Clodfelder-Miller Buffie J, Kanda Hirosato, Gu Jianguo G, Creighton Judy R, Ness Timothy J, DeBerry Jennifer J
Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States.
Department of Anesthesiology and Perioperative Medicine, University of Alabama at Birmingham, Birmingham, AL, United States.
Brain Res. 2018 Jun 15;1689:45-53. doi: 10.1016/j.brainres.2017.12.023. Epub 2017 Dec 30.
There is mounting evidence underscoring a role for the urothelium in urinary bladder sensation. Previous functional studies have identified bladder primary afferents with mechanosensitive properties suggesting urothelial innervation and/or communication. The current study identifies a group of urothelium-innervating afferent neurons in rat, and characterizes and compares the properties of these and non-urothelial afferent neuron populations. Lumbosacral (LS) primary afferent neurons were retrogradely labeled using intraparenchymal (IPar) microinjection or intravesical (IVes) infusion of tracer into the bladder. Using these techniques, separate populations of neurons were differentiated by dorsal root ganglion (DRG) somata labeling and dye distribution within the bladder. IPar- and IVes-labeled neurons accounted for 85.0% and 14.4% of labeled L6-S1 neurons (P < .001), respectively, with only 0.6% of neurons labeled by both techniques. Following IVes labeling, dye was contained only within the periurothelial bladder region in contrast to non-urothelial distribution of dye after IPar labeling. Electrophysiological characterization by in situ patch-clamp recordings from whole-mount DRG preparations indicated no significant difference in passive or active membrane properties of IPar and IVes DRG neurons. However, calcium imaging of isolated neurons indicates that a greater proportion of IPar- than IVes-labeled neurons express functional TRPA1 (45.7% versus 25.6%, respectively; P < .05). This study demonstrates that two anatomically distinct groups of LS bladder afferents can be identified in rat. Further studies of urothelial afferents and the phenotypic differences between non-/urothelial afferents may have important implications for normal and pathophysiological bladder sensory processing.
越来越多的证据强调了尿路上皮在膀胱感觉中的作用。先前的功能研究已经确定了具有机械敏感特性的膀胱初级传入神经，提示存在尿路上皮神经支配和/或通讯。本研究在大鼠中鉴定出一组支配尿路上皮的传入神经元，并对这些神经元以及非尿路上皮传入神经元群体的特性进行了表征和比较。通过向膀胱实质内（IPar）微量注射或膀胱内（IVes）注入示踪剂，对腰骶部（LS）初级传入神经元进行逆行标记。使用这些技术，通过背根神经节（DRG）胞体标记和膀胱内染料分布区分不同的神经元群体。IPar标记和IVes标记的神经元分别占L6-S1标记神经元的85.0%和14.4%（P < 0.001），两种技术同时标记的神经元仅占0.6%。IVes标记后，染料仅存在于膀胱尿路上皮周围区域，而IPar标记后染料呈非尿路上皮分布。对整装DRG制剂进行原位膜片钳记录的电生理特性表明，IPar和IVes DRG神经元的被动或主动膜特性无显著差异。然而，对分离神经元的钙成像表明，表达功能性TRPA1的IPar标记神经元比例高于IVes标记神经元（分别为45.7%和25.6%；P < 0.05）。本研究表明，在大鼠中可以鉴定出两组解剖学上不同的LS膀胱传入神经。对尿路上皮传入神经以及非/尿路上皮传入神经之间表型差异的进一步研究可能对正常和病理生理状态下的膀胱感觉处理具有重要意义。
