Circadian Rhythms in the CNS and Peripheral Clock Disorders: The Circadian Clock and Hyperlipidemia

Abstract

Abstract. A circadian clock controls various physiological and behavioral rhythms. In mammals, a master circadian clock exists in the suprachiasmatic nucleus of the hypothalamus, and slave oscillators can be found in most tissues. These circadian oscillations are controlled by "clock genes". The negative feedback loop is thought to function as a molecular mechanism of the circadian clock. It is plausible that clock genes may control lipid metabolism through so-called clock-controlled genes and that lipid metabolism-related clock-controlled genes may play important roles in the circadian change of lipid metabolism. Recently research has focused on the relationships between the clock system and lipid metabolism. In this review, we discuss the following items: 1) circadian clock system, 2) effect of the diet on clock gene expression, 3) effect of clock mutation on lipid metabolism, and 4) effect of streptozotocin-induced diabetes and ob mutation on clock gene expression and lipid metabolism. In this review we have summarized how the circadian clock affects lipid metabolism through the expression of lipid metabolism-related clock-controlled genes and at the same time discussed how abnormal metabolism of lipid affects the expression of clock genes. Further experiments are needed to elucidate the detailed mechanism of interaction between clock genes and lipid metabolisms.

Sleep disturbance and cardiovascular risk in adolescents

“…22 Recent small community-based studies have also observed trends between short sleep duration, metabolic dysfunction and adiposity in children less than 10 years of age. 23,24 Mechanisms mediating the relation between inadequate or disturbed sleep, high cholesterol and weight gain include changes in the appetiteregulating hormones ghrelin and leptin, 25 preference for fatty foods 26 and circadian alterations in lipid metabolism. 26 In one study, the odds of obesity increased 5-fold for every hour reduction in sleep duration.…”

“…23,24 Mechanisms mediating the relation between inadequate or disturbed sleep, high cholesterol and weight gain include changes in the appetiteregulating hormones ghrelin and leptin, 25 preference for fatty foods 26 and circadian alterations in lipid metabolism. 26 In one study, the odds of obesity increased 5-fold for every hour reduction in sleep duration. 27 Similarly, Senegalese girls aged 13-14 years had a reduction in sleep of 6.85 minutes for every 1.0 increase in BMI.…”

Sleep and circadian rhythms: Key components in the regulation of energy metabolism

“…This also means that a disrupted molecular circadian clock may underlie a wide-range of disorders and disease processes, including obesity, diabetes, and other components of the metabolic syndrome. Recent reviews have described detailed pathways by which the circadian clock may directly mediate lipid and glucose metabolism, as well as cardiovascular function [41,67,69,70]. Of particular interest are CCGs that contain binding sites in their promoter regions for core clock genes, which include albumin D-element binding protein (Dbp), orphan nuclear receptors (NRs) (i.e.…”

Alleviating effects of melatonin on oxidative changes in the testes and pituitary glands evoked by subacute chlorpyrifos administration in Wistar rats

“…Melatonin (N-acetyl-5-methoxytryptamine), the principal secretory product of the pineal gland, produced during the dark phase of the circadian cycle, is a highly conserved antioxidant molecule [24,25] . Melatonin along with its metabolites has been shown to scavenge reactive oxygen species (ROS) or reactive nitrogen species (RNS) [26] .…”