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Intracellular Calcium Spikes in Rat Suprachiasmatic Nucleus Neurons Induced by BAPTA-Based Calcium Dyes


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タイトル: Intracellular Calcium Spikes in Rat Suprachiasmatic Nucleus Neurons Induced by BAPTA-Based Calcium Dyes
著者: Hong, Jin Hee 著作を一覧する
Min, Cheol Hong 著作を一覧する
Jeong, Byeongha 著作を一覧する
Kojiya, Tomoyoshi 著作を一覧する
Morioka, Eri 著作を一覧する
Nagai, Takeharu 著作を一覧する
Ikeda, Masayuki 著作を一覧する
Lee, Kyoung J. 著作を一覧する
発行日: 2010年 3月10日
出版者: Public Library of Science
誌名: PLoS ONE
巻: 5
号: 3
開始ページ: e9634
出版社 DOI: 10.1371/journal.pone.0009634
抄録: Background: Circadian rhythms in spontaneous action potential (AP) firing frequencies and in cytosolic free calcium concentrations have been reported for mammalian circadian pacemaker neurons located within the hypothalamic suprachiasmatic nucleus (SCN). Also reported is the existence of "Ca2+ spikes" (i.e., [Ca2+]c transients having a bandwidth of 10~100 seconds) in SCN neurons, but it is unclear if these SCN Ca2+ spikes are related to the slow circadian rhythms. Methodology/Principal Findings: We addressed this issue based on a Ca2+ indicator dye (fluo-4) and a protein Ca2+ sensor (yellow cameleon). Using fluo-4 AM dye, we found spontaneous Ca2+ spikes in 18% of rat SCN cells in acute brain slices, but the Ca2+ spiking frequencies showed no day/night variation. We repeated the same experiments with rat (and mouse) SCN slice cultures that expressed yellow cameleon genes for a number of different circadian phases and, surprisingly, spontaneous Ca2+ spike was barely observed (<3%). When fluo-4 AM or BAPTA-AM was loaded in addition to the cameleon-expressing SCN cultures, however, the number of cells exhibiting Ca2+ spikes was increased to 13~14%. Conclusions/Significance: Despite our extensive set of experiments, no evidence of a circadian rhythm was found in the spontaneous Ca2+ spiking activity of SCN. Furthermore, our study strongly suggests that the spontaneous Ca2+ spiking activity is caused by the Ca2+ chelating effect of the BAPTA-based fluo-4 dye. Therefore, this induced activity seems irrelevant to the intrinsic circadian rhythm of [Ca2+]c in SCN neurons. The problems with BAPTA based dyes are widely known and our study provides a clear case for concern, in particular, for SCN Ca2+ spikes. On the other hand, our study neither invalidates the use of these dyes as a whole, nor undermines the potential role of SCN Ca2+ spikes in the function of SCN.
資料タイプ: article
出現コレクション:雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

提供者: 永井 健治


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