Pierce Lisa M, Rankin Michelle R, Foster Raymond T, Dolber Paul C, Coates Kimberly W, Kuehl Thomas J, Thor Karl B
Department of Obstetrics and Gynecology, Scott & White Hospital, Temple, TX 76508, USA.
Am J Obstet Gynecol. 2006 Oct;195(4):987-96. doi: 10.1016/j.ajog.2006.02.042. Epub 2006 Apr 25.
This study was undertaken to examine the neurofilament and neurochemical composition of subpopulations of primary afferent neurons innervating the levator ani muscle by combining retrograde tracing and triple labeling immunofluorescence in the female squirrel monkey.
Cholera toxin B subunit (CTB) was injected unilaterally into the levator ani muscle of 3 monkeys to identify primary sensory neurons in the dorsal root ganglia (DRG) and their central projections in the spinal cord. L7-S2 DRG were processed for dual or triple labeling immunofluorescence 3 days after injection to examine labeling of the 200 kD neurofilament marker RT97 (a marker of myelinated neurons), calcitonin gene-related peptide (CGRP; a marker of peptidergic neurons), isolectin B4 (IB4; a marker of small, unmyelinated neurons), and nerve growth factor receptor (TrkA) in CTB-positive neurons.
RT97-negative (C-fiber) neurons were more numerous (74% of total CTB-labeled neurons) and smaller in size than RT97-positive (A-fiber) afferent neurons (26% of CTB-labeled neurons). IB4 labeling was almost exclusively found in RT97-negative afferent neurons. Approximately 43% of all CTB-labeled DRG neurons expressed CGRP, and the majority of these were small. The distribution and sizes of CTB-labeled TrkA-positive DRG neurons were similar to those of CTB-labeled CGRP-positive DRG neurons.
The levator ani muscle is innervated by 3 major subpopulations of primary afferent neurons consisting of cells with large, neurofilament-rich soma and A fibers (putative proprioceptive neurons) and those with small, peptidergic or nonpeptidergic, neurofilament-poor soma and C fibers (putative nociceptive, mechanoreceptive, ergoreceptive, and thermoreceptive neurons). Future investigation is needed to elucidate the relationship between primary sensory neuron subpopulations and changes in neuropeptide and neurotrophin expression on experimental levator ani nerve damage, childbirth, and aging.
本研究旨在通过在雌性松鼠猴中结合逆行追踪和三重标记免疫荧光技术，研究支配提肛肌的初级传入神经元亚群的神经丝和神经化学组成。
将霍乱毒素B亚基（CTB）单侧注射到3只猴子的提肛肌中，以识别背根神经节（DRG）中的初级感觉神经元及其在脊髓中的中枢投射。注射后3天，对L7-S2 DRG进行双重或三重标记免疫荧光处理，以检测200 kD神经丝标志物RT97（有髓神经元的标志物）、降钙素基因相关肽（CGRP；肽能神经元的标志物）、异凝集素B4（IB4；小的无髓神经元的标志物）和神经生长因子受体（TrkA）在CTB阳性神经元中的标记情况。
RT97阴性（C纤维）神经元数量更多（占CTB标记神经元总数的74%），且比RT97阳性（A纤维）传入神经元体积更小（占CTB标记神经元的26%）。IB4标记几乎仅见于RT97阴性传入神经元。所有CTB标记的DRG神经元中约43%表达CGRP，且其中大多数为小神经元。CTB标记的TrkA阳性DRG神经元的分布和大小与CTB标记的CGRP阳性DRG神经元相似。
提肛肌由3个主要的初级传入神经元亚群支配，包括具有大的、富含神经丝的胞体和A纤维的细胞（推测为本体感觉神经元）以及具有小的、肽能或非肽能、神经丝含量少的胞体和C纤维的细胞（推测为伤害性感受、机械感受、本体感受和温度感受神经元）。未来需要进一步研究以阐明初级感觉神经元亚群与实验性提肛肌神经损伤、分娩和衰老过程中神经肽和神经营养因子表达变化之间的关系。
