Zinc Neurotoxicity in Traumatic Brain Injury

锌在创伤性脑损伤中的神经毒性

• 批准号: 6755116
• 负责人: Donald Sanderson Prough
• 金额: $ 35.39万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-06-15 至 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6755116
• 关键词: AMPA receptors; NMDA receptors; apoptosis; biomarker; brain injury; chelation therapy; cytotoxicity; enzyme activity; glutamate receptor; histochemistry /cytochemistry; hypotension; inhibitor /antagonist; laboratory rat; microdialysis; neurons; neurotoxicology; neurotoxins; nonhuman therapy evaluation; terminal nick end labeling; zinc

DESCRIPTION (provided by applicant): After traumatic brain injury (TBI), systemic hypotension causes secondary ischemic brain injury that markedly worsens mortality and neurologic outcome. We will test the hypothesis that, as a consequence of TBI and posttraumatic hemorrhagic hypotension, neurotoxic concentrations of Zn2+ are released from presynaptic glutamatergic vesicles in association with glutamate, enter postsynaptic neurons through receptor-associated calcium channels (especially AMPA/kainite receptors) and voltage-operated calcium channels, and worsen outcome by accumulating in postsynaptic neurons. Specific aim 1: In rats subjected to TBI with our without hypotension, we will test the hypothesis that neuronal Zn2+ accumulation is related to Zn2+ release, which is proportional to the severity of TBI and hypotension and the interval between TBI and hypotension. Methodologies: microdialysis (Zn2+ and glutamate); staining with the Zn2+-specific dye TSQ (intracellular Zn2+ accumulation); vanadium acid fuchsin (VAF) staining (acute cell injury); staining for DNA fragmentation (TUNEL); ribonuclease protection assays (apoptosis); neuronal counts (histopathologic outcome), and beam walking, beam balance and the Morris water maze (neurobehavioral outcome). Specific aim 2: In rats subjected to moderate TBI with or without hypotension, we will address the hypothesis that after TBI, Zn2+ enters neurons through receptor-associated calcium channels and voltage-operated calcium channels (VOCCs) and that entry through (VOCCs) is enhanced by posttraumatic brain tissue acidosis. Interventions: the NMDA receptor antagonist MK-801, the AMPA/kainite receptor antagonist LY300164, the L-type calcium channel antagonist nimodipine, and increases and decreases in extracellular pH. Methodologies: microdialysis, TSQ staining, and VAF staining. Specific aim 3: In rats subjected to moderate TBI and hypotension, we will address the hypothesis that after, TBI and hypotension, modifying extracellular Zn2+ concentrations will modify neurobehavioral and histopathologic injury. We will test this hypothesis by using intracerebroventricular (icv) injection of Zn2+ and by icv injection of the specific Zn2+-binding apoenzyme of carbonic anhydrase. Methodologies: identical to specific aim 1 plus monitoring for signs of neurologic zinc deficiency.

描述（由申请人提供）：创伤性脑损伤（TBI）后，全身性低血压会导致继发性缺血性脑损伤，从而显着恶化死亡率和神经系统结果。 我们将检验以下假设：由于 TBI 和创伤后失血性低血压，神经毒性浓度的 Zn2+ 从与谷氨酸相关的突触前谷氨酸能囊泡中释放出来，通过受体相关的钙通道（特别是 AMPA/kainite 受体）和电压进入突触后神经元。 -操作钙通道，并通过在突触后神经元中积累而恶化结果。 具体目标1：在没有低血压的TBI大鼠中，我们将检验神经元Zn2+积累与Zn2+释放相关的假设，Zn2+释放与TBI和低血压的严重程度以及TBI和低血压之间的时间间隔成正比。 方法：微透析（Zn2+ 和谷氨酸）；用 Zn2+ 特异性染料 TSQ 染色（细胞内 Zn2+ 积累）；钒酸品红 (VAF) 染色（急性细胞损伤）； DNA 片段染色 (TUNEL)；核糖核酸酶保护测定（细胞凋亡）；神经元计数（组织病理学结果），以及平衡木行走、平衡木和莫里斯水迷宫（神经行为结果）。 具体目标 2：在患有或不患有低血压的中度 TBI 大鼠中，我们将提出以下假设：TBI 后，Zn2+ 通过受体相关钙通道和电压操纵钙通道 (VOCC) 进入神经元，并且通过 (VOCC) 进入神经元的途径是因创伤后脑组织酸中毒而增强。 干预措施：NMDA 受体拮抗剂 MK-801、AMPA/红藻氨酸受体拮抗剂 LY300164、L 型钙通道拮抗剂尼莫地平以及升高和降低细胞外 pH 值。 方法：微透析、TSQ 染色和 VAF 染色。 具体目标 3：在遭受中度 TBI 和低血压的大鼠中，我们将提出以下假设：在 TBI 和低血压之后，改变细胞外 Zn2+ 浓度将改变神经行为和组织病理学损伤。 我们将通过脑室内 (icv) 注射 Zn2+ 和 icv 注射碳酸酐酶的特定 Zn2+ 结合脱辅基酶来检验这一假设。 方法：与具体目标 1 相同，并监测神经系统缺锌的迹象。