内嗅皮层γ-氨基丁酸能神经元活动对大鼠感觉运动门控及主动回避学习记忆的影响

Effect of the GABAergic neuron activity of entorhinal cortex on sensorimotor gating and active avoidance learning in rats

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 GABAergic neuron activity of entorhinal cortex in rats on sensorimotor gating and active avoidance learning. Methods： Bilaterally implanted guide cannulae into the medial entorhinal cortex（ MEC） or lateral entorhinal cortex（ LEC）,the rats were infused with GABAAreceptor agonist muscimol（ 1 μg/μL,0. 5 μL per hemisphere） or saline. The behavioral tests were conducted 30 min after infusion. Results： After muscimol infusion,compared with the saline infused control group,the rats in MEC group showed hyperactivity in the open filed test,more entries into the open and closed arm in the elevated plus-maze test and disruption of the prepulse inhibition at intensity of 73 d B,as well as the deficiency of learning and memory in the two-way active avoidance task. Conclusion： The entorhinal cortical neuronal activity,especial the medial entorhinal cortex area,plays important roles in the spontaneous activity,anxiety,sensorimotor gating,as well as the two-way active avoidance learning and memory of rats.