癫痫持续状态大鼠模型的GABAA受体亚单位α1的mRNA表达及[^3H]Flunitrazepam受体配体结合的变化

GABAA α1 subunit mRNA expression and ［3H］ F1 unitrazepam binding in status epilepticus rat model

目的 :本实验研究大鼠癫痫持续状态动物模型的海马等部位 GABAA受体α1亚单位基因表达和受体一配体结合的变化。方法 :成年雄性大鼠经腹腔内注射 32 0～ 34 0± 5 .87毫克 /公斤毛果芸香碱 (Pilocarpine)以制成癫痫持续状态动物模型 ,能在癫痫持续状态 (定义为在皮质脑电图上显示痫性放电的至少 40分钟的持续性痫性发作 )下存活的大鼠在 1小时和 2小时后处于死 ,分别研究 GABA受体基因表达和放射结合位点 ,用原位杂交方法来测定脑部 m RNA水平 ,用 [3H]flunirazepam标记 GABAA 受体 benzodiazepam结合位点。结果 :动物痫性发作 2小时后海马的 CA1和CA3区域 GABAA受体 α1亚单位 m RNA显著下降 ,但是齿状回的 α1m RNA没有变化。 [3H]flunirazepam标记受体 -配体放射结合在持续 2小时持续痫性发作后可见海马的 CA1及 CA3和齿状回中均见下降 ,1小时的持续痫性发作尚未引起海马区域的任何α1m RNA或 [3H]flunirazepam受体 -配体放射结合的任何改变 ,并用结晶染色 1及 2小时后的大脑海马部位。结论 :本研究结果提示大鼠的癫痫持续状态可诱发海马区 GABAA 受体 α1基因表达的改变和 [3H]flinirazepam受体 -配体结合的下降 。

Objective:In the present study, we determind whether status epilepticus or prolonged limbic seizures (induced by pilocarpine) altered GABA A receptor α1 subunit gene expression in the hippocampus. Methods: Status epilepticus was induced in male adult rats by a single i.p. injection of pilocarpine (320~340mg/kg). Rats that survived status epilepticus (definded as continous seizure activity in the EcoG for at least 40min) for 1h and 2h were sacrificed for G4BA A receptor gene expression and binding assay. In situ hybridization was used to measure regional mRNA levels, and [ 3H] flunitrazepam was used to label the benzodiazepine binding sites. Results: We found 2h after the onset of seizure, GABA A receptor α1 mRNA decresed significantly in the CA1 and CA3 fileds of hippocampus. No significant change in α1 mRNA was observed in the dentate gyrus. However, [ 3H] flunitrazepam binding decreased uniformly in CA1, CA3 and dentate gyrus 2h after status epileptius. 1h of continuous seizures did not produce any significant change in either α1 mRNA or [ 3H] flunitrazepam binding in any of the hippoceampal regions studied. Cresyl violet stained brain hippocampus areas 1h or 2h after the seizure onset. Conclusion: These results suggest that status epilepticus induced decreased GABA A receptor α1 gene expression and [ 3H] flunitrazepam biding in the hippocampus. The above changes make the brain more susceptibale for the development of chronic epilepsy.