MPTP BETA CARBOLINES AND THE ETIOLOGY OF PARKINSONISM

帕金森病是一种神经退行性疾病 与衰老有关，目前尚不清楚。我们最初提出(N)- 甲基化β-碳氢化合物(MeBC)，其代谢衍生物 生理性吲哚胺，可能是致病因素。结构上的甲基溴碳化物 镜像N-甲基-4-苯基吡啶(MPP)，线粒体毒性 N-甲基-4-苯基-四氢吡啶的代谢物，一种帕金森病- 在非法街头毒品中引入污染物。支持我们的建议，我们 发现体内报道的去甲基BCS在2-甲基上发生甲基化 氮，更令人惊讶的是，S的9(吲哚)氮- 豚鼠和大鼠脑内腺苷蛋氨酸依赖转移酶(S)的表达。 此外，与MPP一样，7-含氧2-甲基BC，特别是简单的 2，9-Me2BCs是有效的线粒体呼吸抑制剂，但值得注意的是， 因为它们不能N-去质子化，所以只有2，9-Me2BC是线粒体的 像MPP一样被隔离(PNAS，1990)。与这些结果一致，确定 MEBC在体外具有接近MPP的神经毒性(PC12细胞)和 在体内(纹状体微透析或大鼠黑质注射)；重要的是， 对于简单的2-MeBCs，9(吲哚)甲基化显著增强毒性 (科学，提交)。 此应用程序的主要目标集中在一个关键的分析问题上： MeBCs--特别是独特的2，9-Me2BCs--存在并可能 帕金森病早期或晚期人类中枢神经系统的升高？为了回答这个问题，我们将 对帕金森病患者的脑脊液和尸检脑进行检查 采用高效液相色谱/荧光检测法的对照； 在加州大学洛杉矶分校的合作下，质谱学将用于结构和 定量确认。第二个目标的目标是部分 影响2-MeBC和2，9-Me2BC的N-甲基转移酶(S)的特性 在人脑区域的形成，以澄清两者之间的关系 脑组织局部MeBC水平和N-甲基化活性。在我们的第三个目标， 为了更好地了解毒性机制，我们将比较选定的2，9-甲氧基苯乙酸乙酯， 2-BCS和MPP在胎鼠中脑培养中的应用 与H.Rollema博士合作，在大鼠体内进行纹状体微透析。 这一总体方法应该提供关于可能的 甲胎蛋白在帕金森病中的作用。

The etiology of Parkinson's disease (PD), a neurodegenerative disorder linked to aging, remains unclear. We initially proposed that (N)- methylated beta-carbolinium (MeBC) compounds, metabolic derivatives of physiological indoleamines, may be causative factors. MeBCs structurally mirror N-methyl-4-phenyl-pyridinium (MPP+), the mitochondrially toxic metabolite of N-methyl-4-phenyl-tetrahydro-pyridine, a parkinsonism- inducing contaminant in illicit street drugs. Supporting our proposal, we find that normethyl BCs reported in vivo undergo methylation on the 2- nitrogen and, more surprisingly, the 9(indole)-nitrogen by S- adenosylmethionine-dependent transferase(s) in guinea pig or rat brain. Further, like MPP+, the 7-oxygenated 2-MeBCs and particularly the simple 2,9-Me2BCs are effective mitochondrial respiratory inhibitors, but notably, because they cannot N-deprotonate, only the 2,9-Me2BCs are mitochondrially sequestered like MPP+ (PNAS, 1990). Consistent with these results, certain MeBCs have neurotoxic potencies approaching MPP+ in vitro (PC12 cells) and in vivo (striatal microdialysis or nigral injections in rats); importantly, for simple 2-MeBCs, 9(indole)-methylation markedly enhances toxicity (Science, submitted). The main aim of this application focuses on a key analytical question: are MeBCs -- and especially the unique 2,9-Me2BCs -- present and possibly increased in the human CNS during early or late PD? To answer this we will examine both cerebrospinal fluid and postmortem brain from PD subjects and controls employing HPLC/fluorescence detection; with Dr. Faull's collaboration at UCLA, mass spectrometry will be used for structural and quantitative confirmation. The objective of a 2nd aim is to partially characterize the N-methyltransferase(s) effecting 2-MeBC and 2,9-Me2BC formation in human brain regions, in order to clarify relationships between regional brain MeBC levels and N-methylation activity. In our 3rd aim, to better understand the toxic mechanisms, we will compare selected 2,9-MeBCs, 2-BCs and MPP+ using fetal rat mesencephalic cultures and, in ongoing collaboration with Dr. H. Rollema, in vivo striatal microdialysis in rats. This overall approach should provide definitive answers about the possible involvement of MeBCs in PD.