组织学与核磁共振检测大鼠癫痫源性早期脑损伤的跨半球扩布特征

侵性强直电刺激(60Hz,2s)大鼠右侧背海马(hippocampus,DHPC)CAl基树突区,1次/d,连续刺激10d。分别在施加强直电刺激的第2、4、6、8或10d时进行核磁共振成像检测(T2 weighted magnetic resonamce image T2-WI),并对鼠脑进行组织学切片鉴定。结果表明,早期慢性癫痫源性脑损伤的病理性形态特征主要包括：(1)T2-WI检测侧脑室(lateral ventricle,LV)区域信号增强、组织学检测LV扩大和双侧对称性脉络膜丛病理性增生,后两者并非完全平行呈现。(2)组织学切片显示双侧LV扩大面积与T2-WI信号增强区域面积的脑区分布近似。与空白对照组大鼠相比,电刺激2、4、6、8和10d后,T2-WI信号增强区域面积显著增大(P=0．0259;P＝0．0184;P=0．0184;P＝0．0404;P＝0．0259)以及组织学鉴定LV面积增大(P＝0．0210;P＝0．01;P＝0．0100;P=0．0152).(3)定侧分析显示,T2-WI信号增强以及T2-WI信号增强区域面积和组织学鉴定LV面积扩大,在慢性刺激6d时均以植入电极的对侧为主;第10d时均以同侧为主。三项观察结果的一致性证实了癫痫源性早期脑损伤的跨半球动态扩布特征。

Propagation of brain injuries from artificial focus into the opposite hemisphere at the early stage of rat electrogenic epilepsy identified by histology and magnetic resonance image

The popurse of this work was to study the characteristics of rat brain abnormalities at two hemispheres at the early stage of electrogenic epilepsy. Experiments were performed on 37 male Sprague-Dawley rats. Chronically repetitive tetanization (60 Hz, 2 s, 0.4-0.6 mA) was used to stimulate the right dorsal hippocampus (DHPC) of the rat brain once a day for 2, 4, 6, 8 or 10 d, respectively. The T 2 weighted magnetic resonance image (T 2-WI) were obtained from each experimental rat at the end of the experiments. Histological sections were obtained after experimentation. The results showed that the main pathologic changes at the early stage of epilepsy included: (1) T 2-WI hyperintensification, the histological enlargement of lateral ventricle (LV) and pathological hyperplasia of ventricular choroidea plexus occurred. The pathological hyperplasia was symmetric in two hemispheres, but the LV enlargement was not. (2) Histologically enlarged LV area showed a resemblance to T 2-WI hyperintensive area. Compared with the control rats, large T 2-WI hyperintensive area (P=0.0259; P=0.0184; P=0.0184; P=0.0404; P=0.0259) and histologically enlarged LV area (P=0.0210; P=0.01; P=0.0100; P=0.0152) were present in chronically tetanized rats. (3) Dynamic characteristics of histologically enlarged LV area resembled to those of T 2-WI hyperintensity area in chronically tetanized rats at different stimulating day. Lateralization of T 2-WI hyperintensity was in accordance with that of T 2-WI abnormal area and of histologically enlarged LV. These abnormalities were severe on the contralateral side on the stimulating day 6, or on the ipsilateral side on the stimulating day 10. These results imply characteristic propagation of brain abnormalities crossing to the opposite hemisphere at the early stage of an electrogenic rat epilepsy.