戊四氮致癫痫大鼠不同脑区神经肽Y和亮氨酸-脑啡肽的表达及其意义

目的神经肽Y（neuropeptide Y，NPY）和亮氨酸-脑啡肽（leu—enkephalin，L-ENK）在癫痫发生、发展和转归中有着重要作用，本研究在戊四氮（pentylenetetrazol，PTZ）致癫痫大鼠模型中观察神经肽Y和亮氨酸-脑啡肽在不同脑区中的变化趋势，探讨神经肽Y、亮氨酸-脑啡肽与癫痫的关系。方法将清洁级近交系雄性SD大鼠50只分为实验组（A组，n=40）和对照组（B组，n=10）。A组大鼠腹腔注射戊四氮1次，剂量为50mg／kg，B组腹腔注射同等容量生理盐水。A组大鼠腹腔注射戊四氮后，根据癫痫发作进行分级，0～1级（未发生惊厥）为7只（A1组，n=7），立即取脑处理；2级以上发作（大发作）为33只，随机于癫痫发作后立即取脑处理（A2组，n=10）及6h（A3组，n=11），24h（A4组，n=10），72h（A5组，n=2）取脑处理。B组于注射生理盐水后5min～10min内取脑处理。采用放射免疫方法动态观察A，B两组大鼠脑组织的海马、中脑、纹状体和额叶中神经肽Y、亮氨酸-脑啡肽的改变；S-P免疫组化染色法染色，观察A，B两组大鼠海马CAI区神经肽Y、亮氨酸-脑啡肽的表达。结果A1组大鼠中脑、纹状体及额叶的神经肽Y含量较B组升高（P〈0．05）。A，B两组海马CAI区神经肽Y含量比较，差异无显著意义（P〈0．05）。癫痫大发作组（A2，A3和A4组）以上各部位神经肽Y含量均明显高于B组；动态观察结果显示，癫痫发作后，在中脑、海马、纹状体和额叶的神经肽Y含量明显增高，随后呈逐步下降趋势，癫痫发作后24h，其含量与未发生惊厥的A1组神经肽Y含量比较，差异无显著意义（P〉0．05）。S-P免疫组化染色显示，癫痫大发作后，海马神经肽Y的表达明显增加，但随着时间的推移而降低。应用戊四氮后，癫痫大发作大鼠较未出现大发作的大鼠，其额叶、海马、中脑及纹状体中亮氨酸-脑啡肽含量均明湿升高，两组间比较，除中脑外，其余部位差异有显著意义（P％〈．05）；但大发作大鼠海马、中脑及纹状体亮氨酸-脑啡肽含量与B组比较，高于B组，但差异无显著意义（P〉0．05）。癫痫大发作后，各脑区亮氨酸-脑啡肽含量呈逐渐下降趋势。结论神经肽Y和亮氨酸-脑啡肽与癫痫的发生、发展有着密切关系。

Expression of the Neuropeptide Y and Leu-Enkephalin in the Brain of Pentylenetrazol-Induced Epileptic Rat Models

Objective To evaluate the significant changes of the neuropeptide Y （NPY） and leu-enkephalin（L-Enk） in the brain of pentylenetetrazol （PTZ）induced rats in order to understand the relationship among the neuropeptide Y,leu-enkephalin and epilepsy. Methods Fifty male adult SD rats were randomly divided into the experimental group （group A, n=40, intraperitoneal pentylenetetrazol injection 50 mg/kg） and the control group （group B ,n= 10, intraperitoneal tales doses normal saline injection）. According to the modification of seizure activity, the group A was divided into nomseizure group （group A1, n=7） which was decapitated immediately and the seizure group（group A2-A5,n=33）. Rats of the seizure group were decapitated immediately （group A2, n=10）, at the sixth hour（group A3, n=11）, at the 24th hour（group A4, n=10） and at the 72th hour（group A5, n=2） after the seizure. Radioimmunoassay （RIA） and immunocytochemical techniques were used to evaluate the changes of the neuropeptide Y and leu enkephalin in mesencephalon, hippocampus, striatum, and frontal cortex. Results The level of the neuropeptide Y increased significantly in mesencephalon（P〈0. 05）, frontal cortex（P〈0.05）, and striatum （P〈0.01） of the group A in contrast to those of the group B, and no difference was found in hippocampus. The level of the neuropeptide Y in brains of the seizure group（group A2 - A5, n = 33） was significant higher than that of the group B. The level of the neuropeptide Y returned to the value of the non-seizure group at the 24th hour after the seizure. Both groups had an elevated level of the leu-enkephalin in mesencephalon, striatum, hippocampus and frontal cortex. No difference was found between the non-convulsive group and the convulsive group in the four brain areas above, but the leu-enkephalin content of hypothalamus in the convulsive group was higher than that in the non-convulsive group. After the convulsion, the level of the leu--enkephalin decreased. Conclusion The increased level of the neuropeptide Y and leu-enkephalin may play an important role during the epilepsy.