辣椒素对背根神经节神经元钙离子浓度和线粒体膜电位的影响

目的探讨辣椒素对体外原代培养的胎鼠背根神经节（dorsal root ganglion，DRG）神经元钙离子浓度（［Ca²⁺］_i）和线粒体膜电位（mitochondiral membrane potential，MMP）的影响作用。方法分散培养的胎鼠DRG神经元用不同浓度的辣椒素（0.001μmol/L, 0.01μmol/L, 0.1μmol/L, 1μmol/L, 10μmol/L）孵育1min，用共聚焦激光扫描显微镜检测神经元［［Ca²⁺］_i的改变。对于能引起［Ca²⁺］_i升高的浓度组，在辣椒素孵育1min时，用流式细胞术检测神经元MMP的变化；并且在移去辣椒素后10min，重新检测神经元［Ca²⁺］_i的变化。结果0.001μmol/L、0.01μmol/L辣椒素孵育1min，神经元胞内［［Ca²⁺］_i没有变化；0.1μmol/L、1μmol/L和10μmol/L辣椒素孵育1min，神经元胞内［Ca²⁺］_i升高，移去辣椒素后10min，0.1μmol/L、1μmol/L辣椒素孵育的DRG神经元胞内［Ca²⁺］_i恢复到基础水平，10μmol/L辣椒素孵育的标本升高的［Ca²⁺］_i没有明显改变。辣椒素孵育时用无钙溶液，则神经元胞内［Ca²⁺］_i不升高。10?μmol/L辣椒素孵育1min的DRG神经元MMP降低，0.1μmol/L和1μmol/L辣椒素孵育的标本MMP无明显变化。结论一定浓度的辣椒素可使原代培养的DRG神经元胞内［Ca²⁺］_i升高，MMP降低。低浓度辣椒素引起的［Ca²⁺］_i的升高在10min内可以恢复到基础水平，而高浓度辣椒素引起的［Ca²⁺］_i的升高在10min内则不能恢复。辣椒素所致的胞内［Ca²⁺］_i升高可能是由于胞外钙离子内流引起的。

Effects of capsaicin on calcium concentration and mitochondrial membrane potential of dorsal root ganglion neurons

To investigate the effects of capsaicin on calcium concentration (［Ca²⁺］_i) and mitochondiral membrane potential (MMP) of dissociated cultured dorsal root ganglion (DRG) neurons of 15 day embryonic Wistar rats. MethodsDissociated DRG cells were treated with capsaicin at various concentrations (0.001, 0.01, 0.1, 1, 10μmol/L). 1min after capsaicin exposure to the DRG cultures, ［［Ca²⁺］_i was determined by confocal laser scanning microscopy (CLSM), and 10min after removing capsaicin, ［Ca²⁺］_i was determined by CLSM in the ［Ca²⁺］_i increased group with 1min stimulation of capsaicin and MMP was monitored by flow cytometry. ResultsAfter stimulation with 0.001μmol/L or 0.01μmol/L capsaicin, ［Ca²⁺］_i had no change, but after 1 min incubation of capsaicin at 0.1, 1, and 10μmol/L concentrations, ［［Ca²⁺］_i increased. 10min after removing the capsaicin, ［［Ca²⁺］_i returned to the basal level at 0.1 and 1μmol/L capsaicin incubation, however, it remained at the same level induced by 10μmol/L capsaicin. ［Ca²⁺］_i was not changed by capsaicin in Ca²⁺ free extra cellular solution. MMP was decreased after 1?min incubation of capsaicin at 10μmol/L concentration, while it was not changed by 0.1 and 1μmol/L capsaicin. Conclusion ［Ca²⁺］_i increases and MMP decreases after exposure to capsaicin at the given concentrations. After removing capsaicin for 10 min, ［Ca²⁺］_i may return to the basal level in low concentrations but not in high concentrations. The increase of ［Ca²⁺］_i induced by capsaicin may exclusively originate from Ca²⁺ influx.