Soucy J P, Mrini A, Lafaille F, Doucet G, Descarries L
Département de Médecine Nucléaire, Hôpital Notre-Dame, Montréal, Québec, Canada.
Synapse. 1997 Feb;25(2):163-75. doi: 10.1002/(SICI)1098-2396(199702)25:2<163::AID-SYN7>3.0.CO;2-A.
WIN 35428 and GBR 12935, two uptake blocker ligands of the membrane transporter for dopamine (DA), were evaluated as quantitative markers of DA innervation density in CNS tissue. From alternate rat brain slices respectively processed for either light microscope or film autoradiography, counts of DA axon terminals (varicosities) labeled by uptake/storage of [3H]DA were matched with densitometric measurements of the specific binding of [3H]WIN 35428 and [3H]GBR 12935 in the same anatomical areas. The relation between the two parameters was examined in 1) the normal cingulate cortex; 2) the neostriatum severely DA-denervated by unilateral intramesencephalic injections of 6-hydroxydopamine; and 3) the neostriatum, partly DA-reinnervated by an intrastriatal graft of fetal mesencephalic neurons after prior 6-hydroxydopamine lesion. For technical reasons, the hyperdense DA innervation of normal striatum was not amenable to such correlative testing. Data were subjected to multilevel analysis. Specific [3H]WIN binding at 37 degrees C was tightly and linearly correlated with the number of DA varicosities over the full range of DA innervation densities tested. The regression lines for intact cortex and for DA-denervated as well as DA-reinnervated neostriatum had the same slope and crossed the ordinate near zero. In contrast, [3H]GBR 12935 binding at 37 degrees C showed no correlation with the number of DA varicosities. A linear correlation could be obtained after incubation with [3H]GBR 12935 at 4 degrees C in the presence of ZnSO4, but the intercept of this regression line remained significantly above zero at origin, indicating extraneous binding to non-DA transporter sites. Providing that the hyperdense DA innervation of the normal neostriatum does not generate a particular problem in vivo as it does in vitro. WIN 35428, but not GBR 12935, might satisfy the selectivity and sensitivity requirements of a quantitative marker of DA innervation density for eventual use in positron emission tomographic studies.
WIN 35428和GBR 12935是多巴胺（DA）膜转运体的两种摄取阻断剂配体，被评估为中枢神经系统组织中DA神经支配密度的定量标志物。从分别用于光学显微镜或放射自显影的交替大鼠脑切片中，通过[³H]DA摄取/储存标记的DA轴突终末（膨体）计数与相同解剖区域中[³H]WIN 35428和[³H]GBR 12935特异性结合的光密度测量值相匹配。在以下情况中检查了这两个参数之间的关系：1）正常扣带回皮质；2）通过单侧脑内注射6-羟基多巴胺严重去DA神经支配的新纹状体；3）在先前6-羟基多巴胺损伤后，通过胎儿中脑神经元纹状体内移植部分再DA神经支配的新纹状体。由于技术原因，正常纹状体的高密度DA神经支配不适合进行这种相关性测试。数据进行了多级分析。在测试的整个DA神经支配密度范围内，37℃时特异性[³H]WIN结合与DA膨体数量紧密且呈线性相关。完整皮质以及去DA神经支配和再DA神经支配的新纹状体的回归线具有相同的斜率，并且在纵坐标附近与零相交。相比之下，37℃时[³H]GBR 12935结合与DA膨体数量无关。在4℃下于硫酸锌存在下与[³H]GBR 12935孵育后可获得线性相关性，但该回归线在原点处的截距仍显著高于零，表明与非DA转运体部位存在非特异性结合。假设正常新纹状体的高密度DA神经支配在体内不会像在体外那样产生特殊问题。WIN 35428而非GBR 12935可能满足DA神经支配密度定量标志物的选择性和敏感性要求，最终用于正电子发射断层扫描研究。
