| Abstract: | 組織型 (tissue-type) 及尿激素型胞漿素原活化劑 (urokinase type plasminogen activator；tPA and uPA) 參與纖維蛋白溶解系統 (fibrinolysis system)，在細胞外基質 (extracellular matrix) 中將未活化態的胞漿素原 (plasminogen) 催化成具有活性的胞漿素 (plasmin)。近數十年來的研究發現，胞漿素原活化劑在神經系統中扮演了重要的角色，如：組織重組 (tissue remodling)、神經元贅生 (neurite outgrowth)、突觸可塑性 (synaptic plasticity) 及記憶形成 (memory formation)，特別是絲胺酸型蛋白 (serine type protease) 與突觸可塑性有很大的關聯性，而組織型及尿激素型胞漿素原活化劑皆是一種相當典型的絲胺酸型蛋白。在先前的研究中證實，胞漿素原活化劑參與了許多型態的突觸可塑性，如：長期增益效應 (long-term potentiation；LTP) 及windup。而另一種windup-like是藉由反覆低頻刺激骨盆神經 (pelvic never) 所誘發的，稱之為骨盆神經－尿道反射 (pelvic nerve-to-urethral reflex；PUR reflex)，並且被證實為麩胺酸系依賴型 (glutamatergic- dependent) 的神經可塑性，但截至目前的研究並沒有直接的證據可以說明胞漿素原活化劑在骨盆神經－尿道反射迴路上的角色。所以本篇研究的目的為要觀察胞漿素原活化劑對此塑性增益現象的影響及其調控的機制。本篇實驗發現可以藉由電刺激骨盆傳入神經引發骨盆神經－外尿道括約肌反射的塑性增益現象 (測試性及反覆性電刺激分別為1.1 ± 0.1及15.3 ± 0.6 spikes/ stimulation, P<0.01,n=30)，而自椎管注入胞漿素原活化劑及其抑制劑可以改變此塑性增益現象 (RS+ tPA及RS+ tPA-STOP分別為30.1 ± 0.9及5.6 ± 0.1 spikes/ stimulation ,P<0.01, n=7)，並且在胞漿素原活化劑之抑制劑減弱塑性增益現象之後，可以透過注入胞漿素原活化劑將該現象部分回復 (RS+ tPA-STOP及RS+ tPA-STOP+ tPA分別為5.6 ± 0.1及12.2 ± 0.9 spikes/ stimulation,P<0.01,n=7)，而被胞漿素原活化劑之抑制劑所減弱的塑性增益現象同時也可以被麩胺酸系接受器之致效劑部分回復(RS+ tPA-STOP、RS+ tPA-STOP+ NMDA 及RS+ tPA-STOP+ Glu分別為5.6 ± 0.1、25.7 ± 0.3及30.1 ± 1.0 spikes/ stimulation, P< 0.01,n=7)。接下來分別藉由麩胺酸系接受器之抑制劑將塑性增益現象減弱之後，利用蛋白激A (protein kinase A；PKA) 之活化劑將此現象部分回復(RS+ CNQX、RS+ APV及RS+ CNQX+ PKAA、RS+ APV+ PKAA分別為3.3 ± 0.3、1.1 ± 0.9及11.7 ± 0.4、10.0 ± 0.5 spikes/ stimulation,P< 0.01,n=7)，由以上的實驗可以證實，胞漿素原活化劑藉由影響骨盆神經－尿道反射迴路上麩胺酸系接受器的效力，來調控藉由反覆性刺激骨盆傳入神經引發之骨盆神經－外尿道括約肌反射的塑性增益現象，而此調控的角色也許會透過PKA的路徑來促進，但確卻的調控機制需要更進一步實驗來釐清。而胞漿素原活化劑在臨床上是否具有治療尿路動力學上的價值，仍需更多的研究。
Tissue type- and urokinase type plasminogen activator (tPA and uPA) involved in the regulation of fibrinolysis system that catalyse plasminogen to active plasmin in the extracellular matrix. In the last decades,it has been found that PAs play pivotal roles in the nervous system have been suggested,such as tissue remodling, neurite outgrowth, synaptic plasticity and memory formation. Some of serine type protease are involved in the synaptic plasticity,and tPA and uPA are typical serine protease. In the present study,it evidence the PAs play key roles in multiple form of synaptic plasticity as long-term potentiation (LTP) and windup. And another phenomenon is windup-like by repetitive low frequency electrical stimulation,that is named the pelvic nerve-to-urethra reflex (PUR). Be verified it is neuronal plasticity of glutamatergic -dependent that facilitation the potentiation of glutamatergic-NMDA and AMPA receptor through activation cascade of glutamate. The current research so far ,to be short of direct evidence to explain that the role of plasminogen activator in PUR. The aim of this study was to investigated the role of plasminogen activator in the pelvic-to-urethra reflex (PUR) plasticity induced by repetitive stimulation (RS),and mechanism of modulation. These findings suggest that PUR plasticity induced by RS the pelvis afferent nerve (1.1 ± 0.1 and 15.3 ± 0.6 spikes/ stimulation in TS and RS groups, respectively,P<0.01,n=30). Intrathecal injection of tPA and tPA- STOP facilitation (30.1 ± 0.9 spikes/ stimulation, P<0.01,n=7) and attenuated (5.6 ± 0.1 spikes/ stimulation, P<0.01,n=7) RS-induced PUR plasticity,respectively. This attenuated of RS-induced PUR plasticity by tPA-STOP (5.6 ± 0.1 and 12.2 ± 0.9 spikes/ stimulation,P<0.01,n=7) could reverse after treatment tPA (12.2 ± 0.9 spikes/ stimulation, P<0.01, n=7)、NMDA (25.7 ± 0.3 及 30.1 ± 1.0 spikes/ stimulation, P< 0.01,n=7) and Glu (30.1 ± 1.0 spikes/ stimulation, P< 0.01,n=7),respectively. On the other hand,intrathecal CNQX and APV elicited attenuated and abolished on RS-induced reflex plasticity,respectively (3.3 ± 0.3、 1.1 ± 0.9 spikes/ stimulation,P< 0.01,n=7). This influence of RS-induced PUR plasticity by CNQX and APV (5.6 ± 0.1 and 12.2 ± 0.9 spikes/ stimulation, P<0.01, n=7) could reverse after treatment PKA activator (11.7 ± 0.4 and 10.0 ± 0.5 spikes/ stimulation,P< 0.01,n=7),respectively. These findings indicate that plasminogen activator influence RS-induced PUR plasticity via to modulated glutamatergic-receptor efficacy. Then, modulating RS-induced PUR plasticity. The role of modulation may be enhanced via PKA signaling pathway,but the definite mechanism of the modulator to needed clear by more study. The further,whether the PAs has therapeutical value of urinary dynamics on clinical, demand to more reliable evidence. |
