| PrefaceEpilepsy is a common disease in neurology. Some studies indicate : recurrent seizures or status epilepsy ( SE) can lead to brain damage, especially in vulnerable areas such as hippocampus which, in turn may also cause seizures; both are cause and result each other reciprocally. The relationship between induced-epilepsy adult rats and hippocampal damages has been studied widely and deeply, while the condition of immature rats in this aspect is studied rarely. Epidemiology studies indicate that incidence of epilepsy in children is higher than in adult. Thus, animal experimental studies about immature rats early episode are very important.In my study, a Lithium-Pilocarpin-induced status epilepticus model was used. Conventional histopathological method and electron microscope were utilized to observe morphological changes in hippocampal formation. In addition, Timm histochemical technique was a-dopted to study mossy fiber sprouting.Materials and methodsWe divided 54 healthy naive rats into three groups randomly, every group has 18 naive rats. The first group ( I ) : physiological saline control group ; the second group ( II ) : diazepam intervene group ; the third group ( III) : experimental group. Lithium chloride and pi-locarpin were administered intraperitoneally to the experimental group animals in succession, which induced status epilepticus. The physiological saline control group animals received an equivalent volume of saline instead of pilocarpine. Others methods are the same to the experimental group. The diazepam intervene group animals received diazepam (4mg/kg) intraperitoneally before pilocarpin was given. The purpose of it is not to lead to episode. All animals were killed by per-fusion fixing on 7 day. Morphological changes in hippocampal formation and mossy fiber sprouting were studied by histopathological method and Timm histochemical technique.Results1. Behavioral manifestation: In the physiological saline control group, all of rats was 0 grade; the diazepam intervene group animals also have no convulsion, only very few animals have excited manifestation. At first, the experimental group animals manifestated agitation, scratching movement, wash-face movements, single limb clonus, wet-dog shakes and ataxia, and later developed tonic myoclonus of both the forelimbs and hindlimbs accompanied standing. At last developed to V grade.2. Histomorphometric examination of the rat brain in HE: In the physiological saline control group and diazepam intervene group, all had no brain damage; The experimental group animals have badly damage in brain, which was prominent in the areas of CA1,CA3 and dentate gyrus of hippocampus.3. Examination results of electron microscope: There is no obvious change in hypermicroscopical structure in the physiological saline control group and diazepam intervene group. In the experimental group, some neurons concentrate and degenerate, nucleuses become deformed, nuclear membranes are sunken; hyperplastic rough endo-plasmic reticulums also can be seen; mitochondria swell and cristae repture; the pericytopasm is devoid of organelles, but a lot of vacuoles surround the nucleus. There are vacuole degeneration in glial cells.4. Timm histochemical results of mossy fiber sprouting: Compared with physiological saline control group and diazepam intervene group, the experimental group animals develop obvious mossy fiber sprouting in CA3 region. Timm scoring results of each group in CA3; physiological saline control group I ( 0. 33 + 0. 49 ) ; diazepam intervene group II (0.42 +0. 52) ; experimental group III ( 1. 83 +0.39 ). Rank sum tests show: q I III=5.73 , P <0. 01 ; q II III =8.00 , P < 0.01. There is no statistics difference between I group and II group ( q I II =0. 53 , P > 0. 01) . In inner molecular layer of dentate gyrus , prominent Timm-stained granules can be seen in the experimental group, but there are nearly no Timm-stained granules in the rest two groups. Rank sum tests indicate the experimental group Timm-scoring in inner m...
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