AGING AND NEURONAL 5 LIPOXYGENASE

衰老与慢性神经退行性疾病有关， 增加大脑的脆弱性，可能导致更糟糕的结果， 老年人的脑损伤比年轻人多。炎症是一种 慢性和急性的病理生理机制 神经变性 白三烯是炎性脂质介质， 花生四烯酸的形成由5-脂氧合酶（5-LO）引发。 5-LO也在神经元中表达，并可被脑激活 损伤，而5-LO抑制剂可以提供神经保护。 的 5-LO基因的表达似乎受到松果体的抑制， 荷尔蒙，褪黑激素，它也是一种有效的神经保护剂。 褪黑激素缺乏症通常随着年龄的增长而发展。 我们发现， 或松果体切除，即，缺乏褪黑激素的老鼠 对红藻氨酸盐引发的兴奋性毒性边缘脑损伤的影响 相应的年轻人或假松果体切除对照， 松果体切除或衰老导致边缘系统5-LO表达增强 结构. 我们假设，大脑老化的风险更高， 通过衰老抑制褪黑激素分泌的神经变性和 结果5-LO表达上调，而抑制5-LO表达， 表达和/或活动将增加大脑对 损伤 这些假设将在以下AIMS中进行检验：（1） 在衰老大鼠中表征（即，在2、6、12和24个月龄时）： 5-LO在神经元中的表达及其激活 蛋白FLAP;红藻氨酸对白三烯形成的影响， 海马和内嗅皮质的神经元损伤;血液和 大脑褪黑素水平（2）年轻人大脑边缘结构的特征 核褪黑激素受体激动剂的作用 CGP-52608或褪黑激素对5-L0表达和红藻氨酸诱导的 白三烯的形成和神经元损伤;（3）探讨 不同种类的5-LO抑制剂对红藻氨酸诱导的白三烯的影响 形成和神经元损伤;和（4）调查红藻氨酸是否是 在5-LO-缺陷中神经毒性较小（即，敲除）小鼠，以及 衰老同样影响5-LO-缺乏和 年龄匹配的野生老鼠 使用的技术包括： 5-LO和FLAP mRNA的逆转录/聚合酶链反应， 5-LO和FLAP免疫细胞化学/免疫印迹，酶或放射性 免疫测定，气相色谱/质谱，TUNEL/Nissl 染色和计算机辅助定量形态测定法。 结果 有望阐明5-LO在衰老中的作用， 神经退行性变，并指出神经保护疗法， 以5-LO通路为目标。

Aging is associated with chronic neurodegenerative diseases and increased brain vulnerability that may lead to a worse outcome from brain insults in elderly than in young subjects. Inflammation is one of the pathophysiological mechanisms of both chronic and acute neurodegeneration. Leukotrienes are inflammatory lipid mediators whose formation from arachidonic acid is initiated by 5-lipoxygenase (5-LO). 5-LO is also expressed in neurons and can be activated by brain injuries, whereas 5-LO inhibitors can provide neuroprotection. The expression of the 5-LO gene appears to be inhibited by the pineal hormone, melatonin, which also is a potent neuroprotective agent. Melatonin deficiency normally develops with aging. We found that old or pinealectomized, i.e., melatonin-deficient, rats are more susceptible to kainate-triggered excitotoxic limbic brain injury than the corresponding young or sham-pinealectomized controls, and that pinealectomy or aging result in an enhanced expression of 5-LO in limbic structures. We hypothesize that an aging brain is at a higher risk of neurodegeneration via aging-suppressed melatonin secretion and the resultant upregulation of 5-LO expression, and that suppressing the 5-LO expression and/or activity will increase the brain's resistance to injury. These hypotheses will be tested in the following AIMS: (1) Characterize in aging rats (i.e., at 2, 6, 12, and 24 months of age): the neuronal expression of mRNAs and proteins of 5-LO and its activating protein FLAP; the effect of kainate on leukotriene formation and neuronal damage in the hippocampus and the entorhinal cortex; blood and brain melatonin levels (2) Characterize in limbic structures of young and old rats the effects of the nuclear melatonin receptor agonist CGP-52608 or melatonin on 5-L0 expression and kainate-induced leukotriene formation and neuronal damage; (3) Investigate the action of different classes of 5-LO inhibitors on kainate-induced leukotriene formation and neuronal damage; and (4) Investigate whether kainate is less neurotoxic in 5-LO-deficient (i.e., knockout) mice, and whether aging equally affects the vulnerability to kainate of 5-LO-deficient and age-matched wild mice. Techniques to be used include: quantitative reverse transcription/polymerase chain reaction for 5-LO and FLAP mRNAs, 5-LO and FLAP immunocytochemistry/immonobloting, enzyme- or radio- immunoassays, gas chromatography/mass spectrometry, TUNEL/Nissl stainings, and computer-assisted quantitative morphometry. The results are expected to elucidate the role of 5-LO in aging and neurodegeneration and to indicate neuroprotective therapies that would target the 5-LO pathway.