【作者】 王国卿； 傅春玲； 李建祥； 杜玉珍； 童建；

【Author】 WANG Guo-Qing, FU Chun-Ling,LI Jian-Xiang,DU Yu-Zhen,TONG Jian Department of Physiology,Medical School;Chronobioiogy Laboratory,Department of Toxicology,School of Radiation Medicine & Public Health,Soochow University, Suzhou215123, China

【机构】 苏州大学医学院基础医学系生理学教研室； 苏州大学放射医学与公共卫生学院卫生毒理学教研室；

【摘要】 目的:探讨12 h光照、12 h黑暗交替(12 h-light:12 h-dark cycle,LD)及持续黑暗(constant darkness,DD)光制下视交叉上核(suoracguasnatuc nucleus,SCN)与松果体(pineal gland,PG)中Clock基因的昼夜节律性表达及其光反应变化。方法:Sprague-Dawley大鼠在LD和DD光制下分别被饲养4周(n＝36)和8周(n＝36)后,在一昼夜内每隔4h 采集一组SCN和PG组织(n＝6),提取总RNA,用竞争性定量RT-PCR测定不同昼夜时点(circadian times,CT or zeitgeber times,ZT)各样品中Clock基因的mRNA相对表达量,通过余弦法和Clock Lab软件获取节律参数,并经振幅检验是否存在昼夜节律。结果:(1)在DD或LD光制下,SCN和PG中Clock基因mRNA的表达均呈现昼夜节律陸振荡(P<0．05)。(2)在DD光制下,SCN和PG之间Clock基因转录显示相似的节律外观(P>0．05),峰值出现于主观夜晚(SCN为CT15,PG为CT18),谷值位于主观白天(SCN为CT3,PG为CT6)。(3)与DD光制下比较,LD光制下松果体Clock基因的转录也展示出上述类似的节律外观,但其表达的振幅及峰值相的mRNA水平均明显降低(P<0．05),而其在SCN中转录的相应参数变化却恰恰相反(P<0．05)。(4)在LD光制下,PG中Clock 基因转录的节律外观反时相于SCN。结论:Clock基因的昼夜转录在SCN和松果体中存在同步的内源性节律本质, 而光导引在这西个中枢核团调节Clock基因昼夜节律性转录方面有着不同的作用。更多还原

【Abstract】 ABSTRACT Objective: The aim of this study was to investigate the circadian rhythms and photoresponses of Clock gene transcriptions in the rat suprachiasmatic nucleus (SCN) and the pineal gland (PG) under the 12 h-light:12 h-dark cycle condition (LD) and constant darkness (DD). Methods: Sprague-Dawley rats housed under the light regime of LD (?36) for 4 weeks and of DD (?36) for 8 weeks were sampled for the SCN and the PG once a group (?6) every 4 h in a circadian day. The total RNA was extracted from each sample and the semiquantitative reverse transcription polymerase chain reaction (RT-PCR) was used to determine the temporal changes in mRNA levels of Clock gene in the SCN and the PG during different circadian times (CT) or zeitgeber times (ZT). The data were analysed by the cosine function software, Clock Lab software and the amplitude F test was used to reveal the circadian rhythm. Results: (1) In DD or LD condition, the mRNA levels of Clock gene in both the SCN and the PG displayed robust circadian oscillation (P < 0.05). (2) In DD regime, the circadian profiles of Clock gene transcriptions in the SCN were similar in pattern to those in the PG (P > 0.05) with each peak at the subjective night (CT15 in the SCN or CT18 in the PG) and trough during the subjective day (CT3 in the SCN or CT6 in the PG). (3) In comparison with DD condition, the pineal Clock gene transcription in LD also showed the above-mentioned circadian profiles similarly, but the amplitudes and the mRNA levels at peaks of Clock gene transcriptions in LD in the PG were remarkably decreased (P < 0.05), while the corresponding rhythmic parameters in LD in the SCN were significantly increased (P < 0.05). (4) Moreover, in LD cycle, the circadian profiles of Clock gene transcriptions in the PG were quite different from those in the SCN (P < 0.05) in which the Clock transcription rhythms were anti-phasic to the case in the PG Conclusion: The findings of the present study indicate a synchronous endogenous nature of the Clock gene circadian transcriptions in the SCN and the pineal gland, and different roles of light entrainment in modulating circadian transcriptions of Clock gene in the two central nuclei.更多还原