老化對線蟲嗅覺神經的影響

Abstract

感覺纖毛是一種由微管構成的胞器，主要功能為偵測化學性或物理性的刺激。老化會造成感覺系統的功能喪失。我們先前發現，在線蟲中的一個感覺器官，amphid，其中具有纖毛的感覺神經在老化時會有結構上的變化，像是感溫神經AFD在老化時會產生微絨毛的減少以及纖毛的膨大，或是化學感覺神經ASI和ASE在老化時所產生的纖毛旁膜室的擴大。為了描述其他在amphid中的感覺神經在老化時的變化，我們以嗅覺神經AWB和AWC作為研究對象。我們觀察到老化時，AWB的纖毛會有局部膨大的現象，而AWC的纖毛則會有捲曲以及出現堆積物的現象。當我們在AWC嗅覺神經中表現TAX-2陽離子通道而使神經活化，發現可以減緩老化所造成的感覺纖毛的形態變化，這代表神經活性在老化時扮演著維持纖毛形狀的角色。總括來說，我們發現嗅覺神經纖毛在老化時有形狀上的改變，這種老化相關的纖毛形態變化，可作為神經老化的指標。

Sensory cilia, microtubule-based subcellular organelles, are involved in sensing chemical or mechanical stimuli. Dysfunction of the sensory system occurs during aging. Previously, we have described age-related morphological changes in amphid sensory cilia in C. elegans, such as reduced AFD ciliated endings and enlargement of periciliary membrane compartments of ASI and ASE neurons. To characterize the morphological changes of other amphid sensory neurons in C. elegans during aging, we studied the olfactory sensory neurons, AWB and AWC. We found focal enlargement of AWB cilia and curling of AWC cilia. Overexpression of TAX-2 cation channel, which activates the neurons, improves age-related AWC cilia defects, suggesting a role for neural activity in sensory cilia maintenance during aging. In summary, we found that olfactory sensory cilia showed morphological deterioration during aging, which may be one of the indicators of aging of the sensory neurons.