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在花斑致死小鼠的无神经节直肠平滑肌中鉴定功能性肌内直肠机械感受器。

Identification of functional intramuscular rectal mechanoreceptors in aganglionic rectal smooth muscle from piebald lethal mice.

作者信息

Spencer Nick J, Kerrin Aoife, Zagorodnyuk Vladimir P, Hennig Grant W, Muto Melodie, Brookes Simon J, McDonnell Orla

机构信息

Dept. of Human Physiology, School of Medicine, Flinders Univ., South Australia, Australia.

出版信息

Am J Physiol Gastrointest Liver Physiol. 2008 Apr;294(4):G855-67. doi: 10.1152/ajpgi.00502.2007. Epub 2008 Jan 24.

Abstract

The mechanosensitive endings of low-threshold, slowly adapting pelvic afferents that innervate the rectum have been previously identified as rectal intraganglionic laminar endings (rIGLEs) that lie within myenteric ganglia. We tested whether the aganglionic rectum of piebald-lethal (s(l)/s(l)) mice lacks rIGLEs and whether this could explain impaired distension-evoked reflexes from this region. Extracellular recordings were made from fine rectal nerves in C57BL/6 wild-type and s(l)/s(l) mice, combined with anterograde labeling. In C57BL/6 mice, graded circumferential stretch applied to the rectum activated graded increases in firing of slowly adapting rectal mechanoreceptors. In s(l)/s(l) mice, graded stretch of the aganglionic rectum activated similar graded increases in rectal afferent firing. Stretch-sensitive afferents responded at low mechanical thresholds and fired more intensely at noxious levels of stretch. They could also be activated by probing their receptive fields with von Frey hairs and by muscle contraction. Anterograde labeling from recorded rectal nerves identified the mechanoreceptors of muscular afferents in the aganglionic rectal smooth muscle. A population of afferents were also recorded in both C57BL/6 and s(l)/s(l) mice that were activated by von Frey hair probing, but not stretch. In summary, the aganglionic rectum is innervated by a population of stretch-sensitive rectal afferent mechanoreceptor which develops and functions in the absence of any enteric ganglia. These results suggest that in patients with Hirschsprung's disease the inability to activate extrinsic distension reflexes from the aganglionic rectum is unlikely to be due to the absence of stretch-sensitive extrinsic mechanoreceptors.

摘要

先前已确定,支配直肠的低阈值、慢适应盆腔传入神经的机械敏感末梢是位于肌间神经节内的直肠神经节内分层末梢(rIGLEs)。我们测试了花斑致死(s(l)/s(l))小鼠的无神经节直肠是否缺乏rIGLEs,以及这是否可以解释该区域扩张诱发反射受损的原因。在C57BL/6野生型和s(l)/s(l)小鼠的直肠细神经上进行细胞外记录,并结合顺行标记。在C57BL/6小鼠中,对直肠施加分级圆周拉伸可激活慢适应直肠机械感受器放电的分级增加。在s(l)/s(l)小鼠中,无神经节直肠的分级拉伸也激活了直肠传入神经放电的类似分级增加。拉伸敏感传入神经在低机械阈值下作出反应,并在有害拉伸水平下放电更强烈。它们也可以通过用von Frey毛探测其感受野和肌肉收缩来激活。从记录的直肠神经进行顺行标记,确定了无神经节直肠平滑肌中肌肉传入神经的机械感受器。在C57BL/6和s(l)/s(l)小鼠中还记录到一群传入神经,它们被von Frey毛探测激活,但未被拉伸激活。总之,无神经节直肠由一群拉伸敏感的直肠传入机械感受器支配,这些感受器在没有任何肠神经节的情况下发育并发挥功能。这些结果表明,在先天性巨结肠病患者中,无法激活来自无神经节直肠的外在扩张反射不太可能是由于缺乏拉伸敏感的外在机械感受器。

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