Biorhythms in Metabolic Tissues

Study Overview
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Brief Summary
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Metabolism is increasingly recognized as being highly regulated by anticipatory biological rhythms (circadian rhythms or biorhythms), which are driven by molecular feedback loops, and which are approximately 24 hours long (circa diem). These circadian rhythms exist both centrally, in the brain, but also in the periphery, and are specific to many tissues depending on their main biological function or functions. Whereas these circadian rhythms have been thoroughly characterized in other organisms, their role in humans remain poorly understood, partly because of the difficulty in studying these rhythms in peripheral tissues. The investigators therefore aim to characterize these rhythms in primarily skeletal muscle and adipose tissue in healthy young volunteers (using the so-called constant routine paradigm), and how these rhythms interact with one another at various genetic and molecular levels. At the same time, the investigators aim to study how an unhealthy vs. healthy diet can alter these circadian rhythms, and how they interact with circadian rhythms in other tissue compartments such as those expressed by blood cells.

Official Title
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Biological Rhythms in Metabolic Tissues: Impact of Diet

Conditions
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Sleep Deprivation, Metabolic Disturbance, Biological Clocks, Healthy

Intervention / Treatment
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* Other: Low-fat dietary intervention
* Other: High-fat dietary intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age 18-33 yr Healthy (self-reported) and not on medication BMI 18-28 kg/m2 (and waist circumference <102 cm), and weight stable (±5% body weight in past 6 months) Non-smoker and non-nicotine user Regular sleep-wake pattern, with sleep duration of 7-9.25 hrs per night Sedentary to moderately active with regular exercise habits the last 2 months Regular daily meal pattern with 3 main meals Exclusion Criteria: Major or chronic illness, e.g. diabetes, renal disease or inflammatory bowel disease Current or history of endocrine or metabolic disorders Psychiatric or neurological disorders (e.g. bipolar disorder, epilepsy) Frequent gastrointestinal symptoms Chronic medication Any sleep disorder (e.g. irregular bedtimes, symptoms of insomnia) Any issues with or allergies against the provided food items or utilized anesthesia Shift work in the preceding three months or for a long duration Time travel over two time zones in the preceding month Too much weight gain or weight loss in the preceding 6 months Pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 32 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Participants will be studied in a crossover design both after a healthy diet, and after an unhealthy diet
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Healthy diet<br>'Low-fat dietary intervention' to be administered to participants | Other: Low-fat dietary intervention<br>* Low-fat diet (5-7 days) preceding extended wakefulness under standardized conditions<br>|
| Experimental: Unhealthy diet<br>'High-fat dietary intervention' to be administered to participants | Other: High-fat dietary intervention<br>* High-fat diet (5-7 days) preceding extended wakefulness under standardized conditions<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in clock gene & associated omic circadian rhythms | Changes in clock gene & associated clock-regulated & clock-independent metabolic and omic circadian rhythms (e.g. in epigenome, transcriptome, metabolites) in peripheral tissues (primarily skeletal muscle and adipose tissue), and interplay between these rhythms across the 24-h period and under the different dietary conditions | Measured repeatedly (every 6 hours for 24 hours) during a period of extended wakefulness, following each dietary intervention (i.e. over a total period of 6-7 weeks) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Wakefulness-induced changes and subsequent recovery at omic levels | Changes at omic levels (e.g. DNA methylation, transcriptome, proteome, metabolome) in peripheral tissues (primarily skeletal muscle and adipose tissue), urine and feces samples due to extended wakefulness following subsequent recovery, following each dietary intervention | Following each dietary intervention (i.e. over a total period of 6-7 weeks), measured repeatedly (every 2-6 hours for 24 hours) during a period of extended wakefulness, and after recovery sleep | 
| 24-h rhythms in blood | Changes in rhythms in blood-borne cells, proteins and other molecular factors such as DNA, hormones, and proteins, due to the preceding dietary intervention, and relation to other rhythms measured across 24 hrs following the two dietary conditions | Measured repeatedly (every 2-3 hours over 24 hours) during a period of extended wakefulness and after subsequent recovery, following each dietary intervention (i.e. over a total period of 6-7 weeks) | 
| Diet-induced changes in gut microbiota and relation to circadian rhythms | Changes in gut microbiota (metagenomic, compositional) due to dietary intervention, and relation to circadian rhythms measured across 24 hrs in peripheral tissues following the two dietary conditions | Measured throughout study participation, i.e. on average over 6-7 weeks | 
| Energy expenditure rhythms | Changes in energy expenditure rhythms due to the preceding dietary intervention, and relation to other rhythms measured across 24 hrs following the two dietary conditions | Measured repeatedly (every 2 hours over 24 hours) during a period of extended wakefulness and after subsequent recovery, following each dietary intervention (i.e. over a total period of 6-7 weeks) | 
| Urine metabolite rhythms | Changes in levels of urine metabolites due to dietary intervention, and relation to circadian rhythms across 24 hrs in peripheral tissues following the two dietary conditions | Measured throughout study participation, i.e. on average over 6-7 weeks | 
| Rhythms of blood markers of damage to the central nervous system | Assessment of rhythms in of blood markers of damage to the central nervous system (e.g. Olink Proseek multiplex panel, neuron-specific enolase, S-100b) across a 24-h period and following subsequent recovery sleep, following the two dietary conditions | Measured repeatedly (every 1-3 hours over 24 hours) during a period of extended wakefulness and after subsequent recovery, following each dietary intervention (i.e. over a total period of 6-7 weeks) | 
| 24-h rhythms in saliva | Changes in rhythms in saliva-borne cells, proteins and other molecular factors such as DNA, hormones, and proteins, due to the preceding dietary intervention, and relation to other rhythms measured across 24 hrs following the two dietary conditions | Measured repeatedly (every 2-3 hours over 24 hours) during a period of extended wakefulness and after subsequent recovery, following each dietary intervention (i.e. over a total period of 6-7 weeks) | 
| Central circadian rhythms | Changes in centrally driven circadian rhythms (e.g. temperature and melatonin), due to the preceding dietary intervention, and relation to other rhythms measured across 24 hrs following the two dietary conditions | Measured repeatedly (every 1-3 hours over 24 hours) during a period of extended wakefulness and after subsequent recovery, following each dietary intervention (i.e. over a total period of 6-7 weeks) |