Cerebral hippocampal neuronal apoptosis following kainic acid-induced epilepsy and the intervention of antagonists of dopamine D1 and D2 receptors / 中国组织工程研究

ABSTRACT

BACKGROUND: Dopamine is closely associated with occurrence of epilepsy and transmission in central nerval system, and its various functions are determined by specific receptors.OBJECTIVE: To establish temporal epilepsy model so as to probe into the influences of SCH23390, the antagonist of dopamine D1 receptors and haloperidol, the antagonist of dopamine D2 receptors injected in substantia nigra on temporal epileptic seizure induced by kainic acid and on electroencephalic activityDESIGN: Randomized controlled verified experiment.SETTING: Neurology Medicine Institute of Zhujiang Hospital Affiliated to Southern Medical University.MATERIALS The experiment was performed in General Military Neurology Medicine Institute of Zhujiang Hospital Affiliated to First Military University of Chinese PLA from August to December 2004, in which, 30SD adult male rats were employed, massed varied from 250 to 300 g.METHODS: ① 30 rats were randomized into physiological saline (control) group (6 rats), kainic acid (KA) group (6 rats) and experimental group (18 rats). The experimental group was divided into 3 subgroups, named the antagonist of dopamine D1 receptors, SCH23390 + kainic acid group (D1 +KA group), the antagonist of dopamine D2 receptors,haloperidol + kainic acid group (D2+KA group) and physiological saline + kainic acid group (PS + KA group), 6 rats in each. In the control, physi ological saline 2 μL was injected in the right cerebral ventricle unilaterally. In KA group, kainic acid 2 μL was injected in the right ventricle. In each of experimental group, SCH23390, the antagonist of dopamine D1 re ceptors, haloperidol, the antagonist of dopamine D2 receptors and physio logical saline 1 μL for each was injected in substantia nigra on the right side successively and simultaneously, kainic acid 2 μL was injected in the right ventricle. ② Observed items alters of EEG on the 0.5th 1st, 2nd, 6th and 24th hours after medication in each experimental group (compared with EEG of non-epileptic behavior, appearance of sharp wave, spike wave,sharp (spike) slow comprehensive wave and multi-spike slow wave determines epileptic activity) and changes in animal behaviors (0 grade normal; Ⅰ grade wet dog-like trembling, paroxysmal facial spasm, like winking,beard moving, rhythmic chawing; Ⅱ grade rhythmic nodding; Ⅲ gradeparoxysmal spasm of anterior limbs; Ⅳ grade paroxysmal spasm of bilateral anterior limbs when standing; Ⅴ grade falling down, loss of balance and convulsion of four limbs). Cerebral hippocampal neural cell apoptosis was observed and the rats were sacrificed on the 5' day of medication. Cerebral hippocampal section was prepared and determined after in situ end labeling staining.MAIN OUTCOME MEAUSRES ① Changes in behavior in rats before and after epilepsy and electroencephalogram (EEG) alters. ② Results of cerebra hippocampal neural cell apoptosis.RESULTS: Thirty rats entered result analysis. ① Epilepsy seizure In the control group, there was no epilepsy attacked. In KA group, all of rats ap pear seizure, which attacked 10 minutes after KA injected in brain ventricle, reached the peak in 1 hour and stopped in 3 to 6 hours. ② EEG record In the control group, there was not epileptic activity manifestations,like sharp wave, spike wave, spike slow comprehensive wave, etc. In KA group, epileptic wave presented in 10 minutes after injection, the seizure developed to the peak in about 1 hour, the wave amplitude was decreased in 3 to 6 hours, presenting paroxysmal slow and spike slow waves and no epileptic wave appeared after 12 hours. ③ Neuronal apoptosis In the control group, few neural cell apoptosis was visible in hippocampus after injection.In KA group, neural cell apoptosis was visible obviously in hippocampus in 5 days after injection (P =0.00). With SCH23390, the antagonist of dopamine D1 receptors, hippocampal cell apoptosis was not reduced remarkably (P ＞0.05) and with haloperidol, the antagonist of dopamine D2 receptors injected in substantia nigra, hippocampal cell apoptosis was aggravated (P =0.00).CONCLUSION: Injection of SCH23390, the antagonist of dopamine D1 receptors in substantia nigra cannot block kainic acid inducing epilepsy and epileptic electroencephalic activity is not weakened remarkably. Injection of haloperidol,the antagonist of dopamine D2 receptors enhances epileptic electroencephalic activity in kainic acid induced epilepsy and increases cell apoptosis remarkably in cerebral hippocampal CA3 area.It is to explain that it is dopamine D2 acceptor that is involved in regulation of temporal epilepsy in substantia nigra rather than D1 acceptor.