Title: Focal Ischemia in Hippocampus Causes Deficits in Local Field Potential and Synaptic Plasticity
Authors: Shaoli Wang a, Jingyun Zhangd, Tao Shengc, Wei Lu b, d *, Dengshun Miaoa *
Institutions: a The Research Center for Bone and Stem Cells, Department of Human Anatomy;b Department of Neurobiology; c The Center of Metabolic Disease Research
Nanjing Medical University, Nanjing, Jiangsu Province 210029, People¡¯s Republic of China; dThe Key Laboratory of Developmental Genes and Human Disease, Institute of Life Sciences, Southeast University, Nanjing, Jiangsu Province 210096, People¡¯s Republic of China.
Abstract: The long-term enhancement in glutamate receptor mediated excitatory responses has been observed in stroke model. This pathological form of plasticity, termed post-ischemic long-term potentiation (i-LTP), points to the functional reorganization after stroke. Little is known, however, about whether and how this i-LTP would affects subsequent induction of synaptic plasticity. Here, we first directly confirmed the i-LTP can be induced in ET-1-induced ischemia model as described previously in other in vitro models. Then we demonstrated the increased expression level of NR2B, CaMKII and p-CaMKII that these results are reminiscent of i-LTP. We further induced LTP of field excitatory postsynaptic potentials (fEPSPs) on CA1 hippocampal neurons in peri-infarct regions of endothelin-1 (ET-1)-induced mini-stroke model. We found that LTP of fEPSPs induced by high-frequency stimulation (HFS) displayed a progressive impairment at 12 hours and 24 hours after ischemia. Moreover, using in vivo multi-channel recording, we found that the local field potential (LFP), which represents electrical property of cell ensembles in more restricted regions, was also dampened at these two time-points. These results point to the notion that i-LTP elevates the induction threshold of subsequent synaptic plasticity. Our data helps to deepen the knowledge on metasynaptic regulation of plasticity after focal ischemia.
Keywords: LTP, LFP, Ischemia, i-LTP, Endothelin-1, Multi-channel in vivo recording
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