Circadian rhythmicity of synapses in mouse somatosensory cortex
Circadian rhythmicity of synapses in mouse somatosensory cortex
复制标题
DOI：
10.1111/ejn.13045
复制
发表时间：
2015-10-01
影响因子：
3.4
通讯作者：
Pyza, Elzbieta
中科院分区：
文献类型：
--
作者：
Jasinska, Malgorzata;Grzegorczyk, Anna;Pyza, Elzbieta
小鼠运动行为表现出的昼夜节律性：夜间活动，白天休息；感觉输入的相关变化反映在位于躯体感觉(桶)皮质的胡须代表中的周期性突触可塑性。目前尚不清楚以前在桶状皮质观察到的突触密度的昼夜节律变化是由于动物活动的变化，还是由于每日的明/暗(LD)节律，或者是由内源性时钟驱动的。在LD12：12h条件下和恒定黑暗(DD)条件下，观察了C57BL/6小鼠炮管皮质的上述变化。用连续电子显微镜切片的体视学分析来评估突触的数密度。在LD条件下饲养的小鼠，在光照期间(静止期)，突触的总密度和树突棘上的兴奋性突触密度较高。相反，在暗期(活动期)，树突棘上的抑制性突触密度增加。在DD条件下，活动期抑制性突触仍有上调，但兴奋性突触密度未见周期性变化。结果表明，昼夜节律可塑性只涉及棘突上的突触(而不是树突上的突触)，兴奋性突触和抑制性突触在24小时的周期中受到不同的调节：兴奋性突触受光的影响，而抑制性突触受内源性生物钟的驱动。
The circadian rhythmicity displayed by motor behavior of mice: activity at night and rest during the day; and the associated changes in the sensory input are reflected by cyclic synaptic plasticity in the whisker representations located in the somatosensory (barrel) cortex. It was not clear whether diurnal rhythmic changes in synapse density previously observed in the barrel cortex resulted from changes in the activity of the animals, from daily light/dark (LD) rhythm or are driven by an endogenous clock. These changes were investigated in the barrel cortex of C57BL/6 mouse strain kept under LD 12:12h conditions and in constant darkness (DD). Stereological analysis of serial electron microscopic sections was used to assess numerical density of synapses. In mice kept under LD conditions, the total density of synapses and the density of excitatory synapses located on dendritic spines was higher during the light period (rest phase). In contrast, the density of inhibitory synapses located on dendritic spines increased during the dark period (activity phase). Under DD conditions, the upregulation of the inhibitory synapses during the activity phase was retained, but the cyclic changes in the density of excitatory synapses were not observed. The results show that the circadian plasticity concerns only synapses located on spines (and not those on dendritic shafts), and that excitatory and inhibitory synapses are differently regulated during the 24h cycle: the excitatory synapses are influenced by light, whilst the inhibitory synapses are driven by the endogenous circadian clock.