Journal of Circadian Rhythms最新文献

{"title":"Synaptophysin is involved in resetting of the mammalian circadian clock.","authors":"Marie Aramendy,&nbsp;Sascha Seibert,&nbsp;Philipp Treppmann,&nbsp;Karin Richter,&nbsp;Gudrun Ahnert-Hilger,&nbsp;Urs Albrecht","doi":"10.1186/1740-3391-11-11","DOIUrl":"https://doi.org/10.1186/1740-3391-11-11","url":null,"abstract":"<p><strong>Background: </strong>Mammals can adapt to changing light/dark conditions by advancing or delaying their circadian clock phase. Light pulses evoke changes in gene expression and neuronal activity in the suprachiasmatic nuclei (SCN), the central pacemaker of the circadian system. Alterations in neuronal activity are partially mediated by changes in synaptic vesicle (SV) fusion at the presynaptic membrane, which modulates release of neurotransmitters.</p><p><strong>Methods: </strong>Male synaptophysin (Syp) knock-out and littermate control wild type mice were tested in an Aschoff type I resetting paradigm. Additionally, gene expression of cFos, Per1 and Per2 was assessed in the SCN. Finally, complexes between the synaptic vesicle proteins Syp and synaptobrevin (Syb) were studied in order to correlate behavior with protein complexes at synaptic vesicles.</p><p><strong>Results: </strong>Here we show that mice lacking Syp, a modulator of neurotransmitter release, are defective in delaying clock phase. In contrast, clock phase advances as well as clock period are normal in Syp-/- knock-out mice. This correlates with the formation of Syp/Syb complexes.</p><p><strong>Conclusions: </strong>Our findings suggest that Syp is involved specifically in the response to a nocturnal light pulse occurring in the early night. It appears that the SV component Syp is critically involved in the delay portion of the resetting mechanism of the circadian clock.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"11"},"PeriodicalIF":0.0,"publicationDate":"2013-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-11","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31773042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An out-of-lab trial: a case example for the effect of intensive exercise on rhythms of human clock gene expression.","authors":"Akihiko Okamoto,&nbsp;Takuro Yamamoto,&nbsp;Ritsuko Matsumura,&nbsp;Koichi Node,&nbsp;Makoto Akashi","doi":"10.1186/1740-3391-11-10","DOIUrl":"https://doi.org/10.1186/1740-3391-11-10","url":null,"abstract":"<p><strong>Background: </strong>Although out-of-lab investigation of the human circadian clock at the clock gene expression level remains difficult, a recent method using hair follicle cells might be useful. While exercise may function as an entrainment cue for circadian rhythms, it remains unclear whether exercise affects human circadian clock gene expression.</p><p><strong>Methods: </strong>Efforts to observe apparent effects of exercise on clock gene expression require that several specific conditions be met: intense exercise should be habitually performed at a relatively uncommon time of day over an extended period; and any relative phase shift thereby observed should be validated by comparison of exercise and no-exercise periods. Wake-up and meal times should be kept almost constant over the experimental period. The present study was conducted using a professional fighter who met these strict criteria as subject. Facial hair samples were collected at 4-h intervals around the clock to ascertain rhythms of clock gene expression.</p><p><strong>Results: </strong>During a period in which nighttime training (from 20:00 to 22:00) was habitually performed, circadian clock gene expression was phase-delayed by 2 to 4 h compared with that during a no-exercise period. Maximum level and circadian amplitude of clock gene expression were not affected by the nighttime training.</p><p><strong>Conclusion: </strong>Our trial observations illustrate the possibility that heavy physical exercise might strongly affect the circadian phase of clock gene expression. Exercise might be therefore effective for the clinical care of circadian disorders. The results also suggest that athletes may require careful scheduling of heavy physical exercise to maintain normal circadian phase and ensure optimal athletic performance.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"10"},"PeriodicalIF":0.0,"publicationDate":"2013-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-10","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31706777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Circadian behavior of mice deficient in PER1/PML or PER2/PML.","authors":"Takao Miki,&nbsp;Misty Chen-Goodspeed,&nbsp;Zhaoyang Zhao,&nbsp;Cheng Chi Lee","doi":"10.1186/1740-3391-11-9","DOIUrl":"https://doi.org/10.1186/1740-3391-11-9","url":null,"abstract":"<p><strong>Background: </strong>Our recent studies demonstrate that the murine homolog of the human tumor suppressor promyelocytic leukemia (PML) regulates circadian behavior of mice. To further gather insight into PML's contribution to circadian behavior, we generated two strains of mice deficient in one of the two period (Per) genes and the PML gene, with Per1-/-/Pml-/- and Per2-/-/Pml-/- genotypes.</p><p><strong>Results: </strong>Here we report the circadian behavior of these mice based on wheel-running behavioral analysis. In a free-running environment, the Per1-/-/Pml-/- mice maintained circadian rhythm but displayed a significantly shorter period of 22.2 h. In addition, these mice displayed significantly enhanced phase response to a light pulse given at zeitgeber time (ZT) 14 and 22. The Per2-/-/Pml-/- mice lose persistent rhythm when in a free-running environment, as also the case for Per2-/- mice. A transient post-light pulse rhythm seen in the arrhythmic Per2-/- mice was less apparent in Per2-/-/Pml-/- mice. Both the Per1-/-/Pml-/- and Per2-/-/Pml-/- mice displayed a more advanced phase angle of entrainment activity during light-dark cycles than the single gene deficient mice.</p><p><strong>Conclusions: </strong>Beyond merely regulating PER1 and PER2, the current behavioral studies suggest PML has additional roles in mouse circadian behavior.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"9"},"PeriodicalIF":0.0,"publicationDate":"2013-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31691197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diurnal and nutritional adjustments of intracellular Ca2+ release channels and Ca2+ ATPases associated with restricted feeding schedules in the rat liver.","authors":"Adrián Báez-Ruiz,&nbsp;Karina Cázares-Gómez,&nbsp;Olivia Vázquez-Martínez,&nbsp;Raúl Aguilar-Roblero,&nbsp;Mauricio Díaz-Muñoz","doi":"10.1186/1740-3391-11-8","DOIUrl":"https://doi.org/10.1186/1740-3391-11-8","url":null,"abstract":"<p><strong>Background: </strong>Intracellular calcium is a biochemical messenger that regulates part of the metabolic adaptations in the daily fed-fast cycle. The aim of this study was to characterize the 24-h variations of the liver ryanodine and IP3 receptors (RyR and IP3R) as well as of the endoplasmic-reticulum and plasma-membrane Ca2+-ATPases (SERCA and PMCA) in daytime restricted feeding protocol.</p><p><strong>Methods: </strong>A biochemical and immunohistochemical approach was implemented in this study: specific ligand-binding for RyR and IP3R, enzymatic activity (SERCA and PMCA), and protein levels and zonational hepatic-distribution were determined by immunoblot and immunohistochemistry respectively under conditions of fasting, feeding, and temporal food-restriction.</p><p><strong>Results: </strong>Binding assays and immunoblots for IP3R1 and 2 showed a peak at the light/dark transition in the ad-libitum (AL) group, whereas in the restricted-feeding (RF) group the peak shifted towards the food-access time. In the case of RyR binding experiments, both AL and RF groups showed a modest elevation during the dark period, with the RF rats exhibiting increased binding in response to feeding. The AL group showed 24-h rhythmicity in SERCA level; in contrast, RF group showed a pronounced amplitude elevation and a peak phase-shift during the light-period in SERCA level and activity. The activity of PMCA was constant along day in both groups; PMCA1 levels showed a 24-h rhythmicity in the RF rats (with a peak in the light period), meanwhile PMCA4 protein levels showed rhythmicity in both groups. The fasted condition promoted an increase in IP3R binding and protein level; re-feeding increased the amount of RyR; neither the activity nor expression of SERCA and PMCA protein was affected by fasting-re-feeding conditions. Histochemical experiments showed that the distribution of the Ca2+-handling proteins, between periportal and pericentral zones of the liver, varied with the time of day and the feeding protocol.</p><p><strong>Conclusions: </strong>Our findings show that RF influences mainly the phase and amplitude of hepatic IP3R and SERCA rhythms as well as discrete zonational distribution for RyR, IP3Rs, SERCA, and PMCA within the liver acinus, suggesting that intracellular calcium dynamics could be part of the rheostatic adaptation of the liver due to diurnal meal entrainment/food entrained oscillator expression.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"8"},"PeriodicalIF":0.0,"publicationDate":"2013-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31671234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Methods for serial analysis of long time series in the study of biological rhythms.","authors":"Antoni Díez-Noguera","doi":"10.1186/1740-3391-11-7","DOIUrl":"10.1186/1740-3391-11-7","url":null,"abstract":"<p><p>When one is faced with the analysis of long time series, one often finds that the characteristics of circadian rhythms vary with time throughout the series. To cope with this situation, the whole series can be fragmented into successive sections which are analyzed one after the other, which constitutes a serial analysis. This article discusses serial analysis techniques, beginning with the characteristics that the sections must have and how they can affect the results. After consideration of the effects of some simple filters, different types of serial analysis are discussed systematically according to the variable analyzed or the estimated parameters: scalar magnitudes, angular magnitudes (time or phase), magnitudes related to frequencies (or periods), periodograms, and derived and / or special magnitudes and variables. The use of wavelet analysis and convolutions in long time series is also discussed. In all cases the fundamentals of each method are exposed, jointly with practical considerations and graphic examples. The final section provides information about software available to perform this type of analysis. </p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"7"},"PeriodicalIF":0.0,"publicationDate":"2013-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3723718/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31232340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Maximum entropy spectral analysis for circadian rhythms: theory, history and practice.","authors":"Harold B Dowse","doi":"10.1186/1740-3391-11-6","DOIUrl":"https://doi.org/10.1186/1740-3391-11-6","url":null,"abstract":"<p><p>There is an array of numerical techniques available to estimate the period of circadian and other biological rhythms. Criteria for choosing a method include accuracy of period measurement, resolution of signal embedded in noise or of multiple periodicities, and sensitivity to the presence of weak rhythms and robustness in the presence of stochastic noise. Maximum Entropy Spectral Analysis (MESA) has proven itself excellent in all regards. The MESA algorithm fits an autoregressive model to the data and extracts the spectrum from its coefficients. Entropy in this context refers to \"ignorance\" of the data and since this is formally maximized, no unwarranted assumptions are made. Computationally, the coefficients are calculated efficiently by solution of the Yule-Walker equations in an iterative algorithm. MESA is compared here to other common techniques. It is normal to remove high frequency noise from time series using digital filters before analysis. The Butterworth filter is demonstrated here and a danger inherent in multiple filtering passes is discussed. </p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"6"},"PeriodicalIF":0.0,"publicationDate":"2013-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31571964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wavelet analysis of circadian and ultradian behavioral rhythms.","authors":"Tanya L Leise","doi":"10.1186/1740-3391-11-5","DOIUrl":"https://doi.org/10.1186/1740-3391-11-5","url":null,"abstract":"<p><p>: We review time-frequency methods that can be useful in quantifying circadian and ultradian patterns in behavioral records. These records typically exhibit details that may not be captured through commonly used measures such as activity onset and so may require alternative approaches. For instance, activity may involve multiple bouts that vary in duration and magnitude within a day, or may exhibit day-to-day changes in period and in ultradian activity patterns. The discrete Fourier transform and other types of periodograms can estimate the period of a circadian rhythm, but we show that they can fail to correctly assess ultradian periods. In addition, such methods cannot detect changes in the period over time. Time-frequency methods that can localize frequency estimates in time are more appropriate for analysis of ultradian periods and of fluctuations in the period. The continuous wavelet transform offers a method for determining instantaneous frequency with good resolution in both time and frequency, capable of detecting changes in circadian period over the course of several days and in ultradian period within a given day. The discrete wavelet transform decomposes a time series into components associated with distinct frequency bands, thereby facilitating the removal of noise and trend or the isolation of a particular frequency band of interest. To demonstrate the wavelet-based analysis, we apply the transforms to a numerically-generated example and also to a variety of hamster behavioral records. When used appropriately, wavelet transforms can reveal patterns that are not easily extracted using other methods of analysis in common use, but they must be applied and interpreted with care. </p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"5"},"PeriodicalIF":0.0,"publicationDate":"2013-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31547434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A tryptophan-rich breakfast and exposure to light with low color temperature at night improve sleep and salivary melatonin level in Japanese students.","authors":"Kai Wada,&nbsp;Shota Yata,&nbsp;Osami Akimitsu,&nbsp;Milada Krejci,&nbsp;Teruki Noji,&nbsp;Miyo Nakade,&nbsp;Hitomi Takeuchi,&nbsp;Tetsuo Harada","doi":"10.1186/1740-3391-11-4","DOIUrl":"https://doi.org/10.1186/1740-3391-11-4","url":null,"abstract":"<p><strong>Background: </strong>Epidemiological studies in Japan have documented an association between morning type and a tryptophan-rich breakfast followed by exposure to sunlight in children. The association may be mediated by enhanced melatonin synthesis, which facilitates sleep at night. However, melatonin is inhibited by artificial light levels with high color-temperature common in Japanese homes at night. In this study, we investigated whether a combination of tryptophan-rich breakfast and light with low color-temperature at night could enhance melatonin secretion and encourage earlier sleep times.</p><p><strong>Methods: </strong>The intervention included having breakfast with protein- and vitamin B6 - rich foods and exposure to sunlight after breakfast plus exposure to incandescent light (low temperature light) at night (October-November, 2010). The participants were 94 members of a university soccer club, who were divided into 3 groups for the intervention (G1: no intervention; G2: asked to have protein-rich foods such as fermented soybeans and vitamin B6-rich foods such as bananas at breakfast and sunlight exposure after breakfast; G3: the same contents as G2 and incandescent light exposure at night). Salivary melatonin was measured around 11:00 p.m. on the day before the beginning, a mid-point and on the day before the last day a mid-point and on the last day of the 1 month intervention.</p><p><strong>Results: </strong>In G3, there was a significantly positive correlation between total hours the participants spent under incandescent light at night and the frequency of feeling sleepy during the last week (p = 0.034). The salivary melatonin concentration of G3 was significantly higher than that of G1 and G2 in combined salivary samplings at the mid-point and on the day before the last day of the 1 month intervention (p = 0.018), whereas no such significant differences were shown on the day just before the start of the intervention (p = 0.63).</p><p><strong>Conclusion: </strong>The combined intervention on breakfast, morning sunlight and evening-lighting seems to be effective for students including athletes to keep higher melatonin secretion at night which seems to induce easy onset of the night sleep and higher quality of sleep.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 ","pages":"4"},"PeriodicalIF":0.0,"publicationDate":"2013-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31456429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FMR1, circadian genes and depression: suggestive associations or false discovery?","authors":"Daniel F Kripke,&nbsp;Caroline M Nievergelt,&nbsp;Gregory J Tranah,&nbsp;Sarah S Murray,&nbsp;Katharine M Rex,&nbsp;Alexandra P Grizas,&nbsp;Elizabeth K Hahn,&nbsp;Heon-Jeong Lee,&nbsp;John R Kelsoe,&nbsp;Lawrence E Kline","doi":"10.1186/1740-3391-11-3","DOIUrl":"https://doi.org/10.1186/1740-3391-11-3","url":null,"abstract":"<p><strong>Background: </strong>There are several indications that malfunctions of the circadian clock contribute to depression. To search for particular circadian gene polymorphisms associated with depression, diverse polymorphisms were genotyped in two samples covering a range of depressed volunteers and participants with normal mood.</p><p><strong>Methods: </strong>Depression mood self-ratings and DNA were collected independently from a sample of patients presenting to a sleep disorders center (1086 of European origin) and from a separate sample consisting of 399 participants claiming delayed sleep phase symptoms and 406 partly-matched controls. A custom Illumina Golden Gate array of 768 selected single nucleotide polymorphisms (SNPs) was assayed in both samples, supplemented by additional SNPlex and Taqman assays, including assay of 41 ancestry-associated markers (AIMs) to control stratification.</p><p><strong>Results: </strong>In the Sleep Clinic sample, these assays yielded Bonferroni-significant association with depressed mood in three linked SNPs of the gene FMR1: rs25702 (nominal P=1.77E-05), rs25714 (P=1.83E-05), and rs28900 (P=5.24E-05). This FMR1 association was supported by 8 SNPs with nominal significance and a nominally-significant gene-wise set test. There was no association of depressed mood with FMR1 in the delayed sleep phase case-control sample or in downloaded GWAS data from the GenRED 2 sample contrasting an early-onset recurrent depression sample with controls. No replication was located in other GWAS studies of depression. Our data did weakly replicate a previously-reported association of depression with PPARGC1B rs7732671 (P=0.0235). Suggestive associations not meeting strict criteria for multiple testing and replication were found with GSK3B, NPAS2, RORA, PER3, CRY1, MTNR1A and NR1D1. Notably, 16 SNPs nominally associated with depressed mood (14 in GSK3B) were also nominally associated with delayed sleep phase syndrome (P=3E10-6).</p><p><strong>Conclusions: </strong>Considering the inconsistencies between samples and the likelihood that the significant three FMR1 SNPs might be linked to complex polymorphisms more functionally related to depression, large gene resequencing studies may be needed to clarify the import for depression of these circadian genes.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"3"},"PeriodicalIF":0.0,"publicationDate":"2013-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31328761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of locomotor activity circadian rhythms in athymic nude mice.","authors":"Natalia Paladino,&nbsp;José M Duhart,&nbsp;Malena L Mul Fedele,&nbsp;Diego A Golombek","doi":"10.1186/1740-3391-11-2","DOIUrl":"https://doi.org/10.1186/1740-3391-11-2","url":null,"abstract":"<p><strong>Unlabelled: </strong></p><p><strong>Background: </strong>The relation between circadian dysregulation and cancer incidence and progression has become a topic of major interest over the last decade. Also, circadian timing has gained attention regarding the use of chronopharmacology-based therapeutics. Given its lack of functional T lymphocytes, due to a failure in thymus development, mice carrying the Foxn1(Δ/Δ) mutation (nude mice) have been traditionally used in studies including implantation of xenogeneic tumors. Since the immune system is able to modulate the circadian clock, we investigated if there were alterations in the circadian system of the athymic mutant mice.</p><p><strong>Methods: </strong>General activity circadian rhythms in 2-4 month-old Foxn1(Δ/Δ) mice (from Swiss Webster background) and their corresponding wild type (WT) controls was recorded. The response of the circadian system to different manipulations (constant darkness, light pulses and shifts in the light-dark schedule) was analyzed.</p><p><strong>Results: </strong>Free-running periods of athymic mice and their wild type counterpart were 23.86 ± 0.03 and 23.88 ± 0.05 hours, respectively. Both strains showed similar phase delays in response to 10 or 120 minutes light pulses applied in the early subjective night and did not differ in the number of c-Fos-expressing cells in the suprachiasmatic nuclei, after a light pulse at circadian time (CT) 15. Similarly, the two groups showed no significant difference in the time needed for resynchronization after 6-hour delays or advances in the light-dark schedule. The proportion of diurnal activity, phase-angle with the zeitgeber, subjective night duration and other activity patterns were similar between the groups.</p><p><strong>Conclusions: </strong>Since athymic Foxn1(Δ/Δ) mice presented no differences with the WT controls in the response of the circadian system to the experimental manipulations performed in this work, we conclude that they represent a good model in studies that combine xenograft implants with either alteration of the circadian schedules or chronopharmacological approaches to therapeutics.</p>","PeriodicalId":15461,"journal":{"name":"Journal of Circadian Rhythms","volume":"11 1","pages":"2"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1186/1740-3391-11-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"31204025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}