[Imaging the functions of central neurons].
The dynamic behavior of biomolecules underlies various life functions including brain functions. Imaging techniques enable direct visualization of such behavior and afford us the opportunity to understand the mechanisms of the functions in spatiotemporal contexts. We have developed imaging techniques for visualization of IP3 and NO. A fluorescent IP3 probe GFP-PHD, which consists of GFP and the PH domain, translocates from plasma membrane to cytoplasm upon IP3 elevation. We can thus evaluate the changes in IP3 concentrations by imaging the translocation. Analysis with GFP-PHD revealed spatiotemporal IP3 dynamics underlying calcium oscillations and waves. We also discovered a novel mechanism for IP3 production which is mediated by AMPA receptor activation in cerebellar Purkinje neurons. A fluorescent NO probe HBR-GFP, consisting of GFP and the heme binding region of soluble guanylyl cyclase, reports NO by its fluorescence intensity. NO imaging in Purkinje neurons showed that a firing of parallel fibers elicits the localized NO signals which ensure synapse independence in LTP induction. The amount of NO production depended on the temporal firing patterns of parallel fibres: 1 Hz is the optimal frequency. In addition, 1 Hz firing effectively induced LTP. The above results indicate that imaging is useful to study the functions of central neurons.
Hirose
Kenzo
K
Department of Cell Physiology, Nagoya University School of Medicine, 65 Tsurumai, Showa-ku, Nagoya 466-8550, Japan. kenzo@med.nagoya-u.ac.jp
D000818:Animals; D001921:Brain; D020013:Calcium Signaling; D003952:Diagnostic Imaging / Q000379:methods*; D049452:Green Fluorescent Proteins; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000502:physiology*; D017774:Long-Term Potentiation; D036881:Long-Term Synaptic Depression; D008967:Molecular Biology / Q000379:methods*; D009474:Neurons / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology*; D011689:Purkinje Cells / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
D018377:Neurotransmitter Agents; D049452:Green Fluorescent Proteins; D009569:Nitric Oxide; D015544:Inositol 1,4,5-Trisphosphate