鈣離子感知接受器在嗅覺誘發腎臟血液動力學變化與剛性勃起以及血管內皮上促進血小板依附作用的雙重角色

Abstract

鈣離子感知接受器在身體內多種器官中扮演鈣離子濃度與特定多元胺濃度的感知功能。本研究論文首重於確立鈣離子感知接受器在嗅覺粘膜上與血管內皮中的表現，並以此為基礎探求其後續誘發之生理反應。 透過組織免疫化學染色、免疫螢光呈色與西方墨點法，確立了鈣離子感知接受器確實會表現於嗅覺感覺神經元的纖毛與鞭毛上。透過鼻腔共染細胞內鈣離子螢光指示劑後，於嗅球上觀測到嗅神經在受到鈣離子感知接受器活化後出現顯著鈣離子內流的去極化現象。由此可知，大鼠嗅覺感覺神經元上的鈣離子感知接受器的活化會形成嗅覺衝動。 在鈣離子感知接受器的活化劑與抑制劑的交叉比對實驗中，嗅覺神經上的鈣離子感知接受器的活化，會造成血壓上升、心跳變慢、腎交感神經活性強化與腎臟血流充盈度下降的現象。透過動態對比增強的腎臟核磁共振影像，本研究更發現鼻腔內鈣離子感知接受器的活化會導致腎過濾率的下降。與腎神經阻斷術的老鼠相比較後可以確定，腎臟的血流充盈度與腎過濾率的下降，皆為腎交感神經的活化所導致。 鈣離子感知接受器會受到精胺的刺激所活化，同時精胺為構成精液氣味的主要的多元胺，因此嗅神經上鈣離子感知接受器的活化，極有可能會造成公大鼠的性功能展現差異。透過陰部神經活性與陰莖海綿體內壓的紀錄，嗅神經上鈣離子感知接受器的活化會透過增強陰部神經的活動造成大鼠在低強度的電刺激勃起下會出現剛性勃起。 鈣離子本身過去一直被認為是促進凝血機制的重要一環，故本研究認為血管內皮上的鈣離子感知接受器或許與凝血機制有關聯。與過去的研究相符，血管內皮細胞具有鈣離子感知接受器的表現。透過離體的大鼠主動脈的測試可以發現到，血管內皮細胞的鈣離子感知接受器的活化會增強血小板對血管壁的依附性。進一步，我們在兩種腎臟疾病大鼠與人類冠狀動脈內皮初代細胞實驗中發現，血液中的血管加壓素II會增加血管內皮的鈣離子感知接受器，並使得血管內皮容易釋放出溫韋伯氏凝血因子並誘發血栓形成與動脈狹窄的問題。 本研究證實鈣離子感知接受器在嗅神經與血管內皮上為功能性的表現。嗅覺上的鈣離子感知接受器的活化會強化全身性交感神經系統的活性並導致腎臟血液動力學的改變同時也會誘發公大鼠會出現剛性勃起。在血管內皮上的鈣離子感知接受器的活化會導致內皮釋放出溫韋伯氏凝血因子促進血小板對於血管壁的依附作用。本研究的結果證實了鈣離子感知接受器於嗅覺與凝血功能上的重要性。Calcium-sensing receptor is the calcium and polyamine detecting receptor expressed in multiple organs. In this research, we first focused on the expression of calcium-sensing receptor on olfactory epithelium and vascular endothelium. Based on this finding, we explored for the following physiological responses after the activation of calcium-sensing receptors. After immunohistochemistry, immunofluorescence and western blotting, we confirm the expression of calcium-sensing receptor on the cilia and flagella of olfactory sensory neuron. Nose-loading with calcium detecting dye, we observed the depolarization of olfactory sensory neuron after intranasal exposure with the agonists of calcium-sensing receptor. Therefore, the activation of calcium-sensing receptors on olfactory sensory neurons would forming olfactory stimulation in rats. Furthermore, the activation of olfactory calcium-sensing receptor would cause the increase of blood pressure and renal sympathetic nervous activities, the decrease of heart rate and renal blood flow. Through dynamic contrast-enhanced magnetic resonance renography, we further found that the activation of olfactory calcium-sensing receptor would decrease the renal filtration rate. Comparing with the data of renal denervated rats, we confirmed that the decrease of renal blood flow and renal filtration was caused via the increase of renal sympathetic nervous activities. Calcium-sensing receptor is activated by spermine which is the main polyamine contributing the favor of semen. Therefore, the activation of olfactory calcium-sensing receptor might relate with the modulation of sexual expression in male rats. Via the recording of pudendal sympathetic nervous activities and intracavernous pressure, the activation of olfactory calcium-sensing receptor would cause the rigid erection in cavernous nervous low-voltage electrical stimulation induced erection through the increase of pudendal sympathetic nervous activities. Since calcium is one main factor of coagulation, we consider the connection between coagulation and the calcium-sensing receptor on the vascular endothelium. Matched with past research, calcium-sensing receptor expressed on the vascular endothelium. In rat aorta in vitro experiment, we found the activation of endothelial calcium-sensing receptor would enhance the platelet adhesion. Furthermore, the increase of serum angiotensin II would increase the expression of calcium-sensing receptor and make the vascular endothelium easier to release von Willebrand factor to cause the thrombosis and arterial stenosis in two renal disease rat models and human coronary arterial endothelial primary cell experiment. In this research, we confirm the expression of calcium-sensing receptor on olfactory sensory neuron and vascular endothelium. The activation of olfactory calcium-sensing receptor would activate the global sympathetic nervous system to impair the renal hemodynamics and induce the rigid erection in cavernous nervous low-voltage electrical stimulation. The activation of endothelial calcium-sensing receptor would cause the release of von Willebrand factor from vascular endothelium and enhance the platelet adhesion. The results in this study confirm the importance of calcium-sensing receptor on olfaction and coagulation.