皮层-丘脑轴起源肌阵挛动物模型的建立

Establishment of animal model of myocionus originating from axis of cortex-thalamus

目的创建在发生机制、发作行为、神经电生理及药效学特性与临床更趋一致的肌阵挛系列实验动物模型。方法γ-氨基丁酸（GABA）．受体拮抗剂SR95531在sD大鼠初级运动皮层（PMC）、纹状体和丘脑网状核（NRT）定点微量注射诱发肌阵挛（同步肌电图暴发活动~〈400ms），观察肌阵挛发作潜伏期、达峰时间、最大发作频率、高峰持续时间和总持续时间等行为学特征。以多导电生理同步记录肌阵挛发作期脑电图、肌电图及抽动逆向锁定的脑电叠加分析（JLA），以论证及认定肌阵挛起源。选择对控制肌阵挛具不同效力的丙戊酸、氯硝西泮和卡马西平等抗癫痫药（AED），按达到半数有效浓度（EC50）剂量预处理动物后，根据各自药效学择时诱导肌阵挛发作，观测AED预处理后肌阵挛发作行为与电生理学变化特征。结果（1）PMC区起源肌阵挛具有最短诱导潜伏期、最短达峰时间和最长高峰持续时间[（2．2±0．4）min、（15．0±2．5）min和（98±12）min，均P〈0．01]。PMC和纹状体区肌阵挛主要起始于注射对侧前肢，而NRT区起源肌阵挛起始于注射同侧肢体。（2）PMC起源肌阵挛发作期肌电图时程（70±14）ms，纹状体区起源者[（120±28）InS]远较PMC起源者长（P〈0．01），NRT肌阵挛肌电暴发时程达（174±58）ms，与前两者比较差异均有统计学意义（均P〈0．01），发作中三者均伴有与肌电图同步的脑电图棘、尖波放电。（3）经JLA分析，3种起源肌阵挛均获得具锁时关系的脑电图叠加波，分别在各自肌电图前（12．1±2．9）、（17．1±4．3）和（29．0±6．1）ms。（4）在一次性EC50下给药后，丙戊酸组和氯硝西泮组PMC、纹状体和NRT起源肌阵挛的最大发作频率均明显少于对照组（P〈0．01或P〈0．05），PMC和纹状体起源肌阵挛的高峰持续时间和总持续时间明显短于对照。卡马西平组PMC、纹状体及NRT各起源点肌阵挛发作的高峰持续时间和总持续时间均长于对照组（P〈0．01或P〈0．05），PMC、NRT起源肌阵挛的达峰时间均短，同步测试PMC、纹状体、NRT起源肌阵挛肌电图暴发时程均显著延长（均P〈0．01）。结论沿皮层丘脑轴的PMC、纹状体、NRT等部位成功获取一组在发作行为、神经电生理及药效学诸多特性均与临床不同起源肌阵挛相接近的系列动物模型。

Objective To develop a series of experimental animal models of myoclonus with different origins consistent with myoclonus seizure in clinic setting. Methods GABAA antagonist SR95531 was microinjected into the primary motor cortex （PMC）, corpus striatum, nucleus reticular of the thalamus （NRT） to induce myoclonus （EMG burst of myochmus ≤400 ms）. The behavior characteristics including latency, peak time, duration of seizure peak, maximal seizure frequency and total duration were observed. EMGs and ictal EEGs were recorded synchronously. The origin of myoclonus and its correlation with epileptic discharges were further confirmed by jerk-locked back averaging （JLA）. A group of rats were pretreated with VPA, CZP and CBZ at the doses corresponding to their ECs0. Myoclonus was induced at the time when the drug level was within their effective anticonvulsion concentration. The changes of behaviors and neuroelectrophysiological characteristics of myoclonus after pretreatment of AEDs were observed. Results （1） The myoclonus originating from PMC had the shortest latency and time to reach its peak as well as the longest duration of peak duration [ （ 2. 2 ±0. 4 ） , （ 15.0 ± 2. 5 ）, （ 98 ± 12 ） min ]. The myoclonus originating from PMC and corpus striatum usually started from forelimb contralateral to injection. On the contrary, the myoclonus arising from NRT affected mainly the limb ipsilateral to the microinjection. （2） The EMG burst duration of myoclonus was（70 ± 14） ms （PMC） , （ 120 ± 28 ） ms （ corpus striatum） and （ 174± 58 ） ms （NRT） respectively （ F = 9. 48, P 〈 0. 01 ）. All of them were accompanied with synchronic and regular spike or sharp discharges in EEG. （3） All the myoclonus originating from PMC, corpus striatum and NRT acquired time-locked cortical waves in average were ahead of their synchronous EMG（ 12. 1 ± 2. 9）ms, （ 17.1 ± 4.3 ） ms and （29. 0 ± 6. 1 ） ms respectively. （4） Under EC50 concentration of those AEDs ： VPA and CZP decreased the maximal seizure frequency of myoclonus originating from PMC, corpus striatum and NRT respectively（ P 〈 0. 01 or P 〈 0. 05 ） ;the duration of peak time and the total time of myoclonus arising from PMC and corpus striatum were shortened notably, but there was no significant influence of NRT upon myoclonus. The duration of peak time and total time of myoclonus seizures were remarkably extended by CBZ （ P 〈 0. 01 or P 〈 0. 05 ）. Conclusion A series of experimental myoclonus models of different origins are successfully established. They are consistent with the mechanism, behavior, neuroelectrophysiological and pharmacodynamic characteristics of clinic myoclonus.