Rat Merkel Cells Are Mechanoreceptors and Osmoreceptors
Rat Merkel Cells Are Mechanoreceptors and Osmoreceptors
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DOI：
10.1371/journal.pone.0007759
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发表时间：
2009-11-09
期刊：
影响因子：
3.7
通讯作者：
Misery, Laurent
中科院分区：
文献类型：
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作者：
Boulais, Nicholas;Pennec, Jean-Pierre;Misery, Laurent
与神经末梢相关的Merkel细胞（MCs）构成MC-neurite复合物，参与缓慢适应的I型机械感受。虽然已知MCs表达电压门控Ca（2+）通道，并且已知低张力诱导的膜变形可导致Ca（2+）瞬态，但MCs是否启动机械转导目前尚不清楚。为了回答这个问题，用报告载体转染大鼠MCs，使其能够被识别。通过电生理研究研究了它们的性质。如前所述，确定了电压门控K(+), Ca（2+）和Ca（2+）激活的K(+) （K(Ca)）通道。在这里，我们也报道了组胺激活Ca（2+）通道和乙酰胆碱抑制Ca（2+）通道。作为一个主要发现，我们证明了直接机械刺激在MCs中诱导强烈的内向Ca（2+）电流。去极化取决于刺激的强度和长度。此外，拉伸通道拮抗剂钆可以抑制触摸诱发电流。这些数据证实了MCs的机械转导能力。此外，我们发现fm1 -43标记的MCs中渗透受体TRPV4的激活会引起神经分泌颗粒胞外分泌。由于FM1-43阻断了机械感觉通道，这表明低渗透压在没有机械传导的情况下激活了MCs。因此，机械转导和渗透接受可能是不同的途径。
Merkel cells (MCs) associated with nerve terminals constitute MC-neurite complexes, which are involved in slowly-adapting type I mechanoreception. Although MCs are known to express voltage-gated Ca(2+) channels and hypotonic-induced membrane deformation is known to lead to Ca(2+) transients, whether MCs initiate mechanotransduction is currently unknown. To answer to this question, rat MCs were transfected with a reporter vector, which enabled their identification. Their properties were investigated through electrophysiological studies. Voltage-gated K(+), Ca(2+) and Ca(2+)-activated K(+) (K(Ca)) channels were identified, as previously described. Here, we also report the activation of Ca(2+) channels by histamine and their inhibition by acetylcholine. As a major finding, we demonstrated that direct mechanical stimulations induced strong inward Ca(2+) currents in MCs. Depolarizations were dependent on the strength and the length of the stimulation. Moreover, touch-evoked currents were inhibited by the stretch channel antagonist gadolinium. These data confirm the mechanotransduction capabilities of MCs. Furthermore, we found that activation of the osmoreceptor TRPV4 in FM1-43-labeled MCs provoked neurosecretory granule exocytosis. Since FM1-43 blocks mechanosensory channels, this suggests that hypo-osmolarity activates MCs in the absence of mechanotransduction. Thus, mechanotransduction and osmoreception are likely distinct pathways.