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Seasonality and light phase-resetting in the mammalian circadian rhythm. Sci Rep 2020; 10:19506. [PMID: 33177530 PMCID: PMC7658258 DOI: 10.1038/s41598-020-74002-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 09/18/2020] [Indexed: 11/13/2022] Open
Abstract
We study the impact of light on the mammalian circadian system using the theory of phase response curves. Using a recently developed ansatz we derive a low-dimensional macroscopic model for the core circadian clock in mammals. Significantly, the variables and parameters in our model have physiological interpretations and may be compared with experimental results. We focus on the effect of four key factors which help shape the mammalian phase response to light: heterogeneity in the population of oscillators, the structure of the typical light phase response curve, the fraction of oscillators which receive direct light input and changes in the coupling strengths associated with seasonal day-lengths. We find these factors can explain several experimental results and provide insight into the processing of light information in the mammalian circadian system. In particular, we find that the sensitivity of the circadian system to light may be modulated by changes in the relative coupling forces between the light sensing and non-sensing populations. Finally, we show how seasonal day-length, after-effects to light entrainment and seasonal variations in light sensitivity in the mammalian circadian clock are interrelated.
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Buijink MR, Olde Engberink AHO, Wit CB, Almog A, Meijer JH, Rohling JHT, Michel S. Aging Affects the Capacity of Photoperiodic Adaptation Downstream from the Central Molecular Clock. J Biol Rhythms 2020; 35:167-179. [PMID: 31983261 PMCID: PMC7134598 DOI: 10.1177/0748730419900867] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Aging impairs circadian clock function, leading to disrupted sleep-wake patterns and a reduced capability to adapt to changes in environmental light conditions. This makes shift work or the changing of time zones challenging for the elderly and, importantly, is associated with the development of age-related diseases. However, it is unclear what levels of the clock machinery are affected by aging, which is relevant for the development of targeted interventions. We found that naturally aged mice of >24 months had a reduced rhythm amplitude in behavior compared with young controls (3-6 months). Moreover, the old animals had a strongly reduced ability to adapt to short photoperiods. Recording PER2::LUC protein expression in the suprachiasmatic nucleus revealed no impairment of the rhythms in PER2 protein under the 3 different photoperiods tested (LD: 8:16, 12:12, and 16:8). Thus, we observed a discrepancy between the behavioral phenotype and the molecular clock, and we conclude that the aging-related deficits emerge downstream of the core molecular clock. Since it is known that aging affects several intracellular and membrane components of the central clock cells, it is likely that an impairment of the interaction between the molecular clock and these components is contributing to the deficits in photoperiod adaptation.
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Affiliation(s)
- M Renate Buijink
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Anneke H O Olde Engberink
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Charlotte B Wit
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Assaf Almog
- Lorentz Institute for Theoretical Physics, Leiden University, Leiden, the Netherlands
| | - Johanna H Meijer
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Jos H T Rohling
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Stephan Michel
- Department of Cellular and Chemical Biology, Laboratory for Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
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3
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Duncan MJ. Interacting influences of aging and Alzheimer's disease on circadian rhythms. Eur J Neurosci 2019; 51:310-325. [DOI: 10.1111/ejn.14358] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 01/03/2019] [Accepted: 01/11/2019] [Indexed: 01/01/2023]
Affiliation(s)
- Marilyn J. Duncan
- Department of NeuroscienceUniversity of Kentucky Medical School Lexington Kentucky
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4
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Manoogian ENC, Panda S. Circadian rhythms, time-restricted feeding, and healthy aging. Ageing Res Rev 2017; 39:59-67. [PMID: 28017879 PMCID: PMC5814245 DOI: 10.1016/j.arr.2016.12.006] [Citation(s) in RCA: 199] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 12/16/2016] [Accepted: 12/18/2016] [Indexed: 12/29/2022]
Abstract
Circadian rhythms optimize physiology and health by temporally coordinating cellular function, tissue function, and behavior. These endogenous rhythms dampen with age and thus compromise temporal coordination. Feeding-fasting patterns are an external cue that profoundly influence the robustness of daily biological rhythms. Erratic eating patterns can disrupt the temporal coordination of metabolism and physiology leading to chronic diseases that are also characteristic of aging. However, sustaining a robust feeding-fasting cycle, even without altering nutrition quality or quantity, can prevent or reverse these chronic diseases in experimental models. In humans, epidemiological studies have shown erratic eating patterns increase the risk of disease, whereas sustained feeding-fasting cycles, or prolonged overnight fasting, is correlated with protection from breast cancer. Therefore, optimizing the timing of external cues with defined eating patterns can sustain a robust circadian clock, which may prevent disease and improve prognosis.
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Affiliation(s)
- Emily N C Manoogian
- Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
| | - Satchidananda Panda
- Salk Institute for Biological Studies, 10010 N. Torrey Pines Rd, La Jolla, CA 92037, USA; University of California Center for Circadian Biology, 9500, Gilman Drive, La Jolla, 92093, USA.
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5
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Circadian Plasticity of Mammalian Inhibitory Interneurons. Neural Plast 2017; 2017:6373412. [PMID: 28367335 PMCID: PMC5358450 DOI: 10.1155/2017/6373412] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 01/15/2017] [Accepted: 02/19/2017] [Indexed: 12/11/2022] Open
Abstract
Inhibitory interneurons participate in all neuronal circuits in the mammalian brain, including the circadian clock system, and are indispensable for their effective function. Although the clock neurons have different molecular and electrical properties, their main function is the generation of circadian oscillations. Here we review the circadian plasticity of GABAergic interneurons in several areas of the mammalian brain, suprachiasmatic nucleus, neocortex, hippocampus, olfactory bulb, cerebellum, striatum, and in the retina.
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6
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Castro A, Becerra M, Manso MJ, Anadón R. Neuronal organization of the brain in the adult amphioxus (Branchiostoma lanceolatum): A study with acetylated tubulin immunohistochemistry. J Comp Neurol 2015; 523:2211-32. [DOI: 10.1002/cne.23785] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 09/11/2014] [Accepted: 09/19/2014] [Indexed: 12/28/2022]
Affiliation(s)
- Antonio Castro
- Department of Cell and Molecular Biology; Faculty of Sciences; University of A Coruña; 15008 A Coruña Spain
| | - Manuela Becerra
- Department of Cell Biology and Ecology; CIBUS, University of Santiago de Compostela; 15706 Santiago de Compostela Spain
| | - María Jesús Manso
- Department of Cell and Molecular Biology; Faculty of Sciences; University of A Coruña; 15008 A Coruña Spain
| | - Ramón Anadón
- Department of Cell Biology and Ecology; CIBUS, University of Santiago de Compostela; 15706 Santiago de Compostela Spain
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7
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Abstract
Aging is associated with a deterioration of daily (circadian) rhythms in physiology and behavior. Deficits in the function of the central circadian pacemaker in the suprachiasmatic nucleus (SCN) have been implicated, but the responsible mechanisms have not been clearly delineated. In this report, we characterize the progression of rhythm deterioration in mice to 900 d of age. Longitudinal behavioral and sleep-wake recordings in up to 30-month-old mice showed strong fragmentation of rhythms, starting at the age of 700 d. Patch-clamp recordings in this age group revealed deficits in membrane properties and GABAergic postsynaptic current amplitude. A selective loss of circadian modulation of fast delayed-rectifier and A-type K+ currents was observed. At the tissue level, phase synchrony of SCN neurons was grossly disturbed, with some subpopulations peaking in anti-phase and a reduction in amplitude of the overall multiunit activity rhythm. We propose that aberrant SCN rhythmicity in old animals--with electrophysiological arrhythmia at the single-cell level and phase desynchronization at the network level--can account for defective circadian function with aging.
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Hasan S, Dauvilliers Y, Mongrain V, Franken P, Tafti M. Age-related changes in sleep in inbred mice are genotype dependent. Neurobiol Aging 2010; 33:195.e13-26. [PMID: 20619936 DOI: 10.1016/j.neurobiolaging.2010.05.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2009] [Revised: 05/04/2010] [Accepted: 05/10/2010] [Indexed: 01/10/2023]
Abstract
Aging produces major changes in sleep structure and intensity which might be linked to cognitive impairment in the elderly. In this study, the genetic contribution to age-related changes in sleep was assessed in three inbred mouse strains of various ages. Baseline sleep and the response to 6 hours sleep deprivation (SD) achieved by gentle handling were quantified in young, middle-aged, and older male mice using electroencephalography. Total sleep time initially increased with age but then decreased in the oldest group mainly due to changes in sleep duration during the active phase. The effect of age on electroencephalographic (EEG) delta power depends on genotype and sleep pressure level with SD increasing the age-related differences. The strong effect of age upon the spectral profile of the different behavioral states was modulated by genetic background. Overall, our results suggest that sleep pressure can modulate the effect of age, that most sleep variables do not monotonically change with age in contrast to previous reports in humans and other species, and that genetic factors have a major impact on the aging processes affecting sleep.
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Affiliation(s)
- Sibah Hasan
- Center for Integrative Genomics, University of Lausanne, Genopode Building, CH-1015 Lausanne, Switzerland
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Biello SM. Circadian clock resetting in the mouse changes with age. AGE (DORDRECHT, NETHERLANDS) 2009; 31:293-303. [PMID: 19557547 PMCID: PMC2813053 DOI: 10.1007/s11357-009-9102-7] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Accepted: 06/08/2009] [Indexed: 05/28/2023]
Abstract
The most widely recognised consequence of normal age-related changes in biological timing is the sleep disruption that appears in old age and diminishes the quality of life. These sleep disorders are part of the normal ageing process and consist primarily of increased amounts of wakefulness and reduced amounts of deep sleep. Changes in the amplitude and timing of the sleep-wake cycle appear to represent, at least in part, a loss of effective circadian regulation of sleep. Understanding alterations in the characteristics of stimuli that help to consolidate internal rhythms will lead to recommendations to improve synchronisation in old age. Converging evidence from both human and animal studies indicate that senescence is associated with alterations in the neural structure thought to be primarily responsible for the generation of the circadian oscillation, the suprachiasmatic nuclei (SCN). Work has shown that there are changes in the anatomy, physiology and ability of the clock to reset in response to stimuli with age. Therefore it is possible that at least some of the observed age-related changes in sleep and circadian timing could be mediated at the level of the SCN. The SCN contain a circadian clock whose activity can be recorded in vitro for several days. We have tested the response of the circadian clock to a number of neurochemicals that reset the clock in a manner similar to light, including glutamate, N-methyl-D-aspartate (NMDA), gastrin-releasing peptide (GRP) and histamine (HA). In addition, we have also tested agents which phase shift in a pattern similar to behavioural 'non-photic' signals, including neuropeptide Y (NPY), serotonin (5HT) and gamma-aminobutyric acid (GABA). These were tested on the circadian clock in young and older mice (approximately 4 and 15 months old). We found deficits in the response to specific neurochemicals but not to others in our older mice. These results indicate that some changes seen in the responsiveness of the circadian clock to light with age may be mediated at the level of the SCN. Further, the responsiveness of the circadian clock with age is attenuated to some, but not all stimuli. This suggests that not all clock stimuli lose their effectiveness with age, and that it may be possible to compensate for deficits in clock performance by enhancing the strength of those stimulus pathways which are intact.
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Effect of melatonin on age induced changes in daily serotonin rhythms in suprachiasmatic nucleus of male Wistar rat. Biogerontology 2009; 11:299-308. [PMID: 19774481 DOI: 10.1007/s10522-009-9248-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Accepted: 09/10/2009] [Indexed: 01/08/2023]
Abstract
The decline in physiological functions with aging may affect the ability of the SCN, the biological clock, circadian pacemaker to transmit rhythmic information to other neural target sites, and thereby modify the expression of biological rhythms resulting in circadian disorders. Neurotransmitter serotonin plays important role in the photic and non-photic regulation of circadian rhythms and is a precursor of neurohormone melatonin, an internal zeitgeber. To assess effects of aging on the functional integrity of circadian system, we studied daily serotonin rhythms in the SCN by measuring serotonin levels at variable time points in wide range of age groups such as 15 days, 1, 2, 3 (adult), 4, 6, 9, 12, 18 and 24 months old male wistar rats. Animals were maintained in light-dark conditions (LD; 12:12) two weeks prior to experiment. We report here that in 15 days, 1 and 2 months old rat SCN the mean serotonin level is low and daily serotonin rhythm is just beginning; at 3, 4 and 6 months, serotonin levels and rhythms are robust and at 9, 12, 18 and 24 months mean serotonin levels are low again and rhythm is becoming more disrupted. Previous studies have shown the 5-HT rhythmicity was established by 3 month in rat brain but disintegrated by 6 months of age. As melatonin, an endogenous synchronizer and an antiaging agent, declines with aging, the effects of exogenous melatonin administration on serotonin rhythmicity in SCN in 3, 6, 9 and 24 months old rats were studied to assess effects of aging on responsiveness to melatonin. Our studies indicated an age related loss of sensitivity to melatonin in the restoration of age induced changes in SCN serotonin amplitude and rhythmicity.
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Mansuy V, Risold PY, Glauser M, Fraichard A, Pralong FP. Expression of the GABAA receptor associated protein Gec1 is circadian and dependent upon the cellular clock machinery in GnRH secreting GnV-3 cells. Mol Cell Endocrinol 2009; 307:68-76. [PMID: 19524128 DOI: 10.1016/j.mce.2009.02.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 02/25/2009] [Accepted: 02/25/2009] [Indexed: 11/23/2022]
Abstract
The timely regulation of gonadotropin-releasing hormone (GnRH) secretion requires a GABAergic signal. We hypothesized that GEC1, a protein promoting the transport of GABA(A) receptors, could represent a circadian effector in GnRH neurons. First, we demonstrated that gec1 is co-expressed with the GABA(A) receptor in hypothalamic rat GnRH neurons. We also confirmed that the clock genes per1, cry1 and bmal1 are expressed and oscillate in GnRH secreting GnV-3 cells. Then we could show that gec1 is expressed in GnV-3 cells, and oscillates in a manner temporally related to the oscillations of the clock transcription factors. Furthermore, we could demonstrate that these oscillations depend upon Per1 expression. Finally, we observed that GABA(A) receptor levels at the GnV-3 cell membrane are timely modulated following serum shock. Together, these data demonstrate that gec1 expression is dependent upon the circadian clock machinery in GnRH-expressing neurons, and suggest for the first time that the level of GABA(A) receptor at the cell membrane may be under timely regulation. Overall, they provide a potential mechanism for the circadian regulation of GnRH secretion by GABA, and may also be relevant to the general understanding of circadian rhythms.
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Affiliation(s)
- Virginie Mansuy
- Services of Endocrinology, Diabetology, and Metabolism of the University Hospital of Lausanne, Switzerland
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12
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Bentivoglio M, Deng XH, Nygård M, Sadki A, Kristensson K. The aging suprachiasmatic nucleus and cytokines: functional, molecular, and cellular changes in rodents. Chronobiol Int 2009; 23:437-49. [PMID: 16687317 DOI: 10.1080/07420520500545797] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The aging process brings about a switch to a low-grade chronic inflammatory condition in the periphery and brain, a condition which may prime brain cells, including those of the hypothalamic suprachiasmatic nucleus (SCN). Little information is available, however, on the responses of the SCN to neuroinflammation and immune-related challenges, and such responses have not been hitherto investigated during aging. We here provide an overview of these issues and summarize data we obtained in the study of the SCN of young and aged mice. In particular, we analyzed: i) the electrophysiological properties of the SCN core (the retino-recipient region) in tissue slices; ii) expression and day/night variation of transcripts encoding the receptors for the cytokines interferon-gamma and tumor necrosis factor-alpha, as well as the expression of transcripts encoding the proteins "suppressors of cytokine signaling" SOCS1 and SOCS3, by means of quantitative real-time polymerase chain reaction; levels of mRNAs were correlated with neuronal activation, revealed by Fos induction, elicited in the SCN by intracerebroventricular injections of a mixture of interferon-gamma and tumor necrosis factor-alpha during the daytime and nighttime; and iii) response of astrocytes and microglia in the SCN to the same paradigm of cytokine administration. Marked changes of all the above-mentioned parameters were found in the aged SCN, indicating that the circadian pacemaker is a target of the aging process. In addition, the findings indicate that neurons and glial cells of the biological clock are sensitive to inflammatory signals, and that the response to such signals is altered during senescence.
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Affiliation(s)
- Marina Bentivoglio
- Department of Morphological and Biomedical Sciences, University of Verona, Italy.
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Palomba M, Nygård M, Florenzano F, Bertini G, Kristensson K, Bentivoglio M. Decline of the presynaptic network, including GABAergic terminals, in the aging suprachiasmatic nucleus of the mouse. J Biol Rhythms 2008; 23:220-31. [PMID: 18487414 DOI: 10.1177/0748730408316998] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Biological rhythms, and especially the sleep/wake cycle, are frequently disrupted during senescence. This draws attention to the study of aging-related changes in the hypothalamic suprachiasmatic nucleus (SCN), the master circadian pacemaker. The authors here compared the SCN of young and old mice, analyzing presynaptic terminals, including the gamma-aminobutyric acid (GABA)ergic network, and molecules related to the regulation of GABA, the main neurotransmitter of SCN neurons. Transcripts of the alpha3 subunit of the GABAA receptor and the GABA-synthesizing enzyme glutamic acid decarboxylase isoform 67 (GAD67) were analyzed with real-time RT-PCR and GAD67 protein with Western blotting. These parameters did not show significant changes between the 2 age groups. Presynaptic terminals were identified in confocal microscopy with synaptophysin immunofluorescence, and the GABAergic subset of those terminals was revealed by the colocalization of GAD67 and synaptophysin. Quantitative analysis of labeled synaptic endings performed in 2 SCN subregions, where retinal afferents are known to be, respectively, very dense or very sparse, revealed marked aging-related changes. In both subregions, the evaluated parameters (the number of and the area covered by presynaptic terminals and by their GABAergic subset) were significantly decreased in old versus young mice. No significant differences were found between SCN tissue samples from animals sacrificed at different times of day, in either age group. Altogether, the data point out marked reduction in the synaptic network of the aging biological clock, which also affects GABAergic terminals. Such alterations could underlie aging-related SCN dysfunction, including low-amplitude output during senescence.
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Affiliation(s)
- Maria Palomba
- Department of Morphological and Biomedical Sciences, University of Verona, Italy
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14
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Subash S, Subramanian P. Influence ofN-phthaloyl gamma-aminobutyric acid on circadian rhythms of lipid peroxidation products and antioxidants. BIOL RHYTHM RES 2008. [DOI: 10.1080/09291010601048950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Böttner M, Leonhardt S, Wuttke W, Jarry H. Changes of expression of genes related to the activity of the gonadotrophin-releasing hormone pulse generator in young versus middle-aged male rats. J Neuroendocrinol 2007; 19:779-87. [PMID: 17850460 DOI: 10.1111/j.1365-2826.2007.01589.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In females, it is well established that changes in the expression of neurotransmitters and peptides regulating the activity of the gonadotrophin-releasing hormone (GnRH) pulse generator are altered during ageing. By contrast, little is known about whether those age-related changes also occur in males. Therefore, we designed an animal study with orchidectomised young and middle-aged male rats to investigate changes in luteinising hormone (LH) secretion profiles and changes in the mRNA expression of genes regulating the activity of the GnRH pulse generator. Our results demonstrate that middle-aged rats exhibit lower serum LH levels and relatively fewer LH pulses with attenuated amplitude compared to young animals. Furthermore, upon ageing, GnRH mRNA expression is up-regulated in the preoptic area and the septum where GnRH neurones reside. Analysis of mRNA levels of glutamate decarboxylase (GAD) enzymes revealed that GAD(65) and GAD(67) mRNA expression increased in the mediobasal hypothalamus (MBH) and that GAD(67) mRNA levels decreased in the suprachiasmatic nucleus. In addition, we observed an age-related increase of oestrogen receptor (ER)alpha mRNA in the MBH, and both ERalpha and ERbeta mRNA expression was up-regulated in the pituitary of middle-aged rats compared to young animals. Taken together, our data support the existence of a male 'andropause' that is, like the menopause in females, accompanied by changes in neurotransmitter and hormone receptor expression that are involved in regulating the function of the GnRH pulse generator.
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Affiliation(s)
- M Böttner
- Department of Anatomy, University of Kiel, Kiel, Germany.
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Wu YH, Swaab DF. Disturbance and strategies for reactivation of the circadian rhythm system in aging and Alzheimer's disease. Sleep Med 2007; 8:623-36. [PMID: 17383938 DOI: 10.1016/j.sleep.2006.11.010] [Citation(s) in RCA: 182] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Revised: 11/09/2006] [Accepted: 11/11/2006] [Indexed: 12/15/2022]
Abstract
Circadian rhythm disturbances, such as sleep disorders, are frequently seen in aging and are even more pronounced in Alzheimer's disease (AD). Alterations in the biological clock, the suprachiasmatic nucleus (SCN), and the pineal gland during aging and AD are considered to be the biological basis for these circadian rhythm disturbances. Recently, our group found that pineal melatonin secretion and pineal clock gene oscillation were disrupted in AD patients, and surprisingly even in non-demented controls with the earliest signs of AD neuropathology (neuropathological Braak stages I-II), in contrast to non-demented controls without AD neuropathology. Furthermore, a functional disruption of the SCN was observed from the earliest AD stages onwards, as shown by decreased vasopressin mRNA, a clock-controlled major output of the SCN. The observed functional disconnection between the SCN and the pineal from the earliest AD stage onwards seems to account for the pineal clock gene and melatonin changes and underlies circadian rhythm disturbances in AD. This paper further discusses potential therapeutic strategies for reactivation of the circadian timing system, including melatonin and bright light therapy. As the presence of melatonin MT1 receptor in the SCN is extremely decreased in late AD patients, supplementary melatonin in the late AD stages may not lead to clear effects on circadian rhythm disorders.
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Affiliation(s)
- Ying-Hui Wu
- Netherlands Institute for Neuroscience, Meibergdreef 47, 1105 BA Amsterdam, The Netherlands
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