AN INVITRO MODEL OF 1-METHYL-4-PHENYL-PYRIDINIUM (MPP+) TOXICITY - INCUBATION OF RABBIT CAUDATE-NUCLEUS SLICES WITH MPP+ FOLLOWED BY BIOCHEMICAL AND FUNCTIONAL-ANALYSIS
AN INVITRO MODEL OF 1-METHYL-4-PHENYL-PYRIDINIUM (MPP+) TOXICITY - INCUBATION OF RABBIT CAUDATE-NUCLEUS SLICES WITH MPP+ FOLLOWED BY BIOCHEMICAL AND FUNCTIONAL-ANALYSIS
复制标题
DOI：
10.1111/j.1476-5381.1988.tb11665.x
复制
发表时间：
1988-10-01
影响因子：
7.3
通讯作者：
HERTTING, G
中科院分区：
文献类型：
--
作者：
FEUERSTEIN, TJ;HEDLER, L;HERTTING, G
将兔尾状核切片在体外神经毒性化合物1-甲基-4-苯基吡啶（MPP+）中预孵育24小时。采用高效液相色谱法测定其内源性单胺含量。浓度高于32 nM的MPP+显著降低了切片内多巴胺水平，且呈浓度和时间依赖性；32亩。M耗竭量大于95%。多巴胺的主要代谢物二羟基酚乙酸（DOPAC）浓度在MPP+浓度下降低，但不改变多巴胺水平。因此，MPP+增加了多巴胺/DOPAC比值。相比之下，在纳米摩尔浓度的MPP+下，5-羟色胺（5-HT）水平和5-HT/5-羟基吲哚乙酸（5-HIAA）比值均升高。5-HT仅在32 μ m时显著降低。多巴胺摄取抑制剂诺非芬胺降低了MPP+对多巴胺和DOPAC含量的消耗作用。MPP+预处理24 h后，兔尾状核切片对[3H]-多巴胺的摄取增强(0.32 .mu；M, 1。M和3.2 .mu。M MPP+)或减少(在32 .mu。M MPP +)。用10 .mu。mmpp +仅作用1小时增加了其3h标记（与预处理24小时相比），而9小时后未检测到净增加。MPP+预处理1和9 h后，MPP+处理切片的培养液中[3H]-多巴胺脱胺代谢物明显少于对照切片。这些发现表明MPP+在破坏多巴胺能（和5-羟色胺能）末端之前强烈抑制单胺氧化酶（MAO）。为了从功能上验证所提出的体外模型，我们在MPP+处理的切片和对照中研究了[3H]-乙酰胆碱（[3H]-ACh）的电诱发释放。MPP+降低了d2受体拮抗剂多潘立酮的促进作用和儿茶酚胺摄取抑制剂诺非芬胺对[3H]-ACh释放的抑制作用；抑制多巴胺能输入减少对胆碱能神经元的影响。这些发现还表明，多巴胺能神经元的末端区域尾状核是MPP+毒性的一个部位。目前的体外模型可能有助于研究MPP+的作用及其在特定条件下与其他药物的相互作用。
Slices of rabbit caudate nucleus were preincubated for up to 24 h in vitro in the presence of the neurotoxic compound 1-methyl-4-phenyl-pyridinium (MPP+). Subsequently the levels of endogenous monoamines in the slices were determined by h.p.l.c. with electrochemical detection. MPP+, in concentrations higher than 32 nM significantly diminished the dopamine levels within the slices in a concentration- and time-dependent manner; at 32 .mu.M the depletion was more than 95%. The concentration of the major metabolite of dopamine, dihydroxyphenol acetic acid (DOPAC) was decreased at concentrations of MPP+ that did not alter dopamine levels. Thus, MPP+ increased the dopamine/DOPAC ratio. In contrast, both 5-hydroxytryptamine (5-HT) levels and 5-HT/5-hydroxyindolacetic acid (5-HIAA) ratios were increased at nanomolar concentrations of MPP+. 5-HT was significantly reduced only at 32 .mu.M. The dopamine uptake inhibitor nomifensine reduced the depletory effect of MPP+ on dopamine and DOPAC content. Following 24 h pretreatment with MPP+, the uptake of [3H]-dopamine into rabbit caudate nucleus slices was either enhanced (at 0.32 .mu.M, 1 .mu.M and 3.2 .mu.M MPP+) or reduced (at 32 .mu.M MPP+). Preincubation of slices with 10 .mu.M MPP+ for only 1 h increased their 3H-labelling (in contrast to 24 h pretreatment) whereas after 9 h no net increase was detectable. After 1 and 9 h MPP+ pretreatment, much less deaminated metabolites of [3H]-dopamine were found in the incubation medium of MPP+ treated slices than in medium of control slices. These findings suggest that MPP+ strongly inhibits the enzyme monoamine oxidase (MAO) within dopaminergic (and 5-hydroxytryptaminergic) terminals before destroying them. To validate the proposed in vitro model functionally, the electrically evoked release of [3H]-acetylcholine ([3H]-ACh) was investigated in MPP+ treated slices and controls. MPP+ reduced both the facilitatory effect of the D2-receptor antagonist domperidone and the inhibitory effect of the catecholamine uptake inhibitor nomifensine on [3H]-ACh release; effects compatible with a diminished inhibitory dopaminergic input on cholinergic neurones. These findings also show that the terminal region of dopaminergic neurones, the caudate nucleus, is a site for MPP+ toxicity. The present in vitro model may be useful for investigating the effects of MPP+ and its interaction with other drugs under defined conditions.