Most of the life forms on Earth have gradually evolved an endogenous biological clock under the long-term influence of periodic daily light-dark cycles. This biological clock system plays a crucial role in the orderly progression of life activities. In mammals, central circadian clock is located in the suprachiasmatic nucleus of the hypothalamus and the function of the biological clock relies on a transcription-translation negative feedback loop. As a negative regulator in this loop, the function of CHRONO is less known. To deeply explore the role of the Chrono gene in rhythm entrainment and physiology, we constructed a Chrono gene knockout mouse strain using the CRISPR/Cas9 technology and analyzed its entrainment ability under different T cycles. Running wheel tests and glucose tolerance tests were also performed. The results showed that the period of the endogenous biological clock of Chrono knockout mice was prolonged, and the entrainment rate under the T21 cycle was decreased. In addition, metabolic abnormalities, including weight gain and impaired glucose tolerance, were observed in the non-entrained mice. Overall, this study reveals a crucial role of the Chrono gene in maintaining circadian rhythms and metabolic balance, providing a new perspective for understanding the relationship between the biological clock and metabolism. Further research is needed to fully understand the underlying molecular mechanisms.
Animals ; Mice, Knockout ; Mice ; Circadian Rhythm/genetics* ; Metabolic Diseases/physiopathology* ; Photoperiod ; Male ; Period Circadian Proteins/physiology* ; Light ; Circadian Clocks/physiology*

Circadian clocks are the endogenous oscillators that harmonize a variety of physiological processes within the body. Although many urinary functions exhibit clear daily or circadian variation in diurnal humans and nocturnal rodents, the precise mechanisms of these variations are as yet unclear. In the present study, we demonstrate that Per2 promoter activity clearly oscillates in neonate and adult bladders cultured ex vivo from Per2::Luc knock-in mice. In subsequent experiments, we show that multiple local oscillators are operating in all the bladder tissues (detrusor, sphincter and urothelim) and the lumbar spinal cord (L4-5) but not in the pontine micturition center or the ventrolateral periaqueductal gray of the brain. Accordingly, the water intake and urine volume exhibited daily and circadian variations in young adult wild-type mice but not in Per1-/- Per2-/- mice, suggesting a functional clock-dependent nature of the micturition rhythm. Particularly in PDK mice, the water intake and urinary excretion displayed an arrhythmic pattern under constant darkness, and the amount of water consumed and excreted significantly increased compared with those of WT mice. These results suggest that local circadian clocks reside in three types of bladder tissue and the lumbar spinal cord and may have important roles in the circadian control of micturition function.
Animals ; *Circadian Clocks ; Drinking ; Mice ; Organ Specificity ; Periaqueductal Gray/metabolism/physiology ; Period Circadian Proteins/genetics/*metabolism ; Pons/metabolism/physiology ; Spinal Cord/*metabolism/physiology ; Urinary Bladder/innervation/metabolism/*physiology ; Urination

OBJECTIVETo investigate the molecular biological mechanism of chronoexercise regulating circadian.

METHODSExpressions of mPer1 and mPer2 in the diencephalon of golden hamster were determined 2 hours after acute exhaustive exercise (circadian time 6) by quantitative RT-PCR.

RESULTSChronoexercise at CT6 significantly decreased expressions of mPer1 and mPer2 in the diencephalon of golden hamster.

CONCLUSIONInhibitory effect of chronoexercise on Per1 and Per2 mRNA levels in the diencephalon of golden hamster at CT6 may be achieved transcription-translation-based autoregulatory negative feedback loop.

Animals ; Circadian Rhythm ; physiology ; Cricetinae ; Gene Expression ; Period Circadian Proteins ; genetics ; metabolism ; Physical Conditioning, Animal ; RNA, Messenger ; genetics ; Reverse Transcriptase Polymerase Chain Reaction