- 學位論文
探討雄性費洛蒙對成年雌鼠副嗅球內之神經元新生的影響
The effects of male pheromones on adult neurogenesis in the accessory olfactory bulb of female mice
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摘要
目前已知在成年哺乳類動物大腦內有神經幹細胞存在。其中一處位於側腦室旁的側腦室下區（subventricular zone）。此處的神經幹細胞分化為神經母細胞後會往嗅球遷移，並分化成中間神經元（interneuron）。此過程稱為神經元新生，並由細胞增生、遷移、分化及細胞存活四個過程所組成。嗅球按其結構可以分成主嗅球與副嗅球兩大部分，分別掌管環境中氣味因子及費洛蒙的訊息傳遞。根據日前研究顯示，雄性小鼠的費洛蒙可以刺激雌鼠副嗅球內的神經元新生，而且也會對懷孕的雌鼠造成布魯斯效應（Bruce effect）¬－懷孕早期的雌鼠暴露於非交配雄鼠的費洛蒙氣味下，所造成的流產情形。雖然目前已知費洛蒙會對神經元新生造成影響，但對於它們是否會影響新細胞的增生、分化或存活則還不清楚。此外，目前也還不清楚是否雌鼠副嗅球內的神經元新生對於費洛蒙記憶形成的重要性。因此，本實驗主要想探討雄性費洛蒙對於雌鼠副嗅球內之神經元新生所造成的影響。根據實驗結果，我們發現雄性費洛蒙可以促進側腦室下區的細胞增生及副嗅球內新細胞的存活，但對於副嗅球內的神經元分化則沒有影響。當有費洛蒙記憶的雌鼠暴露於含有另一雄性費洛蒙環境下時，會降低副嗅球內新細胞的存活率。而此由費洛蒙誘導之神經元新生，可能需經由正腎上腺素調控。由以上結果可知，雄性費洛蒙對雌鼠副嗅球內之神經元新生具有相當重要的角色。
並列摘要
It has been known that stem cells exist in two areas of adult mammalian brains. One of these is the subventricular zone along the lateral ventricle. These stem cells give rise to neuroblasts and differentiate into olfactory bulb interneurons which play important roles in odor discrimination. This process is called neurogenesis and is composed by four aspects: proliferation, migration, differentiation and survival. The olfactory bulb consists of two functionally distinct parts, the main olfactory bulb (MOB) and the accessory olfactory bulb (AOB), which detect environmental odorants and pheromones, respectively. Previous studies have shown that male pheromones could stimulate neurogensis in the female AOB. Also, it could cause Bruce effect, the male-induced pregnancy block when the pregnant female is exposed to pheromones of a new male. Although the roles of pheromones in adult neurogenesis are emerging, whether they affect cell proliferation, neuronal differentiation or survival remain elusive. It is also unclear whether adult neurogenesis in the AOB is required for the formation of pheromonal memory in female mice. Therefore, the aim of this work is to study the effects of male pheromones on different aspects of AOB neurogenesis in female mice. We found that male pheromones could promote cell proliferation in SVZ and new cell survival but not neuronal differentiation of newborn cells in AOB. Moreover, survival of newborn cells was decreased when females were exposed to pheromones from a second male. Also, pheromone-induced AOB neurogenesis may be regulated by norepinephrine. In conclusion, male pheromones play important roles in adult AOB neurogenesis of female mice.
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