1. 本文實驗在12到16天大之新生大白鼠( Wistar rats )的中腦環導水管灰質區( Periaqueductal Gray, PAG )冠面活體 切片腹側區神經細胞，以blind patch whole cell recording技術闡明鍵結電流特性，並藉由觀察嗎啡呔類藥物拮 抗劑 naloxone在各種刺激條件下，對鍵結電流之影響，求證內生性嗎啡呔在PAG之生理功能。
2. 在kynurenic acid阻斷興奮性神經傳遞時，鍵前刺激可引發抑制性鍵結電流(inhibitory postsynaptic currents, IPSC) ，其反轉電位為-68 ± 3 mV，且可被bicuculline阻斷，故該IPSC為GABAA受體所媒介。
3. 將細胞膜電位固定在IPSC的反轉電位時，鍵前刺激會引發快的興奮性鍵結電流( fast excitatory postsynaptic currents, fEPSC )，其可被CNQX所阻斷，故此fEPSC為AMPA/kainate受體所媒介。
4. 在bicuculline和CNQX存在下，鍵前刺激會引發慢的興奮性鍵結電流( sEPSC )，其可被APV所阻斷，故此sEPSC 為NMDA受體所媒介。其電流對電壓的關係圖顯示，在接近靜止膜電位的極化電位時，會被生理濃度的鎂離 子所阻斷。
5. Naloxone對細胞靜止膜電位和低頻刺激引發的鍵結電流( postsynaptic currents, PSC )並無影響，但只對高頻連 續刺激( 10 Hz, 5 sec；30 Hz, 3 sec；50Hz, 1 sec )後PSC的振幅變化有顯著的影響。
6. 高頻連續刺激後，有36 %細胞PSC會增大，為post-train potentiation ( PTP )；38 %細胞的PSC會減小，為 post-train depression ( PTD )，其餘細胞的PSC則無變化。
7. 在EPSC產生PTP的細胞，其中64 %可被naloxone完全壓掉，可能因naloxone拮抗了嗎啡呔藉由抑制GABA細胞 而興奮glutamate細胞的作用。其餘的此類細胞，naloxone則僅減少PTP程度，但不影響其持續時間，此類細胞 可能除了嗎啡呔外，還有興奮性生呔參與興奮glutamate細胞。
8. 在IPSC產生PTP的細胞中，naloxone完全壓掉，可能因嗎啡呔抑制了平時即活化的GABA細胞對鍵前細胞的抑 制作用，即嗎啡呔對鍵前細胞產生disinhibition作用，而naloxone拮抗之。
9. 在EPSC產生PTD的細胞，其中69 %可被naloxone完全壓掉，可能因naloxone拮抗了嗎啡呔對glutamate細胞的抑 制作用。其餘的此類細胞，naloxone均使PTD反轉成PTP的現象，可能是因除了嗎啡呔外，還有興奮性生呔參 與興奮glutamate細胞所致。
10. 在IPSC產生PTD的細胞中，naloxone完全壓掉其PTD，可能因naloxone拮抗了嗎啡呔對GABA細胞的抑制作用 所致。
11. 在高頻連續刺激後EPSC不變的細胞中，naloxone使之產生PTP，可能因naloxone雖拮抗了嗎啡呔對glutamate 細胞的抑制作用，但同時又有興奮性生呔參與興奮glutamate細胞所致。
12. 在高頻連續刺激後IPSC不變的細胞中，naloxone使之產生PTD，可能是因naloxone雖拮抗了嗎啡呔對鍵前細 胞的disinhibition，但同時又有興奮性生呔可興奮平時便活化的GABA細胞所致。
13. 我們結論，鍵前刺激ventrolateral PAG可依序引發三種電位：可被CNQX抑制的fEPSP、可被bicuculline抑制的 IPSP和可被APV抑制的sEPSP。而高頻連續刺激的確可以激發出內生性嗎啡呔，其對神經傳遞的影響，則是 依該嗎啡呔細胞和glutamate或GABA細胞與記錄細胞間鍵結情況而定。在有些情況下，興奮性生呔也可能參 與調控。

1. We used the blind patch whole cell recording technique to characterize the synaptic transmission in ventrolateral PAG. We also tried to reveal the role of endogenous opioids at ventrolateral PAG slices from newborn rats by investigating the effect of naloxone on synaptic transmission evoked by train stimulations.
2. In the presence of kynurenic acid which blocks the excitatory synaptic transmission, focal stimulation evoked an inhibitory postsynaptic current ( IPSC ). The IPSC reversed at -68 ± 3 mV and was inhibited by bicuculline. The IPSC, therefore, is mediated by GABAA receptors.
3. While the cell membrane potential was clamped at the reversal potential of the IPSC, focal stimulation evoked a fast excitatory postsynaptic current ( fEPSC ), which was inhibited by CNQX. The fEPSC, therefore, is mediated by AMPA/kainate receptors.
4. In the presence of bicuculline and CNQX, focal stimulation evoked a slow EPSC ( sEPSC ), which was inhibited by APV. The sEPSC, therefore, is mediated by NMDA receptors. The I-V curve of sEPSC shows a voltage-dependent block by extracellular Mg2+.
5. Naloxone had no effect on resting membrane potential and postsynaptic currents ( PSC ) induced by basal stimulation (0.05 Hz). It, however, significantly affected the trend of PSC evoked by high frequency stimulations ( 10 Hz, 5 sec; 30 Hz, 3 sec; 50 Hz, 1 sec ).
6. After train stimulation, the PSCs became larger, termed post-train potentiation effect ( PTP ) in 36 % cells and in 38 % cells, became smaller, termed post-train depression effect ( PTD ). The PSCs in others did not change after train stimulation.
7. Among the cells showing PTP of EPSCs, naloxone abolished the PTP in 64 % cells. It suggests that naloxone antagonize the effect of opioid which activates the presynaptic glutamergic cell by inhibiting a GABAergic cell which inhibits the target cell presynaptically. In other cells, naloxone only decreased the degree of PTP. It suggests that in addition to opioids, an excitatory peptide was elicited during train stimulation and contributed to the regulation of the synaptic transmission.
8. Naloxone abolished all the PTP of IPSPs. It suggests that naloxone antagonized the effect of opioid which inhibits the tonically active GABAergic cell that inhibits the target cell presynaptically.
9. Among the cells showing PTD of EPSCs, naloxone abolished the PTD in 69 % cells. It suggests that naloxone antagonize the effect of opioid which inhibits the presynaptic glutamergic cell. In other cells, naloxone reversed PTD into PTP. It suggests that in addition to opioids, an excitatory peptide was also involved in the regulation of the synaptic transmission.
10. Naloxone abolished all the PTD of IPSCs. It suggests that naloxone antagonized the effect of opioid which inhibits the GABAergic cells.
11. In cells showing no change of the trend of post-train EPSCs, naloxone induced a PTP. It suggests that naloxone antagonized the inhibitory effect of opioid but spared the excitatory effect of the excitatory peptide on the presynaptic glutamergic cell.
12. In cells showing no change of the trend of post-train IPSCs, naloxone induced a PTD. It suggests that naloxone antagonized the inhibitory effect of opioid but spare the excitatory effect of the excitatory peptide on a tonically active GABAergic cell. The latter presynaptically inhibits the afferent GABAergic neuron.
13. In conclusion, a focal stimulation at ventrolateral PAG can induce a CNQX-sensitive fEPSP, followed by a bicuculline-sensitive IPSP and then an APV-sensitive sEPSP. After train stimulation, endogenous opioids can be evoked and participate in the regulation of synaptic transmission. Its effect on synaptic transmission depends on the synaptic connection of opioid cells with glutamergic or GABAergic cells. In some situations, the excitatory peptide neuron might participate in the regulation of the synaptic transmission.

英文摘要 ------------------------------------------------------------ 1
中文摘要 ------------------------------------------------------------ 5
第一章 緒論 ------------------------------------------------------ 8
第二章 實驗材料及方法 --------------------------------------- 12
第三章 實驗結果 ------------------------------------------------ 19
第四章 討論 ------------------------------------------------------ 32
圖表 ------------------------------------------------------------------ 41
參考文獻 ------------------------------------------------------------ 89

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