| 摘要: | 背景：葡萄糖為腦部主要能量來源，當葡萄糖缺乏時會造成 reactive oxygen species (ROS) 生成與粒線體功能異常，導致β-amyloid (Aβ) 產生，而酮體在缺乏葡萄糖時可作為腦部能量來源。自噬作用為細胞營養缺乏下分解有害蛋白並提供能量的保護機制，被認為可以減少Aβ並扮演保護神經的角色。酮體可降低Akt/mTOR signaling 促進自噬作用，支持電子傳遞鏈正常運作以減少 ROS 生成，刺激自噬體分解，加速 Autophagic flux 以避免自噬體堆積造成細胞死亡。目的：探討β-hydroxybutyrate (BHB) 是否可調節人類神經纖維瘤母細胞株 SH-SY5Y 細胞自噬作用以清除因葡萄糖缺乏而產生的Aβ並減少細胞死亡。材料方法：研究以 Retinoic acid (RA) 分化 SH-SY5Y細胞後，加入BHB於無葡萄糖培養基中培養 24 小時，檢測細胞存活率並觀察Akt/mTOR signaling、自噬作用相關蛋白及Aβ之表現。結果：葡萄糖缺乏下會降低p-Akt/Akt、p-mTOR/mTOR，提高LC3-II/LC3-I、Aβ含量並降低細胞存活率。在葡萄糖缺乏下介入不同濃度BHB與無葡萄糖組相比，p-Akt/Akt、p-mTOR/mTOR、LC3-II/LC3-I、Aβ及細胞存活率並不受影響，而在12 mM BHB介入下 p62 表現會提升。結論：BHB降低Akt/mTOR signaling及增加自噬體形成的影響可能與無葡萄糖組重疊，且由於SH-SY5Y細胞缺乏succinyl-CoA:3-ketoacid CoA transferase (SCOT) 使其無法利用酮體產能，造成自噬體堆積使p62上升、Aβ增加與細胞死亡。
Background：Glucose is the major energy substrate in brain. Glucose deprivation will cause the production of ROS and mitochondrial dysfunction, leading to generate Aβ. Ketone bodies can substitute for glucose. Autophagy can solve damage proteins and supply energy in nutrient depletion, and be thought to reduce Aβ and protect neurons. Ketone bodies can attenuate Akt/mTOR signaling to promote autophagy, support electron transfer chain to decrease ROS production, and stimulate autophagic flux to reduce cell death. Purpose：To investigate whether BHB can regulate SH-SY5Y cell autophagy to scavenge Aβ generated by glucose deprivation and reduce the cell death. Methods：After cell differentiation by RA, SH-SY5Y cells were treated with BHB for 24 hours, and then tested cell viability, Akt/mTOR signaling, autophagy related proteins and Aβ expression. Results：Glucose deprivation decreased p-Akt/Akt, p-mTOR/mTOR and cell viability, and increased LC3-II/LC3-I and Aβ. Compared to glucose free group, the groups treated with different concentration of BHB shows no difference in p-Akt/Akt, p-mTOR/mTOR, LC3-II/LC3-I, Aβ and cell viability, but increased p62 in 12 mM BHB group. Conclusion：BHB might has the same condition of glucose deprivation decreasing Akt/mTOR signaling and increasing autophagosome. Due to the absence of SCOT, SH-SY5Y cells are blocked ketone bodies utilization, causing increase of autophagosome, p62, Aβ and cell death |
