Chrono-biology, Chrono-pharmacology, and Chrono-nutrition

Abstract

Molecular mechanisms of the circadian clock systemThe circadian clock system has been widely maintained in many species, from prokaryotes to mammals. "Circadian" means "around [a] day" in Latin, and therefore "circadian rhythm" refers to a cycle of approximate 24 h. The earth rotates once every 24 h, and the circadian system has evolved to adjust functions and behavior to this cycle in order to efficiently utilize sunlight for photosynthesis in the case of plants and cyanobacteria and to obtain food in the case of animals. One of the most important features of our circadian system is that circadian clocks can endogenously maintain time under constant darkness and without external stimuli, suggesting that our body has its own internal clocks. In 1972, Moore and Eichler (1) investigated the effects of destroying the suprachiasmatic nucleus (SCN) in the rat hypothalamus. Their results revealed the loss of sleep-wake cycles and corticosterone rhythms. Since then, the SCN is regarded as the location of the master clock system in mammals. The SCN receives light-dark information directly through the retinal-hypothalamic tract and organizes the local clock in the peripheral tissues through multiple pathways involving neural and hormonal functions (2, 3). The molecular mechanism of the circadian system in mammals has been well studied over the past two decades. The transcriptional-translational feedback loop of the major clock genes Bmal1, Clock, Per1/2, and Cry1/2 is the main component of the circadian system (2) (Fig. 1A). Bmal1 and Clock, which are transcriptional activators, play a positive role in activating the Per and Cry genes through a specific promoter sequence known as the E-box. Per and Cry are translated into proteins in the cytoplasm and are then transported back into the nucleus after interacting with each other, and they subsequently stop their transcription by binding to BMAL1 and CLOCK. Thus, Per and Cry are rhythmically expressed over a 24-h period. This transcriptional regulation induces rhythmic expression of approximately 10% of all genes in each peripheral cell (4 -6). In addition to such transcriptional regulation of the circadian clock, post-transcriptional regulation and translational regulation have recently been reported to play important roles in maintaining circadian rhythms. Genome-wide RNA-seq and Chip-seq analyses found that only 22% of the rhythmically oscillating messenger RNAs are driven by de novo transcription, with RNA polymerase II recruitment and chromatin remodeling also exhibiting such rhythms (7). Furthermore, it was reported that the non-transcriptional redox cycle has a 24-h rhythm in Chrono-biology, Chrono-pharmacology, and Chrono-nutrition Tokyo 162-8480, Japan Received October 25, 2013; Accepted January 5, 2014 Abstract. The circadian clock system in mammals drives many physiological processes including the daily rhythms of sleep-wake behavior, hormonal secretion, and metabolism. This system responds to daily environmental changes, such as the light-dark cycle, food...

The Timing Effects of Soy Protein Intake on Mice Gut Microbiota

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“…Chrono-nutrition is the science of nutrition, which is based on chronobiology. Hormonal secretion and the metabolism and absorption of nutrients have circadian variations [16]. Therefore, some food components have the most effective intake timing [22,23].…”

Forced rather than voluntary exercise entrains peripheral clocks via a corticosterone/noradrenaline increase in PER2::LUC mice

“…Rodent peripheral clock oscillation is entrained by a restricted feeding schedule2122 and also by scheduled exercise232425. Recent reports have demonstrated that insulin release is a critical step in the entrainment of the mouse peripheral clock by restricted feeding2627.…”

Real-Time Model Predictive Control of Human Bodyweight Based on Energy Intake

“…It is also proposed that previous models addressed the body adaptation process as an open-loop systems instead as a closed-loop one [11].Therefore, although theoretical models provide a good insight in weight control process, there are other external and internal factors, which affect macronutrient metabolization and energy flux balances and that should be considered. For instance, new insights from the domain of chrono-nutrition indicate that, the rate of energy absorption varies in time [35,36]. These recent insights determine the best time to consume meals and the suitable meal proportions and its impact on bodyweight Appl.…”