Environmental chemicals affect circadian rhythms: An underexplored effect influencing health and fitness in animals and humans. (April 2021)

• Record Type: Journal Article
• Authors: Zheng, Xuehan; Zhang, Kun; Zhao, Yanbin; Fent, Karl
• Is Part Of: Environment international. Volume 149(2021)
• Publication Date: 2021-04
• Subjects: Circadian rhythm -- Aquatic organism -- Environmental chemicals -- Ecotoxicology -- Toxicology -- Human implications; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2020.106159
• Languages: English
• ISSNs: 0160-4120

Abstract

Graphical abstract: Highlights: 40 environmental compounds are shown to dysregulate circadian rhythm in fish. Steroid hormones are of most importance and exhibit effects at environmental levels. Understanding of the modes of action and links to physiological outcomes are still limited. Current state of knowledge is surprisingly limited, particularly in humans and mammals. Abstract: Circadian rhythms control the life of virtually all organisms. They regulate numerous aspects ranging from cellular processes to reproduction and behavior. Besides the light-dark cycle, there are additional environmental factors that regulate the circadian rhythms in animals as well as humans. Here, we outline the circadian rhythm system and considers zebrafish ( Danio rerio ) as a representative vertebrate organism. We characterize multiple physiological processes, which are affected by circadian rhythm disrupting compounds (circadian disrupters). We focus on and summarize 40 natural and anthropogenic environmental circadian disrupters in fish. They can be divided into six major categories: steroid hormones, metals, pesticides and biocides, polychlorinated biphenyls, neuroactive drugs and other compounds such as cyanobacterial toxins and bisphenol A. Steroid hormones as well as metals are most studied. Especially for progestins and glucocorticoids, circadian dysregulation was demonstrated in zebrafish on the molecular and physiological level, which comprise mainly behavioral alterations. Our review summarizes the current state of knowledge on circadian disrupters, highlights their risks to fish and identifies knowledge gaps in animals and humans. While most studies focus on transcriptional and behavioral alterations, additional effects and consequences are underexplored. Forthcoming studies should explore, which additional environmental circadian disrupters exist. They should clarify the underlying molecular mechanisms and aim to better understand the consequences for physiological processes.