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 / 生理学报

ABSTRACT

The purpose 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.