Sanchez-Ramos J, Facca A, Basit A, Song S
Department of Neurology, University of South Florida, James A. Haley VA Medical Center, Research 151, 13000 Bruce B Downs Boulevard, Tampa, Florida 33612, USA.
Exp Neurol. 1998 Apr;150(2):263-71. doi: 10.1006/exnr.1997.6770.
Dieldrin can be retained for decades in lipid-rich tissue and has been measured in some postmortem PD brains. Dieldrin has been reported to deplete brain monoamines in several species and has been shown to inhibit mitochondrial respiration. To further investigate the possibility that it may be involved in the pathogenesis of parkinsonism, its toxicity for dopaminergic (DA) neurons was assessed in a mesencephalic cell culture model. Primary neuronal cultures of mesencephalic neurons were prepared from fetal rats or fetal mice, grown for 1 week and incubated with Dieldrin (0.01-100 microM) for 24 or 48 h. Toxicity for DA neurons was determined by measuring density of surviving tyrosine hydroxylase immunoreactive (TH-ir) cells. Toxicity for gamma-aminobutyric acid (GABA)-ergic neurons was determined by measuring survival of glutamate decarboxylase (GAD)-ir neurons. General, nonselective cytotoxicity was determined by counting cells visualized by phase contrast microscopy or by DAPI-stained cells with fluorescence microscopy. Dieldrin exposure for 24 h resulted in a dose-dependent decrease in survival of TH-IR cells (DA neurons) with a 50% decrease (EC50) produced by 12 microM in rat mesencephalic cultures. Dieldrin also produced a dose- and time-dependent decrease in mouse DA-ergic and GABA-ergic neurons in mouse mesencephalic cultures. GABA-ergic neurons were less sensitive to the toxin compared to DA-ergic neurons. Cellular uptake of 3H-DA was also affected by lower concentrations of Dieldrin (EC50 = 7.98 microM) than uptake of 3H-GABA (EC50 = 43 microM). Thus, Dieldrin appears to be a relatively selective DA-ergic neurotoxin in mesencephalic cultures. Dieldrin, which may be ubiquitous in the environment, is proposed as an agent which can initiate and promote dopaminergic neurodegeneration in susceptible individuals.
狄氏剂可在富含脂质的组织中留存数十年，并且在一些帕金森病患者的尸检大脑中已检测到其存在。据报道，狄氏剂会使多种物种的脑单胺类物质耗竭，并且已证明它会抑制线粒体呼吸。为了进一步研究其可能参与帕金森症发病机制的可能性，在中脑细胞培养模型中评估了其对多巴胺能（DA）神经元的毒性。从中枢神经系统的神经元制备原代神经元培养物，这些神经元取自胎鼠或胎鼠，培养1周后，用狄氏剂（0.01 - 100微摩尔）孵育24或48小时。通过测量存活的酪氨酸羟化酶免疫反应性（TH-ir）细胞的密度来确定对DA神经元的毒性。通过测量谷氨酸脱羧酶（GAD）免疫反应性神经元的存活情况来确定对γ-氨基丁酸（GABA）能神经元的毒性。通过相差显微镜观察细胞或用荧光显微镜观察经DAPI染色的细胞来计数，从而确定一般的、非选择性的细胞毒性。暴露于狄氏剂24小时导致TH-IR细胞（DA神经元）的存活率呈剂量依赖性下降，在大鼠中脑培养物中，12微摩尔的狄氏剂可导致存活率下降50%（半数有效浓度）。狄氏剂还使小鼠中脑培养物中的小鼠DA能和GABA能神经元数量呈剂量和时间依赖性减少。与DA能神经元相比，GABA能神经元对该毒素的敏感性较低。较低浓度的狄氏剂（半数有效浓度 = 7.98微摩尔）对3H-DA细胞摄取的影响也大于对3H-GABA细胞摄取的影响（半数有效浓度 = 43微摩尔）。因此，在中脑培养物中，狄氏剂似乎是一种相对选择性的DA能神经毒素。狄氏剂在环境中可能普遍存在，它被认为是一种能够在易感个体中引发和促进多巴胺能神经变性的物质。
