蚤蝇的昼夜活动节律及睡眠行为研究

蚤蝇是重要的法医昆虫,同时是实验室中遗传、发育和生物测定等研究的重要对象。然而,蚤蝇的昼夜活动节律和睡眠行为及其在脑部的神经网络目前还不清晰。本文通过捕获本地蚤蝇并对其进行分子鉴定,研究了蚤蝇的昼夜活动节律和睡眠行为,同时表征了蚤蝇脑部核心钟神经元和多巴胺神经元。结果表明:蚤蝇在12h光照∶12h黑暗(12L∶12D)条件下不存在对开灯前或关灯前的活动预期,其双峰活动模式是对开关灯的光反应行为。在全黑暗(DD)条件下蚤蝇内源活动周期接近24h。黑腹果蝇神经肽PDF抗体免疫显示蚤蝇脑部核心钟神经元4~5个,不像黑腹果蝇一样存在明显的神经轴突。在睡眠行为上,蚤蝇雄虫和雌虫在整体活动强度、睡眠节律模式、总睡眠上均没有明显差异。相反,雄虫总睡眠次数和晚上睡眠次数低于雌虫,而总睡眠持续时间、晚上睡眠持续时间、总入睡时间和晚上入睡时间高于雌虫。此外,影响睡眠的重要多巴胺神经元在蚤蝇脑部的分布与黑腹果蝇类似。     

Effect of LED light spectra on exogenous prolactin-regulated circadian rhythm in goldfish,Carassius auratus

We investigated the effect of light spectra on circadian rhythm by exogenous prolactin (PRL) using light-emitting diodes (LEDs): red, green and purple. We injected PRL into live fish or treated cultured brain cells with PRL. We measured changes in the expressions of period 2 (Per2), cryptochrome 1 (Cry1), melatonin receptor 1 (MT1) mRNAs, and MT1 proteins, and in the plasma PRL, serotonin and melatonin levels. After PRL injection and exposure to green light, MT1 expression and plasma melatonin levels were significantly lower, but the expressions of Per2 and Cry1 were significantly higher than the others. Plasma serotonin after PRL injection and exposure to red light was significantly lower than others. These results indicate that injection of high concentration PRL inhibits melatonin, and inhibited melatonin regulates circadian rhythm via clock genes and serotonin. Thus, exogenous PRL regulates the circadian rhythm and light spectra influence the effect of PRL in goldfish.     

The inner clock—Blue light sets the human rhythm

Visible light synchronizes the human biological clock in the suprachiasmatic nuclei of the hypothalamus to the solar 24‐hour cycle. Short wavelengths, perceived as blue color, are the strongest synchronizing agent for the circadian system that keeps most biological and psychological rhythms internally synchronized. Circadian rhythm is important for optimum function of organisms and circadian sleep–wake disruptions or chronic misalignment often may lead to psychiatric and neurodegenerative illness. The beneficial effect on circadian synchronization, sleep quality, mood, and cognitive performance depends not only on the light spectral composition but also on the timing of exposure and its intensity. Exposure to blue light during the day is important to suppress melatonin secretion, the hormone that is produced by the pineal gland and plays crucial role in circadian rhythm entrainment. While the exposure to blue is important for keeping organism's wellbeing, alertness, and cognitive performance during the day, chronic exposure to low‐intensity blue light directly before bedtime, may have serious implications on sleep quality, circadian phase and cycle durations. This rises inevitably the need for solutions to improve wellbeing, alertness, and cognitive performance in today's modern society where exposure to blue light emitting devices is ever increasing.      

Twofold effect of blue light on a circadian rhythm in Acetabularia

Abstract

The circadian chloroplast migration in Acetabularia mediterranea was monitored by continuously measuring the transmission of the cells near the apex. Under continuous red light the amplitude of the rhythm decreased rapidly within a few days. However, circadian changes of chloroplast density were still detectable even after 28 days of red light, indicating the persistence of the rhythm. When blue light was added after red light preirradiation of several days phase shifts were observed which were expressed as advances as well as delays. The period of the rhythm proved to be strongly dependent on the intensity of the continuous blue light which was given in addition to red light. Different red light intensities did not change the period. The occurrence of both effects indicates that the sensory transduction of blue light photoreception in Acetabularia works in two different ways: quanta counting processes and processes of light intensity measurement.     

Effects of melatonin and antagonists of MT1 and MT2 receptors on somatic pain induced within the fixed circadian rhythm

We studied behavioral pain-related reactions (PRRs) induced in mice by subcutaneous injections of 5% formalin within different phases of the fixed circadian illumination rhythm under conditions of administration of exogenous melatonin and of blocking of MT1 and MT2 melatonin receptors. It was demonstrated that modulation of experimentally induced somatic pain depends considerably on the phase of the preset circadian rhythm. In the norm, the duration of PRRs in the middle of the dark phase was 30% smaller than that in the middle of the light phase. Administration of exogenous melatonin in the middle of the light phase decreased the duration of episodes of noxious behavior by 43%, on average. Injections of melatonin within the dark phase resulted in no significant changes in the duration of PRRs. In the dark phase, the blockade of MT1 receptors by luzindole led to an increase in the duration of PRRs by 45%, as compared with the norm, while in the light phase we observed no significant alterations of this duration under conditions of blocking of the above-mentioned receptors. The blockade of MT2 receptors by prazocine in the middle of dark and light phases increased the durations of PRRs by 92 and 28%, respectively. Our data indicate that the analgesic effect of melatonin depends significantly on the level of this hormone in the organism; in turn, such a level is determined by the illumination conditions. The antinoxious effect of melatonin is mediated by MT receptors, in particular by MT2 receptors. Neirofiziologiya/Neurophysiology, Vol. 39, No. 3, pp. 255–259, May–June, 2007.     

Effects of various LED light spectra on circadian rhythm during starvation in the olive flounder (Paralichthys olivaceus)

In aquaculture, feeding is essential for the maintenance of metabolic processes and homoeostasis of fish. However, fasting acts as a stressor. In this study, we investigated the effect of circadian rhythm under various LED wavelengths [blue (460 nm), green (520 nm) and red (630 nm)] and two light intensities (0.3 and 0.6 W m^?2) over a 9-days period in the olive flounder (Paralichthys olivaceus). We analysed clock genes like period 2 (Per 2) and cryptochrome 1 (Cry 1), and serotonin and arylalkylamine-N-acetyltransferase 2 (AANAT 2), which control circadian rhythms. Per 2, Cry 1, serotonin and AANAT 2 were significantly decreased during the starvation period compared to the normal feeding group. Nevertheless, their levels increased in the groups exposed to green- and blue LED light during the experimental period. These results confirmed that green and blue wavelengths are effective in maintaining the circadian rhythm in olive flounder.     

A randomized,double-blind and placebo-controlled crossover trial on the effect of l-ornithine ingestion on the human circadian clock

ABSTRACT

In mammals, daily physiological events are regulated by the circadian rhythm, which comprises two types of internal clocks: the central clock and peripheral clocks. Circadian rhythm plays an important role in maintaining physiological functions including the sleep-wake cycle, body temperature, metabolism and organ functions. Circadian rhythm disorder, which is caused, for example, by an irregular lifestyle or long-haul travel, increases the risk of developing disease; therefore, it is important to properly maintain the rhythm of the circadian clock. Food and the circadian clock system are known to be closely linked. Studies on rodents suggest that ingesting specific food ingredients, such as the flavonoid nobiletin, fish oil, the polyphenol resveratrol and the amino acid L-ornithine affects the circadian clock. However, there are few reports on the foods that affect these circadian clocks in humans. In this study, therefore, we examined whether L-ornithine affects the human central clock in a crossover design placebo-controlled human trial. In total, 28 healthy adults (i.e. ≥20 years) were randomly divided into two groups and completed the study protocol. In the 1st intake period, participants were asked to take either L-ornithine (400 mg) capsules or placebo capsules for 7 days. After 7 days’ interval, they then took the alternative test capsules for 7 days in the 2nd intake period. On the final day of each intake period, saliva was sampled at various time points in the dim light condition, and the concentration of melatonin was quantified to evaluate the phase of the central clock. The results revealed that dim light melatonin onset, a recognized marker of central circadian phase, was delayed by 15 min after ingestion of L-ornithine. Not only is this finding an indication that L-ornithine affects the human central clock, but it also demonstrates that the human central clock can be regulated by food ingredients.     

Late circadian phase in adults and children is correlated with use of high color temperature light at home at night

Light is the strongest synchronizer of human circadian rhythms, and exposure to residential light at night reportedly causes a delay of circadian rhythms. The present study was conducted to investigate the association between color temperature of light at home and circadian phase of salivary melatonin in adults and children. Twenty healthy children (mean age: 9.7 year) and 17 of their parents (mean age: 41.9 years) participated in the experiment. Circadian phase assessments were made with dim light melatonin onset (DLMO). There were large individual variations in DLMO both in adults and children. The average DLMO in adults and in children were 21:50 ± 1:12 and 20:55 ± 0:44, respectively. The average illuminance and color temperature of light at eye level were 139.6 ± 82.7 lx and 3862.0 ± 965.6 K, respectively. There were significant correlations between color temperature of light and DLMO in adults (r = 0.735, p < 0.01) and children (r = 0.479, p < 0.05), although no significant correlations were found between illuminance level and DLMO. The results suggest that high color temperature light at home might be a cause of the delay of circadian phase in adults and children.     

Time estimation circadian rhythm in shift workers and diurnally active humans

The ability of shift workers to estimate timer intervals of short duration was examined. The study included 22 shift workers and 10 diurnally working control subjects. A circadian rhythm in time estimates was documented in control subjects, but it was found to bed disrupted in shift workers. Spectral analysis revealed frequency or circadian component in time estimates to be lower among the shift workers. Furthermore, an interesting relationship was marked between time estimates and oral temperature in 4 control subjects and 6 shift workers in that the time of the closest estimation coincided with the peak time of their body temperature.     

The development of circadian rhythm of human body temperature

Abstract

Daily periodic changes of body temperature were examined in 138 subjects ranging in age between 5 days and 44 years. Whereas the circadian rhythm of human body temperature was not discerned in newborn babies, body temperatures were higher during daytime than during nighttime in infants over one month. Temperature rhythm similar to that of adults, with respect to phase, was observed in the age groups of ten to eleven months and over, earlier than previously reported. The amplitude in circadian oscillation was, however, significantly larger in children between 7 months and 7 years of age than in adults. Thus, it is concluded that the adult type of circadian rhythm of human body temperature is fully established with respect to phase and amplitude after 7 years of age.     

Effect of light on the development of the circadian rhythm of motor activity in the mouse

In previous experiments, we found that rats raised in constant light (LL) manifested a more robust circadian rhythm of motor activity in LL and showed longer phase shifts after a light pulse in constant darkness (DD) than those raised under constant darkness. In addition, we observed that the effects produced by constant light differed depending on the time of postnatal development in which it was given. These results suggest that both sensitivity to light and the functioning of the circadian pacemaker of the rat could be affected by the environmental conditions experienced during postembryonic development. Thus, the present experiment aimed to study whether postnatal exposure to light could also affect the circadian system of the mouse. Three groups of mice were formed: One group was raised under constant darkness during lactation (DD group), the second under constant light (LL group), and the third under light-dark cycles (LD group). After lactation, the three groups were submitted first to constant light of high intensity, then to LD cycles, and finally to constant darkness. In the DD stage, a light pulse was given. Finally, mice were submitted to constant light of low intensity. We observed that the circadian rhythm of the DD group was more disturbed under constant light than the rhythm of the LL group, and that, when light intensity increased, the period of the rhythm of the DD group lengthened more than that of the LL group. No significant differences among the groups were found in the phase shift induced by the light pulse. Therefore, it appears that DD mice are more sensitive to light than their LL counterparts. However, at present there is no evidence to affirm that the light environment experienced by the mouse during postnatal development affects the circadian pacemaker. (Chronobiology International, 18(4), 683-696, 2001)     

Effects of bisphenol A and light conditions on the circadian rhythm of the goldfish Carassius auratus

We investigated how exposure to bisphenol A (BPA) under different photoperiodic conditions affected the expression of clock genes in the brain and liver of the goldfish, Carassius auratus. Three photoperiodic conditions were used: control, LD; continuous light, LL; and continuous dark, DD; the fish were exposed to three concentrations of BPA, namely 0, 10, or 100 μg/L. We measured changes in the expression of cryptochrome 1 (Cry1), period 2 (Per2), and melatonin receptor 1 (MT-R1). The levels of Cry1, Per2, and MT-R1 mRNAs decreased with increasing BPA concentration and with increasing exposure time. Expression of Cry1 and Per2 increased more in the LL group than in the LD and DD groups. However, for MT-R1, the DD group showed increased expression compared to the LL and LD groups. Our analysis shows that circadian rhythms in goldfish can be disrupted by exposure to BPA and that the response can be modified by regulating the photoperiod.     

Is there a 24-hour rhythm in alcohol craving and does it vary by sleep/circadian timing?

ABSTRACT

Increasing evidence implicates sleep/circadian factors in alcohol use; however, the role of such factors in alcohol craving has received scant attention. Prior research suggests a 24-hour rhythm in related processes (e.g., reward motivation), but more research directly investigating a rhythm in craving is needed. Moreover, prior evidence is ambiguous whether such a rhythm in alcohol craving may vary by sleep/circadian timing. To examine these possibilities, 36 late adolescents (18–22 years of age; 61% female) with regular alcohol use but without a current alcohol use disorder were recruited to complete smartphone reports of alcohol craving intensity six times a day for two weeks. During these two weeks, participants wore wrist actigraphs and completed two in-lab assessments (on Thursday and Sunday) of dim light melatonin onset (DLMO). Average actigraphically derived midpoint of sleep on weekends and average DLMO were used as indicators of sleep and circadian timing, respectively. Multilevel cosinor analysis revealed a 24-hour rhythm in alcohol craving. Findings across the sleep and circadian timing variables converged to suggest that sleep/circadian timing moderated the 24-hour rhythm in alcohol craving. Specifically, people with later sleep/circadian timing had later timing of peak alcohol craving. These findings add to the growing evidence of potential circadian influences on reward-related phenomena and suggest that greater consideration of sleep and circadian influences on alcohol craving may be useful for understanding alcohol use patterns and advancing related interventions.     

A rapid circadian rhythm of carbon-dioxide metabolism in Bryophyllum fedtschenkoi

Leaves of Bryophyllum fedtschenkoi Hamet et Perrier maintained in a stream of normal air and at 15° C exhibit a circadian rhythm of CO₂ uptake in continuous light but not in continuous darkness. The rhythm is unusual in that it persists for at least 10 d, and has a short period of approximately 18 h. The mechanism by which this rhythm is generated is discussed.Abbreviation PEPCase phosphoenolpyruvate carboxylase     

The individual development of circadian temperature rhythm in infants

Abstract

The aim of this study was to explore the individual development of the circadian rhythm of human body temperature. Dailyperiodicchanges of body temperature were examined longitudinally in four infants from 3 to 18 months of age. At the 3rd month of life, the day‐night rhythm of the body temperature was obscure but at the 6th month it became moreevident. From the 12th month on, the circadian temperature rhythm with phase similar to that of the adult was discerned. However, the amplitude in circadian rhythm was significantly larger in children between 6 and 18 months of age than in the adult. These findings suggest that the adult type of circadian rhythm of human body temperature is established during the first year of life with regard to phase but not to amplitude.     

Rest-activity circadian rhythm and sleep quality in patients with binge eating disorder

Recent findings suggest that altered rest-activity circadian rhythms (RARs) are associated with a compromised health status. RARs abnormalities have been observed also in several pathological conditions, such as cardiovascular, neurological, and cancer diseases. Binge eating disorder (BED) is the most common eating disorder, with a prevalence of 3.5% in women and 2% in men. BED and its associate obesity and motor inactivity could induce RARs disruption and have negative consequences on health-related quality of life. However, the circadian RARs and sleep behavior in patients with BED has been so far assessed only by questionnaires. Therefore, the purpose of this study was to determine RARs and sleep parameters by actigraphy in patients with BED compared to a body mass index-matched control group (Ctrl). Sixteen participants (eight obese women with and eight obese women without BED diagnosis) were recruited to undergo 5-day monitoring period by actigraphy (MotionWatch 8®, CamNtech, Cambridge, UK) to evaluate RARs and sleep parameters. In order to determine the RARs, the actigraphic data were analyzed using the single cosinor method. The rhythmometric parameters of activity levels (MESOR, amplitude and acrophase) were then processed with the population mean cosinor.

The Actiwatch Sleep Analysis Software (Cambridge Neurotecnology, Cambridge, UK) evaluated the sleep patterns. In each participant, we considered seven sleep parameters (sleep onset: S-on; sleep offset: S-off; sleep duration: SD; sleep latency: SL; movement and fragmentation index: MFI; immobility time: IT; sleep efficiency: SE) calculated over a period of five nights.

The population mean cosinor applied to BED and Ctrl revealed the presence of a significant circadian rhythm in both groups (p < 0.001). The MESOR (170.0 vs 301.6 a.c., in BED and Ctrl, respectively; p < 0.01) and amplitude (157.66 vs 238.19 a.c., in BED and Ctrl, respectively p < 0.05) differed significantly between the two groups. Acrophase was not different between BED and Ctrl, as well as all sleep parameters. Both groups displayed a low level of sleep quality (SE 80.7% and 75.7% in BED and Ctrl, respectively). These data provided the first actigraphy-based evidence of RARs disruption and sleep behavior disorder in patients with BED. However, while sleep disorders could be reasonably ascribed to overweight/obesity and the related lower daily physical activity, RARs disruption in this pathology should be ascribed to factors other than reduced physical activity. The circadian timing approach can represent a novel potential tool in the treatment of patients with eating disorders. These data provide exploratory evidence of behavioral association in a small population of patients that, if confirmed in a wider number of subjects and across different populations, may lead to a revision and enhancement of interventions in BED patients.     

Analysis of trough and peak of plasma melatonin circadian rhythm in ewes

This study evaluates the pattern of plasma melatonin during the trough and the peak of its daily rhythm. Blood samples from 8 ewes were collected every 3 h for a 48-h period. On the third day, blood samples were collected from 10:00 to 13:00 (trough) and from 20:00 to 23:00 (peak) every 20 min. Our results showed a robust daily rhythm of melatonin in both days of monitoring, with nocturnal acrophase. During the trough, a significant decrease was observed starting from the 10:40 with a progressive decrease about every 40 min. During the peak of the plasma melatonin daily rhythm, an increase was observed starting from the 20:40 with a progressive increase about every 40 min. These data could be taken in consideration to monitor the plasma melatonin variations during the 24 h, and for the administration of melatonin for breeding in ewes.     

褪黑素对大鼠下丘脑薄片视交叉上核神经元放电昼夜节律性的调制

先用持续光照和松果腺切除预处理大鼠,然后制成下丘脑薄片,记录其视交叉上核（ＳＣＮ）神经元自发放电,观察其昼夜变化和褪黑素（ＭＥＬ）对它的影响。实验结果表明：⑴在正常光照（光照：黑暗＝１２：１２）条件下,ＳＣＮ神经元自发放电频率呈现昼夜低的节律性。在昼夜时间（ＣＴ）６－８出现放电高峰,频率约为８．３Ｈｚ;在ＣＴ１８－２０出现低谷,频率约为３．８Ｈｚ。松果腺切除后,ＳＣＮ神经元自发放电的昼夜节律性基本     

生物钟信号调控的营养学

近日节律是生物界普遍存在的一种生理现象,而内源性生物钟是产生近日节律的物质基础,它能使生物体感知并适应环境中的光、温度和食物等周期信号,从而使生物体与外界环境保持周期同步。研究表明,葡萄糖、胆固醇、腺苷、咖啡因、维生素A和视黄酸等营养物质能通过各自不同的方式调控哺乳动物的生物钟,影响其近日节律的信号输出。本文概述了至今为止研究发现的各类与生物钟信号调控相关的营养物质及功能的相关研究进展。     

Melatonin administration modifies circadian motor activity under constant light depending on the lighting conditions during suckling

Early lighting conditions have been described to produce long-term effects on circadian behavior, which may also influence the response to agents acting on the circadian system. It has been suggested that melatonin (MEL) may act on the circadian pacemaker and as a scavenger of reactive oxygen and nitrogen species. Here, we studied the oxidative and behavioral changes caused by prolonged exposure to constant light (LL) in groups of rats that differed in MEL administration and in lighting conditions during suckling. The rats were exposed to either a light–dark cycle (LD) or LL. At 40 days old, rats were treated for 2 weeks with a daily subcutaneous injection of MEL (10?mg/kg body weight) or a vehicle at activity onset. Blood samples were taken before and after treatment, to determine catalase (CAT) activity and nitrite level in plasma. As expected, LL-reared rats showed a more stable motor activity circadian rhythm than LD rats. MEL treatment produced more reactivity in LD- than in LL rats, and was also able to alter the phase of the rhythm in LD rats. There were no significant differences in nitrite levels or CAT activity between the groups, although both variables increased with time. Finally, we also tested depressive signs by means of sucrose consumption, and anhedonia was found in LD males treated with MEL. The results suggest that the lighting conditions in early infancy are important for the long-term functionality of the circadian system, including rhythm manifestation, responses to MEL and mood alterations.