Differences Of FeCl₃-induced Epilepsy Between Juvenile And Adult Rats

Posttraumatic epilepsy is one of complications resulted from head injury, which severely interferes with patients'living. Although the etiopathogenisis of PTE hasn't been completely illuminated nowadays, many investigations disclose that the dominant feature of PTE is extravasation and salvation of red blood cells, hemosiderin deposition in nervous tissue, revoking a series of pathological changes, and ultimately resulting in epileptic seizure. Retrospective analysis of large sample clinic cases hints that PTE is characteristic of certain age dependability. That is younger children are more likely to have PTE than adults. The tetanus toxin induced model of epilepsy and the lithium-pilocarpine model of epilepsy are characteristic of certain age dependability, too. The epileptic model induced by FeCl3commendably imitates pathological and physiological mechanism, EEG and behavior of PTE, and is one of suitable focal epilepsy animal models. But nowadays there has been few contrast investigations of this model involving in age factor. Therefore we establish the models with acute and chronic epilepsy induced by FeCl3 in juvenile rats and adult rats to investigate the age dependability of this model. Objective To establish the models with acute and chronic epilepsy induced by FeCl3 in juvenile rats and adult rats, observe the changes of EEG and pathology, and study the differences in seizure frequency and seizure location.Methods Rats were divided into juvenile group (three weeks) and adult group (two months) according to age. Acute experiment: Identical doses of chloride ferric were injected into the left sensorimotor cortexes with stereotactic technique. in 6h following injection EEG signals were recorded by an EEG polygraph and the pathologic examination was performed by means of HE. Chronic experiment: in 12h following injection EEG signals were recorded by an EEG polygraph and the pathologic examination was performed by means of HE after the epilepsy rats were raised in single cage for one month.Results Acute experiment: In the models with epilepsy induced by FeCl3, the achievement ratio of adult group was 80%, but juvenile group only 60%. Semblable epileptic waveforms were observed in the two groups. Seizure amplitude in adult group was higher than that in juvenile group. Seizure cumulative time and number of times in adult group were different from those in juvenile group (P<0.001). Distribution phase was resembled in seizure location in two groups. Otherwise, slight seizure activity was observed in two groups, significant in juvenile group (40%). And the two groups were not different in pathological change. Chronic experiment: the achievement ratio of adult group was 50%, but juvenile group only 30%. Semblable epileptic waveforms were observed in the two groups. Seizure cumulative time(ρ=0.271) and number of times (ρ=0.348)in adult group were not different from those in juvenile group. The focus damage of the two groups both exceeded the cortical field, and juvenile group were more severe in focus damage than adult group.Conclusions EEG in adult group were steadier than those in juvenile group. The EEG and pathology of FeCl3 - induced epileptic model of rats were characteristic of certain age dependability. It is possible that in different ages the nerve system has different reaction to the stimulation of ferric iron. But this model is not agreed with human PTE in age dependability. Therefore it is not a suitable model for correlative investigation of age factor in human PTE.