Publications by year

<embed>

Publications by Authors

Recent Publications

Contact Us

Head of Institute: Prof. Ido Braslavsky

Administrative manager: Rakefet Kalev

Office Address:
Institute of Biochemistry, Food Science and Nutrition,
Robert H. Smith Faculty of Agriculture, Food and Environment,
The Hebrew University of Jerusalem, 
Herzl 229, Rehovot 7610001, ISRAEL

Tel: +972 - (0)8-9489385
Fax: +972 - (0)8-9363208
Email Address: rakefetk@savion.huji.ac.il

Publications

2021
Saibaba, G. ; Ruzal, M. ; Shinder, D. ; Yosefi, S. ; Druyan, S. ; Arazi, H. ; Froy, O. ; Sagi, D. ; Friedman-Einat, M. Time-Restricted Feeding in Commercial Layer Chickens Improves Egg Quality in Old Age and Points to Lack of Adipostat Activity in Chickens. FRONTIERS IN PHYSIOLOGY 2021, 12.Abstract
In mammals, time-restricted feeding (TRF) with no caloric restriction provides health benefits and extends longevity, usually with a minor (similar to 3%) or no reduction in total food consumption. In the current study, a TRF regimen of 6 h free access to food (08:00-14:00 h) was applied to Leghorn chickens from 25 to 86 weeks of age; control birds ate freely during the light hours (06:00-20:00 h). Unexpectedly, the TRF-treated birds consumed, on average, 11.7% less food than the controls. This was manifested by an average reduction of 9.6% in body weight, 2.6-fold in visceral fat accumulation, and 6.5% in egg weight. Hen-housed egg production was reduced by 3.6% in the TRF group compared with the control, along the first 40 weeks of the follow-up (P < 0.05), and changed into a tendency of 0.7% higher egg production thereafter. Several parameters of egg quality showed significant improvement (P < 0.05) in the TRF group compared with the controls. A comparison of diurnal patterns of feed consumption revealed a higher rate of hourly consumption in the TRF group and increased consumption before dark in the control group. In conclusion, the reduced feed intake in response to the TRF treatment and loss in visceral fat accumulation supports the lack of a strong adipostat activity in chickens and different appetite regulation mechanisms compared with mammals. Therefore, future TRF studies in chickens should be adjusted by extending the ad libitum time window. The lower feed intake by the TRF-treated chickens compared with the ad libitum-fed controls seems to reduce the efficiency of egg production. Nevertheless, the improved egg quality and persistence of egg lay at the older age suggest that similarly to mammals, the TRF treatment delayed at least some of the negative impacts associated with advanced age.
Tsameret, S. ; Jakubowicz, D. ; Landau, Z. ; Wainstein, J. ; Ganz, T. ; Raz, I. ; Chapnik, N. ; Froy, O. Serum from type 2 diabetes patients consuming a three-meal diet resets circadian rhythms in cultured hepatocytes. DIABETES RESEARCH AND CLINICAL PRACTICE 2021, 178.Abstract
Aims: Feeding regimens alter circadian rhythms in peripheral tissues, but the mechanism is not understood. We aimed to study whether soluble factors, rather than neuronal-based communication, directly influence circadian rhythms in the liver, in response to a nutritional treatment in type 2 diabetes (T2D) patients. Methods: Cultured hepatocytes were treated with serum of insulin-treated T2D patients following either a three-meal diet (3Mdiet) or six-meal diet (6Mdiet) and the circadian expression of clock and metabolic genes was measured. Results: Serum of the 3Mdiet group led to increased amplitudes and daily mRNA levels of the positive limb of the circadian clock (Clock, Bmal1, Rora). In parallel, serum of the 3Mdiet group led to the downregulation of the negative limb of the circadian clock (Cry1 and Per1), compared to both baseline and 6Mdiet. In contrast, serum of the 6Mdiet group led to a more distorted expression pattern. The catabolic genes Sirt1 and Ampk were significantly upregulated only by serum of the 3Mdiet group. Conclusions: Our results show that serum of type 2 diabetes patients consuming the 3Mdiet contains soluble factors that reset circadian rhythms leading to an expression pattern similar to that of healthy people. This clock pattern contributes to improved glucose metabolism. (c) 2021 Elsevier B.V. All rights reserved.
Dadon-Freiberg, M. ; Chapnik, N. ; Froy, O. REV-ERB alpha alters circadian rhythms by modulating mTOR signaling. MOLECULAR AND CELLULAR ENDOCRINOLOGY 2021, 521.Abstract
REV-ERB alpha is a nuclear receptor that inhibits Bmal1 transcription as part of the circadian clock molecular mechanism. Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a master regulator of cell and whole-body energy homeostasis, that serves as an important link between metabolism and circadian clock, in part, by regulating BMAL1 activity. While the connection of REV-ERB alpha to the circadian clock molecular mechanism is well characterized, the interaction between mTORC1, REV-ERB alpha and the circadian clock machinery is not very clear. We used leucine and rapamycin to modulate mTORC1 activation and evaluate this effect on circadian rhythms. In the liver, mTORC1 was inhibited by leucine. REV-ERB alpha overexpression activated the mTORC1 signaling pathway via transcription inhibition of mTORC1 inhibitor, Tsc1, antagonizing the effect of leucine, while its silencing downregulated mTORC1 signaling. Activation of mTORC1 led to increased BMAL1 phosphorylation. Activation as well as inhibition of mTORC1 led to altered circadian rhythms in mouse muscle. Inhibition of liver mTORC1 by leucine or rapamycin led to low-amplitude circadian rhythms. In summary, our study shows that leucine inhibits liver mTORC1 pathway leading to dampened circadian rhythms. REV-ERB alpha activates the mTORC1 pathway, leading to phosphorylation of the clock protein BMAL1.
2020
Gillon-Keren, M. ; Kaufman-Shriqui, V. ; Goldsmith, R. ; Safra, C. ; Shai, I. ; Fayman, G. ; Berry, E. ; Tirosh, A. ; Dicker, D. ; Froy, O. ; et al. Development of Criteria for a Positive Front-of-Package Food Labeling: The Israeli Case. NUTRIENTS 2020, 12.Abstract
Efforts to shape the food environment are aimed at reducing diet-related co-morbidities. Front-of-package labeling (FOPL) may support the consumers to make an informed decision at the point of purchase and encourage industry to reformulate food products. The Israeli Ministry of Health (MOH) implemented a unique FOPL system, using two colors: A mandatory warning (red) label alongside a voluntary positive (green) label. An independent Scientific Committee, from academia, the healthcare system, and MOH was appointed to determine the core principles for the positive FOPL. The criteria were based on the Mediterranean diet principles, with adjustments to the Israeli dietary habits, focusing on the health advantages of the food and considering its processing level. The food products eligible for positive FOPL are foods in their natural form or with added spices or herbs, or those that underwent minimal processing, with no food additives. Based on population consumption data, 19.8% of food products were eligible for positive FOPL; of them, 54% were fruits and vegetables, 20% dairy, and 14% grains. An evaluation plan is needed to assess the degree of acceptance of the positive FOPL by the industry, retailers, and the public, and its impact on food consumption and on public health.
Weintraub, Y. ; Cohen, S. ; Chapnik, N. ; Yerushalmy-Feler, A. ; Ben-Tov, A. ; Dotan, I. ; Tauman, R. ; Froy, O. Clock gene expression levels can differentially distinguish between ulcerative colitis and Crohn's disease. JOURNAL OF CROHNS & COLITIS 2020, 14, S198-S199.
Weintraub, Y. ; Cohen, S. ; Chapnik, N. ; Ben-Tov, A. ; Yerushalmy-Feler, A. ; Dotan, I. ; Tauman, R. ; Froy, O. Clock Gene Disruption Is an Initial Manifestation of Inflammatory Bowel Diseases. CLINICAL GASTROENTEROLOGY AND HEPATOLOGY 2020, 18, 115+.Abstract
BACKGROUND & AIMS: Sleep disruption modifies the immune system and can trigger flares of inflammatory bowel diseases (IBD). Changes in expression of clock genes have been reported in patients with IBD. We investigated whether a change in the circadian clock is an early event in development of IBD. METHODS: We performed a prospective study of patients younger than 21 years old who underwent diagnostic endoscopies at the pediatric and adult gastroenterology units at the Tel Aviv Sourasky Medical Center from August 2016 through August 2017. Questionnaires were completed by 32 patients with IBD (8-21 years old) and 18 healthy individuals (controls) that provided data on demographics, sleep, disease activity scores. We also obtained data on endoscopic scores, anthropometric parameters, blood level of C-reactive protein (CRP), and fecal level of calprotectin. Peripheral blood and intestinal mucosa samples were analyzed for expression levels of clock gene (CLOCK, BMAL1, CRY1, CRY2, PER1, and PER2). RESULTS: Levels of CRP and fecal calprotectin were significantly higher in patients with IBD compared with controls (P<.05). Expression levels of clock genes (CLOCK, CRY1, CRY2, PER1, and PER2) were significantly lower in inflamed intestinal mucosa from patients compared with intestinal mucosa from controls (P<.05). Expression levels of all clock genes except for PER2, were also significantly lower in non-inflamed intestinal mucosal tissues from patients compared with controls (P<.05). Expression levels of clock genes (CLOCK, BMAL1, CRY1, CRY2, PER1 and PER2) were lower in white blood cells from patients with IBD compared with controls. This reduction was greater in white blood cells from patients with ulcerative colitis than in patients with Crohn's disease. CONCLUSION: Young, newly diagnosed, untreated patients with IBD have reduced expression of clock genes in inflamed and non-inflamed intestinal mucosal samples, and also in blood cells, compared with healthy individuals. Alterations in expression of clock genes might be an early event in IBD pathogenesis.
Dadon-Freiberg, M. ; Chapnik, N. ; Froy, O. REV-ERB alpha activates the mTOR signalling pathway and promotes myotubes differentiation. BIOLOGY OF THE CELL 2020, 112, 213-221.Abstract
Background Information Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a master regulator of cell and whole-body energy homoeostasis. REV-ERB alpha is a nuclear receptor that plays an important role in metabolism. While mTORC1 activation is necessary for muscle differentiation, the role of REV-ERB alpha is less clear. Results We studied the effect of REV-ERB alpha overexpression and silencing as well as mTORC1 activation and inhibition on the differentiation of C2C12 myoblasts to myotubes. mTOR, myogenin and REV-ERB alpha were induced during differentiation of myoblasts into myotubes. REV-ERB alpha was found to activate mTORC1 during the differentiation process even in the absence of the differentiation medium. This activation was presumably through the downregulation of the expression of TSC1, an mTORC1 inhibitor. Conclusion Herein we show that REV-ERB alpha promotes myoblasts differentiation via the activation of the mTORC1 signalling pathway. Significance REV-ERB alpha modulation can activate mTORC1 signalling and promote myoblasts differentiation.
Froy, O. Response to Comment on Jakubowicz et al. Reduction in Glycated Hemoglobin and Daily Insulin Dose Alongside Circadian Clock Upregulation in Patients With Type 2 Diabetes Consuming a Three-Meal Diet: A Randomized Clinical Trial. Diabetes Care 2019;42:2171-2. DIABETES CARE 2020, 43, E13-E14.
2019
Tal, Y. ; Chapnik, N. ; Froy, O. Non-obesogenic doses of palmitate disrupt circadian metabolism in adipocytes. Adipocyte 2019, 8 392-400. Publisher's VersionAbstract
Saturated fatty acids, such as palmitate, lead to circadian disruption. We aimed at studying the effect of low doses of palmitate on circadian metabolism and to decipher the mechanism by which fatty acids convey their effect in adipocytes. Mice were fed non-obesogenic doses of palm or olive oil and adipocytes were treated with palmitate and oleate. Cultured adipocytes treated with oleate showed increased AMPK activity and induced the expression of mitochondrial genes indicating increased fatty acid oxidation, while palmitate increased ACC activity and induced the expression of lipogenic genes, indicating increased fatty acid synthesis. Low doses of palmitate were sufficient to alter circadian rhythms, due to changes in the expression and/or activity of key metabolic proteins including GSK3β and AKT. Palmitate-induced AKT and GSK3β activation led to the phosphorylation of BMAL1 that resulted in low levels as well as high amplitude of circadian clock expression. In adipocytes, the detrimental metabolic alteration of palmitate manifests itself early on even at non-obesogenic levels. This is accompanied by modulating BMAL1 expression and phosphorylation levels, which lead to dampened clock gene expression. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
Jakubowicz, D. ; Landau, Z. ; Tsameret, S. ; Wainstein, J. ; Raz, I. ; Ahren, B. ; Chapnik, N. ; Barnea, M. ; Ganz, T. ; Menaged, M. ; et al. Reductioninglycatedhemoglobin and daily insulin dose alongside circadian clock upregulation in patients with type 2 diabetes consuming a three-meal diet: A randomized clinical trial. Diabetes Care 2019, 42, 2171-2180. Publisher's VersionAbstract
OBJECTIVE In type 2 diabetes, insulin resistance and progressive b-cell failure require treatment with high insulin doses, leading to weight gain. Our aim was to study whether a three-meal diet (3Mdiet) with a carbohydrate-rich breakfast may upregulate clock gene expression and, as a result, allow dose reduction of insulin, leading to weight loss and better glycemic control compared with an isocaloric six-meal diet (6Mdiet). RESEARCH DESIGN AND METHODS Twenty-eight volunteers with diabetes (BMI 32.4 6 5.2 kg/m2 and HbA1c 8.1 6 1.1% [64.5 6 11.9 mmol/mol]) were randomly assigned to 3Mdiet or 6Mdiet. Body weight, glycemic control, continuous glucose monitoring (CGM), appetite, and clock gene expression were assessed at baseline, after 2 weeks, and after 12 weeks. RESULTS 3Mdiet, but not 6Mdiet, led to a significant weight loss (25.4 6 0.9 kg) (P < 0.01) and decreased HbA1c (212 mmol/mol [21.2%]) (P < 0.0001) after 12 weeks. Fasting glucose and daily and nocturnal glucose levels were significantly lower on the 3Mdiet. CGM showed a significant decrease in the time spent in hyperglycemia only on the 3Mdiet. Total daily insulin dose was significantly reduced by 26 6 7 units only on the 3Mdiet. There was a significant decrease in the hunger and cravings only in the 3Mdiet group. Clock genes exhibited oscillation, increased expression, and higher amplitude on the 3Mdiet compared with the 6Mdiet. CONCLUSIONS A 3Mdiet, in contrast to an isocaloric 6Mdiet, leads to weight loss and significant reduction in HbA1c, appetite, and overall glycemia, with a decrease in daily insulin. Upregulation of clock genes seen in this diet intervention could contribute to the improved glucose metabolism. © 2019 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered. More information is available at http://www.diabetesjournals.org/content/license.
Rozenblit-Susan, S. ; Chapnik, N. ; Froy, O. Serotonin Prevents Differentiation of Brown Adipocytes by Interfering with Their Clock. Obesity 2019, 27, 2018-2024. Publisher's VersionAbstract
Objective: Serotonin was shown to interfere with the differentiation of brown adipocytes. In addition, clock components inhibit brown adipogenesis through direct transcriptional control of key components of the transforming growth factor β pathway. The aim of this study was to investigate whether serotonin abrogates brown adipogenesis by affecting clock functionality. Methods: Nondifferentiated and differentiated HIB1B brown adipocytes were treated with serotonin, and their clock expression and functionality and differentiation state were examined. Results: Nondifferentiated HIB1B brown adipocytes treated with serotonin showed increased brown adipocyte markers alongside increased brain-muscle Arnt-like protein 1 (Bmal1) and RAR related orphan receptor A (Rora) but decreased nuclear receptor Rev-erbα mRNA levels. BMAL1 overexpression together with serotonin led to significantly lower brown adipocyte markers. Serotonin in the differentiation cocktail led to reduced brown adipocyte markers as well as clock gene expression. After differentiation, serotonin treatment significantly decreased brown adipocyte markers and reduced BMAL1 and RORα but increased REV-ERBα protein levels. Addition of serotonin to the differentiation medium or addition after differentiation reduced activity of calcium/calmodulin-dependent protein kinase type II subunit gamma, which interferes with circadian locomoter output cycles protein kaput (CLOCK):BMAL1 dimerization and transactivation. Conclusions: Clock expression is required at the early stages of differentiation to brown adipocytes, and serotonin interferes with this process by modulating clock functionality. Serotonin interferes with clock functionality by reducing the levels of the active form of calcium/calmodulin-dependent protein kinase type II subunit gamma. © 2019 The Obesity Society
Weintraub, Y. ; Cohen, S. ; Chapnik, N. ; Ben-Tov, A. ; Yerushalmy-Feler, A. ; Dotan, I. ; Tauman, R. ; Froy, O. Clock Gene Disruption is an Initial Manifestation of Inflammatory Bowel Disease. Clinical Gastroenterology and Hepatology 2019. Publisher's VersionAbstract
Background & AimsSleep disruption modifies the immune system and can trigger flares of inflammatory bowel diseases (IBD). Changes in expression of clock genes have been reported in patients with IBD. We investigated whether a change in the circadian clock is an early event in development of IBD. Methods We performed a prospective study of patients younger than 21 years old who underwent diagnostic endoscopies at the pediatric and adult gastroenterology units at the Tel Aviv Sourasky Medical Center from August 2016 through August 2017. Questionnaires were completed by 32 patients with IBD (8–21 years old) and 18 healthy individuals (controls) that provided data on demographics, sleep, disease activity scores. We also obtained data on endoscopic scores, anthropometric parameters, blood level of C-reactive protein (CRP), and fecal level of calprotectin. Peripheral blood and intestinal mucosa samples were analyzed for expression levels of clock gene (CLOCK, BMAL1, CRY1, CRY2, PER1, and PER2). Results Levels of CRP and fecal calprotectin were significantly higher in patients with IBD compared with controls (P<.05). Expression levels of clock genes (CLOCK, CRY1, CRY2, PER1, and PER2) were significantly lower in inflamed intestinal mucosa from patients compared with intestinal mucosa from controls (P<.05). Expression levels of all clock genes except for PER2, were also significantly lower in non-inflamed intestinal mucosal tissues from patients compared with controls (P<.05). Expression levels of clock genes (CLOCK, BMAL1, CRY1, CRY2, PER1 and PER2) were lower in white blood cells from patients with IBD compared with controls. This reduction was greater in white blood cells from patients with ulcerative colitis than in patients with Crohn's disease. Conclusion Young, newly diagnosed, untreated patients with IBD have reduced expression of clock genes in inflamed and non-inflamed intestinal mucosal samples, and also in blood cells, compared with healthy individuals. Alterations in expression of clock genes might be an early event in IBD pathogenesis. ClinicalTrials.gov Identifier: NCT03662646
Tal, Y. ; Chapnik, N. ; Froy, O. Non-obesogenic doses of fatty acids modulate the functionality of the circadian clock in the liver. Cellular and Molecular Life Sciences 2019, 76, 1795 - 1806. Publisher's VersionAbstract
Saturated fatty acids, such as palmitate, lead to circadian disruption in cell culture. Moreover, information regarding the effects of unsaturated fatty acids on circadian parameters is scarce. We aimed at studying the effects of low doses of saturated as well as unsaturated fatty acids on circadian metabolism in vivo and at deciphering the mechanism by which fatty acids convey their effect. Mice were fed non-obesogenic doses of palm or olive oil and hepatocytes were treated with palmitate and oleate. Mice fed non-obesogenic doses of palm oil showed increased signaling towards fatty acid synthesis, while olive oil increased signaling towards fatty acid oxidation. Low doses of palmitate and oleate were sufficient to alter circadian rhythms, due to changes in the expression and/or activity of key metabolic proteins. Palmitate, but not oleate, counteracted the reduction in lipid accumulation and BMAL1-induced expression of mitochondrial genes involved in fatty acid oxidation. Palmitate was also found to interfere with the transcriptional activity of CLOCK:BMAL1 by preventing BMAL1 deacetylation and activation. In addition, palmitate, but not oleate, reduced PER2-mediated transcriptional activation and increased REV-ERBα-mediated transcriptional inhibition of Bmal1. The inhibition of PER2-mediated transcriptional activation by palmitate was achieved by interfering with PER2 nuclear translocation. Indeed, PER2 reduced fat accumulation in hepatocytes and this reduction was prevented by palmitate. Herein, we show that the detrimental metabolic alteration seen with high doses of palmitate manifests itself early on even with non-obesogenic levels. This is achieved by modulating BMAL1 at several levels abrogating its activity and expression.
2018
Froy, O. ; Garaulet, M. The Circadian Clock in White and Brown Adipose Tissue: Mechanistic, Endocrine, and Clinical Aspects. Endocrine reviews 2018, 39, 261 - 273. Publisher's VersionAbstract
Obesity is a major risk factor for the development of illnesses, such as insulin resistance and hypertension, and has become a serious public health problem. Mammals have developed a circadian clock located in the hypothalamic suprachiasmatic nuclei (SCN) that responds to the environmental light-dark cycle. Clocks similar to the one located in the SCN are found in peripheral tissues, such as the kidney, liver, and adipose tissue. The circadian clock regulates metabolism and energy homeostasis in peripheral tissues by mediating activity and/or expression of key metabolic enzymes and transport systems. Knockouts or mutations in clock genes that lead to disruption of cellular rhythmicity have provided evidence to the tight link between the circadian clock and metabolism. In addition, key proteins play a dual role in regulating the core clock mechanism, as well as adipose tissue metabolism, and link circadian rhythms with lipogenesis and lipolysis. Adipose tissues are distinguished as white, brown, and beige (or brite), each with unique metabolic characteristics. Recently, the role of the circadian clock in regulating the differentiation into the different adipose tissues has been investigated. In this review, the role of clock proteins and the downstream signaling pathways in white, brown, and brite adipose tissue function and differentiation will be reviewed. In addition, chronodisruption and metabolic disorders and clinical aspects of circadian adiposity will be addressed.
Christ, P. ; Sowa, A. S. ; Froy, O. ; Lorentz, A. The Circadian Clock Drives Mast Cell Functions in Allergic Reactions. Frontiers in immunology 2018, 9 1526 - 1526. Publisher's VersionAbstract
Allergic diseases are known to vary in the severity of their symptoms throughout the day/night cycle. This rhythmicity is also observed in mast cell function and responsiveness. Mast cells are key effector cells of allergic reactions and release cytokines, chemokines, and important inflammatory mediators such as histamine, which have been shown to display diurnal variation. Recent research clarified that mast cells are controlled by their internal clock-which is regulated by a specific set of clock genes-as well as external factors such as light sensed by the suprachiasmatic nuclei, hormonal status, or diet. Here, we give an overview of the connections between circadian clock, mast cells, and allergic disease. Further work aimed at studying the role of chronotherapy/chronomedicine should take into account this rhythmic nature of not only mast cells but also the immune responses generated by mast cell signaling.
Weintraub, Y. ; Cohen, S. ; Dotan, I. ; Tauman, R. ; Chapnik, N. ; Froy, O. P334 Does the circadian clock have a role in the pathogenesis of inflammatory bowel disease (IBD)?. Journal of Crohn's and Colitisecco-jcc 2018, 12, S270 - S271. Publisher's VersionAbstract
Sleep dysfunction modifies the immune system and has been implicated as a potential trigger of IBD flares. Sleep dysfunction also alters the synchrony among clock genes leading to disruption of overall circadian regulation. Specifically, in the intestine, it is manifested by increased gut cellular permeability. We hypothesised that changes in mucosal immune balance may be reflected by alterations in the circadian clock and constitute an unattended pathogenic mechanism of IBD. Our aim was to investigate intestinal and systemic clock gene expression (in patients with newly diagnosed IBD and in healthy controls).Patients and controls were recruited upon diagnostic endoscopic evaluation. Demographics, familial medical history, sleep questionnaires, disease activity indices, and endoscopic scores were recorded. Anthropometric parameters, C-reactive protein (CRP), albumin, haemoglobin (Hb), and fecal calprotectin (Fcal) were measured as well. Peripheral blood and tissue samples were analysed for clock gene (Clock, Bmal1, Cry1, Cry2, Per1, and Per2) expression.Of the 32 participants recruited (age 8–25 years, median: 16.1), 14 had newly diagnosed IBD and 18 were healthy controls. Age, gender, sleep questionnaire scores, and time of endoscopy were not statistically different between the groups. Hb, CRP, and Fcal levels were significantly higher in the IBD compared with the healthy controls group (p < 0.05), while albumin was significantly lower (p < 0.05). Clock gene expression (Clock, Cry1, Cry2, Per1, and Per2) in WBC was decreased in newly diagnosed IBD patients compared with health controls (p < 0.05). Similarly, the expression level of the aforementioned genes was lower in inflamed intestinal tissues (p < 0.05). Interestingly, similar reduction in clock gene expression was seen even in healthy (non-inflamed) intestinal tissue from IBD patients (p < 0.05).Clock gene expression is reduced in both inflamed and non-inflamed intestinal tissue in patients with newly diagnosed IBD. Moreover, IBD patients show a systemic reduction in clock gene expression. Our findings may lead to new therapeutic approaches and strategies as well as serve as diagnostic tools in IBD.
Froy, O. Circadian rhythms, nutrition and implications for longevity in urban environments. Proceedings of the Nutrition Society 2018, 77, 216-222. Publisher's VersionAbstract
Presently, about 12% of the population is 65 years or older and by the year 2030 that figure is expected to reach 21%. In order to promote the well-being of the elderly and to reduce the costs associated with health care demands, increased longevity should be accompanied by ageing attenuation. Energy restriction, which limits the amount of energy consumed to 60–70% of the daily intake, and intermittent fasting, which allows the food to be available ad libitum every other day, extend the life span of mammals and prevent or delay the onset of major age-related diseases, such as cancer, diabetes and cataracts. Recently, we have shown that well-being can be achieved by resetting of the circadian clock and induction of robust catabolic circadian rhythms via timed feeding. In addition, the clock mechanism regulates metabolism and major metabolic proteins are key factors in the core clock mechanism. Therefore, it is necessary to increase our understanding of circadian regulation over metabolism and longevity and to design new therapies based on this regulation. This review will explore the present data in the field of circadian rhythms, ageing and metabolism.
2017
Rozenblit-Susan, S. ; Chapnik, N. ; Froy, O. Serotonin prevents differentiation into brown adipocytes and induces transdifferentiation into white adipocytes. International Journal of Obesity 2017, 42, 704 -. Publisher's Version
2016
Rozenblit-Susan, S. ; Chapnik, N. ; Genzer, Y. ; Froy, O. Serotonin suppresses food anticipatory activity and synchronizes the food-entrainable oscillator during time-restricted feeding. 2016, 297, 150 - 154. Publisher's VersionAbstract
The serotonergic and circadian systems are intertwined as serotonin modulates the response of the central brain suprachiasmatic nuclei (SCN) clock to light. Time-restricted feeding (RF) is characterized by increased food anticipatory activity (FAA) and controlled by the food-entrainable oscillator (FEO) rather than the SCN. Our objective was to test whether serotonin affects the FEO. Mice were treated with the selective serotonin reuptake inhibitor (SSRI) fluvoxamine (FLX) or the tryptophan hydroxylase inhibitor parachlorophenylalanine (PCPA) and locomotor activity under ad libitum feeding, RF and different lighting conditions was monitored. Under AL, FLX administration did not affect 24-h locomotor activity, while mice treated with PCPA exhibited increased activity. RF-FLX-treated mice showed less FAA 2h before food availability (ZT2–ZT4) compared to RF- or RF-PCPA-fed mice. Under DD, RF-PCPA-treated mice displayed increased activity, as was seen under LD conditions. Surprisingly, RF-PCPA-treated mice showed free running in the FAA component. These results emphasize the role of serotonin in SCN-mediated activity inhibition and FEO entrainment and activity.
Rozenblit-Susan, S. ; Chapnik, N. ; Froy, O. Metabolic effect of fluvoxamine in mouse peripheral tissues. 2016, 424, 12 - 22. Publisher's VersionAbstract
Serotonin leads to reduced food intake and satiety. Disrupted circadian rhythms lead to hyperphagia and obesity. The serotonergic and circadian systems are intertwined, as the central brain clock receives direct serotonergic innervation and, in turn, makes polysynaptic output back to serotonergic nuclei. Our objective was to test the hypothesis that peripherally serotonin alters circadian rhythms leading to a shift towards fat synthesis and weight gain. We studied the effect of serotonin and fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), on the circadian clock and metabolic gene and protein expression in mouse liver, muscle and white adipose tissue (WAT) and cell culture. We found that serotonin and/or the SSRI fluvoxamine led to fat accumulation in mouse liver and hepatocytes by shifting metabolism towards fatty acid synthesis mainly through low average levels of phosphorylated acetyl CoA carboxylase (pACC) and phosphorylated protein phosphatase 2A (pPP2A). This shift towards fat synthesis was also observed in adipose tissue. Muscle cells were only slightly affected metabolically by serotonin or fluvoxamine. In conclusion, although centrally it leads to increased satiety, in peripheral tissues, such as the liver and WAT, serotonin induces fat accumulation.