Henshall D C, Sinclair J, Simon R P
Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA.
Brain Res. 2000 Mar 10;858(2):290-302. doi: 10.1016/s0006-8993(99)02452-x.
The specific electrographic activity responsible for seizure-induced DNA damage remains little explored. We therefore examined the regional and temporal appearance of DNA fragmentation and cell death and its relationship to specific electrographic seizure patterns in a rat model of focally evoked limbic epilepsy. Animals received intra-amygdaloid injection of kainic acid (KA) to induce seizures for 45 min during continuous electroencephalographic (EEG) monitoring, after which diazepam (30 mg/kg) was administered. DNA polymerase I-mediated biotin-dATP nick translation (PANT) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) were used to detect single- and double-stranded DNA breaks, respectively. Injection of 0.01 microg KA induced seizures characterized by ictal fast activity but without consequent brain injury. By contrast, 0.1 microg KA induced an additional pattern of seizure activity characterized by bursts of high frequency polyspike paroxysmal discharges. In these animals, there was a significant reduction in numbers of pyramidal neurons within the ipsilateral and contralateral CA3 subfield of the hippocampus, detectable as little as 4 h following seizures. PANT- and TUNEL-positive cells appeared in similar numbers 16 h following seizure cessation within the CA3, declining after 72-96 h. Varying the duration of polyspike paroxysmal discharges determined that as little as 30 s elicited maximal injury. These data suggest single- and double-stranded DNA breaks are generated during the cell death process and are consequent on a specific component of seizure activity electrographically determined.
导致癫痫发作诱导的DNA损伤的特定脑电图活动仍未得到充分研究。因此，我们在局灶性诱发边缘性癫痫大鼠模型中，研究了DNA片段化和细胞死亡的区域和时间出现情况及其与特定脑电图癫痫发作模式的关系。动物在持续脑电图（EEG）监测期间接受杏仁核内注射海藻酸（KA）以诱发癫痫发作45分钟，之后给予地西泮（30mg/kg）。分别使用DNA聚合酶I介导的生物素-dATP缺口平移（PANT）和末端脱氧核苷酸转移酶介导的dUTP缺口末端标记（TUNEL）来检测单链和双链DNA断裂。注射0.01μg KA诱发的癫痫发作以发作期快速活动为特征，但无后续脑损伤。相比之下，0.1μg KA诱发了另一种癫痫发作活动模式，其特征为高频多棘波阵发性放电爆发。在这些动物中，海马同侧和对侧CA3亚区内的锥体神经元数量显著减少，癫痫发作后4小时即可检测到。癫痫发作停止后16小时，CA3区内PANT和TUNEL阳性细胞数量相似，72-96小时后减少。改变多棘波阵发性放电的持续时间确定，仅30秒即可引发最大损伤。这些数据表明，单链和双链DNA断裂是在细胞死亡过程中产生的，并且是由脑电图确定的癫痫发作活动的特定成分所导致的。
