Ng M C, Iacopino A M, Quintero E M, Marches F, Sonsalla P K, Liang C L, Speciale S G, German D C
Department of Biomedical Sciences, Baylor College of Dentistry, Dallas, TX 75266-067, USA.
Brain Res Mol Brain Res. 1996 Mar;36(2):329-36. doi: 10.1016/0169-328x(95)00266-u.
The calcium-binding protein calbindin-D28k (CALB) has been localized in high concentrations in several neuronal populations within the central nervous system (CNS) and is believed to act as an intracellular calcium (Ca2+) buffer. There has been much interest and speculation concerning its potential neuroprotective function. However, there is little direct evidence linking CALB content of individual neurons to Ca2+ buffering ability, resistance to Ca(2+)-mediated excitotoxicity, or vulnerability to Ca(2+)-mediated degeneration. It is necessary to demonstrate these relationships on a cellular level so that more definitive conclusions can be made. We have utilized immunocytochemical and Western blot techniques to determine whether cellular CALB content is altered in the nucleus A10 dopaminergic region of the midbrain following administration of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Our data demonstrate a significant increase in the CALB content of nucleus A10 neurons (up to 227 +/- 23% above control) 3 and 6 h after MPTP treatment. CALB elevation demonstrated both time and dosage dependence as 6-h groups exhibited larger increases than 3-h groups, and a 60 mg/kg dosage induced a larger increase than a 20 mg/kg dosage. These data support the hypothesis that MPTP is neurotoxic by causing increases in free intracellular Ca2+ and that increased CALB in the midbrain dopaminergic neurons is a protective response to elevated intracellular free Ca2+.
钙结合蛋白钙结合蛋白-D28k（CALB）在中枢神经系统（CNS）的多个神经元群体中高浓度定位，被认为起着细胞内钙（Ca2+）缓冲剂的作用。关于其潜在的神经保护功能，已经有很多关注和猜测。然而，几乎没有直接证据将单个神经元的CALB含量与Ca2+缓冲能力、对Ca(2+)介导的兴奋性毒性的抗性或对Ca(2+)介导的变性的易感性联系起来。有必要在细胞水平上证明这些关系，以便得出更明确的结论。我们利用免疫细胞化学和蛋白质印迹技术来确定在给予神经毒素1-甲基-4-苯基-1,2,3,6-四氢吡啶（MPTP）后，中脑黑质A10多巴胺能区域的细胞CALB含量是否发生改变。我们的数据表明，MPTP处理后3小时和6小时，A10核神经元的CALB含量显著增加（比对照组高227 +/- 23%）。CALB升高表现出时间和剂量依赖性，因为6小时组的增加幅度大于3小时组，60 mg/kg剂量诱导的增加幅度大于20 mg/kg剂量。这些数据支持以下假设：MPTP通过引起细胞内游离Ca2+增加而具有神经毒性，并且中脑多巴胺能神经元中CALB的增加是对细胞内游离Ca2+升高的一种保护反应。
