Effects Of Sleep Deprivation And Hypoxia Stress On Liver Circadian Clock Gene Expression And Alteration Of Liver Bio-marker Levels In Rats

The circadian rhythm is involved in regulating human behaviors and physiological functions.It adapts to the changes of external environment by the approximately 24 h rhythmic oscillation cycle.The biological clock is composed of central clock and peripheral clock.In mammals,the central biological clock is located in the superachiasmatic nucleus(SCN).Apart from SCN,it’s shown that peripheral biological clocks are widely distributed in organs,tissues and cells.Circadian rhythms are generated by endogenous biological clocks,which depends on the regulation of clock genes.Biological clock genes regulates the expression of clock controlled genes in the lower reaches by transcription-translation feedback loops to maintain normal circadian rhythms.It’s shown that sleep is a physiological activity with circadian rhythm.The biological clock plays an important role in the sleep homeostasis.Sleep rhythm disorders are closely related to the abnormal circadian rhythm and the dysfunction of the clock gene system,and hypoxia stress is considered to be an important inducement of sleep rhythm disorders.Therefore,we firstly clarified the main target organ of human health hazards caused by sleep deprivation,then studied the effects of sleep deprivation and hypoxia stress on liver clock gene expression and alteration of liver bio-marker levers in rats to approach the relationship between liver and sleep deprivation and hypoxia stress.Part Ⅰ Effects of sleep deprivation on central and peripheral biological clock gene expression in ratsPurpose The aim was to filter the main target organ involved in rats under sleep deprivation.Design Rats were randomly divided into control group and sleep deprivation group(SD group).And rats in SD group were given 72 h intermittent sleep deprivation stimulation and 36 h continuous sleep deprivation stimulation.After that,the heart,liver,spleen,kidney,brain of rats were obtained and stored at-80℃.Then RT-PCR and Western Blot was used to detect the effects of sleep deprivation on the expression of clock genes in different organs.Results Compared with the control group,the expression of liver clock gene bmal1,clock,npas2 was reduced,and per1,rorα was obviously up-regulated in rats after sleep deprivation(P<0.05).However,only sharp down-regulation of cry1 and per2 gene was observed in spleen and brain respectively in the SD group(P<0.05).And no obvious change was found in the samples from the heart and kidney(P>0.05).Part Ⅱ Effects of sleep deprivation on liver bio-marker levers in ratsPurpose The aim was to explore the bio-markers of liver dysfunction induced by sleep deprivation in rats.Design Rats were randomly divided into control group and sleep deprivation group.And rats in SD group were given 36 h continuous sleep deprivation stimulation.After that,blood and urine were obtained and kept at-80℃.And the changes of liver bio-marker levels in rats’ blood and urine induced by sleep deprivation were tested with ELISA.Results Compared with that in control group,blood 8-OHd G,OCT,HMGB1 contents in SD group raised obviously(P<0.05),and blood TBA,5-HIAA,GDH contents were without any change(P>0.05);levels of urine TBA,8-OHd G,OCT,GDH,HMGB1 were up-regulated,and urine 5-HIAA levels dropped down(P<0.05).Part Ⅲ Effects of sleep deprivation and hypoxia stress on the expression of liver clock genes and inflammatory factor HMGB1 in ratsPurpose The aim was to determine whether the effects of the two stress factors on the expression of liver clock genes and HMGB1 have duplicate effect.Design Rats were randomly divided into control group,sleep deprivation group,hypoxia stress group and sleep deprivation with hypoxia stress group.Livers of rats were taken and stored at-80℃.Western Blot was used to detect the effects of sleep deprivation and hypoxia stress on the expression of liver clock genes and inflammatory factor HMGB1 in rats.Results After sleep deprivation and hypoxia stress,the changes of the expression of liver clock gene encoding protein-RORα have duplicate effect,but the changes of the expression of liver clock gene encoding proteins-BMAL1,CLOCK,PER1,NPAS2 and inflammatory factor HMGB1 don’t have duplicate effect.Part Ⅳ Effects of sleep deprivation and hypoxia stress on liver bio-marker levers in ratsPurpose The aim was to determine whether the effects of the two stress factors on bio-markers of liver dysfunction have duplicate effect.Design Rats were randomly divided into control group,sleep deprivation group,hypoxia stress group and sleep deprivation with hypoxia stress group.Urine was obtained and kept at-80℃.And the changes of liver bio-marker levels in rats’ urine induced by sleep deprivation and hypoxia stress were tested with ELISA.Results After sleep deprivation and hypoxia stress,the changes of urine OCT contents have duplicate effect,but the changes of urine HMGB1,8-OHd G levels don’t have duplicate effect.Conclusion1.Sleep rhythm disorders are closely related to the dysfunction of liver clock gene system.And liver may be the main target organ of human health hazards caused by sleep deprivation.2.Urine 8-OHd G,OCT,HMGB1 might be used as noninvasive bio-markers to reflect liver injury under SD stress condition.And it can provide references for noninvasive screening of circadian rhythm disorders.3.To some extent,hypoxia stress could strengthen the dysfunction of liver clock gene system and liver injury caused by sleep deprivation,and partial indexes of sleep deprivation and hypoxia stress have duplicate effect.