Energy-responsive timekeeping

Abstract

An essential component of energy homeostasis lies in an organism's ability to coordinate daily patterns in activity, feeding, energy utilization and energy storage across the daily 24-h cycle. Most tissues of the body contain the molecular clock machinery required for circadian oscillation and rhythmic gene expression. Under normal circumstances, behavioural and physiological rhythms are orchestrated and synchronized by the suprachiasmatic nucleus (SCN) of the hypothalamus, considered to be the master circadian clock. However, metabolic processes are easily decoupled from the primarily light-driven SCN when food intake is desynchronized from normal diurnal patterns of activity. This dissociation from SCN based timing demonstrates that the circadian system is responsive to changes in energy supply and metabolic status. There has long been evidence for the existence of an anatomically distinct and autonomous food-entrainable oscillator (FEO) that can govern behavioural rhythms, when feeding becomes the dominant entraining stimulus. But now rapidly growing evidence suggests that core circadian clock genes are involved in reciprocal transcriptional feedback with genetic regulators of metabolism, and are directly responsive to cellular energy supply. This close interaction is likely to be critical for normal circadian regulation of metabolism, and may also underlie the disruption of proper metabolic rhythms observed in metabolic disorders, such as obesity and type-II diabetes.

Ketogenic Diet Disrupts the Circadian Clock and Increases Hypofibrinolytic Risk by Inducing Expression of Plasminogen Activator Inhibitor-1

“…Cellular energy status such as the ratio of reduced to oxidized nicotinamide adenosine dinucleotides [NAD(P)H/NAD(P) ϩ ] might be involved in the kDa-induced phase-shift of the circadian clock. 41,42 To determine which brain structures are activated by kDa is important. The central nervous system (CNS) is the primary consumer of ketone bodies under hypoglycemic conditions and epilepsy has been treated by KDs since the 1920s, 43 although the antiepileptic mechanisms remain essentially unknown.…”

Influence of feeding schedules on the chronobiology of renin activity, urinary electrolytes and blood pressure in dogs

“…Feedingrelated signals that are capable of entraining peripheral oscillators include autonomic outputs from the central nervous system, dietary sodium, glucose and insulin (Mistlberger & Antle, 2011). Entrainment signals may also be provided by biochemical pathways affected by energy metabolism (Bechtold, 2008), such as the intracellular ratio of reduced to oxidized nicotinamide adenine dinucleotide cofactors (Rutter et al, 2001). In addition, timed feeding has the ability to synchronize the activity of central oscillators, as shown by Kurumiya & Kawamura (1991) in a rodent experiment where the peak activity of neurons located in the hypothalamus was driven by the time of food intake.…”

Ghrelin induces clock gene expression in the liver of goldfish in vitro via protein kinase C and protein kinase A pathways

“…It is well known that the light-dark and feeding cycles may act as potent synchronizers of locomotor activity daily rhythms in vertebrates, including teleosts (Bechtold, 2008;Madrid et al, 2001;Mistlberger, 2011;Sánchez-Vázquez and Madrid, 2001;Spieler, 1992;Stephan, 2002). However, the food-related signals that entrain the molecular clocks (food-entrainable oscillators, FEOs) in the circadian system remain unknown.…”