Christianson Julie A, Traub Richard J, Davis Brian M
Department of Medicine, University of Pittsburgh Medical Center, 3550 Terrace Street, Pennsylvania 15261, USA.
J Comp Neurol. 2006 Jan 10;494(2):246-59. doi: 10.1002/cne.20816.
Visceral pain is a prevalent clinical problem and one of the most common ailments for which patients seek medical attention. Recent studies have described many of the physiological properties of visceral afferents, but not much is known regarding their anatomical characteristics. To determine the spinal distribution and neurochemical phenotype of colonic afferents in rodents, Alexa Fluor-conjugated cholera toxin-beta (CTB) was injected subserosally into the proximal and distal portions of the descending colon in Sprague Dawley rats and C57Bl/6 mice. Dorsal root ganglia (T10-S2) were processed for fluorescent immunohistochemistry and visualized by confocal microscopy. In the mouse, CTB-positive neurons were most numerous in the lumbosacral region (LS; L6-S1), with a smaller contribution in the thoracolumbar ganglia (TL; T13-L1). In contrast, CTB-positive neurons in the rat were most numerous in the TL ganglia, with a smaller contribution in the LS ganglia. The vast majority of CTB-positive neurons in both mouse and rat were positive for TRPV1 and CGRP and most likely unmyelinated, in that most colonic afferents were not positive for neurofilament heavy chain. In the mouse, the TL ganglia had a significantly higher percentage of TRPV1- and CGRP-positive neurons than did the LS ganglia, whereas no differences were observed in the rat. The high incidence of TRPV1-positive colonic afferents in rodents suggests that hypersensitivity from the viscera may be partially a TRPV1-mediated event, thereby providing a suitable target for the treatment of visceral pain.
内脏痛是一个普遍存在的临床问题，也是患者寻求医疗关注的最常见疾病之一。最近的研究描述了内脏传入神经的许多生理特性，但对其解剖特征了解不多。为了确定啮齿动物结肠传入神经的脊髓分布和神经化学表型，将Alexa Fluor偶联的霍乱毒素β（CTB）浆膜下注射到Sprague Dawley大鼠和C57Bl/6小鼠降结肠的近端和远端。对背根神经节（T10-S2）进行荧光免疫组织化学处理，并通过共聚焦显微镜观察。在小鼠中，CTB阳性神经元在腰骶部区域（LS；L6-S1）最多，在胸腰神经节（TL；T13-L1）中的比例较小。相比之下，大鼠中CTB阳性神经元在TL神经节中最多，在LS神经节中的比例较小。小鼠和大鼠中绝大多数CTB阳性神经元对TRPV1和CGRP呈阳性，很可能是无髓的，因为大多数结肠传入神经对神经丝重链不呈阳性。在小鼠中，TL神经节中TRPV1和CGRP阳性神经元的百分比显著高于LS神经节，而在大鼠中未观察到差异。啮齿动物中TRPV1阳性结肠传入神经的高发生率表明，内脏超敏反应可能部分是由TRPV1介导的事件，从而为内脏痛的治疗提供了一个合适的靶点。
