Histochemical and physiological study of delayd neuronal death
Grant-in-Aid for Scientific Research (C)
|Research Institution||Jichi Medical School|
OGURO Keiji Jichi Medical School, Assistant Professor, 医学部, 講師 (90231232)
増沢 紀男 自治医科大学, 医学部, 教授 (60049038)
川合 述史 自治医科大学, 医学部, 教授 (00073065)
太田 敏子 筑波大学基礎医学系, 助教授 (40233134)
MASUZAWA Toshio Jichi Medical School, Professor
OTA Toshiko Tsukuba University, Associate Professor
KAWAI Nobufumi Jichi Medical School, Professor
|Project Fiscal Year
1996 – 1997
Completed(Fiscal Year 1997)
|Budget Amount *help
¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1997 : ¥700,000 (Direct Cost : ¥700,000)
|Keywords||cerebral ischemi / gluramate recepto / Ca^<2+>-ATPase / protein kinase C / slice / hippocampus / mongolian gerbi / 脳虚血 / グルタミン酸受容体 / Ca2^+-ATPase / プロテインキナーゼC / スライス / 海馬 / 砂ネズミ / Ca^+-ATPase|
1.Making plasmamembrane Ca^<2+>-ATPase antibody, immunohistochemistry
Using Ca^<2+>-ATPase type II antibody we made a immunohistochemical mapping of that enzyme in normal rat and gerbil brain. In hippocampus, the distribution of the enzyme is similar to that one which we have detected enzymehistochemically. That is, the enzyme is diffusely located on the plasma membrane of pyramidal neurons, axon, dendrite. There is no differences in distributional density between CA1, CA3 and dentate gyrus.
2.Physiological study of gerbil hippocampal slices
We studied N-methyl-D-aspartate (NMDA) receptor-mediated synaptic potentials in CA1 pyramidal neurons using hippocampal slices of the gerbils after transient forebrain ischemia. In the presence of 6-cyanc 7-nitroquinoxaline-2,3-dione (CNQX) and bicucullin, stimulation on Schaffer collateral/commissural fibers induced field excitatory postsynaptic potentials (fEPSP) activated by NMDA receptors. We found that in many slices after ischemia, low frequency
stimulation (0.1-10Hz) to input fibers caused repeated depression and potentiation of the NMDA-mediated fEPSP.The cyclic changes in fEPSP amplitude were dependent on stimulus frequency, ranging from 0.08 to 2.5 cycle/min. The cyclic changes were blocked by application of 1 bis (o-aminophenoxy) ethane-N,N,N', N'-tetraacety1, tetraacetoxymethy1 ester (BAPTA-AM), a membrane permeable Ca^<2+> chelator, but they were little affected by application of vera-pamil or by reducing Ca^<2+>in bathing solution. Intracellular recordings showed periodic depolarizations of membrane potential synchroniz with depression of EPSP.The cyclic phenomenon was significantly attenuated by application of 1-(5-soquinolinylsulfony1)-2-methylpiperazine (H-7) and K252a, protein kinase C (PKC) antagonist.
These results suggest that stimulus dependent NMDA-receptor activation, medi-ated by PKC,takes place the postischemic CA1 neurons and the cyclic change may reflect abnormal intracellular Ca^<2+> signaling process towards neuronal degeneration re-sulted in periodic membrane depolarization.
3.Potential mapping of the gerbil hippocampus stimulated on the contralateral commisural fibers
We made potential mapping of postischemic gerbil hippocampus by recording EPSP induced by contralateral commisural fiber stimulation. We revealed that CA1 pyramidal neurons are in the hyper excitatory state in the early stage (2-8h) following ischemic insult and LTP is significantly increased in that period compared with the non-ischemic group. This is the first report of the abnormal physiological conditions in the early postischemic period in vivo.
in vivoにおいて、虚血後の砂ネズミ海馬の対側交連線維刺激による定位的なEPSPの記録を行い、電位マッピングを施行した。その結果、虚血後2-8時間の早期にはCAl錐体細胞は過興奮状態にあり、非虚血群に比し、LTPも有意に増大していることが判明した。虚血後早期の電気生理学的現象をin vivoに捉えた初の報告であり、遅発性神経細胞死形成機序解明に寄与するものと考えられる。 Less
Research Output (5results)