Ginovart Nathalie, Hassoun Wadad, Le Cavorsin Marion, Veyre Laurent, Le Bars Didier, Leviel Vincent
CERMEP Cyclotron Unit, 59 Boulevard Pinel, 69003 Lyon, France.
Neuropsychopharmacology. 2002 Jul;27(1):72-84. doi: 10.1016/S0893-133X(02)00285-3.
The effects of halothane and ketamine anesthesia on [11C]raclopride binding were assessed in the cat striatum at basal conditions and after drug- or depolarization-induced dopamine (DA) release using Positron Emission Tomography. At baseline, Scatchard analyses revealed that the higher [11C]raclopride binding found under halothane anesthesia was mainly attributable to a higher radioligand apparent affinity. Decreased [11C]raclopride binding was demonstrated following amphetamine under ketamine but not under halothane anesthesia. Under ketamine anesthesia transient DA overflows induced by direct stimulations of DA neurons through an intracerebral electrode induced transient changes in [11C]raclopride binding with a remarkable spatiotemporal accuracy. No effect was observed under halothane anesthesia. The failure to detect competition between DA and [11C]raclopride for binding on D(2)-receptors under halothane anesthesia might reflect, as already reported for other brain receptor systems, a halothane-promoted conversion of D(2)-receptors to a state of lower affinity for DA. It is suggested that the affinity state of receptors is a factor to be considered in in vivo ligand-activation studies.
使用正电子发射断层扫描技术，在基础条件下以及药物或去极化诱导多巴胺（DA）释放后，评估氟烷和氯胺酮麻醉对猫纹状体中[¹¹C]雷氯必利结合的影响。在基线时，Scatchard分析显示，氟烷麻醉下较高的[¹¹C]雷氯必利结合主要归因于较高的放射性配体表观亲和力。氯胺酮麻醉下，苯丙胺给药后[¹¹C]雷氯必利结合减少，但氟烷麻醉下未出现这种情况。在氯胺酮麻醉下，通过脑内电极直接刺激DA神经元诱导的短暂DA溢出，会导致[¹¹C]雷氯必利结合出现具有显著时空准确性的短暂变化。氟烷麻醉下未观察到任何影响。氟烷麻醉下未能检测到DA与[¹¹C]雷氯必利在D₂受体上结合的竞争，这可能如已报道的其他脑受体系统一样，反映了氟烷促进D₂受体转变为对DA亲和力较低的状态。提示在体内配体激活研究中，受体的亲和力状态是一个需要考虑的因素。
