Autoradio graphic study of the cerebral blood flow and neuro transmitter receptor in epleptic focus using the double tracer technique

采用多重示踪自动显像技术研究了卡因酸致痫模型脑血流量（CBF）和神经递质（NMDA、乙酰胆碱、GABA、苯二氮平、5-羟色胺）的变化。在清醒和不受约束的情况下，通过预先植入的插管将kainic酸（KA） 2杯/毫升注射到Wistar大鼠的左杏仁核。如前所述，所有注射KA的大鼠出现边缘癫痫发作。注射1个月后，在氟烷麻醉下插管大鼠股动脉和股静脉。麻醉恢复后，大鼠注射^<14>C-IAP。连续动脉采血，注射C-IAP后30秒处死大鼠。大脑很快被取出并冷冻。用低温恒温器连续制作冠状切片。脑血流测量采用^<14>C-IAP体内放射自显影法。用Tris缓冲液清洗相邻切片，去除^<14>的C-IAP。使用^3H-MK801， ^3H-QNB,^3H-Muscimol, ^3H-Ro15-1788， ^3H-5-HT对这些相邻切片进行体外多重示踪自显像。用图像分析仪测定受体结合。左杏仁核和海马体所有区域的脑血流减少。左侧杏仁核和左侧海马锥体细胞层的受体结合均减少。然而，双侧海马齿状筋膜中GABA、苯二氮卓、5-羟色胺受体呈负相关增加。脑内神经递质受体的变化比脑血流的变化更受限制。在我们机构对人类颞叶癫痫患者的临床研究中也得到了类似的结果。使用SPECT或PET扫描的神经递质受体的神经成像似乎对癫痫病灶的定位非常有希望。

Cerebral blood flow (CBF) and neuro transmitters (NMDA,Acetylocholine, GABA,Benzodiazepine, 5-HT) in kainic acid induced epilepsy models were studied by multiple tracer auto radio graphy. The kainic acid (KA), 2 mug/mul, was injected into the left amygdala of Wistar rats through previously implanted cannula in awake and unrestrained condition. All rats with the KA injection developed limbic seizure as reported earlier. One month after the KAinjection, femoral artery and vein of the rats were cannulated under Halothane anesthesia. After recovery from tlhe anesthesia, the rats were injected with ^<14>C-IAP.Serial arterial blood samplings were performed and the rats were decapitated 30 seconds after the ^<14>C-IAP injection. The brain was quickly removed and frozen. Serial coronal sections were made with a cryostat. The CBF was measured by ^<14>C-IAP in vivo autoradio graphy. The adjacent slices were washed with Tris buffer to remove the ^<14>C-IAP.In vitro multiple tracer autoradio graphy on these adjacent sections was performed using ^3H-MK801, ^3H-QNB,^3H-Muscimol, ^3H-Ro15-1788, ^3H-5-HT.The receptor bindings were measured with image analyzer. The CBF was decreased in the left amygdala and all regions of the hippocampus. All the receptor bindings were decreased in the left amygdala and pyrmidal cell layr of the left hippocampus. However, the GABA,Benzodiazepine, 5-HT receptors were inversely increased in the fascia dentata of the hippocampus bilaterally. The changes of neuro transmitter receptor tend to be more restricted in the brain than that of CBF.Similar results were obtained from the clinical study of the human patients with temporal lobe epilepsy in our institution. Neuro imaging of the neuro transmitter receptor using the SPECT or PET scan seems to be very promissing for the localization of the epileptic focus.