Department of Medicine, Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada.
J Cell Mol Med. 2009 Sep;13(9B):3528-40. doi: 10.1111/j.1582-4934.2009.00689.x. Epub 2009 Feb 9.
The colon of Ws/Ws mutant rats shows impairment of pacemaker activity and altered inhibitory neurotransmission. The present study set out to find structural correlates to these findings to resolve mechanisms. In the colon of Ws/Ws rats, interstitial cells of Cajal associated with Auerbach's plexus (ICC-AP) were significantly decreased and ICC located at the submuscular plexus and intramuscular ICC were rarely observed based on immunohistochemistry and electron microscopy. Ultrastructural investigations revealed that there was no overall loss of all types of interstitial cells combined. Where loss of ICC was observed, a marked increase in fibroblast-like ICC (FL-ICC) was found at the level of AP. Immunoelectron microscopy proved FL-ICC to be c-Kit(-) but gap junction coupled to each other and to c-Kit(+) ICC; they were associated with enteric nerves and occupied space normally occupied by ICC in the wild-type rat colon, suggesting them to be immature ICC. In addition, a marked increase in immunoreactivity for insulin-like growth factor 1 receptor (Igf1r) occurred, co-localized with CD34 but not with c-Kit. A significantly higher number of Igf1r(+)/CD34(+) cells were found in Ws/Ws compared to wild-type rat colons. These CD34(+)/Igf1r(+) cells in the Ws/Ws colon occupied the same space as FL-ICC. Hence we propose that a subset of immature ICC (FL-ICC) consists of adult progenitor cells. Immunohistochemistry revealed a reduction of neurons positive for neuronal nitric oxide synthase. The functional capabilities of the immature ICC and the regenerative capabilities of the adult progenitor cells need further study. The morphological features described here show that the loss of pacemaker activity is not associated with failure to develop a network of interstitial cells around AP but a failure to develop this network into fully functional pacemaker cells. The reduction in nitrergic innervation associated with the Ws mutation may be the result of a reduction in nitrergic neurons.
Ws/Ws 突变大鼠的结肠显示起搏活动受损和抑制性神经传递改变。本研究旨在寻找这些发现的结构相关性，以解决机制问题。在 Ws/Ws 大鼠的结肠中，与 Auerbach 丛相关的 Cajal 间质细胞（ICC-AP）显著减少，基于免疫组织化学和电子显微镜观察，很少观察到位于黏膜下丛和肌内 ICC 的 ICC。超微结构研究表明，并非所有类型的间质细胞都整体丢失。在观察到 ICC 丢失的地方，在 AP 水平发现纤维母细胞样 ICC（FL-ICC）明显增加。免疫电子显微镜证明 FL-ICC 为 c-Kit(-)，但彼此之间以及与 c-Kit(+)ICC 之间存在缝隙连接；它们与肠神经相连，并占据了野生型大鼠结肠中 ICC 的正常空间，表明它们是未成熟的 ICC。此外，胰岛素样生长因子 1 受体（Igf1r）的免疫反应性显著增加，与 CD34 共定位，但与 c-Kit 不共定位。在 Ws/Ws 大鼠结肠中发现的 Igf1r(+)/CD34(+)细胞数量明显高于野生型大鼠结肠。在 Ws/Ws 结肠中，这些 CD34(+)/Igf1r(+)细胞占据了与 FL-ICC 相同的空间。因此，我们提出，不成熟 ICC（FL-ICC）的一个亚群由成年祖细胞组成。免疫组织化学显示神经元一氧化氮合酶阳性神经元减少。不成熟 ICC 的功能能力和成年祖细胞的再生能力需要进一步研究。这里描述的形态特征表明，起搏活动的丧失与 AP 周围间质细胞网络的发育失败无关，而是与该网络发育为完全功能性起搏细胞的失败有关。与 Ws 突变相关的 nitrergic 神经支配的减少可能是 nitrergic 神经元减少的结果。
