Excitotoxicity of TNFalpha derived from KA activated microglia on hippocampal neurons in vitro and in vivo.
Highly activated microglia and followed excessive expression of inflammatory cytokines are associated with neuroexcitotoxic injuries. We use electrophysiological techniques, ELISA, western-blot, RT-PCR assay and TUNEL method to explore whether over-produced tumor necrosis factor alpha (TNFalpha) released from activated microglia results in neuronal injuries, and further causes apoptosis through increasing excitotoxicity of hippocampal neurons. Our data showed that kainic acid (KA) activated microglia highly expressed TNFalpha, mRNA and protein. KA activated microglia conditioned media ((KA-MCM) significantly enhanced the amplitude of the population spike at rat's hippocampal CA3 region. It also increased the Ca(2+) current amplitude and density in cultured hippocampal neurons, as well as the high expression of NMDAR1, iNOS, and caspase 3 mRNA and protein at both hippocampal neurons and tissues. KA-MCM also increased TUNEL-positive cells in hippocampal neurons, whereas addition of anti-TNFalpha to the KA-MCM before its application significantly reduced those effects. These studies suggest that TNFalpha derived from KA activated microglia increases excitotoxicity of hippocampal neurons, and might induce neuronal apoptosis in vitro and in vivo.
Zhu
Wei
W
Department of Brain Research, Division of Anatomy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Zheng
Honghua
H
Shao
Xinli
X
Wang
Wei
W
Yao
Qing
Q
Li
Zhengli
Z
D000200:Action Potentials; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000502:physiology; D053148:Caspase 3 / Q000096:biosynthesis / Q000235:genetics; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D007608:Kainic Acid / Q000494:pharmacology*; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000473:pathology* / Q000502:physiology; D052247:Nitric Oxide Synthase Type II / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000096:biosynthesis / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis* / Q000235:genetics
D002118:Calcium; D015220:Calcium Channels; D053148:Caspase 3; D017077:Culture Media, Conditioned; D007608:Kainic Acid; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D014409:Tumor Necrosis Factor-alpha