Lipids in Brain Disease: Animal Models

大鼠兴奋性毒性模型 过量谷氨酸引起的兴奋性毒性有助于进行性人脑疾病中的脑损伤和功能障碍。兴奋性毒性的机制已在体内进行了研究，但完整的动物模型是有限的。我们开发了一个兴奋性中毒的动物，每天注射大鼠21天，与谷氨酸受体激动剂，N-甲基-D-天冬氨酸（NMDA）。这些大鼠的大脑表现出花生四烯酸（AA）代谢和神经炎症（白细胞介素-1 β，肿瘤坏死因子α，胶质细胞酸性蛋白和诱导型一氧化氮合酶）的标记物升高，但抗凋亡标记物Bcl-2和BDNF的表达降低，以及它们的转录因子磷酸化CREB。促凋亡Bax、Bad和14-3- 3 zeta的表达增加，神经元损失明显。该动物模型现在可用于检查和治疗与人脑疾病相关的体内兴奋性毒性中涉及的过程（Kim等人，2009年）。 花生四烯酸在神经炎症中的选择性作用 在神经炎症的大鼠模型中，由6天的脑室内注入细菌脂多糖，我们报告了显着的干扰脑花生四烯酸（AA，20：4 n-6）代谢。在本研究中，我们证明，在这个模型中，脑二十二碳六烯酸（DHA，22：6 n-3）代谢的参数不受影响。应考虑用非甾体类阿片类或其他药物选择性靶向脑AA代谢以治疗与神经炎症相关的人脑疾病（Rosenberger et al.，2010年）。 单侧帕金森病大鼠模型脑内花生四烯酸酶的上调 我们已经报道了花生四烯酸（AA）信号在单侧6-羟基多巴胺（6-OHDA）损伤大鼠的尾壳核和额叶皮质中上调，这是一种不对称帕金森病模型。在本研究中，我们证实，这种上调与AA代谢，胞浆磷脂酶A2（cPLA 2）和环氧合酶（考克斯）-2，在尾壳核和额叶皮质病变同侧的两种酶的表达增加。这证实了损伤大鼠中同侧AA信号的紧张性增加对应于AA代谢级联中cPLA 2和考克斯-2表达的上调;如果存在于帕金森病中，则这种变化可能导致这种疾病的症状和病理学（Lee et al.，2010年）。 花生四烯酸对HIV-1转基因大鼠神经炎症的显像研究 人类免疫缺陷病毒（HIV）-1相关感染涉及携带病毒的单核细胞进入大脑，随后是小胶质细胞活化、神经炎症和花生四烯酸（AA）代谢酶上调。HIV-1转基因（Tg）大鼠是一种非感染性HIV-1模型，在5个月大后表现出神经和行为异常。我们使用我们的体内成像方法与定量放射自显影，以证明大脑AA代谢升高，在6-7个月大的未麻醉的HIV-1 Tg大鼠。胞质磷脂酶A2（cPLA 2-IV）、分泌型sPLA 2和钙非依赖性iPLA 2-VI（从膜磷脂中释放AA和二十二碳六烯酸）的脑活性以及促炎性前列腺素E2和白三烯B4的浓度也升高，与神经炎症和AA代谢增加一致。我们现在计划使用我们的正电子发射断层扫描与1- 11 CAA的临床方法来测试在HIV-1感染患者中脑AA代谢是否上调作为神经炎症的标志物（Basselin等人，2010年）。

RAT MODEL OF EXCITOXICITY Excitotoxicity caused by excessive glutamate contributes to brain damage and dysfunction in progressive human brain diseases. Mechanisms of excitotoxicity have been studied in vivo, but intact animal models are limited. We developed an excitotoxic animal by injecting rats daily for 21 days, with the glutamate receptor agonist, N-methyl-D-aspartate (NMDA). The brain of these rats demonstrated elevated markers of arachidonic acid (AA) metabolism and neuroinflammation (interleukin-1beta, tumor necrosis factor alpha, glial fibrillary acidic protein and inducible nitric oxide synthase), but decreased expression of the anti-apoptotic markers Bcl-2 and BDNF, and of their transcription factor, phospho-CREB. Expression of pro-apoptotic Bax, Bad, and 14-3-3zeta was increased, and neuronal loss was evident. This animal model now can be used to examine and treat processes involved in in vivo excitotoxicity relevant to human brain disease (Kim et al., 2009). SELECTIVE INVOLVEMENT OF ARACHIDONIC ACID IN NEUROINFLAMMATION In a rat model of neuroinflammation, produced by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide, we reported marked disturbances in brain arachidonic acid (AA, 20:4n-6) metabolism. In the present study, we demonstrated that parameters of brain docosahexaenoic acid (DHA, 22:6n-3) metabolism were unaffected in this model. Selective targeting of brain AA metabolism with non-steroidal antiinflammatory or other drugs should be considered for treating human brain diseases associated with neuroinflammation (Rosenberger et al., 2010). UPREGULATED BRAIN ARACHIDONIC ACID ENZYMES IN RAT MODEL OF UNILATERAL PARKINSON DISEASE We had reported that arachidonic acid (AA) signaling is upregulated in the caudate-putamen and frontal cortex of unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats, a model for asymmetrical Parkinson disease. In the present study, we confirmed that this upregulation was associated with increased expression of two enzymes involved in AA metabolism, cytosolic phospholipase A2 (cPLA2) and cyclooxygenase (COX)-2, ipsilateral to the lesion in the caudate putamen and frontal cortex. This confirms that the tonically increased ipsilateral AA signal in the lesioned rat corresponds to upregulated cPLA2 and COX-2 expression within the AA metabolic cascade; such changes, if present in Parkinson disease, may contribute to symptoms and pathology of this disorder (Lee et al., 2010). IMAGING NEUROINFLAMMATION WITH ARACHIDONIC ACID IN HIV-1 TRANSGENIC RAT Human immunodeficiency virus (HIV)-1 associated infection involves entry of virus-bearing monocytes into brain, followed by microglial activation, neuroinflammation, and upregulated arachidonic acid (AA) metabolic enzymes. The HIV-1 transgenic (Tg) rat, a noninfectious HIV-1 model, shows neurologic and behavioral abnormalities after 5 months of age. We used our in vivo imaging method with quantitative autoradiography to demonstrate that brain AA metabolism was elevated in 6-7 month old unanesthetized HIV-1 Tg rats. Brain activities of cytosolic phospholipase A2 (cPLA2-IV), secretory sPLA2, and calcium independent iPLA2-VI, which release AA and docosahexaenoic acid from membrane phospholipids, and concentrations of proinflammatory prostaglandin E2 and leukotriene B4, also were elevated, consistent with neuroinflammation and increased AA metabolism. We now plan to use our clinical method of positron emission tomography with 1-11CAA, to test whether brain AA metabolism is upregulated in HIV-1-infected patients as a marker of neuroinflammation (Basselin et al., 2010).