생쥐 대뇌겉질의 발생단계별 Synaptophysin 발현량 차이에 관한 연구
Differential Expression Levels of Synaptophysin through Developmental Stages in Cerebral Cortices of Mouse Brain
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초록
신경연접(neural synapse)의 형성은 신경세포 사이의 전기적 신호전달 시작을 의미하므로 신경세포의 분화와 더불어 중추신경계의 발생 및 성장에 매우 중요한 단계라 할 수 있다. 본 연구는 생쥐(mouse)의 대뇌겉질(cerebral cortex)에서 신경연접표지인자(synaptogenic marker) 중의 하나인 synaptophysin의 발현양상 및 그 양적차이를 대뇌겉질의 발달단계에 따라 층별로 비교분석하여 각각의 특징을 밝혀내는 것을 목적으로 진행되었다. 이를 위해 본 연구에서는 synaptophysin에 대한 면역형광염색을 하였으며, 최종적으로 소프트웨어를 활용한형태학적 정량를 시행하였다. 배아(embryo)와 신생(neonate) 생쥐의 synaptophysin 발현은 대뇌겉질의 얕은층(superficial layer)보다 깊은층(deep layer)에서 더 높게 나타났으며 통계적으로 유의한 차이를 보였다. 또한 분자층(molecular layer)에 해당하는부위에서도 상대적으로 많이 발현되는 것이 확인되었다. 대뇌겉질의 깊은층에서 synaptophysin 발현의 유의한 증가는 주로 배아기에 국한되어 나타났으며, 이후 층 사이의 synaptophysin 발현 차이는 점차 감소하여 성숙한 생쥐에서는 차이가 없었다. 연구결과, 대뇌겉질에서 신경연접의 형성은 중추신경계의 성장단계에 따라 층별로 다르게 나타남을 알 수 있다. 이는 신경연접형성과 관련된 중추신경계의 부위별 특징을 파악하고 나아가 중추신경계의 발달과정에서 나타나는 다양한 병태생리를 이해하는 데 도움을 줄 것으로 기대한다.
Abstract
It is well known that differentiation and growth of central nervous system are accomplished through relatively early stages of development. The formation of neural synapse indicates beginning of electrical signaling between neurons, so that may be a critical step in the differentiation of neurons as well as the development and growth of central nervous system. The purpose of this study was to investigate the differential expression levels and patterns of synaptic marker (synaptophysin) between superficial and deep layers of cerebral cortex according to the developmental stages. We introduced immunofluorescence staining of synaptophysin combined with densitometric analysis for the morphological quantification. The intensities of synaptophysin immuno-reactivities in deep layers of cerebral cortices were significantly higher compared to superficial layers in cerebral cortices of embryonic and neonatal mice. The significant increase of synaptophysin expression in the deep layer of cerebral cortex was mainly confined to the embryonic stage. As the expression of synaptophysin gradually decrease thereafter, the difference of expression level between superficial and deep layers could not find in the adult mice. From this study, we could confirm indirectly through synaptophysin that synaptogenic activities in the deep layer of cerebral cortex shows unique pattern especially during the early stages of brain development. Results from this study will be helpful for understanding different patterns of synaptogenesis among the various regions of developing brain.
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