China
Africa
Explore chapters and articles related to this topic
Treatment Options for Chemical Sensitivity
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
An intriguing question remains the extent to which NHRs modulate circadian systems according to changing environmental conditions, such as humoral or nutritional factors. For example, variation in the concentration of glucocorticoid hormone, retinoic acid, heme, and fatty acids affect GRs, retinoic acid receptor (RAR), REV-ERBα, neuronal Per-Arnt-Sim (PAS) doman protein 2 (NPAS2), and PPARs. Therefore, variation in cellular concentrations of any one of these ligands may influence Bmal1 transcription, and thereby modulate local cellular circadian rhythms. Within the brain, heme and carbon monoxide may modulate NPAS2 activity,86 whereas within the vascular cells, retinoic acid influences circadian oscillations through activation of RARα and RXRα.87 Similarly, rhythmic variation in NHR ligands may exert distinct effects on local tissue clock function at different times in the day–night cycle.
The potential interaction of environmental pollutants and circadian rhythm regulations that may cause leukemia
Published in Critical Reviews in Environmental Science and Technology, 2022
Francisco Alejandro Lagunas-Rangel, Błażej Kudłak, Wen Liu, Michael J. Williams, Helgi B. Schiöth
Circadian clocks constitute the evolutionary molecular machinery for keeping track of time and optimizing daily life during day-night cycles and seasonal changes in day length. These coordinate multiple physiological processes by establishing oscillations of biological variables with a 24-hour periodicity, which are called circadian rhythms (Sulli et al., 2019). Suprachiasmatic nuclei (SCN) are the master circadian pacemakers of mammals, they receive photic information from retinal ganglion cells (RGCs) and synchronize peripheral clocks with external light/dark cycles through neural and humoral pathways (Shostak, 2017). The mammalian circadian clock at the molecular level is made up of a time-delayed transcription-translation feedback loop (TTFL) (Figure 2A). Two enhancer box (E-box) specific transcription factors, brain and muscle ARNT-like 1 (BMAL1) and circadian locomotor output cycles kaput (CLOCK) (or its paralog neuronal PAS domain-containing protein 2 (NPAS2)), form the activating arm of the TTFL, while the cryptochrome (CRY1 and CRY2) and period (PER1, PER2 and probably PER3) proteins constitute the repressor arm. This primary TTFL is consolidated by a secondary loop formed by the nuclear receptors reverse strand of ERB alpha (REV-ERBa) and the retinoic acid receptor-related orphan receptor alpha (RORA) (Sancar & Van Gelder, 2021).