| Background: All living organisms experience aging,and some age-related diseases become more serious with time.Such as obesity,cardiovascular disease,diabetes,sleep disorders,and chronic diseases.And Some endogenous rhythms are also weakened by aging,which in turn affects the cellular,tissue and physiological functions regulated by these rhythms.As a result,older people are more likely to have sleep problems and suffer from metabolic diseases than younger adults.The eating-fasting pattern is an external signal that affects the stability of daily biorhythms.Unstable eating patterns can disrupt metabolism and biorhythms,which can lead to chronic disease.Restricted feeding(RF)is a form of intermittent fasting(IF),which does not restrict the amount of calories consumed,but requires a consistent daily eating window.This type of diet has shown beneficial effects in animals.In rodent models,RF has been shown to protect mice fed a high-fat diet from obesity,hyperinsulinemia,hepatic steatosis,and inflammation.However,the specific mechanisms by which restricted feeding improves metabolic health and sleep quality in the elderly are not known.The aim of this study was to investigate the effects of restricted feeding on metabolic health and sleep-wake cycle in aged mice and its mechanisms.Objective: To investigate the effects and mechanisms of restricted feeding on the metabolic health and sleep-wake rythems of aged mice by limiting the feeding window to 8:00-10:00 p.m.everyday,and then mainly measuring metabolism-related biochemical indices and assessing sleep-wake conditions.Methods: After the mice were anesthetized and fixed in the stereotaxic apparatus,holes were drilled in the skull,two stainless steel screws were inserted into the holes as EEG electrodes,and two stainless steel wires were placed in the muscles on both sides of the neck as EMG electrodes for 14 days of postoperative recovery.After that,Cable wire was connected to the head of the mice,and the other end of Cable wire was connected to the sleep recording system,and the mice were placed in the sleep recording chamber for 3 days to adapt before starting EEG and EMG recordings.Collected the EEG/EMG signals during this period as baseline data.Next,the experimental group mice(20-22 months old aged C57BL/6 mice)were given a restricted feeding regimen,two hours of food(18:00-20:00)per day for 14 days,during which the sleep-wake cycles of the control and experimental mice under the restricted food condition were recorded.At the end of the experiment,the samples were collected and the body weights of mice in the experimental and control groups were measured to compare the changes in body weights before and after RF;the blood samples were collected to determine the biochemical indexes related to metabolism;the EEG/EMG signals were read;the brain tissues were collected to determine the dopamine content in the midbrain and striatum,and the expression of c-Fos protein in different brain regions were determined by immunohistochemistry.Results:1.After two weeks of restricted feeding,the body weight of mice in the experimental group decreased significantly,and the activities of blood glucose,cholesterol,alkaline phosphatase and lipase decreased significantly.It indicates that food restriction can improve the metabolic health of aged mice.2.Before the start of RF mode,the reduction of sleep in mice was during the dark phase rather than the light phase.After RF started and achieved stable food induction(day 7 after the start of RF mode),the time that mice were in the awakened state during the light during the two hours before food acquisition significantly increased,thus increasing the mean duration of awakenings and reducing the number of awakenings that occurred.The RF group had no significant difference in the dark phase.And there was no significant difference in the duration of sleep awakenings in the RF group during the dark phase,nor was there a significant change in the total number of sleep awakenings during 24 hours compared to the control group.It indicates that older mice during FAA while the total amount of sleep time was reduced.3.The analysis of the EEG power density during the light phase revealed a significant increase in the slow-wave power density of NREM sleep,indicating that the sleep quality of the mice was improved during this time period.4.Dopamine levels in the midbrain of the experimental mice increased significantly during the RF protocol,and dopamine levels in the striatum also tended to increase,suggesting that the increase in dopamine transmission prior to food availability may have led to an increase in arousal.5.Quantitative analysis of c-Fos protein expression in the mouse brain revealed that multiple nuclei including the midbrain,striatum,and ventral dorsal cap region of the hypothalamus are involved in RF-mediated arousal.Conclusion:1.In the aging process,RF stops or delays the onset of age-related diseases by improving metabolic health;2.RF reduces the duration of NREM sleep,but increases the slow-wave power density during NREM sleep;3.RF is a novel,non-pharmacological intervention to prevent metabolic disorders in the elderly population. |
