Analysis of ontogeny of circadian rhythm and the transmission of circadian-rhythm-information

我们研究了生物节律中枢视交叉上核(SCN)昼夜节律的个体发生，以及昼夜节律信息从SCN到其他脑区的传递。已知的SCN中的时钟机制涉及一个转录负反馈环，其中时钟和BMAL1起正调节作用，三个周期基因产物起负反馈作用。1)为了阐明母体对昼夜节律个体发育的影响，我们测定了在明暗(LD)周期和反向LD(DL)周期下饲养的视力正常大鼠幼鼠(两组)SCN中rPer2、rBmla1和rAVP(来自SCN的输出信号传递物精氨酸加压素)mRNAs的昼夜节律。用RT-PCR方法检测m RNA，并用β-肌动蛋白m RNA进行归一化。RPer2、rBMal1和rAVP mRNA的节律性均为…即使在LD牵引性条件下，在护理期间也有更多的自由奔跑。在第二周，环境照明周期与大坝合作，以缠绕幼崽的节奏。PER2对rBMal1的转录激活可能是在时钟机制成熟后才开始发挥作用。结果表明，哺乳围栏部分地改变了幼犬的昼夜节律。2)为了解SCN至松果体的昼夜节律信号转导系统，我们测定了褪黑激素(1 mg/kg，i.p.)对松果体的影响。大鼠松果体、下丘脑室旁核和松果体中rPer2和AVP mRNAs的表达。同时测定SCN和PVN的AVP多肽含量。PVN.在SCN中，rPer2含量在光暗期均升高，而AVP基因的表达无明显变化。在PVN中，rPer2在光照期和暗期分别降低和升高。松果体注射褪黑素后，rPer2基因在60℃时表达增加。最近，褪黑素-AVP相互作用系统的研究进展。这些结果可能表明，PVN与SCN的时钟活动在时间上是耦合的。我们至少部分地阐明了视交叉上核的昼夜节律的发展和SCN的输出机制。较少

We investigated 1)ontogeny of the circadian rhythm in the suprachiasmatic nucleus (SCN), a center of biological rhythm, and 2)transmission of circadian-rhythm-information from the SCN to the other brain area. A clock mechanism in the SCN known to involve a transcriptional negative feedback loop in which CLOCK and BMAL1 function as positive regulators and three period gene products play a role in negative feedback. 1)To clarify the maternal effects on the ontogeny of circadian rhythm, we measured the circadian rhythm of rPer2, rBmla1 and rAVP (arg-vasopressin, an output signal transmitter from the SCN) mRNAs in the SCN of sighted rat-pups nursed under the light-dark (LD) cycle and nursed under the reversed LD (DL) cycle (two groups) which were i) nursed from the day of birth and ii) 6 days after birth) or under the constant dim light (DD), and kept. The m RNAs were determined using RT-PCR and normalized by beta-actin mRNA in each sample. The rPer2, rBmal1 and rAVP mRNA rhythmicity were … More free run during the nursing period even under the LD entrained condition. At the 2nd week of age, environmental lighting cycle with the dam co-operate to entrain the pup's rhythm. The rBmal1 transcriptional activation by PER2 might be functioning after the maturation of clock mechanisms. The results indicate that the nursing dam partially entrains pup's circadian rhythm. 2)To know the transduction system of circadian signals from the SCN to the pineal gland, we determined the effects of melatonin injection on (1 mg/kg, i.p.) rPer2 and AVP mRNAs in the punched out SCN, PVN and pineal gland of rats by using PT PER as in 1). AVP peptide contents were also measured in SCN and PVN. PVN. In the SCN, rPer2 content increased at both light and dark period, however no fluctuations were shown in the AVP mRNA. In the PVN, rPer2 decreased and increased at light and dark period, respectively. In the pineal gland, rPer2 mRNA increased at 60 after the melatonin injection. Recently, the melatonin-AVP reciprocal systems. The results might indicate that PVN is temporally coupled with the SCN clock activity.We clarified the development of circadian rhythm in the suprachiasmatic nucleus and the output mechanisms from the SCN, at least in part. Less