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17-21.10 - Neuroscience 2009, Chicago, USA |
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  October 17th - 21st
A talk will be hold by Pascal Jourdain at Society for Neuroscience conference Neuroscience 2009 to be held in Chicago on October 17th - 21st, 2009. | Program#/Poster#: | 104.7/FF113 | | Title: | Imaging with digital holographic miroscopy (DHM) glutamate-induced phase signals in a neuronal network in primary culture: Role of KCC2 and NKCC1 co-transporters | | Location: | South Hall A | | Presentation Time: | Saturday, Oct 17, 2009, 3:00 PM - 4:00 PM | | Authors: | P. JOURDAIN1, C. MORATAL1, B. RAPPAZ1, C. DEPEURSINGE2, P. MARQUET3, *P. J. MAGISTRETTI1;
2Inst. d'optique appliquée, 1Ecole Polytechnique, Lausanne, Switzerland; 3Dept. de psychiatrie DP-CHUV, Ctr. de Neurosciences Psychiatriques, Lausanne, Switzerland | | Abstract: | The currently available techniques to study cellular activity in situ are invasive, often requiring an external element (electrode, contrast agents, fluorescent dyes, etc.). Digital Holographic Microscopy (DHM) is a non invasive optical imaging technique able to provide quantitative phase images of living cells. Our initial work has shown that the quantitative monitoring of the phase signal with DHM provides a simple and label-free optical method to study neurotransmitter-mediated responses (Jourdain et al., submitted). Here, we show that with DHM, neuronal viability can be assessed non-invasively. Thus, after a short application of glutamate (30μM, 30s), we recorded 3 main types of phase shifts in primary cortical neuronal cultures: biphasic (Biph.), reversible decrease (RD) and irreversible decrease (ID) responses. The shape and amplitude of the optical signals following glutamate application reflected the physio-pathological status of the cell. Thus, the ID response, apparent during the first 5 minutes following application of glutamate, is the optical signature of cell death that will occur within a few hours ; this signal is linked to a NMDA receptor activation, as indicated by antagonism with MK 801 and is concomitant to a persistent inward current described as associated to pathological processes leading to death. Biph. and RD responses are also blocked by glutamate receptors antagonists, particularly by the NMDA receptor antagonist, MK801. Electrophysiological recording have shown that the RD cells had a more depolarized resting potential than Biph. cells and displayed a more pronounced NMDA-component in their response. Finally, furosemide and bumetanide, 2 inhibitors of sodium and/or potassium-coupled chloride movement strongly modified the phase shift. Additional pharmacological data indicate that the neuronal co-transporter KCC2 is involved in the genesis of the Biph and RD optical signals, while NKCC1, another neuronal co-transporter known to be strongly activated during pathological processes such epilepsy, is only involved in RD response. Combining these data with electrophysiological observations , we conclude that the optical signals detected with DHM are correlated to the physiological or pathological status of neurons. Moreover, DHM is the first technique able to dynamically and in situ monitor the activity of the KCC2 and NKCC1co-transporters during physiological and/or pathological neuronal processes. |
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