MICRODIALYSIS OF NAA/NAAG IN FOCAL EPILEPTOGENESIS

NAA/NAAG 在局灶性癫痫发生中的微透析

• 批准号: 2393053
• 负责人: JOHN M SLOPIS
• 金额: $ 9.02万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-04-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2393053
• 关键词: anticonvulsants; aspartate; enzyme activity; enzyme inhibitors; extracellular; gas chromatography mass spectrometry; glutamates; high performance liquid chromatography; homeostasis; kindling; laboratory rat; microdialysis; neurons; neurotransmitters; partial seizure; pathologic process; peptidyl dipeptidase; valproate

Epilepsy is a major public health problem with estimated incidence of 30.9 to 56.8 per 100,000. The mechanism of epileptogenesis and actions of anticonvulsant drugs are poorly understood. We propose to study the amino acids N-acetyl-aspartate (NAA), N-acetyl-aspartyl-glutamate (NAAG), and the excitotoxin glutamate (GLU) in the rat kindling model of focal epileptogenesis using novel techniques. NAAG is released at some nerve terminals and cleaved by N-alpha-amino-linked-acidic-dipeptidase (NAALADase) to form NAA and GLU. Regional elevation in NAALADase may contribute to epileptogenesis by locally elevating GLU concentrations. The commonly used anticonvulsant valproic acid (VPA) is known to block kindling and to decrease brain levels of NAA, possibly by inhibition of NAALADase which would inhibit GLU production. Regional variation in NAAG synaptic release and NAALDase activity have not been studied in vivo. We developed gas chromatography mass spectrometry (GCMS) to directly quantify these amino acids following local neuronal depolarization in rat brain as sampled by microdialysis, and we demonstrated peptidase activity in situ by infusing labeled substrate (NAAG-D3) then quantifying the cleavage product NAA-D3. Our specific aims are to: (1) characterize extracellular levels of NAAG, NAA, and GLU in each region of the kindling circuit through seizure induction, (2) assess NAALADase activity in situ in each region of the kindling circuit through seizure induction to determine its potential role in homeostasis of the circuit, (3) test the hypothesis that VPA inhibits NAALADase as its anticonvulsant/antikindling mechanism of action, 4) test the hypothesis that a specific inhibitor of NAALADase, B-N-acetyl-glutamate will serve as an anticonvulsant/antikindling agent.

癫痫是一个主要的公共卫生问题，估计发病率为30.9 降至每10万人56.8人。癫痫发生机制及其作用的研究进展 人们对抗惊厥药物知之甚少。我们建议研究氨基 N-乙酰天冬氨酸(NAA)、N-乙酰天冬氨酸(NAAG)和 谷氨酸兴奋性毒素在大鼠局灶性点燃模型中的作用 使用新技术的癫痫发生。NAAG在某种程度上被释放了 末端被N-α-氨基连接的酸性二肽酶切割 (NAALADase)形成NAA和GLU。NAALADASE的区域高程可能 通过局部升高GLU浓度促进癫痫的发生。这个 已知常用的抗惊厥剂丙戊酸(VPA)可阻断点燃 并降低大脑NAA水平，可能是通过抑制NAALADase 这会抑制GLU的产生。NAAG突触的区域差异 释放和NAALDase活性尚未在体内进行研究。我们开发了 气相色谱质谱(GCMS)直接定量 大鼠脑内局部神经元去极化后的氨基酸 通过微渗析，我们在原位证明了多肽酶的活性 注入标记底物(NAAG-D3)，然后定量切割产物 NAA-D3。我们的具体目标是：(1)表征细胞外的水平 点燃回路每个区域的NAAG、NAA和GLU通过癫痫发作 诱导，(2)原位评估NAALADase在每个区域的活性 点燃环路通过癫痫诱导来确定其潜在作用 在回路的动态平衡中，(3)检验VPA抑制的假设 NaALADase作为其抗惊厥/抗点燃作用机制，4)实验 NAALADase的特异性抑制剂B-N-乙酰谷氨酸的假说 会起到抗惊厥/防点燃的作用。