Bost Anneka, Shaib Ali H, Schwarz Yvonne, Niemeyer Barbara A, Becherer Ute
Institute of Physiology, CIPMM, Saarland University, 66421 Homburg/Saar, Germany.
Molecular Biophysics, CIPMM, Saarland University, 66421 Homburg/Saar, Germany.
Neuroscience. 2017 Mar 27;346:1-13. doi: 10.1016/j.neuroscience.2017.01.006. Epub 2017 Jan 13.
Peptidergic dorsal root ganglion (DRG) neurons transmit sensory and nociceptive information from the periphery to the central nervous system. Their synaptic activity is profoundly affected by neuromodulatory peptides stored and released from large dense-core vesicles (LDCVs). However, the mechanism of peptide secretion from DRG neurons is poorly understood. Using total internal reflection fluorescence microscopy (TIRFM), we visualized individual LDCVs loaded with fluorescent neuropeptide Y (NPY) and analyzed their stimulation-dependent release. We tested several protocols and found an overall low stimulation-secretion coupling that increased after raising intracellular Ca concentration by applying a weak pre-stimulus. Interestingly, the stimulation protocol also influenced the mechanism of LDCV fusion. Depolarization of DRG neurons with a solution containing 60mM KCl triggered full fusion, kiss-and-run, and kiss-and-stay exocytosis with equal frequency. In contrast, field electrode stimulation primarily induced full fusion exocytosis. Finally, our results indicate that NPY can promote LDCV secretion. These results shed new light on the mechanism of NPY action during modulation of DRG neuron activity, an important pathway in the treatment of chronic pain.
肽能背根神经节（DRG）神经元将感觉和伤害性信息从外周传递到中枢神经系统。它们的突触活动受到储存在大致密核心囊泡（LDCV）中并从中释放的神经调节肽的深刻影响。然而，DRG神经元中肽分泌的机制尚不清楚。利用全内反射荧光显微镜（TIRFM），我们可视化了装载荧光神经肽Y（NPY）的单个LDCV，并分析了它们的刺激依赖性释放。我们测试了几种方案，发现总体上刺激-分泌偶联较低，在通过施加弱预刺激提高细胞内钙浓度后增加。有趣的是，刺激方案也影响了LDCV融合的机制。用含有60mM KCl的溶液使DRG神经元去极化会以相同频率触发完全融合、亲吻-逃离和亲吻-停留胞吐作用。相比之下，场电极刺激主要诱导完全融合胞吐作用。最后，我们的结果表明NPY可以促进LDCV分泌。这些结果为DRG神经元活动调节过程中NPY作用的机制提供了新的线索，这是治疗慢性疼痛的重要途径。
