臺灣博碩士論文加值系統

中文摘要
一、 本實驗以非洲大蝸牛 (Achatina fulica) 的中樞神經元為實驗材料，以一般藥理和電生理學的方法，探討serotonin (5-HT) 對蝸牛中樞神經元之作用及其可能的作用機制。
二、 在正常生理溶液灌流下，非洲大蝸牛食道下神經節(suboesophageal ganglion) 的RP7神經元會產生規則的自發性動作電位。
三、 5-HT (30 microM) 可引起RP7神經元產生動作電位猝發現象，此種猝發現象是可逆的，即以正常生理溶液洗去5-HT後，RP7神經元可恢復為未加入5-HT (30 mciroM) 前之規則自發性動作電位。但是5-HT (30 microM) 於相同蝸牛神經節的其他神經元，如：RP8、LP4，卻無法引起動作電位猝發現象，顯示5-HT (30 microM) 引起猝發現象的作用具有神經元選擇性。
四、 比較各種濃度的5-HT (1 microM, 3 microM, 10 microM, 30 microM, 100 microM, 300 microM) 對RP7神經元上的反應，給藥後20分鐘，1 microM、 3 microM、 10 microM的5-HT無法引起猝發現象；30 microM、 100 microM、300 microM 則可。
五、 5-HT (30 microM) 於RP7神經元引起猝發現象後，分別以hexamethonium (50 microM)、d-tubocurarine (100 microM)、atropine (1mM)灌流，猝發現象皆不被抑制，顯示5-HT (30 microM) 引起的猝發現象與ganglionic、nicotinic、muscarinic的cholinergic受體無關。
六、 5-HT (30 microM) 於RP7神經元引起猝發現象後，分別以prazosin (100 microM)、propranolol (100 microM)、haloperidol (260 microM)灌流，猝發現象皆不受抑制，顯示5-HT (30 microM) 引起的猝發現象與adrenergic 、dopaminergic受體無關。
七、 5-HT (30 microM) 於RP7神經元引起猝發現象後，分別以NAN-190 (50 microM)、ketanserin (100 microM)、mianserin (50 microM)、MDL-72222 (10 microM)灌流，猝發現象皆不被抑制，顯示5-HT (30 microM) 引起的猝發現象與5-HT1A、5-HT2、5-HT3受體無關。
八、 以高鎂 (30mM) 生理溶液灌流RP7神經元20分鐘後，再加入5-HT (30 microM) 可觀察到猝發現象的產生；若先以5-HT (30 microM)引起猝發現象後，再以含5-HT (30 microM) 的高鎂 (30mM) 生理溶液灌流20分鐘，猝發現象並未受到抑制。顯示5-HT (30 microM) 於RP7引起的猝發現象與突觸前需要鈣離子參與 (Ca2+-dependent)而釋放的神經傳遞物無關。
九、 以缺鉀生理溶液灌流RP7神經元20分鐘後，再加入5-HT (30 microM) 可觀察到猝發現象的產生；若先以5-HT (30 microM) 引起猝發現象後再以含5-HT (30 microM) 的缺鉀生理溶液灌流20分鐘後，猝發現象並未受到抑制。顯示：5-HT (30 microM) 於RP7神經元引起的猝發現象和胞外鉀離子無直接相關。
十、 以低鈣 (50%) 生理溶液灌流RP7神經元20分鐘後，再加入5-HT (30 microM) 可觀察到猝發現象的產生；若先以5-HT (30 microM) 引起猝發現象後再以含5-HT (30 microM) 的低鈣 (50%) 生理溶液灌流20分鐘後，猝發現象並未受到抑制。顯示：5-HT (30 microM) 於RP7神經元引起的猝發現象和胞外鈣離子無直接相關。
十一、 以低鈉 (50%) 生理溶液灌流RP7神經元20分鐘後，再加入5-HT (30 microM) 可觀察到猝發現象的產生；若先以5-HT (30 microM) 引起猝發現象後再以含5-HT (30 microM) 的低鈉 (50%) 生理溶液灌流20分鐘後，猝發現象並未受到抑制。顯示：5-HT (30 microM) 於RP7神經元引起的猝發現象和胞外鈉離子無直接相關。
十二、 以5-HT (10 microM) 作用於RP7神經元60分鐘後，仍無猝發現象，在5-HT (10 microM) 仍存在的情況下，若再加入forskolin (adenylate cyclase 活化劑，100 microM) ， 5~10分鐘後，猝發現象產生。顯示：forskolin (100 microM) 可促進5-HT (10 microM) 產生猝發現象。
十三、 Forskolin (100 microM) 單獨作用於RP7神經元時，即使經90分鐘仍無猝發現象產生，在forskolin (100 microM) 仍存在的情況下若再加入IBMX (isobutylmethylxanthine， phosphodiesterase 抑制劑， 500 microM)，約20~30分鐘後可觀察到類似由5-HT (30 microM) 引起的猝發現象。顯示：5-HT可能是經由cAMP於RP7引起猝發現象。
十四、 若先以2',5'-dideoxyadenosine (adenylate cyclase抑制劑) 作用於RP7神經元30分鐘後，再加入5-HT (30 microM)，即使經40分鐘後，仍無猝發現象。顯示：5-HT乃經由活化adenylate cyclase ，接著增加胞內cAMP濃度，此訊息傳遞路徑以於RP7神經元產生猝發現象。

Summary
The effects of serotonin (5-HT) were studied in the central neurons of the giant African snails ( Achatina fulica ) . 5-HT (30 microM) elicited bursting activity of action potentials in Achatina fulica central RP7 neuron but not RP8 and LP4 neurons .
The 5-HT-elicited bursting was not inhibited after continuous perfusion with hexamethonium (50 microM), d-tubocurarine (100 microM), atropine (1mM), prazosin (100 microM), propranolol (100 mciroM), haloperidol (260 microM), NAN-190 (50 microM), ketanserin (100 microM), mianserin (50 microM) and MDL-72222 (10 microM) . These results suggest that the bursting activity elicited by 5-HT was not due to the cholinergic, adrenergic, dopaminergic, 5-HT1A, 5-HT2 and 5-HT3 receptors of the excitable membrane.
Prior treatment with high Mg2+ (30mM), K+ -free, low Ca2+ (50%) and low Na+ (50%) solution didn't inhibit 5-HT to elicit bursting of action potentials in RP7. 5-HT-elicited bursting wasn't inhibited after continuous perfusion with high Mg2+ (30mM), K+-free, low Ca2+ (50%) and low Na+ (50%) solution. These results suggest that the bursting activity elicited by 5-HT may not directly involve in extracellular K+, Ca2+, Na+ and synaptic effects of neurotransmitters.
The 5-HT-elicted bursting activity was potentiated by forskolin (adenylate cyclase activator) and was mimicked by forskolin together with isobutylmethylxanthine (IBMX, phosphodiesterase inhibitor). The 5-HT-elicited bursting was suppressed by prior treatment with 2',5'-dideoxyadnosine ( adenylate cyclase inhibitor ). These results suggest that 5-HT may elicit bursting of action potentials through cAMP in RP7 neuron of Achatina fulica.
It's concluded that 5-HT may elicit bursting of action potentials through cAMP in RP7 neuron of Achatina fulica and that the 5-HT-elicited bursting of action potentials may not directly involve in extracellular K+, Ca2+, Na+ , synaptic effects of neurotransmitters, the cholinergic, adrenergic, dopaminergic, 5-HT1A, 5-HT2 and 5-HT3 receptors of the excitable membrane.

　　　　　　　　　　目錄
　　　　　　　　　　　　　　　　　　　　　頁次
英文摘要-----------------------------------------------------------1
中文摘要-----------------------------------------------------------3
緒論-----------------------------------------------------------------7
實驗方法及材料------------------------------------------------10
結果----------------------------------------------------------------13
討論----------------------------------------------------------------31
參考文獻---------------------------------------------------------40
圖表----------------------------------------------------------------51

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