酚酸改善小鼠神經母細胞瘤缺血性損傷之效果

Abstract

腦部若缺乏血液供應會造成神經細胞損傷並引起不同的疾病如：急性的中風或慢性的缺血性失智症。酚酸是天然植物中常見的抗氧化物質，莓果類的水果即富含許多不同的天然酚酸。許多文獻指出酚酸類物質可以幫助不同細胞對抗不同的逆境如I)氧化損傷 II)缺乏營養素III)高醣環境 等等。目前有關酚酸對抗缺血性神經細胞損傷的研究尚未被廣泛探討，本研究目的係探討常見水果中所含天然酚酸改善缺血性神經損傷的效果。 實驗先以小鼠神經瘤為細胞株 (neuro-2a)，培養於缺氧、缺葡萄糖的環境來摹仿真實情況下的動物腦缺血性損傷，並以MTT assay 來測定小鼠神經纖維母細胞瘤的存活率，評估9種天然酚酸改善小鼠神經纖維母細胞瘤缺血性損傷之效果。實驗的9種酚酸裡面以10 μM ρ-coumaric acid 和 1 μM Chlorogenic acid處理48小時相較於對照組，分別可以顯著提升14.97%和9.49%細胞存活率。許多文獻指出神經細胞在缺乏必須養分下可透過自噬作用走向死亡。本研究結果顯示10 μM ρ-coumaric acid 和1 μM Chlorogenic acid處理48小時後可以顯著改善小鼠神經纖維母細胞瘤自噬作用。文獻指出，細胞自噬作用跟細胞內鈣離子濃度有密切關係。本實驗結果發現，缺血性損傷之小鼠神經纖維母細胞瘤相較於正常細胞，其細胞內鈣離子濃度顯著性較低 (p<0.05)，而缺血性損傷小鼠神經纖維母細胞瘤以 10 μM ρ-coumaric acid和1 μM Chlorogenic acid處理48小時可以顯著提升胞內鈣離子濃度。由上述結果推測，苺果類果汁中含有的ρ-coumaric acid和 Chlorogenic acid可以提升細胞內鈣離子濃度，增加Calpain分泌，而達到減少神經細胞自噬作用，並改善缺血性失智之發展。

Cerebral ischemia, also known as Stroke, is a disease caused by the rapidly loss of blood supply to brain and which might affect intellectual function such as memory, language skills, perception, or cognitive skills including reasoning and judgment. Many studies have shown that a variety of phenols reduce brain damage on rats induced by brain ischemia and reperfusion. Therefore, the purpose of our study is to find some potential phenols to improve neuron damage in vitro. Oxygen glucose deprivation (OGD), a cell model approximating the conditions associated with cerebral ischemia in vivo, induces cell damage by reducing the supply of oxygen and glucose. The brain requires a continuous supply of oxygen and glucose to maintain normal function and viability. In our study, 10 μM ρ-coumaric acid could increase 14.97% of cell viability and 1 μM Chlorogenic acid increase 9.49% of cell viability after experiencing ischemia-like OGD damage. These two phenolic acids, 10 μM ρ-coumaric acid and 1 μM Chlorogenic acid, decrease 40.71% and 25.80% percentage of autophagy. 10 μM ρ-coumaric acid treatment also elevated 24.90% of intracellular calcium concentration and 1 μM Chlorogenic acid raised 88.65% of intracellular calcium concentration compared with OGD damage alone. We supposed that increase in cell viability of these two phenolic acids was through ameliorating autophagy, and the pathway they regular autophagy was elevating intracellular calcium concentration.