| Objective: Epilepsy is a common chronic disease in nervous system, characterized by cerebral dysfunction resulting form abnormal discharge of cerebral neuron. According to the clinical research, about one third of epileptic patients have cognitive impairment including the declination of memory and perceptual ability, the scattering of attention, etc. Recently, people gradually found that the cognitive impairment of epileptic patients effected seriously on their quality of life. Therefore, people pay more attention on the etiological mechanics and the healing of cognitive impairment. Chronic epileptic model rats kindled by PTZ were established and memantine was administrated. We observe the change of the capability of learning and memory in PTZ group and MN group, and the expression of Glycogen synthase kinase-3(GSK-3β) and Phosph- Glycogen synthase kinase-3(Ser9 in GSK-3β) protein and the expression of GSK-3βmRNA through the methods of Western Blot, RT-PCR and Immunohistochemistry, for exploring the mechanism of cognitive impairment in epileptic rats,and paying more attention to the cognition improvement in memantine-treating rats to further explore the therapeutic mechanism.Methods: we establish chronic epileptic model inducing by pentylenetetrazol (PTZ) intraperitoneal injection. Adult male SD rats (7 to 8 weeks, weight200±20g) were selected through Y-Maze tests and then randomized into 3 groups. The 12 rats in the normal control group were injected Sodium Chloride intraperitoneally by 3.5 ml/kg for consecutive 30 days. The 18 rats in PTZ group and 18 ones in MN group respectively received intraperitoneal injection of PTZ by 35 mg/kg for consecutive 30 days. According to Racine criterion, if we observed three times successive seizures of gradeⅣor V ,the lighting in epileptic rats was successful. From the 31st day on, MN group rats (12 rats) was injected memantine intraperitoneally by 10 ml/kg 30 minutes before PTZ injection in the following continuous 14 days. From the 31st day on, PTZ group rats (12 rats) was injected Sodium Chloride intraperitoneally by 10 ml/kg 30 minutes before PTZ injection in the following continuous 14 days. From the 31st day on, NC group rats (12 rats) was injected Sodium Chloride intraperitoneally by 10 ml/kg 30 minutes before Sodium Chloride injection in the following continuous 14 days. The following day, all of the rats were tested with Morris water maze to assess the ability of the learning and memory. 4 rats in each group were anesthetized by 10% chloral hydrate and the hippocampuses were quickly separated. The expression of GSK-3βmRNA and GSK-3β,P-GSK-3βprotein in hippocampus was determined through the methods of RT-PCR, Western Blot, and Immunohistochemistry.Results: 1 Results of behavior: From sixth day to eighth day, rats in PTZ group and MN group began to stare,nod,wash their face and twitch face, and the symptom gradually became seriouser . Their forelimbs began to uplift and their bodies began to clonus. They experienced tonic clonic seizure at last. Accroding to Racine criterion, the numbers of the rats being kindled in PTZ group and MN group were 12 rats respectively. The kindled rats in MN group were injected memantine intraperitoneally by 10 ml/kg 30 minutes before PTZ injection in the following continuous 14 days. The Racine's stage greatly reduced after memantine injection in the NM group. No seizures were found in the normal group.2 Results of Morris water maze: Comparisons were made among the mean escape latencies on each day. First day, the escape latency in PTZ and NC groups were much longer than that in NC group (P<0.05). There was no significant difference between PTZ group and MN group (P>0.05). Second day, the results among NC, PTZ, MN group consisted with the first day. Third day, the escape latency in PTZ group was much longer than that in NC group (P<0.05), but MN group was much shorter than PTZ group (P<0.05). No significant difference was found between NC group and MN group (P>0.05). Fourth day, the results among NC, PTZ, MN groups consisted with the third day.3 Result of Western blot: The expression of P-GSK-3βprotein in PTZ group was decreased obviously compared to NC group (P<0.05). The P-GSK-3βprotein in hippocampus of the rats in MN group increased obviously compared with that in PTZ group (P<0.05). Comparisons of P-GSK-3βprotein between NC group and MN group were of no significant difference (P>0.05). The expression of GSK-3βprotein among NC, PTZ and MN groups were not different in significance (P>0.05).4 The expression of GSK-3βmRNA in the hippocampus of rats: The expression level of GSK-3βmRNA among NC, PTZ and MN groups was not different in significance (P>0.05).5 The change of GSK-3βin the CA3 area of hippocampus: The GSK-3βimmunohistochemical products were brown and most of them were in the endochylema of the neuron. Comparisons of neuron expressing GSK-3β-immunohistochemical products among NC, PTZ and MN groups were of no difference in significance (P>0.05).Conclusions: 1 The ability of learning and memory in PTZ-kindled chronic epilepsy rats was impaired. The expression level of P-GSK-3βprotein in the hippocampus of epilepsy rats was decreased; the GSK-3βprotein and GSK-3βmRNA had no change. The study suggested that GSK-3βmight participate in the mechanism of impaired cognition after epilepsy.2 Memantine could obviously improve the impaired cognitive function of epileptic rats and increased the expression level of P-GSK-3βprotein in the hippocampus, and had no influence on the expression of GSK-3βprotein and GSK-3βmRNA. Accordingly, Memantine could improve cognitive impairment of epileptic patients through the regulation of activity of GSK-3β.
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