Zecca L, Pietra R, Goj C, Mecacci C, Radice D, Sabbioni E
Instituto di Tecnologie Biomediche Avanzate-CNR, Milano, Italy.
J Neurochem. 1994 Mar;62(3):1097-101. doi: 10.1046/j.1471-4159.1994.62031097.x.
Radiochemical neutron activation analysis has been used to determine the concentration of 36 elements in neuromelanin, 22 elements in substantia nigra, and 32 elements in putamen of healthy subjects without signs of neurological disorders. Substantia nigra and putamen tissues were carefully dissected from the brain using special surgical instruments and tools as well as an adequate sampling procedure to avoid the risk of metal contamination during sampling. Neuromelanin was isolated from putamen by a multiple-step procedure (extraction with phosphate buffer, lipid and protein elimination by methanol extraction, and sodium dodecyl sulfate-proteinase). The isolated pigment as well as substantia nigra and putamen underwent neutron activation analysis involving irradiation in a high-neutron-flux reactor, radiochemical separations, and counting of the induced radionuclides by computer-based gamma-ray spectrometry. Iron was the element present in the highest concentration in all analyzed samples. The amount of iron was similar in substantia nigra and putamen (3,000 and 3,830 ng/mg wet weight, respectively) and 10 times higher in neuromelanin (30,800 ng/mg dry weight). Zinc was also present at high levels in three samples, ranging from 16.8 (substantia nigra) to 1,500 ng/mg (neuromelanin). Elements such as Zn, Cr, Se, Sr, Co, Sb, Ni, Hg, Ce, Au, Ag, Ta, and Sc were present in neuromelanin at much higher concentrations than in substantia nigra and putamen. These findings indicate that substantia nigra and putamen contain metals at higher concentrations than observed in blood and that neuromelanin has a particular affinity for metals.
放射化学中子活化分析已被用于测定无神经疾病迹象的健康受试者黑质中36种元素的浓度、壳核中22种元素的浓度以及神经黑色素中32种元素的浓度。使用特殊的手术器械和工具以及适当的采样程序，从大脑中仔细解剖出黑质和壳核组织，以避免采样过程中金属污染的风险。通过多步程序（用磷酸盐缓冲液提取、用甲醇提取去除脂质和蛋白质、用十二烷基硫酸钠 - 蛋白酶处理）从壳核中分离出神经黑色素。分离出的色素以及黑质和壳核都进行了中子活化分析，包括在高中子通量反应堆中辐照、放射化学分离以及通过基于计算机的γ射线光谱法对诱导的放射性核素进行计数。铁是所有分析样品中含量最高的元素。黑质和壳核中铁的含量相似（分别为3000和3830纳克/毫克湿重），而神经黑色素中铁的含量高10倍（30800纳克/毫克干重）。锌在三个样品中也含量较高，范围从16.8（黑质）到1500纳克/毫克（神经黑色素）。锌、铬、硒、锶、钴、锑、镍、汞、铈、金、银、钽和钪等元素在神经黑色素中的浓度比在黑质和壳核中高得多。这些发现表明，黑质和壳核中所含金属的浓度高于血液中的浓度，并且神经黑色素对金属具有特殊的亲和力。
