大鼠松果体钟基因Clock的内源性昼夜表达

Endogenous Circadian Expression of the Clock Gene in the Rat Pineal Gland

目的 探讨松果体钟基因Clock表达是否存在内源性昼夜节律。方法 持续黑暗 (DD)光制下饲养SD大鼠 8周后 ,在一昼夜内每隔 4h采集松果体组织 ,提取总RNA ,进行竞争性定量RT PCR ,测定不同昼夜时点(CT)样品中ClockmRNA的相对表达量 ,用余弦函数获取节律参数 ,并经振幅检验分析是否存在昼夜节律。结果 松果体Clock基因mRNA的表达呈现内源性节律振荡变化 (P <0 .0 5 ) ,峰值和谷值分别位于CT17和CT5 ,峰值相位 - 2 5 3.0 3± 15 .5 1,振幅 0 .30± 0 .10 ,中值 0 .87± 0 .0 9。结论 Clock基因在大鼠松果体中存在明显的内源性昼夜节律表达。

Objective To investigate the endogenous circadian expression of the Clock gene in the rat pineal gland. Methods Thirty six SD rats housed under constant darkness (DD) for eight weeks were sampled for the pineal gland every 4 hours in a circadian day. The total RNA was extracted from the samples and the semiquantitative reverse transcription polymerase chain reaction (RT PCR) was used to determine the temporal changes in mRNA level of the Clock gene during different circadian times (CT). The data parameters were obtained and analysed by both the cosine function software and the amplitude F test to reveal the circadian rhythm. Results The Clock mRNA level in the pineal gland showed a significantly circadian oscillation ( P <0.05), with the peak at CT17 and trough at CT5. The parameter values of the peak phase, amplitude and mesor were -253.03±15.51, 0.30±0.10 and 0.87±0.09, respectively. Conclusion The findings suggest that the endogenous circadian expression of Clock gene in the rat pineal gland is weak during the subjective daytime and robust at subjective nighttime under DD condition.