Leitner M L, Hohmann A G, Patrick S L, Walker J M
Schrier Research Laboratory, Department of Psychology, Brown University, Providence, RI 02912.
Eur J Pharmacol. 1994 Jun 23;259(1):65-9. doi: 10.1016/0014-2999(94)90158-9.
In vitro binding experiments were performed to determine whether known subtypes of the putative sigma receptor exhibit a differential distribution across brain regions and species. Rat brains were dissected into nine regions, pooled, and used to prepare membranes for ligand binding studies. Whole guinea pig brains were prepared in an identical manner for comparison to rat. sigma 1 Receptors were labeled with 3H-pentazocine. sigma 2 Receptors were labeled with [3H]1,3-di-o-tolylguanidine (DTG) in the presence of 1 microM dextrallorphan to mask sigma 1 sites. Non-specific binding was determined in the presence of 10 microM haloperidol. Filtration and scintillation spectroscopy provided the binding values. The experiment revealed marked variation in the ratio of sigma 2 to sigma 1 binding across brain regions ranging from a low of 1.63 in the hindbrain to 3.51 in the cerebellum, that result mainly differences in the density of the receptors. Scatchard analysis on membranes derived from the hindbrain and cortex suggested that the effects were due primarily to regional differences in densities of receptor subtypes rather than different affinities. Guinea pig brain showed a marked preponderance of sigma 1 receptors with a ratio (sigma 2/sigma 1) of 0.67. These findings demonstrate that sigma 1 and sigma 2 receptors are differentially distributed in rat brain.
进行体外结合实验以确定假定的西格玛受体的已知亚型在脑区和物种间是否表现出差异分布。将大鼠脑部分解为九个区域，汇集后用于制备用于配体结合研究的膜。以相同方式制备整个豚鼠脑用于与大鼠进行比较。用3H-喷他佐辛标记西格玛1受体。在1 microM右美沙芬存在下用[3H]1,3-二邻甲苯基胍（DTG）标记西格玛2受体以掩盖西格玛1位点。在10 microM氟哌啶醇存在下测定非特异性结合。过滤和闪烁光谱法提供结合值。实验揭示了跨脑区的西格玛2与西格玛1结合比率的显著变化，范围从后脑的低至1.63到小脑的3.51，这主要是受体密度差异的结果。对源自后脑和皮质的膜进行的Scatchard分析表明，这些影响主要是由于受体亚型密度的区域差异而非不同亲和力所致。豚鼠脑显示西格玛1受体明显占优势，比率（西格玛2/西格玛1）为0.67。这些发现表明西格玛1和西格玛2受体在大鼠脑中差异分布。
