嘌呤能神经-平滑肌传递过程中血小板衍生生长因子受体α阳性细胞的作用

Role of platelet-derived growth factor receptor α positive cells in purinergic inhibitory nerve-smooth muscle transmission

在生理条件下,消化道的运动主要受肠神经系统(enteric nervous system, ENS)的调节。长期以来,神经系统如何将信息传递给平滑肌的机制尚不完全清楚,研究者们认为自主神经末梢在平滑肌层形成许多曲张体(varicosity),其中含有神经递质,当神经兴奋到达曲张体时,可以触发递质释放并直接扩散到平滑肌膜上,与相应受体结合引起平滑肌反应。近10年来,随着对消化道间质细胞的形态、分布特征及功能的研究进展,人们对神经信息向平滑肌传递的机制有了新的认识。目前认为,Cajal间质细胞(interstitial cell of Cajal, ICC)和血小板衍生生长因子受体α阳性(platelet-derived growth factor receptorαpositive, PDGFRα^+)细胞可通过缝隙连接与平滑肌细胞形成合胞体,介导神经与平滑肌之间的信息传递。其中,嘌呤能神经递质可与PDGFRα^+细胞上的P2Y1受体结合,激活小电导钙激活钾通道(small-conductance calcium-activated potassium channel,SK3),使PDGFRα^+细胞超极化,继而这种电活动通过PDGFRα^+细胞与平滑肌之间的电耦联传递给平滑肌,引起平滑肌的超极化和舒张。本文重点综述了近10年关于嘌呤能抑制性神经如何将信息传递给消化道平滑肌的理论演变过程。

Under physiological conditions,the motility of smooth muscle in digestive tract is mainly regulated by enteric nervous system(ENS).However,how neural signal is transmitted to smooth muscle is not fully understood.Autonomic nerve endings in the smooth muscle layer form large number of varicosities which contain neurotransmitters.It was considered that nerve pulses arriving at the varicosities may cause the release of neurotransmitters,which may diffuse to the smooth muscle cells to induce contractile or relaxant responses.Over the past decade,a new understanding of the neurotransmission between ENS and smooth muscle has emerged,which emphasizes the role of a functional syncytium consisting of the interstitial cells of Cajal(ICC),the platelet-derived growth factor receptorαpositive(PDGFRα^+)cells and the smooth muscle cells.Within the syncytium,purine neurotransmitters bind to P2Y1 receptors on PDGFRα^+cells,activating small-conductance calcium activated potassium channel(SK3)to hyperpolarize PDGFRα^+cells,and thus hyperpolarize smooth muscle cells through gap junction,resulting in relaxation of smooth muscle.In this paper,we review the research progress in the field of inhibitory purinergic neurotransmission in the gastrointestinal tract.