尾吊对小鼠肝脏组织中clock与bmal1基因节律的影响

Effects of Tail-suspension on Rhythmic Expression of clock and bmal1 in Mice Liver

目的研究尾吊对持续黑暗条件下小鼠肝脏节律基因clock与bmal1节律表达的影响。方法常规明暗光照条件导引(entrainment)C57BL/6J(C57)小鼠1周后,在持续黑暗条件下采用头低位-30°尾吊C57小鼠,于尾吊第12天、13天、14天每隔4 h连续18个时间点进行肝脏组织取材,提取总RNA,并运用Real-time PCR方法检测肝脏组织clock和bmal1节律基因mRNA的表达变化。结果尾吊组与对照组肝脏clock与bmal1节律基因mRNA水平均呈现出节律性表达特征。在尾吊条件下,clock基因mRNA的峰值相位提前约4 h,bmal1基因mRNA表达节律的振幅在每天授时因子时间(zeitgeber time,ZT)ZT2与ZT6显著下降(P<0.05)。结论在持续全黑暗条件下,C57小鼠肝脏组织节律基因clock与bmal1的mRNA水平表现出明显的近日节律性,尾吊对clock基因产生峰值相位提前的效应,对bmal1基因产生振幅减少的效应。

Objective To investigate the effects of tail suspension（TS） clock and bmal1 mRNA expression in liver tissue of mice under constant darkness（darkness∶darkness,DD） conditions.Methods With 1 week of normal light/dark schedule（light∶darkness=12h∶12h） pretreatment,C57BL/6 mice were exposed to-30° head down tail suspension in constant darkness.Liver tissues were obtained at consecutive time points during the 12th,13th and 14th testing days with equal interval of 4 h.Total RNA was extracted,the rhythmicity patterns of clock and bmal1 mRNA expression were determined by using real-time polymerase chain reaction（RT-PCR）.Results Circadian rhythm of clock and bmal1 mRNA expression was found in each testing day with similar peak phase in both TS and control（Con） mice.Furthermore,compared with Con,the peak phase of clock gene mRNA level in TS mice advanced approximately 4 h,and the amplitude of bmal1 gene mRNA level significantly reduced at zeitgeber time（ZT） ZT2 and ZT6（P0.05）.Conclusion In constant darkness conditions,liver tissue expresses clock and bmal1 mRNA with evident circadian rhythm,and TS treatment can lead to the peak phase advancement of clock gene and amplitude decrease of bmal1 gene.