2012-11-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/688978摘要：幾乎所有在地球上的生物，在演化的過程中發展出一套週期近似於二十四小時的生理時鐘，賦予生物掌握日夜週期的能力。這樣的生理時鐘能讓生物預測一天當中的環境變化，並將資源分配在特定的時間點。更重要的是，光線有辦法對生理時鐘進行調整，甚至重設。而讓生理時鐘與環境的光週期同步的能力，我們稱之為「日周性之光同步導引」（circadian photo-entrainment）。在包括人類的哺乳類當中，生理時鐘由腦中的上視束交叉核調控，並深切地影響我們的消化系統、神經系統、循環系統及免疫系統等等。因此，光線經由生理時鐘影響我們生理的機制其重要性，值得進一步了解。 根據我們的研究指出，感光視神經細胞（intrinsically photosensitive retinal ganglion cells, ipRGCs）至少由五種亞型組成（Neuron 15;67(1), 2010），並由基因表現不同的細胞族群來控制不同的生理功能（Nature 476, 2011）。然而，受制於許多腦神經核的異質性，其中細胞間訊息傳遞的細節至今仍然不明確。傳統上，將整群細胞染色的方法，僅能粗略地顯示出細胞族群在神經迴路上的位置，卻無法透露出在異質性高的腦神經核中，神經元之間彼此複雜串接的方式。在本實驗室中，利用基因轉殖模式小鼠，藉由調節誘導性cre系統上控制報導基因的重組機率，我們有能力在整隻動物中標記出單一的ipRGC。屆時我們將能確認單一神經元的支配區塊、辨別出神經元的突觸組合，並建構出神經元迴路圖譜的細節。本計畫申請書的具體目標如下： (1) 描繪出單一ipRGC到腦之間的連接圖譜 (2) 確認出負責日周性光引導的ipRGC的突觸組合 (3) 解開ipRGC在視網膜內的回饋機制之謎 單一細胞層級的ipRGC神經元迴路之細節一旦被確認，將使我們更能了解視網膜到大腦之間的連接關係，並有助於解釋光線如何藉由ipRGCs來影響生理時鐘。<br> Abstract: Through evolution, organisms living on the surface of the earth develop the ability to track the day night cycle with an intrinsic biological clock which oscillate close to 24 hours. This intrinsic biological clock allow organism to anticipate the daily change of environment and allocate their resource at specific time. More importantly, light can also adjust or even reset our biological clock. The ability of our clock to match the light dark cycle is called circadian photo-entrainment. For mammals including human, our circadian clock, which is controlled by the suprachiasmatic nucleus (SCN) in the brain, influences us deeply throughout many systems including the digestion system, the neural system, the circulation system and the immune system. Thus, it is important to understand how does light influence our physiological through circadian clock. Our studies indicate that ipRGCs comprise with at least five subtypes (Neuron 15;67(1), 2010) and control different physiological functions by genetically distinct population (Nature 476, 2011). However, the detail about how does the information been transmitted are still unclear due to the heterogeneity of many brain nuclei. Conventional staining which labeled whole population of cells could only indicate the gross direction of that specific cell population without any implication on wiring pattern or connection circuitry between different types of neurons. In the lab, we have the ability to label a single ipRGC in the whole animal using genetic mouse model by controlling the recombination probability of reporter line with inducible cre system. We can then determine the innervation area of one neuron, to identify of their synaptic partner and construct the detail mapping of the neuronal circuitry. The specific aims of this proposal are: (1) Illustrate the connection map of single ipRGC to the brain (2) Determine the synaptic partner of ipRGC for circadian photo-entrainment (3) Elucidate the feedback mechanism of ipRGC within the retina By determining the detail neuronal circuitry of ipRGC at single cell level, it will improve our understanding about the connection between the retina and the brain, which will shed some light on how does light influence our circadian clock through ipRGCs.