Transient Receptor Potential Channels TRPM4 and TRPC3 Critically Contribute to Respiratory Motor Pattern Formation but not Rhythmogenesis in Rodent Brainstem Circuits.
Transient Receptor Potential Channels TRPM4 and TRPC3 Critically Contribute to Respiratory Motor Pattern Formation but not Rhythmogenesis in Rodent Brainstem Circuits.
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DOI：
10.1523/eneuro.0332-17.2018
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发表时间：
2018-01
期刊：
影响因子：
3.4
通讯作者：
Smith JC
中科院分区：
文献类型：
--
作者：
Koizumi H;John TT;Chia JX;Tariq MF;Phillips RS;Mosher B;Chen Y;Thompson R;Zhang R;Koshiya N;Smith JC
瞬时受体电位通道（TRPM 4）是Ca 2+激活的非选择性阳离子电流（ICAN）的分子底物，被认为是产生前BötC复合体（pre-BötC）吸气神经元爆发活动的关键因素。另一个TRP通道TRPC 3介导Na+/Ca 2+通量，可能参与调节Ca 2+相关信号，包括影响呼吸前BötC神经元中的TRPM 4/ICAN。然而，TRPM 4和TRPC 3在前BötC吸气神经元中的表达以及这些通道的功能作用仍有待确定。通过单细胞多重RT-PCR，我们显示了这些通道的mRNA表达在前BötC吸气神经元的节奏活跃的延髓在体外切片从新生大鼠和小鼠。功能的贡献进行了分析与TRPM 4或TRPC 3的药理学抑制剂在体外，以及在成熟的啮齿动物动脉灌注原位脑干脊髓制剂。还将呼吸回路活动的扰动与ICAN阻断剂的扰动进行了比较。药理学衰减内源性激活TRPM 4，TRPC 3，或ICAN在体外类似地降低了吸气运动神经元活动的幅度，而没有显著的扰动吸气频率或变异的节奏。振幅扰动与减少吸气mamatergic前BötC神经元的活动，在体外监测多细胞动态钙成像。在更完整的电路在原位，前BötC和运动神经元吸气活动幅度的减少伴随着减少吸气后运动神经元的活动，没有中断的节奏产生。我们的结论是，内源性激活TRPM 4，这可能介导ICAN，和TRPC 3通道在前BötC吸气神经元呼吸模式的形成中发挥重要作用，但不是关键参与呼吸节律的产生。
Transient receptor potential channel, TRPM4, the putative molecular substrate for Ca2+-activated nonselective cation current (ICAN), is hypothesized to generate bursting activity of pre-Bötzinger complex (pre-BötC) inspiratory neurons and critically contribute to respiratory rhythmogenesis. Another TRP channel, TRPC3, which mediates Na+/Ca2+ fluxes, may be involved in regulating Ca2+-related signaling, including affecting TRPM4/ICAN in respiratory pre-BötC neurons. However, TRPM4 and TRPC3 expression in pre-BötC inspiratory neurons and functional roles of these channels remain to be determined. By single-cell multiplex RT-PCR, we show mRNA expression for these channels in pre-BötC inspiratory neurons in rhythmically active medullary in vitro slices from neonatal rats and mice. Functional contributions were analyzed with pharmacological inhibitors of TRPM4 or TRPC3 in vitro as well as in mature rodent arterially perfused in situ brainstem–spinal cord preparations. Perturbations of respiratory circuit activity were also compared with those by a blocker of ICAN. Pharmacologically attenuating endogenous activation of TRPM4, TRPC3, or ICAN in vitro similarly reduced the amplitude of inspiratory motoneuronal activity without significant perturbations of inspiratory frequency or variability of the rhythm. Amplitude perturbations were correlated with reduced inspiratory glutamatergic pre-BötC neuronal activity, monitored by multicellular dynamic calcium imaging in vitro. In more intact circuits in situ, the reduction of pre-BötC and motoneuronal inspiratory activity amplitude was accompanied by reduced post-inspiratory motoneuronal activity, without disruption of rhythm generation. We conclude that endogenously activated TRPM4, which likely mediates ICAN, and TRPC3 channels in pre-BötC inspiratory neurons play fundamental roles in respiratory pattern formation but are not critically involved in respiratory rhythm generation.