Characteristic behavioral seizures and abnormal signal asymmetry of magnetic resonance imaging in an electrogenic rat model of chronic epilepsy.
Chronic tetani (60 Hz, 2 s, 0.4~0.6 mA) were administered to the dorsal hippocampus (DHPC) or the medial temporal lobe neocortex (MTNC) of rats, to study the role of the entorhinal cortex (EC)-hippocampal loop in temporal lobe epileptogenesis. This was repeated once a day for 7 or 10 days. Magnification of hyper-intensity was induced by tetanization of the HPC or the MTNC, as detected by contralateral T(2) weighed magnetic resonance imaging (T(2)-WI). The effects were associated with an enlarged volume of the lateral ventricle (LV), which was verified histologically. T(2)-WI hper-intensities, contralateral to the tetanized hemispheres, were observed with high frequency primary wet dog shakes (WEDS) in the DHPC-stimulated rats and with low frequency WEDS in the MTNC-stimulated rats. It seems likely that the same neural mechanisms are shared by chronic tetanization of the right HPC and the righ MTNC, involving the closed EC-HPC loop. Poor correlation between contralateral T(2)-WI hper-intensities and light primary behavioral seizures in the MTNC-stimulated rats might be attributed to a controlled information flow into or out of this loop because of potential EC gating. In addition, asymmetric T(2)-WI hyper-intensities in the LV area reflected a hemispheric dependence, contralateral to the electrogenic focus in our model of rat epilepsy.
Han
D
D
Department of Physiology, Medical College, Wuhan University, Wuhan 430071. DanHLiLi@public.wuhan.cngb.com
Zhang
X R
XR
Tang
Y F
YF
Liu
M L
ML
Yin
S J
SJ
D000818:Animals; D004558:Electric Stimulation; D004567:Electrodes, Implanted; D004833:Epilepsy, Temporal Lobe / Q000209:etiology / Q000503:physiopathology*; D006624:Hippocampus / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D019579:Neocortex / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley