Short-term simulated weightlessness causes abnormal expression of rat circadian clock gene

  AIM  To evaluate the effects of one-week simulated microgravity on the expression of circadian rhythm in rats.

  METHODS  The tail suspension hindlimb unloading model was used to simulate a space microgravity environment. 48 male SD rats (aged 8 weeks) were randomly assigned to a control (CON) and a tail suspension (SUS) group (24 each). Rats in both groups were housed under the same light conditions (8:00-20:00). Western blotting was used to detect the expression levels of clock genes (Per2, Bmal1) and ion channels Cav1.2 protein in the suprachiasmatic nucleus (SCN) of rats at different time points. Real-time quantitative PCR was used to detect the transcription levels of Per2 and Bmal1 in SCN at different time points.

  RESULTS  Short-term simulated weightlessness caused a decrease in the transcription and protein expression of clock genes Per2 and Bmal1 in rat SCN (P < 0.05) and the fluctuation amplitude was significantly reduced. In addition, compared with that in the control group, simulated weightlessness caused a significant increase in Ca_v1.2 protein expression in SCN of SUS rats.

  CONCLUSION  Short-term simulated weightlessness can cause abnormal expression of rat clock genes, which may be one of the mechanisms that simulate pathological changes of the body caused by weightlessness. This finding provides direct evidence for the direct conversion of gravity-changing signals into time-ratio signals.