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Gonçalves FB, Gonçalves BSB, Cavalcante JS, Azevedo CVM. Aging-related changes on social synchronization of circadian activity rhythm in a diurnal primate ( Callithrix jacchus). Chronobiol Int 2020; 37:980-992. [PMID: 32573282 DOI: 10.1080/07420528.2020.1773495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The input of environmental time cues and expression of circadian activity rhythms may change with aging. Among nonphotic zeitgebers, social cues from conspecific vocalizations may contribute to the stability and survival of individuals of social species, such as nonhuman primates. We evaluated aging-related changes on social synchronization of the circadian activity rhythm (CAR) in a social diurnal primate, the common marmoset. The activity of 18 male marmosets was recorded by actiwatches in two conditions. (1) Experimental - 4 young adult (5 ± 2 yrs of age) and 4 older (10 ± 2 yrs of age) animals maintained under LD 12/12 h and LL in a room with full insulation for light but only partial insulation for sound from vocalizations of conspecifics maintained outdoors in the colony; and (2) Control - 10 young adult animals maintained outdoors in the colony (5 animals as a control per age group). In LL, the CAR of young adults showed more stable synchronization with controls. Among the aged marmosets, two free-ran with τ > 24 h, whereas the other two showed relative coordination during the first 30 days in LL, but free-ran thereafter. These differences were reflected in the "social" phase angles (ψon and ψoff ) between rhythms of experimental and control animal groups. Moreover, the activity patterns of aged animals showed lower social synchrony with controls compared to young adults, with the time lags of the time series between each experimental group and control group being negative in aged and positive in young adult animals (t-test, p < 0.05). The index of stability of the CAR showed no differences according to age, while the intradaily variability of the CAR was higher in the aged animals during LD-resynchronization, who took additional days to resynchronize. Thus, the social modulation on CAR may vary with age in marmosets. In the aged group, there was a lower effect of social synchronization, which may be associated with aging-related changes in the synchronization and generation of the CAR as well as in system outputs.
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Affiliation(s)
- Fabiana B Gonçalves
- Escola Multicampi de Ciências Médicas do Rio Grande do Norte, Universidade Federal do Rio Grande do Norte , Caicó, RN, Brazil
| | - Bruno S B Gonçalves
- Escola de Artes, Ciências e Humanidades, Universidade de São Paulo , São Paulo, SP, Brazil
| | - Jeferson S Cavalcante
- Laboratório de Estudos Neuroquímicos, Departamento de Fisiologia e Comportamento, Universidade Federal do Rio Grande do Norte , Natal, RN, Brazil
| | - Carolina V M Azevedo
- Laboratório de Cronobiologia, Departamento de Fisiologia e Comportamento, Universidade Federal do Rio Grande do Norte , Natal, RN, Brazil
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Majidinia M, Reiter RJ, Shakouri SK, Yousefi B. The role of melatonin, a multitasking molecule, in retarding the processes of ageing. Ageing Res Rev 2018; 47:198-213. [PMID: 30092361 DOI: 10.1016/j.arr.2018.07.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Revised: 07/24/2018] [Accepted: 07/31/2018] [Indexed: 02/07/2023]
Abstract
Biological ageing is generally accompanied by a gradual loss of cellular functions and physiological integrity of organ systems, the consequential enhancement of vulnerability, senescence and finally death. Mechanisms which underlie ageing are primarily attributed to an array of diverse but related factors including free radical-induced damage, dysfunction of mitochondria, disruption of circadian rhythms, inflammaging, genomic instability, telomere attrition, loss of proteostasis, deregulated sensing of nutrients, epigenetic alterations, altered intercellular communication, and decreased capacity for tissue repair. Melatonin, a prime regulator of human chronobiological and endocrine physiology, is highly reputed as an antioxidant, immunomodulatory, antiproliferative, oncostatic, and endocrine-modulatory molecule. Interestingly, several recent reports support melatonin as an anti-ageing agent whose multifaceted functions may lessen the consequences of ageing. This review depicts four categories of melatonin's protective effects on ageing-induced molecular and structural alterations. We also summarize recent findings related to the function of melatonin during ageing in various tissues and organs.
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Fiuza FP, Silva KDA, Pessoa RA, Pontes ALB, Cavalcanti RLP, Pires RS, Soares JG, Nascimento Júnior ES, Costa MSMO, Engelberth RCGJ, Cavalcante JS. Age-related changes in neurochemical components and retinal projections of rat intergeniculate leaflet. AGE (DORDRECHT, NETHERLANDS) 2016; 38:4. [PMID: 26718202 PMCID: PMC5005876 DOI: 10.1007/s11357-015-9867-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 12/21/2015] [Indexed: 06/05/2023]
Abstract
Aging leads to several anatomical and functional deficits in circadian timing system. In previous works, we observed morphological alterations with age in hypothalamic suprachiasmatic nuclei, one central component of this system. However, there are few data regarding aging effects on other central components of this system, such as thalamic intergeniculate leaflet (IGL). In this context, we studied possible age-related alterations in neurochemical components and retinal projections of rat IGL. For this goal, young (3 months), adult (13 months), and aged (23 months) Wistar rats were submitted to an intraocular injection of neural tracer, cholera toxin subunit b (CTb), 5 days before a tissue fixation process by paraformaldehyde perfusion. Optical density measurements and cell count were performed at digital pictures of brain tissue slices processed by immunostaining for glutamic acid decarboxylase (GAD), enkephalin (ENK), neuropeptide Y (NPY) and CTb, characteristic markers of IGL and its retinal terminals. We found a significant age-related loss in NPY immunoreactive neurons, but not in immunoreactivity to GAD and ENK. We also found a decline of retinal projections to IGL with age. We conclude aging impairs both a photic environmental clue afferent to IGL and a neurochemical expression which has an important modulatory circadian function, providing strong anatomical correlates to functional deficits of the aged biological clock.
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Affiliation(s)
- Felipe P Fiuza
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Kayo D A Silva
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Renata A Pessoa
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - André L B Pontes
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Rodolfo L P Cavalcanti
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Raquel S Pires
- Neuroscience Center, University of São Paulo City, São Paulo, SP, Brazil
| | - Joacil G Soares
- Laboratory of Neuroanatomy, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | | | - Miriam S M O Costa
- Laboratory of Neuroanatomy, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Rovena C G J Engelberth
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil
| | - Jeferson S Cavalcante
- Laboratory of Neurochemical Studies, Federal University of Rio Grande do Norte, Natal, RN, Brazil.
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Kovacic P, Somanathan R. Melatonin and Circadian Rhythm: Aging, Cancer, and Mechanism. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/ojpm.2014.47065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hughes ATL, Piggins HD. Feedback actions of locomotor activity to the circadian clock. PROGRESS IN BRAIN RESEARCH 2012; 199:305-336. [PMID: 22877673 DOI: 10.1016/b978-0-444-59427-3.00018-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The phase of the mammalian circadian system can be entrained to a range of environmental stimuli, or zeitgebers, including food availability and light. Further, locomotor activity can act as an entraining signal and represents a mechanism for an endogenous behavior to feedback and influence subsequent circadian function. This process involves a number of nuclei distributed across the brain stem, thalamus, and hypothalamus and ultimately alters SCN electrical and molecular function to induce phase shifts in the master circadian pacemaker. Locomotor activity feedback to the circadian system is effective across both nocturnal and diurnal species, including humans, and has recently been shown to improve circadian function in a mouse model with a weakened circadian system. This raises the possibility that exercise may be useful as a noninvasive treatment in cases of human circadian dysfunction including aging, shift work, transmeridian travel, and the blind.
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Affiliation(s)
- Alun T L Hughes
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom.
| | - Hugh D Piggins
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
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Anea CB, Zhang M, Stepp DW, Bryan Simkins G, Reed G, Fulton DJ, Daniel Rudic R. Vascular disease in mice with a dysfunctional circadian clock. Circulation 2009; 119:1510-7. [PMID: 19273720 PMCID: PMC2761686 DOI: 10.1161/circulationaha.108.827477] [Citation(s) in RCA: 209] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cardiovascular disease is the leading cause of death for both men and women in the United States and the world. A profound pattern exists in the time of day at which the death occurs; it is in the morning, when the endothelium is most vulnerable and blood pressure surges, that stroke and heart attack most frequently happen. Although the molecular components of circadian rhythms rhythmically oscillate in blood vessels, evidence of a direct function for the "circadian clock" in the progression to vascular disease is lacking. METHODS AND RESULTS In the present study, we found increased pathological remodeling and vascular injury in mice with aberrant circadian rhythms, Bmal1-knockout and Clock mutant. In addition, naive aortas from Bmal1-knockout and Clock mutant mice exhibit endothelial dysfunction. Akt and subsequent nitric oxide signaling, a pathway critical to vascular function, was significantly attenuated in arteries from Bmal1-knockout mice. CONCLUSIONS Our data reveal a new role for the circadian clock during chronic vascular responses that may be of significance in the progression of vascular disease.
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Affiliation(s)
- Ciprian B. Anea
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - Maoxiang Zhang
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - David W. Stepp
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - G. Bryan Simkins
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - Guy Reed
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - David J. Fulton
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
| | - R. Daniel Rudic
- Department of Pharmacology & Toxicology (C.B.A., M.Z., G.B.S., D.J.F., R.D.R.); Department of Physiology (D.W.S.); Vascular Biology Center (D.W.S., D.J.F.); and the Cardiology Division, Department of Medicine (G.R.), Medical College of Georgia, Augusta, GA
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Rappold I, Erkert HG. Re‐entrainment, phase‐response and range of entrainment of circadian rhythms in Owl Monkeys(Aotus lemurinus g.)of different age. BIOL RHYTHM RES 2008. [DOI: 10.1080/09291019409360282] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Irene Rappold
- a Zoologisches Institut/Tierphysiologie , Universität Tübingen , Auf der Morgenstelle 28, Tübingen, D‐72076, Germany
| | - Hans G. Erkert
- a Zoologisches Institut/Tierphysiologie , Universität Tübingen , Auf der Morgenstelle 28, Tübingen, D‐72076, Germany
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Turek FW, Penev P, Zhang Y, Van Reeth O, Takahashi JS, Zee P. Alterations in the circadian system in advanced age. CIBA FOUNDATION SYMPOSIUM 2007; 183:212-26; discussion 226-34. [PMID: 7656687 DOI: 10.1002/9780470514597.ch12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In addition to light, a variety of non-photic stimuli can induce phase shifts in the circadian clock of rodents. We have examined the effects of advanced age on the response of the circadian clock to both photic and non-photic stimuli in old hamsters (i.e., over 16 months of age). Among the age-related changes in the circadian rhythm of locomotor activity are: (1) alterations in the phase angle of entrainment to the light-dark cycle; (2) an altered response to the phase-shifting effects of light pulses; (3) changes in the time it takes to re-entrain to a new light-dark cycle; and (4) a loss of responsiveness to the phase-shifting or entraining effects of stimuli which induce an acute increase of activity. Many of the effects of ageing on the circadian clock system can be simulated in young animals by depleting brain monoamine levels, suggesting that ageing alters monoaminergic inputs to the clock. Some of the age-related changes in the response of the clock to an activity-inducing stimulus can be reversed by implanting old animals with fetal suprachiasmatic nuclear tissue. Determining the physiological basis of age-related changes in the responsiveness of the clock to both internal and external stimuli, and the mechanisms by which normal circadian functioning can be restored, should lead to new insight into the functioning of the circadian clock and may suggest new approaches to the normalization of disturbed circadian rhythms.
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Affiliation(s)
- F W Turek
- NSF Science and Technology Center for Biological Timing, Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208-3520, USA
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Carvalho-Bos SS, Riemersma-van der Lek RF, Waterhouse J, Reilly T, Van Someren EJW. Strong association of the rest-activity rhythm with well-being in demented elderly women. Am J Geriatr Psychiatry 2007; 15:92-100. [PMID: 17272729 DOI: 10.1097/01.jgp.0000236584.03432.dc] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objective of this study is to investigate the association between actigraphic estimates of the sleep-wake rhythm and a range of functional domains that contribute to well-being in demented elderly patients. METHOD Eighty-seven women aged 85.5 +/- 5.9 years (mean +/- standard deviation) wore an actigraph for two weeks. Activity profiles were analyzed using nonparametric variables, including dichotomy indices, interdaily stability (IS), intradaily variability (IV), and relative amplitude (RA). The associations between these variables and cognitive, functional, behavioral, and emotional states (obtained from standardized neuropsychologic assessments and questionnaires administered to caregivers) were investigated by partial correlations and stepwise regressions. RESULTS Cognitive, functional, behavioral, and emotional states showed medium to strong correlations with multiple rhythm variables. Partial correlations indicated that this could not be attributed to a uniform worsening with advancing cognitive decline. Stepwise regressions indicated three most distinctive rhythm variables: 1) the interdaily stability of the 24-hour rhythm was most strongly, negatively, related to cognitive decline and depression; 2) the median level of daytime activity was most strongly, negatively, related to impairments of function, of activities of daily living, and of social interaction; and 3) nocturnal restlessness was secondarily, positively, related to impairments of function and social interaction. CONCLUSION Especially the interdaily stability and median daytime activity level, and secondarily nocturnal restlessness, showed a strong relationship with the functional status and well-being of demented elderly. This raises the possibility that treatments that enhance daytime activity and the stability of the rest-activity rhythm may improve well-being.
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Davidson AJ, Yamazaki S, Arble DM, Menaker M, Block GD. Resetting of central and peripheral circadian oscillators in aged rats. Neurobiol Aging 2006; 29:471-7. [PMID: 17129640 PMCID: PMC1635489 DOI: 10.1016/j.neurobiolaging.2006.10.018] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2006] [Revised: 10/13/2006] [Accepted: 10/18/2006] [Indexed: 11/22/2022]
Abstract
The mammalian circadian timing system is affected by aging. Analysis of the suprachiasmatic nucleus (SCN) and of other circadian oscillators reveals age-related changes which are most profound in extra-SCN tissues. Some extra-SCN oscillators appear to stop oscillating in vivo or display altered phase relationships. To determine whether the dynamic behavior of circadian oscillators is also affected by aging we studied the resetting behavior of the Period1 transcriptional rhythm of peripheral and central oscillators in response to a 6h advance or delay in the light schedule. We employed a transgenic rat with a luciferase reporter to allow for real-time measurements of transcriptional rhythmicity. While phase resetting in the SCN following an advance or a delay of the light cycle appears nearly normal in 2-year-old rats, resynchronization of the liver was seriously disrupted. In addition, the arcuate nucleus and pineal gland exhibited faster resetting in aged rats relative to 4-8-month-old controls. The consequences of these deficits are unknown, but may contribute to organ and brain diseases in the aged as well as the health problems that are common in older shift-workers.
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Affiliation(s)
- Alec J Davidson
- Department of Biology, University of Virginia, Charlottesville, VA 22904-4328, USA.
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Koh K, Evans JM, Hendricks JC, Sehgal A. A Drosophila model for age-associated changes in sleep:wake cycles. Proc Natl Acad Sci U S A 2006; 103:13843-7. [PMID: 16938867 PMCID: PMC1564207 DOI: 10.1073/pnas.0605903103] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2006] [Indexed: 11/18/2022] Open
Abstract
One of the most consistent behavioral changes that occurs with age in humans is the loss of sleep consolidation. This can be quite disruptive and yet little is known about its underlying basis. To better understand the effects of aging on sleep:wake cycles, we sought to study this problem in Drosophila melanogaster, a powerful system for research on aging and behavior. By assaying flies of different ages as well as monitoring individual flies constantly over the course of their lifetime, we found that the strength of sleep:wake cycles decreased and that sleep became more fragmented with age in Drosophila. These changes in sleep:wake cycles became faster or slower with manipulations of ambient temperature that decreased or increased lifespan, respectively, demonstrating that they are a function of physiological rather than chronological age. The effect of temperature on lifespan was not mediated by changes in overall activity level or sleep amount. Flies treated with the oxidative stress-producing reagent paraquat showed a breakdown of sleep:wake cycles similar to that seen with aging, leading us to propose that the accumulation of oxidative damage with age contributes to the changes in rhythm and sleep. Together, these findings establish Drosophila as a valuable model for studying age-associated sleep fragmentation and breakdown of rhythm strength, and indicate that these changes in sleep:wake cycles are an integral part of the physiological aging process.
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Affiliation(s)
- Kyunghee Koh
- *Howard Hughes Medical Institute, Department of Neuroscience, School of Medicine, and
| | - Joshua M. Evans
- *Howard Hughes Medical Institute, Department of Neuroscience, School of Medicine, and
| | - Joan C. Hendricks
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Amita Sehgal
- *Howard Hughes Medical Institute, Department of Neuroscience, School of Medicine, and
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Kramer CJ, Kerkhof GA, Hofman WF. Age differences in sleep-wake behavior under natural conditions. PERSONALITY AND INDIVIDUAL DIFFERENCES 2001; 27:853-60. [PMID: 11542386 DOI: 10.1016/s0191-8869(99)00034-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Differences in lifestyle may account for a considerable portion of the reported age-related changes in overt circadian rhythmicity. By instructing a group of healthy, noninstitutionalized, elderly subjects and a group of young adults to keep a sleep-wake log for a period of two weeks, and to wear an activity monitor for an overlapping period of 11 days, we attempted to assess age-related differences in the habitual sleep-wake behavior, in particular its day-to-day variability. Four clusters of coherent variables were constructed, reflecting (1) circadian phase, (2) variability of sleep-wake behavior, (3) sleep-wake continuity and (4) subjective sleep-wake quality. The results showed that, in comparison with the young subjects, the elderly had a relatively advanced and more regular sleep-wake pattern, reported more midnight awakening and did not differ in their subjective sleep evaluation. In spite of a greater regularity in their lifestyle (which would favor a larger amplitude of the overt circadian rhythmicity) oral temperature measurements showed some evidence of a weakened 24-h periodicity in the elderly.
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Affiliation(s)
- C J Kramer
- Department of Psychonomics, University of Amsterdam, Netherlands
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15
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Van Reeth O, Weibel L, Olivares E, Maccari S, Mocaer E, Turek FW. Melatonin or a melatonin agonist corrects age-related changes in circadian response to environmental stimulus. Am J Physiol Regul Integr Comp Physiol 2001; 280:R1582-91. [PMID: 11294784 DOI: 10.1152/ajpregu.2001.280.5.r1582] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of a melatonin agonist, S-20098, included in the diet were tested on a specific effect of aging in hamsters: the marked decline in the phase shifting effects of a 6-h pulse of darkness on a background of constant light. In contrast to young hamsters, old hamsters fed with the control diet showed little or no phase shifts in response to a dark pulse presented in the middle of their inactive or active period. Old hamsters fed with S-20098 showed phase shifts that were ~70% of the ones in young animals and significantly greater than those in old controls. The phase advancing response to a dark pulse presented during the inactive period was dose dependent and reversed after S-20098 discontinuation. Melatonin included in the diet showed comparable restorative effects on the phase shifting response to a dark pulse in old hamsters. Replacement therapy with melatonin or melatonin-related compounds could prove useful in treating, preventing, or delaying disturbances of circadian rhythmicity and/or sleep in older people.
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Affiliation(s)
- O Van Reeth
- Centre d'Etudes des Rythmes Biologiques, School of Medicine, Hôpital Erasme, Université Libre de Bruxelles, 1070 Brussels, Belgium.
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Duncan MJ, Herron JM, Hill SA. Aging selectively suppresses vasoactive intestinal peptide messenger RNA expression in the suprachiasmatic nucleus of the Syrian hamster. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2001; 87:196-203. [PMID: 11245922 DOI: 10.1016/s0169-328x(01)00015-8] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Aging leads to many changes in the expression of circadian rhythms, including reduced amplitude, altered relationship to the environmental illumination cycle, and reduced sensitivity to phase resetting signals. Neuropeptide synthesizing neurons in the suprachiasmatic nucleus (SCN), the principal circadian pacemaker in mammals, play a role in regulating pacemaker function and in coupling the pacemaker to overt circadian rhythms. Aging may alter the activity of neuropeptide neurons in the SCN, which could be reflected in changes in mRNA expression. Therefore, this study investigated whether aging alters the level or rhythm of expression of neuropeptide mRNAs in the SCN of male Syrian hamsters, a well established model for the study of age-related changes in circadian rhythms. Three age groups of hamsters (young [3--5 months old], middle-aged [12--15 months old] and old [19--22 months old] were sacrificed at five times of day. Their brains were dissected and sections through the suprachiasmatic nucleus were prepared and used for in situ hybridization for mRNAs for vasoactive intestinal peptide (VIP), arginine vasopressin (AVP) and somatostatin (SS). Aging selectively decreased the SCN expression of VIP mRNA without affecting AVP mRNA or SS mRNA. Also, only AVP mRNA expression exhibited a robust 24-h rhythm, in contrast to previous findings in other species that VIP mRNA and SS mRNA, as well as AVP mRNA, exhibit 24-h rhythms in the SCN. The present findings suggest that age-related reductions in VIP mRNA expression may contribute to the alterations in entrainment and attenuated sensitivity to phase resetting signals that are characteristic of aging. Furthermore, the results demonstrate that neuropeptide gene expression in the SCN is differentially regulated by aging and varies among species.
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Affiliation(s)
- M J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA.
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Weibel L, Turek FW, Mocaer E, Van Reeth O. A melatonin agonist facilitates circadian resynchronization in old hamsters after abrupt shifts in the light-dark cycle. Brain Res 2000; 880:207-11. [PMID: 11033009 DOI: 10.1016/s0006-8993(00)02806-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Age-related changes in the mammalian circadian system may be associated with a decline in circulating melatonin levels. Using 'jet lag' paradigms involving abrupt shifts in the light-dark cycle, we showed that a melatonin agonist, S-20098, accelerated by approximately 25% resynchronization of the circadian activity rhythm in old hamsters to the new light-dark cycle. It suggests the usefulness of melatonin-related compounds to treat circadian disorders associated with aging.
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Affiliation(s)
- L Weibel
- Centre d'Etudes des Rythmes Biologiques, School of Medicine, H opital Erasme, Université Libre de Bruxelles, Route de Lennik, 808, 1070, Brussels, Belgium
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Duncan MJ, Deveraux AW. Age-related changes in circadian responses to dark pulses. Am J Physiol Regul Integr Comp Physiol 2000; 279:R586-90. [PMID: 10938249 DOI: 10.1152/ajpregu.2000.279.2.r586] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Aging involves many alterations in circadian rhythms, including a loss of sensitivity to both photic and nonphotic time signals. This study investigated the sensitivity of young and old hamsters to the phase advancing effect of a 6-h dark pulse on the locomotor activity rhythm. Each hamster was tested four times during a period of approximately 9 mo; periods of exposure to a 14-h photoperiod were alternated with the periods of exposure to constant light (20-80 lx), during which the dark pulses were administered. There was no significant difference in the phase shifts exhibited by the young (4-10 mo) and old hamsters (19-25 mo) or in the amount of wheel running activity displayed during each dark pulse. However, young hamsters had a significantly greater propensity to exhibit split rhythms immediately after the dark pulses. These results suggest that, although aging does not reduce the sensitivity of the circadian pacemaker to this nonphotic signal, it alters one property of the pacemaker, i.e., the flexibility of the coupling of its component oscillators.
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Affiliation(s)
- M J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, Lexington 40536-0298, USA.
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Turek FW, Zee P, Van Reeth O. Melatonin and aging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2000; 460:435-40. [PMID: 10810545 DOI: 10.1007/0-306-46814-x_52] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Affiliation(s)
- F W Turek
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA.
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21
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Duncan MJ, Wheeler DL. Aging and photoperiod regulate glutamic acid decarboxylase(67) messenger RNA expression. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1999; 71:325-31. [PMID: 10521586 DOI: 10.1016/s0169-328x(99)00206-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Aging and short photoperiod exposure both induce similar long-term changes in circadian rhythms, including alterations in the timing and the amplitude of rhythms. Furthermore, these chronic conditions affect the function of the circadian pacemaker in the suprachiasmatic nuclei (SCN) by altering rhythmic expression of neuropeptide messenger RNAs (mRNAs). Because GABA modulates SCN neuronal activity, and GABAergic neurons innervate peptidergic neurons in the SCN, the present study investigated whether photoperiod or aging affect the expression of mRNA for GAD(67), the enzyme responsible for regulating the tonic levels of GABA. As a control for regional specificity, the reticular thalamic nucleus (RTN) was also examined. In situ hybridization for GAD(67) mRNA was performed on brain sections derived from Siberian hamsters exposed to a long day or a short day photoperiod for 15 days, and on brain sections from young (3-4 months old) and old (12-17 months old) Syrian hamsters exposed to a long photoperiod. The results showed that photoperiod and aging have different effects on GAD(67) mRNA expression. Exposure to short day photoperiod significantly increased GAD(67) mRNA expression in both the SCN and RTN of Siberian hamsters, while aging significantly decreased GAD(67) mRNA expression in the RTN of Syrian hamsters but had no effect on GAD(67) mRNA expression in the SCN. These findings suggest that modulation of GAD(67) mRNA expression in the SCN is associated with photoperiodic regulation of neuropeptide mRNA expression, but is not a common mechanism for chronic regulation of circadian rhythms. Also, GAD(67) mRNA expression in the RTN is differentially affected by photoperiod and aging.
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Affiliation(s)
- M J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA.
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Duncan MJ, Short J, Wheeler DL. Comparison of the effects of aging on 5-HT7 and 5-HT1A receptors in discrete regions of the circadian timing system in hamsters. Brain Res 1999; 829:39-45. [PMID: 10350528 DOI: 10.1016/s0006-8993(99)01311-6] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The circadian timekeeping system exhibits many functional changes with aging, including a loss of sensitivity to time cues such as systemic injections of the serotonergic agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). In order to elucidate the neurochemical mechanisms responsible for this age-related loss of sensitivity of the circadian pacemaker to serotonin agonists, the present study used quantitative autoradiography to determine whether aging decreases serotonin receptor populations in male Syrian hamsters. Four neuroanatomical regions that regulate circadian timekeeping were studied (the suprachiasmatic nuclei [SCN], the lateral geniculate nuclei [LGN], and the median raphe nucleus [MRN] and dorsal raphe nucleus [DRN]). The specific binding of [3H]8-OH-DPAT to serotonin7 (5-HT7) and serotonin1A (5-HT1A) receptors was investigated by competitive inhibition with ritanserin and pindolol, respectively. The results showed that the SCN, IGL, MRN, and DRN of the male Syrian hamster exhibited specific binding of [3H]8-OH-DPAT to both the 5-HT7 and 5-HT1A receptors, and that the latter receptor subtype is more abundant in all of these regions. At 17-19 months of age, a 50% decrease in 5-HT7 receptors was found in the DRN but not in any other regions. No significant age-related changes in 5-HT1A receptors were observed in any regions examined. The finding that a marked decrease in 5-HT7 receptors occurs in the DRN at the age previously characterized by loss of sensitivity to 8-OH-DPAT suggests that this region and this receptor subtype play important roles in 8-OH-DPAT induction of circadian phase shifts in vivo and that they constitute an important locus of aging in the circadian timing system.
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Affiliation(s)
- M J Duncan
- Department of Anatomy and Neurobiology, University of Kentucky Medical Center, 800 Rose Street, Lexington, KY 40536-0298, USA.
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Davis FC, Viswanathan N. Stability of circadian timing with age in Syrian hamsters. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:R960-8. [PMID: 9756523 DOI: 10.1152/ajpregu.1998.275.4.r960] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The causes of age-related disruptions in the timing of human sleep and wakefulness are not known but may include changes in both the homeostatic and circadian regulation of sleep. In Syrian hamsters the free running period of the circadian activity/rest rhythm has been reported to shorten with age. Although this has been observed under a variety of experimental conditions, the changes have been small and their consistency uncertain. In the present study, the wheel running activity/rest rhythm was continuously measured in male Syrian hamsters (Mesocricetus auratus) in dim constant light (<1 lx) from 8 wk of age until death. Fifteen hamsters survived to at least 90 wk (28%). The average free running period of these hamsters did not change with age. In 18 hamsters that died between 50 and 88 wk, free running period also did not change before death. In contrast to free running period, other measures related to activity level changed significantly with age and before death. Despite changes in the expression of the activity/rest rhythm, the free running period of the hamster circadian pacemaker remained remarkably stable with age.
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Affiliation(s)
- F C Davis
- Department of Biology, Northeastern University, Boston, Massachusetts 02115, USA
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24
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Abstract
The concept of chronopharmacology has significant implications for drug delivery systems. Age and illness put the elderly at greater risk for adverse drug effects, and nurses caring for the elderly have a challenging opportunity to measurably improve the quality of their care by applying chronotherapeutic concepts. Pharmacologic chronotherapy is a developing science that holds much hope for increasing the effectiveness of drug therapy and for reducing the incidence of toxic drug reactions. Nurses who are aware of the principles on which chronotherapy is based are in a unique position to improve the effectiveness of pharmacotherapy for all clients. However, appropriate timing of medications is especially important among elderly clients whose physiological processes are altered or changed by age and chronic illness. In this article, the basis of chronotherapy is discussed, and several therapeutic applications are identified.
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Labyak SE, Turek FW, Wallen EP, Zee PC. Effects of bright light on age-related changes in the locomotor activity of Syrian hamsters. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 274:R830-9. [PMID: 9530252 DOI: 10.1152/ajpregu.1998.274.3.r830] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Syrian hamsters display age-related changes in the expression of circadian rhythms and in responsiveness of the circadian system to photic and non-photic stimuli. This study characterized the effects of age on the locomotor activity rhythm of middle-aged and old hamsters and evaluated the effects of strengthening the entraining light signal. Compared with young (4.5 mo) animals, middle-aged (11.25 mo) and old (16 mo) animals displayed increased daily bouts of activity (P < 0.001) and reduced total daily activity and activity rhythm amplitude (P < 0.05) in 14:10-h light-dark cycles. After the light intensity was increased from 300 to 1,500 lx during the light cycle, middle-aged hamsters demonstrated decreased daily activity bouts (P < 0.05) and increased total daily activity (P < or = 0.01) and activity rhythm amplitude (P < or = 0.001) compared with controls maintained in 300 lx. The pattern of changes in the activity rhythm of old experimental animals was similar to trends observed in middle-aged experimental hamsters, although not as robust. Thus age-related changes in the activity rhythm are occurring by middle age in hamsters, and the provision of stronger entraining signals may lead to more stable circadian organization.
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Affiliation(s)
- S E Labyak
- Department of Neurobiology and Physiology, Northwestern University, Evanston 60208-3520, USA
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Van Someren EJ, Lijzenga C, Mirmiran M, Swaab DF. Long-term fitness training improves the circadian rest-activity rhythm in healthy elderly males. J Biol Rhythms 1997; 12:146-56. [PMID: 9090568 DOI: 10.1177/074873049701200206] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In old age, the circadian timing system loses optimal functioning. This process is even accelerated in Alzheimer's disease. Because pharmacological treatment of day-night rhythm disturbances usually is not very effective and may have considerable side effects, nonpharmacological treatments deserve attention. Bright light therapy has been shown to be effective. It is known from animal studies that increased activity, or an associated process, also strongly affects the circadian timing system, and the present study addresses the question of whether an increased level of physical activity may improve circadian rhythms in elderly. In the study, 10 healthy elderly males were admitted to a fitness training program for 3 months. The circadian rest-activity rhythm was assessed by means of actigraphy before and after the training period and again 1 year after discontinuation. As a control for possible seasonal effects, repeated actigraphic recordings were performed during the same times of the year as were the pre and post measurements in a control group of 8 healthy elderly males. Fitness training induced a significant reduction in the fragmentation of the rest-activity rhythm. Moreover, the fragmentation of the rhythm was negatively correlated with the level of fitness achieved after the training. No seasonal effect was found. Previous findings in human and animal studies are reviewed, and several possible mechanisms involved in the effect of fitness training on circadian rhythms are discussed. The results suggest that fitness training may be helpful in elderly people suffering from sleep problems related to circadian rhythm disturbances.
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Affiliation(s)
- E J Van Someren
- Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research, Netherlands
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Mirmiran M, van Someren EJ, Swaab DF. Is brain plasticity preserved during aging and in Alzheimer's disease? Behav Brain Res 1996; 78:43-8. [PMID: 8793036 DOI: 10.1016/0166-4328(95)00217-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Alzheimer's disease is a progressive neurodegenerative disorder believed to involve selective neuronal cell atrophy/loss in certain brain regions. The progress of the disease is accompanied by selective cognitive impairments and behavioral disturbances. The hypothesis has been put forward that by activation of selective brain areas throughout life one might protect or delay the degenerative process. This hypothesis, paraphrased as "a differential level of brain cell activity may account for cell selective loss" or "use it or lose it", further suggests that a certain level of neuronal plasticity persists during aging and even in Alzheimer's disease.
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Affiliation(s)
- M Mirmiran
- Graduate School Neurosciences Amsterdam, Netherlands Institute for Brain Research, The Netherlands.
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28
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Zhang Y, Kornhauser JM, Zee PC, Mayo KE, Takahashi JS, Turek FW. Effects of aging on light-induced phase-shifting of circadian behavioral rhythms, fos expression and CREB phosphorylation in the hamster suprachiasmatic nucleus. Neuroscience 1996; 70:951-61. [PMID: 8848176 DOI: 10.1016/0306-4522(95)00408-4] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Aging is associated with a variety of alterations in circadian rhythms, including changes in the response to environmental stimuli. The underlying causes for these age-related changes in the circadian system remain unknown. Recent studies have demonstrated that light induces the expression of Fos and phosphorylation of the cyclic-AMP response element-binding protein in the rodent suprachiasmatic nuclei, the location of a master circadian pacemaker in mammals, suggesting that these transcription factors may mediate the effects of light on the circadian clock. The purpose of this study was to determine the effects of aging upon light-induced phase-shifting of circadian locomotor activity rhythms, Fos protein expression and cyclic-AMP response element-binding protein phosphorylation in the suprachiasmatic nuclei. Young (three to four months) and old (18-22 months) male golden hamsters free-running in constant darkness were exposed to 5-min monochromatic light pulses of different irradiance levels, at circadian time 19, after which either steady-state phase shifts of locomotor activity rhythms were measured, or else immunocytochemistry for Fos or for phospho-cyclic-AMP response element-binding protein was performed. Old hamsters were approximately 20 times less sensitive to the phase-shifting effects of light on the activity rhythm, and the photic irradiance threshold for Fos-like immunoreactivity induction in the suprachiasmatic nuclei was elevated when compared to young animals. Aging was also associated with a deficit in cyclic-AMP response element-binding protein phosphorylation by light. These data indicate that there are dramatic changes in light-activated molecular responses in the suprachiasmatic nuclei of old hamsters, and suggest that these molecular changes may underlie age-related changes in the effects of light on the circadian clock system.
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Affiliation(s)
- Y Zhang
- Department of Neurobiology and Physiology, Center for Circadian Biology and Medicine, Northwestern University, Evanston, IL 60208, USA
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29
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Myers BL, Badia P. Changes in circadian rhythms and sleep quality with aging: mechanisms and interventions. Neurosci Biobehav Rev 1995; 19:553-71. [PMID: 8684716 DOI: 10.1016/0149-7634(95)00018-6] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Literature is reviewed indicating that aging is characterized by changes in circadian rhythms and sleep quality. The most marked change is an attenuation of amplitude. An advance of phase, a shortening of period, and a desynchronization of rhythms are also evident. The mechanisms underlying these changes are unknown. However, age-related changes in the retina, suprachiasmatic nucleus, and pineal gland seem relevant along with behavioral changes such as a reduction in physical activity and exposure to photic stimulation. Changes in circadian rhythms are frequently associated with a reduction in nighttime sleep quality, a decrease in daytime alertness, and an attenuation in cognitive performance; reversing such changes could enhance the quality of life for a large and rapidly increasing percentage of the population. Reversal appears possible by increasing melatonin levels with either appropriately timed exposure to photic stimulation and/or appropriately timed administration of exogenous melatonin. These interventions may increase aspects of genetic expression that have changed with aging. A hypothesis concerning the potential benefits of enhanced circadian amplitude is also offered.
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Affiliation(s)
- B L Myers
- Psychology Department, Bowling Green State University, OH 43403, USA
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Abstract
While aging has been associated with changes in the period and amplitude of circadian rhythms, little is known about how aging influences the response of the circadian clock to environmental stimuli. In this paper, we report on recent studies designed to determine the effects of advanced age on the response of the circadian clock to both photic and nonphotic stimuli in old hamsters (e.g., over 16 mo of age). Among the most pronounced age-related changes in the circadian rhythm of locomotor activity are: (a) alterations in the phase-angle of entrainment to the light-dark cycle; (b) an increase in the magnitude of phase shifts induced by pulses of light presented at specific circadian times; and (c) a loss of responsiveness to the phase shifting or entraining effects of stimuli which induce an acute increase of activity. Depletion of brain monoamine levels in young animals can induce changes in the responsiveness of the circadian clock to environmental stimuli which are similar to those which occur spontaneously in old animals, suggesting that aging alters monoaminergic inputs to the clock. Some of the age-related changes in the response of the clock to an activity-inducing stimulus can be reversed by implanting old animals with fetal SCN tissue. Determining the physiological basis for age related changes in the responsiveness of the clock to both internal and external stimuli, and the mechanisms by which normal circadian function can be restored, should lead to new insight into the functioning of the circadian clock and may lead to new approaches for normalizing disturbed circadian rhythms.
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Affiliation(s)
- F W Turek
- Department of Neurobiology and Physiology, Northwestern University Center for Biological Timing, Evanston, IL 60208, USA
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Penev PD, Turek FW, Zee PC. A serotonin neurotoxin attenuates the phase-shifting effects of triazolam on the circadian clock in hamsters. Brain Res 1995; 669:207-16. [PMID: 7712176 DOI: 10.1016/0006-8993(94)01237-c] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Several lines of evidence suggest the potential involvement of serotonergic pathways in mediating the effects of activity-inducing stimuli on the circadian clock in rodents. The aim of the present 3 experiments was to examine the effects of the serotonergic neurotoxin, p-chloroamphetamine (PCA, 10 mg/kg) on: (1) the monoamine levels of the hypothalamus, frontal cortex and hippocampus in the hamster; (2) the phase shifts in the circadian rhythm of locomotor activity of hamsters in response to treatment with the short-acting benzodiazepine, triazolam (7.5 mg/kg); and (3) the magnitude of the acute increase in locomotor activity associated with triazolam administration in this species. The administration of PCA to hamsters caused changes of specific monoaminergic systems in the hypothalamus, that were limited to a selective decrease in serotonin levels 7 days post-treatment. The phase shifts of the circadian clock in response to triazolam treatment at CT 6 were considerably attenuated following the administration of the 5-HT neurotoxin. The total amount and the profiles of triazolam-induced wheel-running and general cage activity between CT 6 and CT 12 were not significantly affected by the PCA treatment. The finding that a 5-HT neurotoxin can attenuate the phase-shifting effects of triazolam in hamsters, without interfering with its activity-inducing properties, suggests that serotonergic afferents might be involved in the mechanism for non-photic phase-shifting of the circadian system.
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Affiliation(s)
- P D Penev
- Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208
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Van Reeth O, Zhang Y, Zee PC, Turek FW. Grafting fetal suprachiasmatic nuclei in the hypothalamus of old hamsters restores responsiveness of the circadian clock to a phase shifting stimulus. Brain Res 1994; 643:338-42. [PMID: 8032929 DOI: 10.1016/0006-8993(94)90044-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In the present study, 18-25-month-old hamsters free-running in constant dim light were injected, both before and after receiving fetal grafts containing either cerebellar tissue or the suprachiasmatic nuclei (SCN), with a dose of triazolam given at a time known to reliably phase shift the rhythm of locomotor activity in young hamsters. SCN-grafted animals, but not control animals implanted with fetal cerebellar tissue, showed a significantly greater response to the phase shifting effects of triazolam, demonstrating that at least some age-related changes in the circadian system can be reversed by neuronal transplantation. These results raise the possibility that neuropharmacological interventions that can simulate the effects of fetal SCN grafts might be useful in the treatment of age-related disorders in circadian function.
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Affiliation(s)
- O Van Reeth
- Department of Neurobiology/Physiology, Northwestern University, Evanston, IL 60208
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