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1.
Rev. int. androl. (Internet) ; 21(4): 1-9, oct.-dic. 2023. ilus, tab, graf
Article in English | IBECS | ID: ibc-225999

ABSTRACT

Introduction: Radiofrequency electromagnetic fields (RF-EMFs) are one of the risk factors for male reproductive health and melatonin can be an ideal candidate for therapeutic development against RF-induced male fertility problems due to its antioxidant properties. The possible therapeutic role of melatonin in the destructive effects of 2100MHz RF radiation on rat sperm characteristics is investigated in the present study. Methods: Wistar albino rats were divided into four groups and the experiment continued for ninety consecutive days; Control, Melatonin (10mg/kg, subcutaneously), RF (2100MHz, thirty minutes per day, whole-body), and RF+Melatonin groups. Left caudal epididymis and ductus deferens tissues were placed in sperm wash solution (at 37°C) and dissected. The sperms were counted and stained. Measurements of the perinuclear ring of the manchette and posterior portion of the nucleus (ARC) were performed and the sperms were examined at an ultrastructural level. All of the parameters were evaluated statistically. Results: The percentages of abnormal sperm morphology were significantly increased with RF exposure, while the total sperm count was significantly decreased. RF exposure also showed harmful effects on acrosome, axoneme, mitochondrial sheath, and outer dense fibers at the ultrastructural level. The number of total sperms, sperms with normal morphology increased, and ultrastructural appearance returned to normal by melatonin administration. Discussion: The data showed that melatonin may be a beneficial therapeutic agent for long-term exposure of 2100MHz RF radiation-related reproductive impairments. (AU)


Introducción: Los campos electromagnéticos de radiofrecuencia (RF-EMF) son uno de los factores de riesgo para la salud reproductiva masculina y la melatonina puede ser un candidato ideal para el desarrollo terapéutico contra los problemas de fertilidad masculina inducidos por RF debido a sus propiedades antioxidantes. En el presente estudio se investiga el posible papel terapéutico de la melatonina en los efectos destructivos de la radiación RF de 2100MHz en las características del esperma de rata. Métodos: Se dividieron ratas albinas Wistar en 4 grupos y se continuó el experimento durante 90 días consecutivos: grupos control, melatonina (10mg/kg, por vía subcutánea), RF (2100MHz, 30min por día, cuerpo entero) y RF+melatonina. Los tejidos del epidídimo caudal izquierdo y del conducto deferente se colocaron en una solución de lavado de esperma (a 37°C) y se diseccionaron. Los espermatozoides fueron contados y teñidos. Se realizaron mediciones del anillo perinuclear del manchette y de la porción posterior del núcleo (ARC) y se examinaron los espermatozoides a nivel ultraestructural. Todos los parámetros fueron evaluados estadísticamente. Resultados: Los porcentajes de morfología anormal de los espermatozoides aumentaron significativamente con la exposición a RF, mientras que el recuento total de espermatozoides disminuyó significativamente. La exposición a RF también mostró efectos nocivos en el acrosoma, el axonema, la vaina mitocondrial y las fibras densas externas a nivel ultraestructural. El número total de espermatozoides, los espermatozoides con morfología normal aumentaron y la apariencia ultraestructural volvió a la normalidad mediante la administración de melatonina. Discusión: Los datos mostraron que la melatonina puede ser un agente terapéutico beneficioso para la exposición a largo plazo de las deficiencias reproductivas relacionadas con la radiación de RF de 2100MHz. (AU)


Subject(s)
Animals , Rats , Melatonin/radiation effects , Melatonin/therapeutic use , Reproductive Health , Semen/physiology , Rats, Wistar , Radio Waves/adverse effects , Infertility, Male , Spermatogenesis
2.
Int J Mol Sci ; 21(24)2020 Dec 21.
Article in English | MEDLINE | ID: mdl-33371255

ABSTRACT

The metabolism of pineal indoles is closely related to alterations in the light and dark phases of a daily cycle. Recent research showed important interspecies differences in the pineal biochemistry, and a strong impact of monochromatic light on many physiological processes in birds. Therefore, the aims of study were to characterize the metabolism of melatonin-synthesis indoles in the pineal organ of the domestic turkey, and to determine the changes occurring in this metabolism under the influence of different wavelengths and intensities of light. For this purpose, 3-week-old turkeys were kept under 16 lx white light, or under blue, green, and red light with intensities of 16, 32, and 64 lx during the photophase, and after 7 d were sacrificed at 4 h intervals. The activities of melatonin-synthesizing enzymes and the contents of indoles were measured in the same pineal organ. The results revealed that the activities of tryptophan hydroxylase and arylalkylamine N-acetyltransferase, and the levels of all tryptophan derivatives had significant daily changes in birds kept under each light condition used. The profile of pineal indole metabolism in 4-week-old turkeys was characterized by high-amplitude rhythms in the activity of arylalkylamine N-acetyltransferase and the contents of N-acetylserotonin and melatonin, equal relative amounts of serotonin and 5-hydroxyindoleacetic acid, and higher content of melatonin than N-acetylserotonin. The monochromatic light significantly modified the pineal indole metabolism, and its effects were dependent on the color and intensity of light. Pronounced changes occurred in the level of serotonin synthesis and the daily rhythm course of melatonin synthesis.


Subject(s)
Circadian Rhythm , Indoles/metabolism , Light , Melatonin/biosynthesis , Photoperiod , Pineal Gland/physiology , Animals , Female , Indoles/radiation effects , Melatonin/radiation effects , Pineal Gland/radiation effects , Turkeys
3.
J Biol Rhythms ; 35(6): 628-640, 2020 12.
Article in English | MEDLINE | ID: mdl-33063595

ABSTRACT

There is large interindividual variability in circadian timing, which is underestimated by mathematical models of the circadian clock. Interindividual differences in timing have traditionally been modeled by changing the intrinsic circadian period, but recent findings reveal an additional potential source of variability: large interindividual differences in light sensitivity. Using an established model of the human circadian clock with real-world light recordings, we investigated whether changes in light sensitivity parameters or intrinsic circadian period could capture variability in circadian timing between and within individuals. Healthy participants (n = 12, aged 18-26 years) underwent continuous light monitoring for 3 weeks (Actiwatch Spectrum). Salivary dim-light melatonin onset (DLMO) was measured each week. Using the recorded light patterns, a sensitivity analysis for predicted DLMO times was performed, varying 3 model parameters within physiological ranges: (1) a parameter determining the steepness of the dose-response curve to light (p), (2) a parameter determining the shape of the phase-response curve to light (K), and (3) the intrinsic circadian period (tau). These parameters were then fitted to obtain optimal predictions of the three DLMO times for each individual. The sensitivity analysis showed that the range of variation in the average predicted DLMO times across participants was 0.65 h for p, 4.28 h for K, and 3.26 h for tau. The default model predicted the DLMO times with a mean absolute error of 1.02 h, whereas fitting all 3 parameters reduced the mean absolute error to 0.28 h. Fitting the parameters independently, we found mean absolute errors of 0.83 h for p, 0.53 h for K, and 0.42 h for tau. Fitting p and K together reduced the mean absolute error to 0.44 h. Light sensitivity parameters captured similar variability in phase compared with intrinsic circadian period, indicating they are viable targets for individualizing circadian phase predictions. Future prospective work is needed that uses measures of light sensitivity to validate this approach.


Subject(s)
Biological Variation, Individual , Circadian Clocks/radiation effects , Circadian Rhythm/radiation effects , Light , Humans , Melatonin/radiation effects , Sleep/physiology , Sleep/radiation effects
4.
J Biol Rhythms ; 35(4): 405-415, 2020 08.
Article in English | MEDLINE | ID: mdl-32539484

ABSTRACT

Electric light has enabled humans to conquer the night, but light exposure at night can disrupt the circadian timing system and is associated with a diverse range of health disorders. To provide adequate lighting for visual tasks without disrupting the human circadian timing system, a precise definition of circadian spectral sensitivity is required. Prior attempts to define the circadian spectral sensitivity curve have used short (≤90-min) monochromatic light exposures in dark-adapted human subjects or in vitro dark-adapted isolated retina or melanopsin. Several lines of evidence suggest that these dark-adapted circadian spectral sensitivity curves, in addition to 430- to 499-nm (blue) wavelength sensitivity, may include transient 400- to 429-nm (violet) and 500- to 560-nm (green) components mediated by cone- and rod-originated extrinsic inputs to intrinsically photosensitive retinal ganglion cells (ipRGCs), which decay over the first 2 h of extended light exposure. To test the hypothesis that the human circadian spectral sensitivity in light-adapted conditions may have a narrower, predominantly blue, sensitivity, we used 12-h continuous exposures of light-adapted healthy human subjects to 6 polychromatic white light-emitting diode (LED) light sources with diverse spectral power distributions at recommended workplace levels of illumination (540 lux) to determine their effect on the area under curve of the overnight (2000-0800 h) salivary melatonin. We derived a narrow steady-state human Circadian Potency spectral sensitivity curve with a peak at 477 nm and a full-width half-maximum of 438 to 493 nm. This light-adapted Circadian Potency spectral sensitivity permits the development of spectrally engineered LED light sources to minimize circadian disruption and address the health risks of light exposure at night in our 24/7 society, by alternating between daytime circadian stimulatory white light spectra and nocturnal circadian protective white light spectra.


Subject(s)
Circadian Rhythm/radiation effects , Light , Lighting/methods , Workplace , Adolescent , Adult , Female , Humans , Male , Melatonin/radiation effects , Retina/radiation effects , Young Adult
5.
Exp Eye Res ; 194: 108008, 2020 05.
Article in English | MEDLINE | ID: mdl-32198015

ABSTRACT

The central biological clock system of bird is formed by hypothalamus suprachiasmatic nucleus, pineal gland and retina thereby interacting with each other in a neuroendocrine loop. Previous results have confirmed that monochromatic light can influence the clock genes in the pineal gland, hypothalamus and retina of chicks in vivo. The present work was conducted to study whether the cultured retinal tissue of chick could maintain the circadian oscillation and whether the monochromatic light affect the expression level of cultured retinal circadian clock in vitro. Retinal tissues of 0-day-old chicks were cultured in vitro under 4 light treatments (white, red, green and blue lights) with light dark cycle 12:12 and constant dark. The tissues and culture medium were collected every each 4 h. Melanopsin, clock genes, cAanat, the positive-regulating clock proteins and melatonin were measured. The results showed that cOpn4-1, cOpn4-2, cBmal1, cCry1, cPer2, cPer3, cAanat and melatonin concentrations possessed a significant circadian rhythm in cultured chick retina tissues under different monochromatic lights; while, in constant dark, cBmal1, cCry1, cPer2, cPer3, cAanat and melatonin concentration possessed a significant circadian rhythm. Green light promoted the circadian expression level of cOpn4-1, cOpn4-2, cBmal1, cAanat and BMAL1 proteins and the circadian rhythm of melatonin secretion of retina by increasing the mesors and amplitudes. In addition, green light significantly increased the average expression levels of cClock, cBmal2 and CLOCK proteins which were expressed arrhythmically. Results suggested that the retina is a central oscillator with autonomous circadian rhythm. In isolated retina tissues, green light activated the expression of melanopsin and promoted the expression of positive-regulating clock genes, thereby up-regulating the expression of cAanat and resulting the increasing of the synthesis and secretion of melatonin.


Subject(s)
Circadian Clocks/radiation effects , Circadian Rhythm/physiology , Light , Melatonin/biosynthesis , Retina/metabolism , Animals , Cells, Cultured , Chickens , Male , Melatonin/radiation effects , Models, Animal , Photic Stimulation , Retina/cytology
6.
J Psychiatry Neurosci ; 45(2): 79-87, 2020 03 01.
Article in English | MEDLINE | ID: mdl-32096617

ABSTRACT

Background: Multiple lines of evidence suggest that the onset and course of bipolar disorder is influenced by environmental light conditions. Increased suppression of melatonin by light (supersensitivity) in patients with bipolar disorder has been postulated as an endophenotype by several studies. However, due to methodological shortcomings, the results of these studies remain inconclusive. This study investigated melatonin suppression in euthymic patients with bipolar I disorder using evening blue light specifically targeting the melanopsin system. Methods: Melatonin suppression was assessed in euthymic patients with bipolar I disorder and healthy controls by exposure to monochromatic blue light (λmax = 475 nm; photon density = 1.6 × 1013 photons/cm2/s) for 30 minutes at 2300 h, administered via a ganzfeld dome for highly uniform light exposure. Serum melatonin concentrations were determined from serial blood sampling via radioimmunoassay. All participants received mydriatic eye drops and were genotyped for the PER3 VNTR polymorphism to avoid or adjust for potential confounding. As secondary outcomes, serum melatonin concentrations during dark conditions and after monochromatic red light exposure (λmax = 624 nm; photon density = 1.6 × 1013 photons/cm2/s) were also investigated. Changes in subjective alertness were investigated for all 3 lighting conditions. Results: A total of 90 participants (57 controls, 33 bipolar I disorder) completed the study. Melatonin suppression by monochromatic blue light did not differ between groups (F1,80 = 0.56; p = 0.46). Moreover, there were no differences in melatonin suppression by monochromatic red light (F1,82 = 1.80; p = 0.18) or differences in melatonin concentrations during dark conditions (F1,74 = 1.16; p = 0.29). Healthy controls displayed a stronger increase in subjective alertness during exposure to blue light than patients with bipolar I disorder (t85 = 2.28; p = 0.027). Limitations: Large interindividual differences in melatonin kinetics may have masked a true difference. Conclusion: Despite using a large cohort and highly controlled laboratory conditions, we found no differences in melatonin suppression between euthymic patients with bipolar I disorder and healthy controls. These findings do not support the notion that supersensitivity is a valid endophenotype in bipolar I disorder.


Subject(s)
Bipolar Disorder/blood , Light , Melatonin/radiation effects , Adult , Case-Control Studies , Endophenotypes , Female , Humans , Male , Melatonin/blood , Middle Aged , Photic Stimulation , Rod Opsins
7.
Arch Insect Biochem Physiol ; 102(4): e21605, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31328825

ABSTRACT

The pathways of insect melatonin (MEL) biosynthesis apparently follow the same routes as those identified in vertebrates but information on MEL synthesis variations related with serotonin (5-HT), 5-hydroxy-indole acetic acid (5HIAA), and N-acetylserotonin (NAS) levels, as well as 5-HT N-acetyltransferase (NAT) activity throughout the day, is very limited in the insect nervous system. In the present study, the levels of MEL, metabolites (5-HT, NAS, and 5-HIAA) and enzyme NAT were determined in the optic lobes and the midbrain of the grasshopper Oedipoda caerulescens, in conditions of light and darkness. In both tissues, a different pattern of MEL synthesis was observed over the light/dark cycle. Variations in the levels of 5-HT, NAS and NAT activity related to the synthesis of cerebral MEL follow a pattern very similar to that observed in the pineal of mammals, with a peak of synthesis in the first half of the scotophase. Also, we observed differences in the metabolism of 5-HT between the optic lobes and the midbrain light/dark-dependent.


Subject(s)
Brain/metabolism , Grasshoppers/metabolism , Melatonin/biosynthesis , Animals , Arylalkylamine N-Acetyltransferase/metabolism , Darkness , Grasshoppers/radiation effects , Hydroxyindoleacetic Acid/metabolism , Light , Male , Melatonin/radiation effects , Serotonin/analogs & derivatives , Serotonin/metabolism
8.
J Biol Rhythms ; 34(2): 195-204, 2019 04.
Article in English | MEDLINE | ID: mdl-30821188

ABSTRACT

The intrinsically photosensitive retinal ganglion cells are the main conduit of the light signal emanating from the retina to the biological clock located in the suprachiasmatic nuclei of the hypothalamus. Lighting manufacturers are developing white light sources that are devoid of wavelengths around 480 nm ("cyan gap") to reduce their impact on the circadian system. The present study was designed to investigate whether exposure to a "cyan-gap," 3000 K white light source, spectrally tuned to reduce radiant power between 475 and 495 nm (reducing stimulation of the melanopsin-containing photoreceptor), would suppress melatonin less than a conventional 3000 K light source. The study's 2 phases employed a within-subjects experimental design involving the same 16 adult participants. In Phase 1, participants were exposed for 1 h to 3 experimental conditions over the course of 3 consecutive weeks: 1) dim light control (<5 lux at the eyes); 2) 800 lux at the eyes of a 3000 K light source; and 3) 800 lux at the eyes of a 3000 K, "cyan-gap" modified (3000 K mod) light source. The same protocol was repeated in Phase 2, but light levels were reduced to 400 lux at the eyes. As hypothesized, there were significant main effects of light level ( F1,12 = 9.1, p < 0.05, ηp² = 0.43) and exposure duration ( F1,12 = 47.7, p < 0.05, ηp² = 0.80) but there was no significant main effect of spectrum ( F1,12 = 0.16, p > 0.05, ηp² = 0.01). There were no significant interactions with spectrum. Contrary to our model predictions, our results showed that short-term exposures (≤ 1 h) to "cyan-gap" light sources suppressed melatonin similarly to conventional light sources of the same CCT and photopic illuminance at the eyes.


Subject(s)
Circadian Rhythm/radiation effects , Darkness , Light , Melatonin/radiation effects , Adult , Biological Clocks , Eye/radiation effects , Female , Humans , Male , Middle Aged , Saliva/chemistry , Spectrum Analysis , Time Factors
9.
J Biol Rhythms ; 34(2): 178-194, 2019 04.
Article in English | MEDLINE | ID: mdl-30803301

ABSTRACT

The human circadian system is primarily regulated by the 24-h LD cycle incident on the retina, and nocturnal melatonin suppression is a primary outcome measure for characterizing the biological clock's response to those light exposures. A limited amount of data related to the combined effects of light level, spectrum, and exposure duration on nocturnal melatonin suppression has impeded the development of circadian-effective lighting recommendations and light-treatment methods. The study's primary goal was to measure nocturnal melatonin suppression for a wide range of light levels (40 to 1000 lux), 2 white light spectra (2700 K and 6500 K), and an extended range of nighttime light exposure durations (0.5 to 3.0 h). The study's second purpose was to examine whether differences existed between adolescents' and adults' circadian sensitivity to these lighting characteristics. The third purpose was to provide an estimate of the absolute threshold for the impact of light on acute melatonin suppression. Eighteen adolescents (age range, 13 to 18 years) and 23 adults (age range, 24 to 55 years) participated in the study. Results showed significant main effects of light level, spectrum, and exposure duration on melatonin suppression. Moreover, the data also showed that the relative suppressing effect of light on melatonin diminishes with increasing exposure duration for both age groups and both spectra. The present results do not corroborate our hypothesis that adolescents exhibit greater circadian sensitivity to short-wavelength radiation compared with adults. As for threshold, it takes longer to observe significant melatonin suppression at lower CS levels than at higher CS levels. Dose-response curves (amount and duration) for both white-light spectra and both age groups can guide lighting recommendations when considering circadian-effective light in applications such as offices, schools, residences, and healthcare facilities.


Subject(s)
Circadian Rhythm/radiation effects , Light , Melatonin/radiation effects , Saliva/chemistry , Adolescent , Adult , Age Factors , Female , Humans , Male , Middle Aged , Time Factors , Young Adult
10.
J Biol Rhythms ; 33(4): 420-431, 2018 08.
Article in English | MEDLINE | ID: mdl-29984614

ABSTRACT

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production.


Subject(s)
Color , Lighting/methods , Melatonin/biosynthesis , Melatonin/radiation effects , Temperature , Adult , Circadian Rhythm/radiation effects , Female , Humans , Light/adverse effects , Male , Middle Aged , Photic Stimulation , Saliva/chemistry , Wakefulness , Young Adult
11.
Sleep ; 38(1): 119-26, 2015 Jan 01.
Article in English | MEDLINE | ID: mdl-25325466

ABSTRACT

STUDY OBJECTIVES: To characterize and compare insomnia symptoms within two common phenotypes of Shift Work Disorder. DESIGN: Observational laboratory and field study. SETTING: Hospital sleep center. PARTICIPANTS: 34 permanent night workers. Subjects were classified by Epworth Sleepiness Scale and Insomnia Severity Index into 3 subgroups: asymptomatic controls, alert insomniacs (AI), and sleepy insomniacs (SI). MEASUREMENTS: Sleep parameters were assessed by sleep diary. Circadian phase was evaluated by dim-light salivary melatonin onset (DLMO). Objective sleepiness was measured using the multiple sleep latency test (MSLT). Brain activity was measured using the N1 event-related potential (ERP). A tandem repeat in PER3 was genotyped from saliva DNA. RESULTS: (1) AI group showed normal MSLT scores but elevated N1 amplitudes indicating cortical hyperarousal. (2) SI group showed pathologically low MSLT scores but normal N1 amplitudes. (3) AI and SI groups were not significantly different from one another in circadian phase, while controls were significantly phase-delayed relative to both SWD groups. (4) AI showed significantly longer sleep latencies and lower sleep efficiency than controls during both nocturnal and diurnal sleep. SI significantly differed from controls in nocturnal sleep parameters, but differences during diurnal sleep periods were smaller and not statistically significant. (5) Genotype × phenotype χ² analysis showed significant differences in the PER3 VNTR: 9 of 10 shift workers reporting sleepiness in a post hoc genetic substudy were found to carry the long tandem repeat on PER3, while 4 of 14 shift workers without excessive sleepiness carried the long allele. CONCLUSIONS: Our results suggest that the sleepy insomnia phenotype is comprehensively explained by circadian misalignment, while the alert insomnia phenotype resembles an insomnia disorder precipitated by shift work.


Subject(s)
Phenotype , Sleep Disorders, Circadian Rhythm/complications , Sleep Disorders, Circadian Rhythm/physiopathology , Sleep Initiation and Maintenance Disorders/complications , Sleep Initiation and Maintenance Disorders/physiopathology , Sleep Stages/physiology , Alleles , Attention/physiology , Brain/physiology , Case-Control Studies , Circadian Rhythm/physiology , Disorders of Excessive Somnolence/complications , Disorders of Excessive Somnolence/genetics , Disorders of Excessive Somnolence/physiopathology , Evoked Potentials/physiology , Female , Humans , Light , Male , Melatonin/analysis , Melatonin/biosynthesis , Melatonin/radiation effects , Minisatellite Repeats/genetics , Period Circadian Proteins/genetics , Polysomnography , Saliva , Sleep Disorders, Circadian Rhythm/genetics , Sleep Initiation and Maintenance Disorders/genetics
12.
Horm Behav ; 65(3): 301-7, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24440383

ABSTRACT

Light regulates a variety of behavioral and physiological processes, including activity rhythms and hormone secretory patterns. Seasonal changes in the proportion of light in a day (photoperiod) further modulate those functions. Recently, short (SP) versus long days (LP) were found to markedly increase light sensitivity for phase shifting in Syrian hamsters. To our knowledge, photoperiod effects on light sensitivity have not been studied in other rodents, nor is it known if they generalize to other circadian responses. We tested whether photic phase shifting and melatonin suppression vary in Siberian hamsters maintained under LP or SP. Select irradiances of light were administered, and shifts in activity were determined. Photic sensitivity for melatonin suppression was examined in a separate group of animals via pulses of light across a 4 log-unit photon density range, with post-pulse plasma melatonin levels determined via RIA. Phase shifting and melatonin suppression were greater at higher irradiances for both LP and SP. The lower irradiance condition was below threshold for phase shifts in LP but not SP. Melatonin suppression did not vary by photoperiod, and the half saturation constant for fitted sigmoid curves was similar under LP and SP. Thus, the photoperiodic modulation of light sensitivity for phase shifting is conserved across two hamster genera. The dissociation of photoperiod effects on photic phase shifting and melatonin suppression suggests that the modulation of sensitivity occurs downstream of the common retinal input pathway. Understanding the mechanistic basis for this plasticity may yield therapeutic targets for optimizing light therapy practices.


Subject(s)
Behavior, Animal/physiology , Circadian Rhythm/physiology , Melatonin/metabolism , Phodopus/physiology , Photoperiod , Animals , Behavior, Animal/radiation effects , Circadian Rhythm/radiation effects , Light , Male , Melatonin/blood , Melatonin/radiation effects , Phodopus/metabolism , Random Allocation
13.
J Athl Train ; 47(6): 673-8, 2012.
Article in English | MEDLINE | ID: mdl-23182016

ABSTRACT

CONTEXT: Good sleep is an important recovery method for prevention and treatment of overtraining in sport practice. Whether sleep is regulated by melatonin after red-light irradiation in athletes is unknown. OBJECTIVE: To determine the effect of red light on sleep quality and endurance performance of Chinese female basketball players. DESIGN: Cohort study. SETTING: Athletic training facility of the Chinese People's Liberation Army and research laboratory of the China Institute of Sport Science. Patients or Other Participants: Twenty athletes of the Chinese People's Liberation Army team (age = 18.60 6 3.60 years) took part in the study. Participants were divided into red-light treatment (n = 10) and placebo (n = 10) groups. INTERVENTION(S): The red-light treatment participants received 30 minutes of irradiation from a red-light therapy instrument every night for 14 days. The placebo group did not receive light illumination. MAIN OUTCOME MEASURE(S): The Pittsburgh Sleep Quality Index (PSQI) questionnaire was completed, serum melatonin was assessed, and 12-minute run was performed at preintervention (baseline) and postintervention (14 days). RESULTS: The 14-day whole-body irradiation with red-light treatment improved the sleep, serum melatonin level, and endurance performance of the elite female basketball players (P < .05). We found a correlation between changes in global Pittsburgh Sleep Quality Index and serum melatonin levels (r = -0.695, P = .006). CONCLUSIONS: Our study confirmed the effectiveness of body irradiation with red light in improving the quality of sleep of elite female basketball players and offered a nonpharmacologic and noninvasive therapy to prevent sleep disorders after training.


Subject(s)
Athletes , Basketball/physiology , Light , Melatonin/blood , Physical Endurance/radiation effects , Sleep/radiation effects , Adolescent , Body Mass Index , China , Circadian Rhythm , Cohort Studies , Female , Humans , Lighting , Melatonin/radiation effects , Phototherapy , Whole-Body Irradiation
14.
J Biol Rhythms ; 27(1): 70-8, 2012 Feb.
Article in English | MEDLINE | ID: mdl-22306975

ABSTRACT

Blue light sensitivity of melatonin suppression and subjective mood and alertness responses in humans is recognized as being melanopsin based. Observations that long-wavelength (red) light can potentiate responses to subsequent short-wavelength (blue) light have been attributed to the bistable nature of melanopsin whereby it forms stable associations with both 11-cis and all-trans isoforms of retinaldehyde and uses light to transition between these states. The current study examined the effect of concurrent administration of blue and red monochromatic light, as would occur in real-world white light, on acute melatonin suppression and subjective mood and alertness responses in humans. Young healthy men (18-35 years; n = 21) were studied in highly controlled laboratory sessions that included an individually timed 30-min light stimulus of blue (λ(max) 479 nm) or red (λ(max) 627 nm) monochromatic light at varying intensities (10(13)-10(14) photons/cm(2)/sec) presented, either alone or in combination, in a within-subject randomized design. Plasma melatonin levels and subjective mood and alertness were assessed at regular intervals relative to the light stimulus. Subjective alertness levels were elevated after light onset irrespective of light wavelength or irradiance. For melatonin suppression, a significant irradiance response was observed with blue light. Co-administration of red light, at any of the irradiances tested, did not significantly alter the response to blue light alone. Under the current experimental conditions, the primary determinant of the melatonin suppression response was the irradiance of blue 479 nm light, and this was unaffected by simultaneous red light administration.


Subject(s)
Affect/radiation effects , Arousal/radiation effects , Light , Melatonin/blood , Adolescent , Adult , Attention/radiation effects , Humans , Male , Melatonin/radiation effects
15.
J Physiol Anthropol ; 30(6): 251-8, 2011.
Article in English | MEDLINE | ID: mdl-22197958

ABSTRACT

Bright light at night improves the alertness of night workers. Melatonin suppression induced by light at night is, however, reported to be a possible risk factor for breast cancer. Short-wavelength light has a strong impact on melatonin suppression. A red-visor cap can cut the short-wavelength light from the upper visual field selectively with no adverse effects on visibility. The purpose of this study was to investigate the effects of a red-visor cap on light-induced melatonin suppression, performance, and sleepiness at night. Eleven healthy young male adults (mean age: 21.2±0.9 yr) volunteered to participate in this study. On the first day, the subjects spent time in dim light (<15 lx) from 20:00 to 03:00 to measure baseline data of nocturnal salivary melatonin concentration. On the second day, the subjects were exposed to light for four hours from 23:00 to 03:00 with a nonvisor cap (500 lx), red-visor cap (approx. 160 lx) and blue-visor cap (approx. 160 lx). Subjective sleepiness and performance of a psychomotor vigilance task (PVT) were also measured on the second day. Compared to salivary melatonin concentration under dim light, the decrease in melatonin concentration was significant in a nonvisor cap condition but was not significant in a red-visor cap condition. The percentages of melatonin suppression in the nonvisor cap and red-visor cap conditions at 4 hours after exposure to light were 52.6±22.4% and 7.7±3.3%, respectively. The red-visor cap had no adverse effect on performance of the PVT, brightness and visual comfort, though it tended to increase subjective sleepiness. These results suggest that a red-visor cap is effective in preventing melatonin suppression with no adverse effects on vigilance performance, brightness and visibility.


Subject(s)
Chronobiology Disorders/prevention & control , Clothing , Melatonin/metabolism , Task Performance and Analysis , Work Schedule Tolerance/physiology , Analysis of Variance , Cross-Over Studies , Humans , Light , Male , Melatonin/radiation effects , Saliva/chemistry , Spectrum Analysis , Wakefulness/physiology , Young Adult
16.
Electromagn Biol Med ; 30(4): 219-34, 2011 Dec.
Article in English | MEDLINE | ID: mdl-22047460

ABSTRACT

Recently, there have been several reports referring to detrimental effects due to radio frequency electromagnetic fields (RF-EMF) exposure. Special attention was given to investigate the effect of mobile phone exposure on the rat brain. Since the integrative mechanism of the entire body lies in the brain, it is suggestive to analyze its biochemical aspects. For this, 35-day old Wistar rats were exposed to a mobile phone for 2 h per day for a duration of 45 days where specific absorption rate (SAR) was 0.9 W/Kg. Animals were divided in two groups: sham exposed (n = 6) and exposed group (n = 6). Our observations indicate a significant decrease (P < 0.05) in the level of glutathione peroxidase, superoxide dismutase, and an increase in catalase activity. Moreover, protein kinase shows a significant decrease in exposed group (P < 0.05) of hippocampus and whole brain. Also, a significant decrease (P < 0.05) in the level of pineal melatonin and a significant increase (P < 0.05) in creatine kinase and caspase 3 was observed in exposed group of whole brain as compared with sham exposed. Finally, a significant increase in the level of ROS (reactive oxygen species) (P < 0.05) was also recorded. The study concludes that a reduction or an increase in antioxidative enzyme activities, protein kinase C, melatonin, caspase 3, and creatine kinase are related to overproduction of reactive oxygen species (ROS) in animals under mobile phone radiation exposure. Our findings on these biomarkers are clear indications of possible health implications.


Subject(s)
Brain/radiation effects , Cell Phone , Microwaves , Animals , Antioxidants/metabolism , Antioxidants/radiation effects , Brain/enzymology , Brain/metabolism , Catalase/metabolism , Catalase/radiation effects , Glutathione Peroxidase/metabolism , Glutathione Peroxidase/radiation effects , Male , Melatonin/metabolism , Melatonin/radiation effects , Oxidation-Reduction/radiation effects , Protein Kinase C/metabolism , Protein Kinase C/radiation effects , Rats , Rats, Wistar , Reactive Oxygen Species/metabolism , Reactive Oxygen Species/radiation effects , Superoxide Dismutase/metabolism , Superoxide Dismutase/radiation effects , Time Factors
17.
PLoS One ; 6(1): e16429, 2011 Jan 26.
Article in English | MEDLINE | ID: mdl-21298068

ABSTRACT

BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K) during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task), but not in tasks associated with executive function (Paced Visual Serial Addition Task). This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace.


Subject(s)
Cognition/radiation effects , Light , Melatonin/radiation effects , Reaction Time/radiation effects , Circadian Rhythm/radiation effects , Color , Cross-Over Studies , Fluorescence , Humans , Male , Young Adult
18.
Chronobiol Int ; 27(9-10): 1715-34, 2010 Oct.
Article in English | MEDLINE | ID: mdl-20969519

ABSTRACT

Continuous light is a common practice in salmon farming, where it is used to enhance growth, induce smoltification, and regulate puberty. However, knowledge about how different tissues receive information about daylength is limited. The aim of the present study was to evaluate the daily expression of clock (Per1-like, Cry2, and Clock), the nuclear transcription factor (peroxisome proliferator-activated receptor, PPAR; CCAAT/enhancer binding protein, C/EBP), and the endoplasmic reticulum (ER) stress (protein disulfide isomerase associated 3, PDIA3) genes in the pineal gland, brain, and liver of Atlantic salmon postsmolts reared under 12-h light:12-h dark (LD) regimes or under continuous light (LL) for 6 wks following transfer to seawater. All measured clock mRNAs displayed daily variations in one or more organs under LD, as well as plasma levels of melatonin. Similar variations were noted in the liver c/ebpα, pineal c/ebpδ, and pdia3 mRNAs. Under LL, the clock and nuclear transcription factor mRNAs did not show any daily variation in the studied organs, with the exception of pineal pdia3. Furthermore, LL had the opposite effect on the levels of melatonin and cortisol, as observed by the increase in pineal Clock, Per2, pparα, and c/ebpα and c/ebpδ mRNAs and decrease in liver Clock, Per2, and pparα mRNAs compared to those under LD. The present findings show that the expression of clock genes is affected by the light across organs and that there is a relation between PPAR, C/EBP, and clock mRNAs; however, the functional role of the individual nuclear transcription factors related to this observation remains to be established in the pineal gland and liver. (Author correspondence: Tihu@nifes.no ).


Subject(s)
CLOCK Proteins/genetics , Hydrocortisone/blood , Lighting , Melatonin/blood , Period Circadian Proteins/genetics , Salmo salar/genetics , Animals , Brain/physiology , Cryptochromes/genetics , DNA Primers , Growth/radiation effects , Hydrocortisone/radiation effects , Liver/physiology , Melatonin/radiation effects , Molting/physiology , Pineal Gland/physiology , Polymerase Chain Reaction , RNA, Messenger/genetics , Salmo salar/blood , Salmo salar/growth & development , Seasons
19.
J Biol Rhythms ; 25(3): 208-16, 2010 Jun.
Article in English | MEDLINE | ID: mdl-20484692

ABSTRACT

Multisynaptic neural and endocrine pathways from the suprachiasmatic nucleus of the hypothalamus have been hypothesized to communicate circadian and photic information to the adrenal glands. In humans, light exposure has been reported to have no effect, increase, or decrease cortisol levels. These inconsistent findings in humans may be related to differences among studies including the intensity (approximately 500 to 5500 lux), duration (15 min to 4 h), and circadian phase of light exposure. The authors assessed the influence of exposure to bright light on cortisol levels in humans during the rising and descending phases of the circadian rhythm of cortisol, that is, when cortisol levels are high. Twenty healthy men and women were studied using a within-subject research design. Subjects were studied in an environment free of time cues for 9 to 10 days. Subjects received a 6.7-h exposure of bright light (approximately 10,000 lux; equivalent to ambient light intensity just after sunrise or just before sunset) or dim light (approximately 3 lux; equivalent to candle light) during the biological night and morning. Bright light exposure significantly reduced plasma cortisol levels at both circadian phases studied, whereas dim light exposure had little effect on cortisol levels. The finding of an acute suppressive effect of bright light exposure on cortisol levels supports the existence of a mechanism by which photic information can acutely influence the human adrenal glands.


Subject(s)
Hydrocortisone/blood , Hydrocortisone/radiation effects , Light , Adrenal Glands/radiation effects , Adult , Biological Clocks , Circadian Rhythm , Dose-Response Relationship, Radiation , Female , Humans , Male , Melatonin/blood , Melatonin/radiation effects , Photic Stimulation , Photoperiod
20.
Occup Med (Lond) ; 60(1): 10-20, 2010 Jan.
Article in English | MEDLINE | ID: mdl-20051441

ABSTRACT

The internal circadian clock adapts slowly, if at all, to rapid transitions between different shift schedules. This leads to misalignment (desynchrony) of rhythmic physiological systems, such as sleep, alertness, performance, metabolism and the hormones melatonin and cortisol, with the imposed work-rest schedule. Consequences include sleep deprivation and poor performance. Clock gene variants may influence tolerance of sleep deprivation. Shift work is associated with an increased risk of major disease (heart disease and cancer) and this may also, at least in part, be attributed to frequent circadian desynchrony. Abnormal metabolism has been invoked as a contributory factor to the increased risk of heart disease. There is recent evidence for an increased risk of certain cancers, with hypothesized causal roles of light at night, melatonin suppression and circadian desynchrony. Various strategies exist for coping with circadian desynchrony and for hastening circadian realignment (if desired). The most important factor in manipulating the circadian system is exposure to and/or avoidance of bright light at specific times of the 'biological night'.


Subject(s)
Adaptation, Psychological , Circadian Rhythm , Work Schedule Tolerance/physiology , Workload/psychology , Circadian Rhythm/genetics , Circadian Rhythm/physiology , Humans , Light , Melatonin/metabolism , Melatonin/radiation effects
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