Escubedo Elena, Chipana Carlos, Pérez-Sánchez Mónica, Camarasa Jordi, Pubill David
Unitat de Farmacologia i Farmacognòsia, Facultat de Farmàcia, Nucli Universitari de Pedralbes, Universitat de Barcelona, Spain.
J Pharmacol Exp Ther. 2005 Nov;315(2):658-67. doi: 10.1124/jpet.105.089748. Epub 2005 Aug 2.
In a previous study, we demonstrated that in rat striatal synaptosomes, methamphetamine (METH)-induced reactive oxygen species (ROS) production was prevented by methyllycaconitine (MLA), a specific antagonist of alpha7 neuronal nicotinic acetylcholine receptors (alpha7 nAChR). The aim of this study was to test the influence of MLA on acute METH effects and neurotoxicity in mice, using both in vivo and in vitro models. MLA inhibited METH-induced climbing behavior by 50%. Acute effects after 30-min preincubation with 1 microM METH also included a decrease in striatal synaptosome dopamine (DA) uptake, which was prevented by MLA. METH-induced neurotoxicity was assessed in vivo in terms of loss of striatal dopaminergic terminals (73%) and of tyrosine hydroxylase levels (by 90%) at 72 h post-treatment, which was significantly attenuated by MLA. Microglial activation [measured as 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide binding] was also present at 24 h post-treatment and was fully prevented by MLA, tending to confirm its neuroprotective activity. MLA had no effect on METH-induced hyperthermia. Additionally, flow cytometry assays showed that METH-induced ROS generation occurs inside synaptosomes from mouse striatum. This effect implied release of vesicular DA and was calcium-, neuronal nitric-oxide synthase-, and protein kinase C-dependent. MLA and alpha-bungarotoxin, but not dihydro-beta-erythroidine (an antagonist that blocks nAChR-containing beta2 subunits), fully prevented METH-induced ROS production without affecting vesicular DA uptake. The importance of this study lies not only in the neuroprotective effect elicited by the blockade of the alpha7 nicotinic receptors by MLA but also in that it proposes a new mechanism with which to study METH-induced acute and long-term effects.
在先前的一项研究中，我们证明，在大鼠纹状体突触体中，甲基lycaconitine（MLA）可阻止甲基苯丙胺（METH）诱导的活性氧（ROS）生成，MLA是α7神经元烟碱型乙酰胆碱受体（α7 nAChR）的特异性拮抗剂。本研究的目的是使用体内和体外模型，测试MLA对小鼠急性METH效应和神经毒性的影响。MLA可将METH诱导的攀爬行为抑制50%。与1 microM METH预孵育30分钟后的急性效应还包括纹状体突触体多巴胺（DA）摄取减少，而MLA可阻止这种减少。在体内，通过治疗后72小时纹状体多巴胺能终末损失（73%）和酪氨酸羟化酶水平降低（90%）来评估METH诱导的神经毒性，MLA可显著减轻这种毒性。小胶质细胞活化[以1-(2-氯苯基)-N-甲基-N-(1-甲基丙基)-3-异喹啉甲酰胺结合来衡量]在治疗后24小时也存在，并且MLA可完全阻止，这倾向于证实其神经保护活性。MLA对METH诱导的体温过高没有影响。此外，流式细胞术分析表明，METH诱导的ROS生成发生在小鼠纹状体的突触体内。这种效应意味着囊泡DA的释放，并且是钙、神经元型一氧化氮合酶和蛋白激酶C依赖性的。MLA和α-银环蛇毒素，但不是二氢β-刺桐碱（一种阻断含nAChR的β2亚基的拮抗剂），可完全阻止METH诱导的ROS生成，而不影响囊泡DA摄取。本研究的重要性不仅在于MLA阻断α7烟碱受体所引发的神经保护作用，还在于它提出了一种研究METH诱导的急性和长期效应的新机制。
