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目的:探究内嗅皮层神经元功能活动对大鼠感觉运动门控及学习记忆的影响。方法:采用健康清洁级成年雄性SD大鼠,通过手术分别对大鼠脑的内嗅皮层内侧(medial entorhinal cortex,MEC)区域、内嗅皮层外侧(lateral entorhinal cortex,LEC)区域双侧埋入导管,手术恢复后,双侧微注射γ-氨基丁酸能神经元受体α激动剂蝇蕈醇;对照组微注射生理盐水。微注射30 min后进行旷场实验,高架十字迷宫实验,惊反射前脉冲抑制实验以及主动回避实验,观察内嗅皮层神经元功能活动被暂时性抑制后大鼠行为学的改变。结果:旷场实验结果显示,大鼠微注射蝇蕈醇后,MEC组大鼠自发性活动显著高于对照组(P<0.05);高架十字迷宫测试结果显示,微注射蝇蕈醇后,MEC组大鼠进入开放臂频率显著高于对照组(P<0.05);前脉冲抑制测试结果显示,微注射蝇蕈醇后,当声音刺激强度为73 d B时,MEC组大鼠的前脉冲抑制显著低于对照组(P<0.05);双向主动回避测试结果显示,微注射蝇蕈醇后,MEC组大鼠的条件反射潜伏期显著高于对照组(P<0.05)。结论:抑制MEC区域的神经元功能活动将影响大鼠的自发性活动、焦虑度、感觉运动门控以及主动回避学习记忆能力。
OBJECTIVE: To investigate the effect of functional activities of entorhinal cortical neurons on sensory gating and learning and memory in rats. Methods: Adult male Sprague-Dawley (SD) rats of healthy and clean grade were used to surgically implant the catheters on both sides of medial entorhinal cortex (MEC) and lateral entorhinal cortex (LEC) After surgery, the bilateral microinjection of γ-aminobutyric acid neuron receptor α agonist, muscimol, was given. The control group was injected with physiological saline. After 30 min of microinjection, open field test, elevated plus maze test, shock suppression before pulse suppression test and active avoidance test were performed to observe the change of behavioral changes in rats after functional inhibition of entorhinal cortex neurons was temporarily inhibited. Results: The open-field test results showed that the spontaneous activity of rats in MEC group was significantly higher than that of control group (P <0.05) after microinjection of muscimol into the rats. The results of elevated plus-maze test showed that after MEC The frequency of rats entering the open arms was significantly higher than that of the control group (P <0.05). The results of pre-pulse inhibition test showed that the pre-pulse inhibition of MEC rats was significantly inhibited when the intensity of sound stimulation was 73 d B after microinjection of muscimol (P <0.05). The bidirectional active avoidance test showed that the conditioned reflex latency of MEC group was significantly higher than that of the control group (P <0.05) after the administration of muscimol. CONCLUSIONS: Inhibition of neuronal functional activity in the MEC region will affect spontaneous activity, anxiety, sensory motor gating, and active learning-and-memory abilities in rats.