Gehlert D R, Stephenson D T, Schober D A, Rash K, Clemens J A
Eli Lilly and Co., CNS Division, Indianapolis, IN 46285, USA.
Neurochem Int. 1997 Nov;31(5):705-13. doi: 10.1016/s0197-0186(97)00007-7.
Peripheral benzodiazepine receptors (PBRs) are expressed in a variety of tissues but are normally found at low levels in the brain. Following various types of nerve injury, a reactive gliosis results that exhibits a high expression of this receptor. To further characterize the expression of PBRs following neuronal injury, we evaluated PBR expression in the facial nucleus following facial nerve axotomy (FNA). Injury to a peripheral nerve results in a complex series of metabolic and morphological changes around the injured neuron. Transections of the facial nerve results in a rapid activation of both astrocytes and microglia around axotomized motor neurons. FNA resulted in an increase in the staining for both astrocytes (glial fibrillary acidic protein) and activated microglia (OX42). There was also a reduction in synaptic contacts with the motor nucleus as evidenced by reduced staining for the synaptic marker, synaptophysin. In sections labeled with [3H]-PK11195, the subsequent autoradiograms displayed marked increases in the labeling for PBRs. This increase was observed at 5, 7 and 10 days after nerve transection. The increase was primarily in the level of expression (Bmax), with no change in the affinity of the ligand (Kd). The increase in PBR expression after FNA supports the hypothesis that PBRs can be used as a sensitive marker for CNS injury.
外周苯二氮䓬受体（PBRs）在多种组织中表达，但通常在脑中含量较低。在各种类型的神经损伤后，会出现反应性胶质增生，该受体呈现高表达。为了进一步表征神经元损伤后PBRs的表达情况，我们评估了面神经切断术（FNA）后面神经核中PBR的表达。外周神经损伤会导致受损神经元周围发生一系列复杂的代谢和形态学变化。面神经横断会导致轴突切断的运动神经元周围的星形胶质细胞和小胶质细胞迅速激活。FNA导致星形胶质细胞（胶质纤维酸性蛋白）和活化小胶质细胞（OX42）的染色增加。突触标记物突触素的染色减少也证明了与运动核的突触联系减少。在用[3H]-PK11195标记的切片中，随后的放射自显影片显示PBRs的标记显著增加。在神经横断后5、7和10天观察到这种增加。这种增加主要是在表达水平（Bmax）上，配体亲和力（Kd）没有变化。FNA后PBR表达的增加支持了PBRs可作为中枢神经系统损伤敏感标志物的假说。
