强制性运动通过激活健侧感觉运动皮层沉默突触改善脑缺血后患肢功能的机制研究

Constraint-induced movement therapy (CIMT) emphasizes intensive use of the affected limbs by restraining the unaffected extremities, aiming at overcoming learned non-use. As one of the important clinical treatments, it is widely applied to improve the motor function after stroke. However, the mechanism remains unclear. In our previous studies, we found that the CIMT can enhance neural plasticity of corticospinal tract obviously (using PRV retrograde nerve tracing), and activate some motor-related regions of unaffected hemisphere significantly(using micro-PET imaging). Considering related research at home and abroad, we propose a hypothesis that the mechanism of CIMT improving motor function recovery of the affected limbs lies in activating silent synapses in the unlesioned sensorimotor cortex after cerebral ischemia. To this end, the structure and function of the synapses will be clarified by observing the dendritic characteristics and measuring the content of excitatory neurotransmitters of the unlesioned sensorimotor cortex; then the number of silent synapses will be counted and the concentration of related proteins be determined in order to further understand the molecular mechanism of silent synapses activation; finally, a specific inhibitor which suppresses the activation process of silent synapses, will be stereotactically injected into the unlesioned sensorimotor cortex of the cerebral ischemic rats to reversely validate the role of silent synapses. In one word, this study will be helpful to further explore the mechanism of CIMT promoting functional recovery after cerebral ischemia.

强制性运动（CIMT）是临床上改善脑卒中后运动功能障碍的重要手段之一，它通过限制健肢活动、强化患肢使用，矫正患肢的“习得性废用”，从而促进运动功能的恢复，但其作用机制仍然不明确。我们前期研究发现CIMT可增强健侧皮质脊髓束的可塑性（逆行神经示踪），提高运动相关脑区的代谢水平（Micro-PET）。结合国内外相关研究，我们提出CIMT可能通过激活健侧感觉运动皮层AMPA受体缺失的沉默突触来改善脑缺血后患肢运动功能的假说。为此，我们拟观测健侧感觉运动皮层树突结构，测定兴奋性神经递质含量，以明确突触的结构和功能变化；测定沉默突触的数量和谷氨酸能相关受体及调节蛋白的含量，了解沉默突触的激活情况及其分子机制；最后通过立体定位技术注射一种可抑制沉默突触激活的抑制剂，反向验证沉默突触在脑缺血大鼠CIMT干预后健侧代偿中的作用；以期进一步探讨CIMT促进脑缺血后患肢功能恢复的作用机制。

在临床和动物研究中，强制性运动疗法(CIMT)已被证明是促进脑卒中后功能恢复的有效方法，但其潜在的神经可塑性机制尚不明确。越来越多的证据表明，卒中后康复与突触可塑性密切相关。因此，我们观察了CIMT对脑缺血大鼠同侧和对侧大脑突触可塑性的影响。首先，本研究通过高尔基染色发现，CIMT治疗增强了同侧和对侧感觉运动皮层树突和树突棘的可塑性，增加了同侧感觉运动皮层中突触GluR2的表达。我们进一步分离突触体及突触体膜，发现CIMT增加了同侧感觉运动皮层中含有谷氨酸受体(GluR)2的功能突触的数量，并减少了同侧感觉运动皮层和海马CA3区中不含GluR2 的AMPARs。同时，CIMT增强了同侧感觉运动皮层和海马突触后膜表面AMPAR的表达。因此，我们推测，CIMT通过增强缺血侧大脑AMPAR介导的突触传递，促进卒中后同侧上肢运动功能的恢复。此外，我们通过免疫电镜和高效液相色谱等方法，发现改良CIMT的治疗作用与突触后膜α-氨基-3-羟基-5-甲基-4-异恶唑-丙酸受体的表达上调、运动皮层内氨基酸类神经递质和5-HIVV水平的升高以及p-p70s6k表达降低有关。以上结果表明，CIMT通过调节双侧感觉运动皮层和海马突触的结构和功能促进脑缺血后运动功能恢复。