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標題: | 探討腦部二十二碳六烯酸在維生素A缺乏下對發育大鼠齒狀迴顆粒狀細胞成長之影響 Effects of brain docosahexaenoic acid on neuronal maturation in developing dentate granule cells in vitamin A-deficient rats |
作者: | Kun Han 韓琨 |
指導教授: | 蘇慧敏 |
關鍵字: | 二十二碳六烯酸,維生素A,齒狀迴顆粒狀細胞, docosahexaenoic acid,vitamin A,dentate granule cell, |
出版年 : | 2013 |
學位: | 碩士 |
摘要: | 二十二碳六烯酸 (docosahexaenoic acid, DHA) 與維生素A均為必需營養素,皆在大腦發育及維持神經正常生理功能中扮演重要的角色。DHA主要是在大腦發育時期 (胚胎期與泌乳期) 快速在大腦累積。另有文獻指出DHA亦為維生素A受體的配體之一,可藉之促進神經的生長。本論文探討大鼠大腦發育時期海馬迴DHA的變化及海馬迴中齒狀迴顆粒狀細胞 (dentate granule cells) 形態改變,並探討DHA含量的不同或維生素A缺乏是否會影響其細胞成長及DHA是否可恢復維生素A缺乏對其形態之影響。於母鼠懷孕與泌乳期間,餵食含玉米油之正常飼料或維生素A缺乏之飼料以及補充富含DHA之魚油,並於其子代出生後第零天 (P0)、第七天 (P7)、第十四天 (P14) 以及第二十一天 (P21) 犧牲,以氣相層析儀分析海馬迴脂肪酸成分,Golgi-Cox染色法觀察齒狀迴顆粒狀細胞之形態。結果發現大鼠大腦發育時期腦中DHA含量隨出生天數增加而上升,齒狀迴顆粒狀細胞之樹突總長度、分岔點的數量、末端點的數量、分節的數量、樹突分枝層級、分節數量皆隨出生天數增加而上升,但唯獨維生素A缺乏組在P21時上升的趨勢漸緩。母鼠補充魚油可增加子代在大腦發育時期海馬迴DHA含量,也顯著增加P7和P14大鼠齒狀迴顆粒狀細胞樹突總長度。齒狀迴顆粒狀細胞樹突棘與蘑菇形樹突棘之密度樹突總長度、末端點的數量、分節的數量在餵食維生素A缺乏組較正常組於P21時顯著下降,而魚油補充可恢復其生長。推測DHA可增進並恢復維生素A缺乏對於發育大鼠齒狀迴顆粒狀細胞成長之影響。 Brain docosahexaenoic acid (DHA, 22:6n-3) accumulates rapidly during brain development and is essential for normal neurological function. Vitamin A including retinoid and their derivatives has similar effects to n-3 fatty acids on neurological function. DHA is one of ligands of retinoic receptors which signaling is essential for neurite outgrowth. The aim of this study was to examine the changes of DHA levels and morphology of dentate granule cells during the brain development and the effect of brain DHA levels on neuronal maturation. We also evaluated the effects of vitamin A deficiency on maturation of dentate granule cells and whether it could be recovered by DHA. Rats were exposed to corn oil-based n-3 fatty acid-control or vitamin A-deficient diets or the two diets supplemented with DHA-enriched fish oil from in utero via maternal intake. The pups were sacrificed at the age of 0, 7, 14 and 21 days old. The fatty acid composition in hippocampus and morphology of dentate granule cells were analyzed by gas chromatography and Golgi-Cox staining, respectively. Levels of DHA in brain regions were increased gradually from age of 0 to 21 days old. The morphology of dentate granule cells including total dendritic length, highest order, number of bifurcation nodes, number of terminal endings, and number of segments were increased from 0- to 21-day-old. The DHA levels were significantly higher in rats exposed to fish oil supplementation and DHA enhanced the total dendritic length of dentate granule cells in rats at age of 7-14 day old exposed to control or vitamin A-deficient diets. The total spine density, mushroom type spine density, total dendritic length, highest order, number of bifurcation nodes, number of terminal endings, and number of segments were significantly decreased in 21-day-old rats exposed to vitamin A-deficient diet and the effects was recovered back with fish oil supplementation. This study suggests that DHA and vitamin A are important for the maturation of dentate granule cells and DHA may play a role in retinoid signaling in neuronal development. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/62924 |
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