| Epilepsy is one of the commonest nervous system diseases. It is a group of temporarily mal-functional chronic disorders which results from repeated discharges of neurons in central nervous system, and which is characterized by spontaneously recurrent and refractory seizures. Clinically, the seizures of the patients are often accompanied with decline of learning and memory abilities. It has been proved by many researches that seizures destroyed the hippocampal formation, which is an important neuroanatomical basis for adjusting behavior and learning and memory. The changes of the number of the hippocampal neurons and the synaptic plasticity are important factors influencing learning and memory abilities.Morris water maze is a precise method for detecting the abilities of place navigation and spatial probe, which has been widely used for examining the abilities of learning and memory (special spatial memory ability). Glial fibrillary acidic protein (GFAP) is a specific marker for astrocyte. The increased expression of GFAP indirectly reflects the proliferation of the astrocytes. Synaptophysin (p38), an integral membrane glycoprotein of presynaptic vesicles, has been widely used to research synaptogenesis in both animal models and human patients and reflect the distribution and density of the synapses. In this study, the acute epileptic seizures of rats were induced by subcutaneous injection of a convulsive dose of KA. Morris water maze was used to detect learning and memory abilities of the rats. Thionine staining, GFAP and p38 immunohistochemistry staining and HPLAS pathology image analysis system were used to demonstrate the loss of pyramidal cells and the difference of the immunoreactive products of GFAP and p38 in the hippocampus between the KA group and NS group. The purpose of present study is to supply the morphological evidence for the mechanisms that the seizures cause the learning and memory deficits. 1)The MWM results showed: In place navigation test, there were no significant differences among the escape latencies of the 4 study days in the KA group. However, significant differences were found among the escape latencies of the 4 days in the NS group(P<0.01) and the escape latency reduced according to the increase of the study time. In spatial probe test, only one of the eight rats in the KA group crossed the flat once, while the six of the eight rats in the NS group rats crossed the flat 14 times in all. The probe time in the flat quadrant and the opposite quadrant were significantly different between the NS group and KA group(P<0.05). 2)The results of tissue slices showed: â‘ The thionine staining displayed that the hippocampal pyramidal stratum in the NS group was stained clearly and arranged orderly, moreover, the stratum was rather integrated. However, the staining of CA1 pyramidal cells in the KA group was weakened and the number of the cells decreased, in addition, the stratum was not integrated. â‘¡The GFAP-immunohistochemistry stainting displayed that a few GFAP-immunoreactivity (IR) positive astrocytes scattered all over the slices which had small bodies and protruded many filamentous processes in the NS group, whereas, large numbers of proliferative GFAP-IR positive astrocytes appeared in dentate hilus, CA3 and CA1 in the KA group. The proliferation of the astrocytes in CA1 was the most distinct. There were so many proliferative astrocytes whose bodies and processes were tumid and strongly stained that some collagenous scars were formed in this area. â‘¢ Compared with the NS group, the staining of p38-IR in the stratum lucidum of the CA3 in the KA group was deeper and the density of the big granules were increased. The COD of p38-IR in the stratum lucidum of the KA group was increased significantly than that of the NS group(P<0.05). The results suggest that: (1) the learning and memory abilities of the rats decline 4 weeks after KA-induced acute epileptic seizures. (2) This decline is perhaps associated with the loss of pyramidal cells and the proliferation of the astrocyte...
|
PDF Full Text Request