Cholinergic activation of the murine trachealis muscle via non-vesicular acetylcholine release involving low-affinity choline transporters
Cholinergic activation of the murine trachealis muscle via non-vesicular acetylcholine release involving low-affinity choline transporters
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DOI：
10.1016/j.intimp.2015.08.007
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发表时间：
2015-11-01
影响因子：
5.6
通讯作者：
Kummer, Wolfgang
中科院分区：
文献类型：
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作者：
Nassenstein, Christina;Wiegand, Silke;Kummer, Wolfgang
除了乙酰胆碱(ACh)的定量、囊泡性释放外，运动终板也有非量子释放，除非乙酰胆碱酯酶(AChE)被抑制，否则不足以引起突触后反应。我们在这里通过器官浴实验和(免疫)组织化学方法研究了小鼠气管中潜在的非量子释放。电场刺激神经末梢引起气管收缩，这主要是由于ACh的释放所致。经典的酶组织化学显示肌肉神经纤维中的乙酰胆碱酯酶(AChE)活性和平滑肌细胞中的丁酰胆碱酯酶(BChE)活性。艾司林对这两种酯酶的急性抑制显著提高了对阿托品完全敏感的气管张力。这种作用在AChE基因缺陷小鼠中有所减少，但并未被消除。伊司林引起的气管张力增加不受囊泡乙酰胆碱转运体抑制剂维沙米考(10(-5)M)和有机阳离子转运体抑制剂皮质酮(10(-4)M)的影响。在低浓度下，作为高亲和力胆碱转运体-1(CHT1)的抑制剂，当应用高浓度(10(-4)M)时，可完全消除艾司林效应，指向低亲和力胆碱转运体的参与。为探讨气管ACh非量子释放的细胞来源，采用RT-PCR方法检测了低亲和力胆碱转运蛋白样家族(CTL1-5)的表达。尽管这些转运蛋白在上皮中大量存在，但剥离呼吸道上皮细胞对Eserine诱导的气管收缩没有影响，表明非上皮源的ACh在呼吸道中非量子释放。这些数据为小鼠气管内非上皮非囊泡性、非量子ACh释放涉及低亲和力胆碱转运体提供了证据。(C)2015爱思唯尔B.V.保留所有权利。
In addition to quantal, vesicular release of acetylcholine (ACh), there is also non-quantal release at the motor endplate which is insufficient to evoke postsynaptic responses unless acetylcholinesterase (AChE) is inhibited. We here addressed potential non-quantal release in the mouse trachea by organ bath experiments and (immuno)histochemical methods. Electrical field stimulation (EFS) of nerve terminals elicited tracheal constriction that is largely due to ACh release. Classical enzyme histochemistry demonstrated acetylcholinesterase (AChE) activity in nerve fibers in the muscle and butyrylcholinesterase (BChE) activity in the smooth muscle cells. Acute inhibition of both esterases by eserine significantly raised tracheal tone which was fully sensitive to atropine. This effect was reduced, but not abolished, in AChE, but not in BChE gene-deficient mice. The eserine-induced increase in tracheal tone was unaffected by vesamicol (10(-5) M), an inhibitor of the vesicular acetylcholine transporter, and by corticosterone (10(-4) M), an inhibitor of organic cation transporters. Hemicholinium-3, in low concentrations an inhibitor of the high-affinity choline transporter-1 (CHT1), completely abrogated the eserine effects when applied in high concentrations (10(-4) M) pointing towards an involvement of low-affinity choline transporters. To evaluate the cellular sources of non-quantal ACh release in the trachea, expression of low-affinity choline transporter-like family (CTL1-5) was evaluated by RT-PCR analysis. Even though these transporters were largely abundant in the epithelium, denudation of airway epithelial cells had no effect on eserine-induced tracheal contraction, indicating a non-quantal release of ACh from non-epithelial sources in the airways. These data provide evidence for an epithelium-independent non-vesicular, non-quantal ACh release in the mouse trachea involving low-affinity choline transporters. (C) 2015 Elsevier B.V. All rights reserved.