果蠅蕈狀體 (mushroom bodies) 是一成對的腦區, 各自由約2500 個
Kenyon cells 所組成, 而依據在蕈狀體中所構成的區域, Kenyon cells 可以細分成5 種類型, 分別稱為珈瑪 (γ KCs), 阿法’/貝塔’ (α’/β’ KCs), 前趨阿法/貝塔(pioneer α/β KCs), 早期阿法/貝塔 (early α/β KCs) 以及晚期阿法/貝塔Kenyon
cells (late α/β KCs), 然而尚未有研究指出這5 種細胞的數目.而目前已知在果蠅, 蕈狀體參與和嗅覺連結相關的學習記憶. 雖然已經證明短期記憶的提取需要Kenyon cells 向外的訊息傳遞, 但是Kenyon cells 釋放何種神經傳導物質依舊未可得知. 我們將綠色螢光蛋白 (GFP) 表現在各類型Kenyon cells 的細胞核並且結合新的計數方法, 判定Kenyon cells 共有約2700 顆, 其中有870 顆珈瑪細
胞, 420 顆阿法’/貝塔’細胞, 90 前趨阿法/貝塔細胞, 480 早期阿法/貝塔細胞以及860 晚期阿法/貝塔Kenyon cells. 我們亦使用了遺傳調控方法, 發現大多數的Kenyon cells 使用乙醯膽鹼 (acetylcholine) 作為神經傳導物質, 一小部分的則釋放珈瑪氨基丁酸 (γ-aminobutyric acid), 而某些則會同時使用兩種神經傳導物
質. 另外, 為了治療神經退化性疾病, 我們測試昆蟲20-羥基蛻皮激素(20-hydroxyecdysone) 是否能在果蠅成蟲增加Kenyon cells 的數量. 剛羽化的成蟲經過五天的餵食, 阿法’/貝塔’細胞數目大幅增加百分之20, 珈瑪細胞減少百分之10, 前趨阿法/貝塔和早期阿法/貝塔細胞數目則有些許的改變. 依據我們的實驗結果, 建立了一個可以有效分析細胞數目變異的研究模式, 並且提供具有發展潛力的藥物治療方法.

Mushroom bodies (MBs) formed via sequential birth of five classes of Kenyon cells (KCs) are essential for normal olfactory learning in Drosophila adults. Without knowing the type of neurotransmitter(s) released by KCs, MB outputs have been shown to be required for the retrieval of short-term memory. Here, using genetic reporters together with a total counting method, I determine how many KCs are cholinergic and how many are GABAergic in each of the five KC classes. Using nuclear localization green fluorescent protein (nls-GFP) as a reporter, I found that a MB has about 2700 KCs composed of roughly 870 γ neurons, 420 α’/β’
neurons, 90 pioneer α/β neurons, 480 early α/β neurons, and 860 late α/β neurons. I also found that most KCs are cholinergic while some KCs may be both cholinergic
and GABAergic. To ameliorate brain neurodegenerative diseases, I tested if the steroid hormone 20-hydroxyecdysone (20E) has a mitogenic effect on KCs in
Drosophila adults. After feeding 20E for 5 days, the total number of α’/β’ neurons increases nearly 20%, γ neurons decreases about 10% while the other three KC classes show slight changes. The implication of mitogenic manipulation of brain cells to ameliorate aging related memory loss and brain neurodegenerative diseases are discussed.

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