Ghrelin对小鼠空间记忆和海马神经元突触及生长激素促分泌素受体表达的影响

目的 探讨Ghrelin对正常小鼠空间学习记忆能力和海马神经元突触及生长激素促分泌素受体（GHS-R）表达的影响。方法 8周龄小鼠 20只，随机分为实验组和对照组，分别腹腔注射Ghrelin和等量生理盐水，通过水迷宫实验检测小鼠的空间学习记忆能力，免疫组织化学实验检测海马Ghrelin受体GHS-R表达，并通过电子显微镜观察海马突触的超微结构变化。结果 水迷宫隐匿平台实验中，第2、3、4天，实验组小鼠的逃避潜伏期与对照组相比明显缩短（P <0.05），跨越平台次数明显增加(P <0.05），海马CA3和齿状回区GHS-R免疫阳性产物表达明显增强（P <0.05），神经元突触数量明显增加（P <0.05）。结论 Ghrelin可能通过结合GHS-R，增加海马神经元突触数量，显著改善小鼠的空间学习记忆能力。

Effects of Ghrelin on spatial memory, hippocampal neuron synapses and growth hormone secretagogue receptor expression in mice

Objective To investigate effects of Ghrelin on learning and memory processes, hippocampal neuron synapses and growth hormone secretagogue receptor (GHS-R) expression in mice. Methods Twenty male mice (8 weeks old) were randomly divided into the Ghrelin-treated and control groups (10 mice/group) in which Ghrelin or equal quantity saline was intraperitoneally injected, respectively. The ability of spatial learning and memory were tested with Morris water maze (MWM), expression of Ghrelin receptor GHS-R in hippocampus with immunohistochemical method and image analysis, and structural changes of synapsis in the hippocampal region by transmission electron microscope.Results In the MWM experiment, compared with the control group, the escape latency of the treated group on the day 2, 3 and 4, was significantly shortened, the times crossing hidden platform markedly increased (EM>P/EM> <0.05),expression of GHS-R immunoreactive products increased obviously in hippocampus (EM>P/EM> <0.05),and numbers of hippocampal neuron synapses in the CA3 region were also strikingly increased in the Ghrelin-injected group compared with the control group (EM>P/EM> <0.05).Conclusion Ghrelin may increase the synapse numbers of the hippocampal region, by binding the GHS-R in hippocampus, and subsequently enhance spatial learning and memory