Circadian rhythms are entrained by light-activated signal transduction pathways in the biological clock. Among these, circadian and photic control of mouse suprachiasmatic ERK MAP kinase activation has been reported. In this paper we extend these results to hamsters and to the two other major members of the MAPK family: JNK and p38. The three kinases are rhythmically phosphorylated under light-dark and constant conditions, with maximal values during the day or subjective day. Light pulses during the subjective night induce rapid activation of the three enzymes, suggesting that the three MAP kinases might be implicated in mammalian photic entrainment.
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FEMS Microbiol Ecol
January 2025
School of Science, Engineering and Environment, Salford University, Manchester, UK.
Diurnal rhythms of the gut microbiota are emerging as an important yet often overlooked facet of microbial ecology. Feeding is thought to stimulate gut microbial rhythmicity, but this has not been explicitly tested. Moreover, the role of the gut environment is entirely unexplored, with rhythmic changes to gut pH rather than feeding per se possibly affecting gut microbial fluctuations.
View Article and Find Full Text PDFPigment Cell Melanoma Res
January 2025
Department of Cell Biology and Anatomy, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Alberta, Canada.
Circadian regulation of skin pigmentation is essential for thermoregulation, ultraviolet (UV) protection, and synchronization of skin cell renewal. This regulation involves both cell-autonomous photic responses and non-cell-autonomous hormonal control, particularly through melatonin produced in a light-sensitive manner. Photosensitive opsins, cryptochromes, and melatonin regulate circadian rhythms in skin pigment cells.
View Article and Find Full Text PDFJ Anat
January 2025
Laboratory of Neurochemical Studies, Department of Physiology and Behavior, Bioscience Center, Federal University of Rio Grande do Norte, Natal, Brazil.
Non-image forming (NIF) pathways, a specialized branch of retinal circuitry, play a crucial role supporting physiological and behavioral processes, including circadian rhythmicity. Among the NIF regions, the dorsal raphe nucleus (DRN), a midbrain serotonergic cluster of neurons, is also devoted to circadian functions. Despite indirectly send photic inputs to circadian centers and modulating their activities, little is known about the organization of retina-DRN circuits in primate species.
View Article and Find Full Text PDFBiology (Basel)
November 2024
Department of Psychology, Michigan State University, East Lansing, MI 48824, USA.
Diurnal and nocturnal mammals have evolved unique behavioral and physiological adaptations to optimize survival for their day- or night-active lifestyle. The mechanisms underlying the opposite activity patterns are not fully understood but likely involve the interplay between the circadian time-keeping system and various arousal- or sleep-promoting factors, e.g.
View Article and Find Full Text PDFFront Biosci (Landmark Ed)
December 2024
Halberg Chronobiology Center, University of Minnesota, Minneapolis, MN 55455, USA.
This review explores the intricate relationship between glaucoma and circadian rhythm disturbances. As a principal organ for photic signal reception and transduction, the eye plays a pivotal role in coordinating the body's circadian rhythms through specialized retinal ganglion cells (RGCs), particularly intrinsically photosensitive RGCs (ipRGCs). These cells are critical in transmitting light signals to the suprachiasmatic nucleus (SCN), the central circadian clock that synchronizes physiological processes to the 24-hour light-dark cycle.
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