Long-Term Diabetic Microenvironment Augments the Decay Rate of Capsaicin-Induced Currents in Mouse Dorsal Root Ganglion Neurons
Long-Term Diabetic Microenvironment Augments the Decay Rate of Capsaicin-Induced Currents in Mouse Dorsal Root Ganglion Neurons
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DOI：
10.3390/molecules24040775
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发表时间：
2019-02-02
期刊：
影响因子：
4.6
通讯作者：
Obukhov, Alexander G.
中科院分区：
文献类型：
--
作者：
Chen, Xingjuan;Duan, Yaqian;Obukhov, Alexander G.
患有终末期糖尿病周围神经病变的个体会出现疼痛感下降。瞬时受体电位香草酸 1 型 (TRPV1) 与疼痛信号传导有关，存在于感觉背根神经节 (DRG) 神经元上。我们使用免疫组织化学、活单细胞钙成像和全细胞膜片钳电生理学研究了糖尿病 9 个月时 Ins2(+/Akita) 小鼠 DRG 神经元中 TRPV1 的表达和功能活性。 2,7-二氯二氢荧光素二乙酸酯 (DCFH-DA) 荧光测定用于测定 DRG 中活性氧 (ROS) 的水平。尽管与对照组相比，糖尿病 9 个月时 Ins2(+/Akita) DRG 中表达 TRPV1 的神经元百分比有所增加，但在孤立的 Ins2(+/Akita) DRG 神经元中辣椒素诱导的 Ca2+ 流入较小，表明 TRPV1 功能受损。一致地，在 25 mM 葡萄糖存在下培养 7 天的对照 DRG 神经元中，与用 5.5 mM 葡萄糖培养的对照 DRG 神经元相比，辣椒素诱导的 Ca2+ 流入减少。高葡萄糖环境增加了培养的 DRG 神经元中细胞质 ROS 的积累。膜片钳记录显示，与对照神经元相比，孤立的 Ins2(+/Akita) DRG 神经元中辣椒素激活的电流衰减得更快。我们提出，在控制不佳的糖尿病中，DRG 神经元中辣椒素敏感的 TRPV1 电流衰减速度加快，降低了总体 TRPV1 活性，并导致周围神经病变。
Individuals with end-stage diabetic peripheral neuropathy present with decreased pain sensation. Transient receptor potential vanilloid type 1 (TRPV1) is implicated in pain signaling and resides on sensory dorsal root ganglion (DRG) neurons. We investigated the expression and functional activity of TRPV1 in DRG neurons of the Ins2(+/Akita) mouse at 9 months of diabetes using immunohistochemistry, live single cell calcium imaging, and whole-cell patch-clamp electrophysiology. 2,7-Dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence assay was used to determine the level of Reactive Oxygen Species (ROS) in DRGs. Although TRPV1 expressing neuron percentage was increased in Ins2(+/Akita) DRGs at 9 months of diabetes compared to control, capsaicin-induced Ca2+ influx was smaller in isolated Ins2(+/Akita) DRG neurons, indicating impaired TRPV1 function. Consistently, capsaicin-induced Ca2+ influx was decreased in control DRG neurons cultured in the presence of 25 mM glucose for seven days versus those cultured with 5.5 mM glucose. The high glucose environment increased cytoplasmic ROS accumulation in cultured DRG neurons. Patch-clamp recordings revealed that capsaicin-activated currents decayed faster in isolated Ins2(+/Akita) DRG neurons as compared to those in control neurons. We propose that in poorly controlled diabetes, the accelerated rate of capsaicin-sensitive TRPV1 current decay in DRG neurons decreases overall TRPV1 activity and contributes to peripheral neuropathy.