催产素对癫痫大鼠大脑皮质和海马热休克蛋白70表达的影响

Effect of oxytocin on the expression of heat shock protein 70 in cerebral cortex and hippocampus of rats with epilepsy

目的:探讨青霉素诱导大鼠癫痫发作中催产素对神经元代谢活动有关的持续性癫痫发作的标志-热休克蛋白70表达的影响。方法:实验于2005-02在武汉大学医学院生理实验室完成。取健康3月龄雄性SD大鼠18只,随机分为3组,即对照组、青霉素致痫组与催产素处理组,每组6只。青霉素致痫组腹腔注射青霉素30万U;催产素处理组腹腔注射催产素20μg,30min后再腹腔注射青霉素30万U;对照组腹腔注射等量的生理盐水。各组动物均于给药24h后用100g/L氨基甲酸乙酯(1g/kg)腹腔注射麻醉,断头取脑,切取冠状脑片。免疫组化方法观察青霉素诱导大鼠癫痫发作及催产素干预后大鼠大脑皮质和海马内热休克蛋白70的表达。每只动物脑切片标本抽取3张,每张切片随机选取5个高倍镜视野(SP×200),测定每个视野下阳性反应的吸光度。以每只动物脑切片标本15个视野的平均吸光度为该例的测量值。结果:18只大鼠均进入结果分析。①大鼠给予青霉素后10min左右出现不同程度的癫痫发作症状。表现为不动、凝视、蹲伏、湿狗样抖等。②对照组大脑皮质和海马神经元胞内偶见散在分布的棕黄色颗粒,热休克蛋白70表达弱;青霉素致痫组大脑皮质和海马神经元胞内出现密集的深棕黄色颗粒,热休克蛋白70表达呈强阳性;催产素处理组大脑皮质及海马神经元胞内出现密集的棕黄色颗粒,热休克蛋白70表达呈阳性,但表达量较见青霉素致痫组减少。③青霉素致痫组热休克蛋白70阳性神经元的平均吸光度明显高于对照组,差异有显著性意义眼(0.6652±0.0261),(0.1030±0.0040),t=-51.158,P<0.001演鸦催产素处理组降为(0.5692±0.0645),与青霉素致痫组比较差异有显著性意义(t=5.092,P<0.05)。结论:在癫痫发作过程中,预先用催产素可通过抑制热休克蛋白质70的合成而降低大脑皮质与海马热休克蛋白70的表达。

AIM： To investigate the effect of oxytocin （OT） on the expression of heat shock protein 7.0 （HSP70） as the marker of attack of continuous epilepsy correlated to neuronal metabolism in rats during epileptic seizures induced by penicillin （PNC）. METHODS： The experiment was conducted in the physiological laboratory of the Medical College of Wuhan University in February 2005. Totally 18 healthy male Spragne-Dawley rats were divided randomly into three groups with 6 rats in each group： control group, PNC treated group and OT pretreated group. The rats in the PNC treated group were injected intraperitoneally with PNC （3×10^5 U）; the rats in the OT p.retreated group were injected intraperitoneally with OT 20μg, and after 30 minutes, the PNC （3×10^5 U） was injected; the rats in the control group were given the same dose of saline solution. After 24 hours of administration,all the rats were anaesthetized with 100 g/L urathane （1 g/kg） and decapitated to take out the brains and make the coronary brain sections. method was used to observe the expression of HSP70 in cerebral cortex and hippocampus after epileptic seizures induced by PNC and intervention of OT. Three slices in each sample were selected and observed with 5 random high power fields （SP×200） to detect the absorbance （A） of positive reaction in each field, and the mean A value of 15 visual fields was regarded as the measured value of the sample. RESULTS： All 18 rats were involved in the result analysis. ①Different epileptic symptoms appeared about 10 minutes after the administration of PNC in rats, including resting, staring, squatting and shaking like wet-dog.②In the control group, scattered light brown granules appeared sometimes in cerebral cortex and hippocampal neurons and the expression of HSP70 was weak; in the PNC treated group, dense heavy brown granules appeared in the cerebral cortex and hippocampal neurons and there was a strong positive expression of HSP70; in the OT pretreated group, dense brown granules appeared in cerebral cortex and hippocampal neurons and the expression of HSP70 was positive, which was less than the PNC treated group. ③ The mean A value of HSP70 positive neurons was obviously higher in the PNC treated group than the control group, and the differences were significant [（0.665 2±0.026 1）, （0.103 0±0.004 0）,t=-51.158, P 〈 0.001]; the mean A value of the OT pretreated group decreased to 0.569 2±0.0645, and the differences between the OT pretreated group and the PNC treated group were significant（t=5.092, P 〈 0.05）. CONCLUSION： During epileptic seizures, the oxytocin can be used preliminarily to reduce the expression of HSP70 in cerebral cortex and hippocampus through the inhibition of synthesis of HSP70.