Interactions of Circadian Rhythmicity, Stress and Orexigenic Neuropeptide Systems: Implications for Food Intake Control

Abstract

Many physiological processes fluctuate throughout the day/night and daily fluctuations are observed in brain and peripheral levels of several hormones, neuropeptides and transmitters. In turn, mediators under the “control” of the “master biological clock” reciprocally influence its function. Dysregulation in the rhythmicity of hormone release as well as hormone receptor sensitivity and availability in different tissues, is a common risk-factor for multiple clinical conditions, including psychiatric and metabolic disorders. At the same time circadian rhythms remain in a strong, reciprocal interaction with the hypothalamic-pituitary-adrenal (HPA) axis. Recent findings point to a role of circadian disturbances and excessive stress in the development of obesity and related food consumption and metabolism abnormalities, which constitute a major health problem worldwide. Appetite, food intake and energy balance are under the influence of several brain neuropeptides, including the orexigenic agouti-related peptide, neuropeptide Y, orexin, melanin-concentrating hormone and relaxin-3. Importantly, orexigenic neuropeptide neurons remain under the control of the circadian timing system and are highly sensitive to various stressors, therefore the potential neuronal mechanisms through which disturbances in the daily rhythmicity and stress-related mediator levels contribute to food intake abnormalities rely on reciprocal interactions between these elements.

Central regulation of food intake in fish: an evolutionary perspective

“…Some hormones that participate as internal synchronizers may also provide signals to inform central oscillators about the timing of food intake. In this sense, orexigenic afferent pathways of the FEO have been considered to promote food anticipatory activity (Feillet et al 2006) and orexigenic neurons are controlled by the circadian system (Blasiak et al 2017). In fish, orexins play a role in the crosstalking between orexigenic peptides, as GHRL and NPY, and act as an input to the circadian system, synchronizing locomotor activity rhythms in the absence of external zeitgebers (Nisembaum et al 2014).…”

Snord116-dependent diurnal rhythm of DNA methylation in mouse cortex

“…Daily and seasonal cycles of light, temperature, and feeding govern energy and activity of organisms from all branches of life. These environmental and metabolic inputs play an important role in the synchronization of the core circadian clock with the rhythmic patterns of many physiological and behavioral processes in peripheral tissues [1][2][3] . The genetically encoded circadian cycle and the environmentally regulated diurnal cycle are integrated by a complex regulatory feedback network which acts at the chromatin, transcriptional, and translational levels to coordinate biological and environmental rhythms [4][5][6] .…”

Organization of the Orexin/Hypocretin System in the Brain of Holostean Fishes: Assessment of Possible Relationships with Monoamines and Neuropeptide Y

“…In the case of the suprachiasmatic nucleus, this innervation can explain the tight relationship between the orexinergic system and the control of circadian rhythmicity [Klisch et al, 2009;Blasiak et al, 2017]. In the basal hypothalamus of holostean fishes, along with the OX-ir cells, abundant fibers course in the tuberal region and reach the median eminence, as has also been observed in cladistians, lungfishes, amphibians, reptiles, and mammals Date et al, 2000;López et al, 2009aLópez et al, , 2009bLópez et al, , 2014Domínguez et al, 2010].…”