Molecular mechanisms of an olfactory memory relevant to species survival

雌鼠对与之交配的雄鼠的信息素形成嗅觉记忆。这种嗅觉记忆具有重要的生物学意义，因为它可以防止任何随后暴露于该雄性信息素的神经内分泌机制，从而终止妊娠。来自陌生雄性的信息素（对它们还没有形成记忆）通过犁鼻器受体激活辅助嗅觉系统而引起嗅觉障碍。记忆的形成依赖于交配时的宫颈阴道刺激，但需要在交配后立即延长4至6小时的雄性信息素暴露。记忆的形成依赖于交配诱导的副嗅球（AOB）中去甲肾上腺素能末梢的激活，AOB是副嗅通路中的第一个中继。这种记忆在交配后至少持续30天。在AOB中，当被犁鼻神经输入激活时， ...更多信息 通过在树-树突触处释放谷氨酸使颗粒细胞变大。这种去极化从颗粒细胞释放γ-氨基丁酸，进而使二尖瓣细胞过度增殖。最近的研究表明，线粒体-颗粒树突突触参与了记忆的形成。本研究获得以下结果：1.外源性一氧化氮可诱导非交配条件下的信息素特异性嗅觉记忆，这种记忆至少部分是由去甲肾上腺素介导的。此外，内源性一氧化氮合酶活性的激活也会产生同样的效果。2.我们与Ichikawa、Mori和Matsuoka博士合作，证明了在已经形成记忆的组中，线粒体-颗粒不对称突触的大小明显大于没有形成记忆的组。3.我们以前已经证明了代谢型谷氨酸受体mGluR 2的激活，在AOB允许形成信息素特定的记忆。初步实验表明，缺乏mGluR 2的小鼠的嗅觉记忆受损。少

Female mice form an olfactory memory of the pheromones of the male with which they mate. This olfactory memory is of critical biological importance, because it prevents any subsequent exposure to this male's pheromones from initiating neuroendocrine mechanisms that would terminate pregnancy. Pheromones from strange males, for which no memory has been formed, induce pregnacy block by activating the accessory olfactory system by way of the vomeronasal receptors. Memory formation depends on cervicovaginal stimulation at mating, but requires a prolonged exposure of 4 to 6 h to male phernomones immediately after mating. The memory formation depends on mating-induced activation of noradrenergic terminals in the accessory olfactory bulb (AOB), the first relay in the accessory olfactory pathway. This memory lasts for at least 30 days following mating. The synaptic changes underlying this memory formation occur in the AOB.In the AOB,mitral cells, when activated by vomeronasal nerve inputs, depo … More larize granule cells by means of glutamate released at the dendrodendritic synapses. This depolarization releases gamma-aminobutyric acid from the granule cells which in turn hyperpolarize the mitral cells. Recent studies have implicated the mitral-to-granule dendrodendritic synapse in the formation of the memory. In this study we have obtained the following results.1.Exogenous administration of nitric oxide can induce a pheromone-specific olfactory memory without mating, and that this memory is mediated, at least in part, by noradrenaline. In addition, activation of endogenous nitric oxide synthase activity produces the same effect.2.In collaboration with Drs.Ichikawa, Mori and Matsuoka, we demonstrate that the size of the mitral-to-granule asymmetrical synapse is significantly larger in the group that has formed the memory than in the group that has not formed the memory.3.We have previously demonstrated that activation of mGluR2, a metabotropic glutamate receptor, in the AOB permits the formation of a pheromone-specific memory. Preliminary experiments suggest impairment of the olfactory memory in mice lacking mGluR2. Less