海马M_2受体调节杏仁核内谷氨酸的释放与学习记忆的研究

目的研究海马内M1和M2受体对学习记忆功能的影响及其可能机制。方法SD大鼠分为3组,分别海马内注射等体积的M1-ASODN(M1-AS组)、M2-ASODN(M2-AS组)和生理盐水(对照组),以被动逃避反应的步入潜伏期作为衡量学习记忆功能的指标,以CZE-LIFD法检测杏仁核内游离谷氨酸的浓度。结果M1-ASODN缩短步入潜伏期,为对照组的25%(P<0.01),M2-ASODN使步入潜伏期较对照组增加了75%(P<0.05)。双侧海马内注射ASODN后与对照组相比,M2-AS组杏仁核内谷氨酸的含量增加164%(P<0.01),而M1-AS组无变化(P>0.05)。结论海马内M受体参与恐惧性记忆的调节,M2受体抑制学习记忆,M1受体促进学习记忆。海马内M2受体可能通过调节杏仁核内谷氨酸含量的变化介导被动逃避反应的记忆过程。

M1 and M2 receptors in hippocampus and fear activated memory and the content of glutamate in amygdala

Aim To investigate the effects of M_1 and M_2 muscarinic receptors in the hippocampus on the latency of step-through inhibitory avoidance task and on the content of glutamate in amygdala.Methods Adult male SD rats were divided into three groups(the number of animals in each group is six).The animals were implanted with steel guide cannulae aimed at hippocampus.Bilateral infusions of M_1 and M_2 ASODN were given 16 hours prior to training and testing in a step-through inhibitory avoidance task.CZE-LIFD techniques were used to study the changes of the level of glutamate in amygdala during step-through inhibition avoidance task.Results Intrahippocampal injection of M_1 ASODN impaired retention of memory for inhibitory avoidance. Intrahippocampal injection of M_2 ASODN facilitated fear-activated memory and increased the content of glutamate in amygdala.Conclusion M_1 and M_2 muscarinic receptors in hippocampus modulate learning and memory.M_1 muscarinic receptor in hippocampus enhances the ability of learning and memory,and M_2 muscarinic receptor in hippocampus suppresses learning and memory.Suppressed M_2 mRNA in the ability of hippocampus enhances the releasing of glutamate in amygdala.