Institute for Anatomy and Cell Biology, Justus-Liebig-University, 35385 Giessen, Germany.
Neuroscience. 2010 Jul 14;168(3):842-50. doi: 10.1016/j.neuroscience.2010.04.012. Epub 2010 Apr 13.
Cell bodies of afferent neurons located in lumbosacral dorsal root ganglia (DRG) provide Adelta- and C-fibres to the urinary bladder, reporting bladder wall tension, volume and noxious stimuli. Recent studies suggested an involvement of muscarinic acetylcholine receptors (mAChRs) not only in detrusor contractility but also in modulating afferent function, and this has been linked to the beneficial effects of muscarinic antagonists in the treatment of overactive bladder. Here, we aimed to determine the inventory of mAChR subtypes expressed by bladder afferent neurons in the mouse. Bladder afferent neurons were identified by retrograde neuronal tracing using Fast Blue (FB) or 1, 1'-dioctadecyl-3, 3, 3', 3'-tetramethylindocarbocyanine perchlorhydrate (DiI) injection into the detrusor muscle. DRG L6-S1 were recognized as the major location of bladder afferent perikarya with an additional smaller peak at L1/L2. Retrogradely labelled bladder afferents located in DRG L4-S2 were subjected to immunohistochemistry or to laser-assisted microdissection with subsequent RT-PCR to study expression of mAChRs subtypes M1R-M5R. Immunolabelling for mAChR subtype M2R, validated on DRG from M2R gene-deficient mice, demonstrated this subtype on 35% of FB-labelled bladder afferents. RT-PCR demonstrated expression of subtypes M2R, M3R and M4R, but not of M1R and M5R, in pooled samples (30 section profiles each) of laser microdissected DiI-labelled bladder afferent cell bodies. In conclusion, bladder afferent neurons express different subtypes of mAChRs (M2R, M3R and M4R). Thus, processing of sensory information from the bladder appears to be under direct cholinergic control.
位于腰骶部背根神经节（DRG）中的传入神经元的细胞体为膀胱提供 Adelta 和 C 纤维，报告膀胱壁张力、容量和有害刺激。最近的研究表明，毒蕈碱乙酰胆碱受体（mAChR）不仅参与逼尿肌收缩，而且参与调节传入功能，这与毒蕈碱拮抗剂在治疗膀胱过度活动症中的有益作用有关。在这里，我们旨在确定在小鼠膀胱传入神经元中表达的 mAChR 亚型的目录。通过将 Fast Blue（FB）或 1,1'-二辛基-3,3,3',3'-四甲基吲哚碳菁高氯酸盐（DiI）注入逼尿肌来逆行神经元追踪，鉴定膀胱传入神经元。DRG L6-S1 被认为是膀胱传入神经元体的主要位置，在 L1/L2 处还有一个较小的峰。将逆行标记的位于 DRG L4-S2 的膀胱传入纤维进行免疫组织化学或激光辅助微切割，随后进行 RT-PCR 以研究 mAChR 亚型 M1R-M5R 的表达。在 M2R 基因缺失小鼠的 DRG 上验证的 mAChR 亚型 M2R 的免疫标记表明，35%的 FB 标记的膀胱传入纤维表达该亚型。RT-PCR 表明在激光微切割的 DiI 标记的膀胱传入细胞体的混合样本（每个样本 30 个剖面）中表达亚型 M2R、M3R 和 M4R，但不表达 M1R 和 M5R。总之，膀胱传入神经元表达不同的 mAChR 亚型（M2R、M3R 和 M4R）。因此，来自膀胱的感觉信息的处理似乎受到直接胆碱能控制。
