Enteric NeuroScience Program and Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN 55906, USA.
Neurogastroenterol Motil. 2011 Jul;23(7):e309-23. doi: 10.1111/j.1365-2982.2011.01730.x. Epub 2011 May 24.
Gastrointestinal symptoms, particularly constipation, increase with aging, but their underlying mechanisms are poorly understood due to lack of experimental models. Previously we established the progeric klotho mouse as a model of aging-associated anorexia and gastric dysmotility. We also detected reduced fecal output in these animals; therefore, the aim of this study was to investigate in vivo function and cellular make-up of the small intestinal and colonic neuromuscular apparatus.
Klotho expression was studied by RT-PCR and immunohistochemistry. Motility was assessed by dye transit and bead expulsion. Smooth muscle and neuron-specific gene expression was studied by Western immunoblotting. Interstitial cells of Cajal (ICC) and precursors were analyzed by flow cytometry, confocal microscopy, and three-dimensional reconstruction. HuC/D(+) myenteric neurons were enumerated by fluorescent microscopy.
Klotho protein was detected in neurons, smooth muscle cells, and some ICC classes. Small intestinal transit was slower but whole-gut transit of klotho mice was accelerated due to faster colonic transit and shorter intestinal lengths, apparent only after weaning. Fecal water content remained normal despite reduced output. Smooth muscle myosin expression was reduced. ICC, ICC precursors, as well as nitrergic and cholinergic neurons maintained their normal proportions in the shorter intestines.
CONCLUSIONS & INFERENCES: Progeric klotho mice express less contractile proteins and develop generalized intestinal neuromuscular hypoplasia mainly arising from stunted postweaning growth. As reduced fecal output in these mice occurs in the presence of accelerated colonic and whole-gut transit, it likely reflects reduced food intake rather than intestinal dysmotility.
胃肠道症状，尤其是便秘，随着年龄的增长而增加，但由于缺乏实验模型，其潜在机制尚不清楚。以前，我们建立了 progeric klotho 小鼠作为与衰老相关的厌食和胃动力障碍的模型。我们还发现这些动物的粪便排出量减少；因此，本研究的目的是研究小肠和结肠神经肌肉装置的体内功能和细胞组成。
通过 RT-PCR 和免疫组织化学研究 klotho 的表达。通过染料转运和珠子排出评估运动能力。通过 Western 免疫印迹研究平滑肌和神经元特异性基因表达。通过流式细胞术、共聚焦显微镜和三维重建分析 Cajal 间质细胞（ICC）和前体细胞。通过荧光显微镜计数 HuC/D(+)肌间神经元。
klotho 蛋白在神经元、平滑肌细胞和一些 ICC 类中被检测到。小肠转运速度较慢，但由于结肠转运速度加快和小肠长度缩短，klotho 小鼠的全肠转运速度加快，这一现象仅在断奶后出现。尽管粪便排出量减少，但粪便含水量仍保持正常。平滑肌肌球蛋白表达减少。ICC、ICC 前体以及氮能和胆碱能神经元在较短的肠道中保持其正常比例。
progeric klotho 小鼠表达较少的收缩蛋白，并在断奶后生长迟缓的情况下发展出广泛的肠道神经肌肉发育不良。由于这些小鼠的粪便排出量减少发生在加速的结肠和全肠转运的情况下，这可能反映了进食减少而不是肠道动力障碍。
