários , Estresse PsicológicoRESUMO
We studied the relationship between sequence of foraging, energy acquired and use of torpor as an energy-balancing strategy in diurnally active desert golden spiny mice. We hypothesised that individuals that arrive earlier to forage will get higher returns and consequently spend less time torpid. If that is the case, then early foragers can be viewed as more successful; if the same individuals arrive repeatedly early, they are likely to have higher fitness under conditions of resource limitation. For the first time, we show a relationship between foraging sequence and amount of resources removed, with individuals that arrive later to a foraging patch tending to receive lower energetic returns and to spend more time torpid. Torpor bears not only benefits but also significant costs, so these individuals pay a price both in lower energy intake and in extended periods of torpor, in what may well be a positive feedback loop.
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Adaptação Fisiológica , Metabolismo Energético , Comportamento Alimentar , Murinae/fisiologia , Animais , Ritmo Circadiano , Dinâmica Populacional , TemperaturaRESUMO
Most mammals can be characterized as nocturnal or diurnal. However infrequently, species may overcome evolutionary constraints and alter their activity patterns. We modeled the fundamental temporal niche of a diurnal desert rodent, the golden spiny mouse, Acomys russatus. This species can shift into nocturnal activity in the absence of its congener, the common spiny mouse, Acomys cahirinus, suggesting that it was competitively driven into diurnality and that this shift in a small desert rodent may involve physiological costs. Therefore, we compared metabolic costs of diurnal versus nocturnal activity using a biophysical model to evaluate the preferred temporal niche of this species. The model predicted that energy expenditure during foraging is almost always lower during the day except during midday in summer at the less sheltered microhabitat. We also found that a shift in summer to foraging in less sheltered microhabitats in response to predation pressure and food availability involves a significant physiological cost moderated by midday reduction in activity. Thus, adaptation to diurnality may reflect the "ghost of competition past"; climate-driven diurnality is an alternative but less likely hypothesis. While climate is considered to play a major role in the physiology and evolution of mammals, this is the first study to model its potential to affect the evolution of activity patterns of mammals.
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Evolução Biológica , Ritmo Circadiano , Comportamento Alimentar , Modelos Biológicos , Murinae/fisiologia , Adaptação Fisiológica , Animais , Temperatura Corporal , Ecossistema , Metabolismo Energético , Temperatura , Água/metabolismoRESUMO
The lack of appropriate animal models for affective disorders is a major factor hindering better understanding of the underlying pathologies and the development of more efficacious treatments. Because circadian rhythms play an important role in affective disorders, we recently suggested that diurnal rodents can be advantageous as model animals. We found that in diurnal rodents, short photoperiod induces depression- and anxiety-like behaviors, with similarities to human seasonal affective disorder. In a pilot study we also found that these behaviors are ameliorated by morning bright light administration. In the present study we further evaluated the effects of morning and evening bright light administration on short photoperiod-induced depression- and anxiety-like behaviors in diurnal fat sand rats. Animals were maintained under short (5L:19D) or neutral (12L:12D) photoperiod and treated with morning or evening bright light or red dim light as control. Morning bright light ameliorated the behavioral deficits in the elevated plus maze and social interaction tests whereas evening bright light was effective only in the social interaction test. This is the first detailed presentation of the effects of bright light treatment in an animal model and a clear demonstration to the advantages of utilizing diurnal rodents to study interactions between circadian rhythms and affect.
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Ansiedade/terapia , Ritmo Circadiano , Depressão/terapia , Fotoperíodo , Fototerapia/métodos , Animais , Ansiedade/etiologia , Ansiedade/psicologia , Depressão/etiologia , Depressão/psicologia , Modelos Animais de Doenças , Gerbillinae , Relações Interpessoais , Luz , Aprendizagem em Labirinto/efeitos da radiação , Natação/psicologiaRESUMO
Modern lifestyle reduces environmental rhythmicity and may lead to circadian desynchrony. We are exposed to poor day-time lighting indoors and excessive night-time artificial light. We use air-conditioning to reduce ambient temperature cycle, and food is regularly available at all times. These disruptions of daily rhythms may lead to type 2 diabetes mellitus (T2DM), obesity, cardiometabolic diseases (CMD), depression and anxiety, all of which impose major public health and economic burden on societies. Therefore, we need appropriate animal models to gain a better understanding of their etiologic mechanisms, prevention, and management.We argue that the fat sand rat (Psammomys obesus), a diurnal animal model, is most suitable for studying the effects of modern-life conditions. Numerous attributes make it an excellent model to study human health disorders including T2DM, CMD, depression and anxiety. Here we review a comprehensive series of studies we and others conducted, utilizing the fat sand rat to study the underlying interactions between biological rhythms and health. Understanding these interactions will help deciphering the biological basis of these diseases, which often occur concurrently. We found that when kept in the laboratory (compared with natural and semi-wild outdoors conditions where they are diurnal), fat sand rats show low amplitude, nocturnal or arrhythmic activity patterns, dampened daily glucose rhythm, glucose intolerance, obesity and decreased survival rates. Short photoperiod acclimation exacerbates these pathologies and further dampens behavioral and molecular daily rhythms, resulting in CMD, T2DM, obesity, adipocyte dysfunction, cataracts, depression and anxiety. Increasing environmental rhythmicity by morning bright light exposure or by access to running wheels strengthens daily rhythms, and results in higher peak-to-trough difference in activity, better rhythmicity in clock genes expression, lower blood glucose and insulin levels, improved glucose tolerance, lower body and heart weight, and lower anxiety and depression. In summary, we have demonstrated that fat sand rats living under the correspondent of "human modern lifestyle" conditions exhibit dampened behavioral and biological rhythms and develop circadian desynchrony, which leads to what we have named "The Circadian Syndrome". Environmental manipulations that increase rhythmicity result in improvement or prevention of these pathologies. Similar interventions in human subjects could have the same positive results and further research on this should be undertaken.