| ObjectiverTo ablate the ipsilateral dorsal hippocampus(DH),ventral hippocampus(VH), entire hippocampus(HP) and amygdala(AMY) by ibotenic acid(IBO) Stereotactic infusion for the treatment of temporal lobe epilepsy in rat,explore the selection of targets for the treatment of temporal lobe epilepsy,the curative effect after operation,the effect on spatial learning and memory,at the same time explore the curative mechanism and the pharmacologic characteristics of IBO.Methods: The kainate-induced temporal lobe epilepsy model in rat was successfully created by unilaterally Stereotactic injection of kainic acid (0.8 μ g/0.2μ 1) into the rat right ventral hippocampus,making a unilateral epileptic focus. Subsequently the Stereotactic ablation(the ipsilateral DH,VH, entire HP and AMY) by IBO was performed on Day 10 postinjection of KA. The symptoms of the animals were recorded by a video camera. EEG signals were recorded by an EEG polygraph. Morris water maze test was performed to detect the deficits of the spatial learning and memory. The pathologic examination of the samples was used , including HE staining and Nissl staining to define the site of electrode,the extent of ablating,hippocampal neuron loss,glia hyperplasia,hippocampal atrophy and the damage to surrounding structures.Results:After IBO Stereotactic infusion,the incidence of observed seizures and EEG-defined epileptiform events was markedly reduced in rats from either ipsilateral VH-ablated group(Group C) or entire ipsilateral HP-ablated group(Group D). A significant reduction was noted compared with rats that did not undergo IBO Stereotactic infusion(Group E).EEG-defmed epileptiform events of rats from Group D was significantly reduced compared with those of rats from Group C , which was recorded by both ipsilateral AMY on Day 14 after KA injection and ipsilateral VH on Day 28.A significant reduction was not found-4-between rats from either ipsilateral DH-ablated group(Group A) or ipsilateral AMY-ablated group(Group B) and rats from Group E. While a significant reduction was found when compared with rats from Group C and D. During place navigation and spatial probe test, rats from Group C displayed significantly shorter latencies on Day 4 -. 5 trials and spent significantly more time in the target quadrant than those of rats from Group E, without a significance compared with those of rats that did not undergo KA sterertactic injection(Group F).Rats from Group A, 1 D displayed no difference compared with rats from Group E, while a significant difference was noted compared with rats from Group C and F.Conclusions :l:The hippocampus represents a heterogeneous structure.Hippocampal function exists a differentiation along its longitudinal axis in both epileptogenesisN spatial learning and memory.DH plays a important role in spatial learning and memory ,While VH has a higher seizure susceptibility to KA .2: Only ablating ipsilateral VH by IBO stereotactic infusion can effectively inhibit KA-induced temporal lobe epilepsy,preserving the hippocampal function of spatial learning and memory in rats at the same time .3: The kainate-induced temporal lobe epilepsy model in rat can simulate MTLE in human. Only ablating ipsilateral AMY by IBO stereotactic infusion can not effectively suppress KA-induced temporal lobe epilepsy.4:As compared with KA,IBO infusion in the deep brain has no detectable remote lesions and no prominent epileptic excitation of the hippocampus,can produce more complete and defined focal lesions.IBO has been proved to be a valuable tool to neuroscientific research.5:The method of multi-fractional injections of IBO can make accurately focal lesions according to hippocampus's shape with slight damage to surrouding structures. |
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