Al Haj Ali M, Mensah-Brown E, Chandranath S I, Adeghate E, Adem A
Department of Pharmacology, UAE University, United Arab Emirates.
Growth Factors. 2003 Sep-Dec;21(3-4):131-7. doi: 10.1080/08977190310001637233.
The distribution of insulin-like growth factor-1 (IGF-1) and its receptor in the gut of the one-humped camel (Camelus dromedarius) were studied by immunohistochemistry and quantitative receptor autoradiography. IGF-1-IR cells occurred mainly in the lamina propria and epithelium of the small intestine, while in the large intestine positive cells were seen in the columnar cells of the epithelial layer of colonic glands. IGF-I was also discernible in the muscularis externa of the intestines. Autoradiography revealed a higher concentration of receptors in the mucosa compared to the muscular layer. With regard to the mucosa, the highest density of receptors was discernible in the duodenum. Immunohistochemistry revealed the main sites of the receptors to be the lamina propria, epithelia of the crypts and the villi of intestines. Double immunofluorescence studies with combined antisera to IGF-I and its receptor showed that the ligand and its receptor usually occurred within the same cell in the mucosa. A few cells with varied profiles immunoreacted to either the ligand or the receptor but not to both. Cells with varied profiles immunoreacted to antiserum of the receptors but not to the ligand in the muscle layer. Thus IGF-1 might be acting on its receptor via both an autocrine and paracrine modes in the camel mucosa. In the muscularis layer, IGF-1 may be acting by different mechanisms. Our data demonstrate that unlike all other mammals studied, the camel contains a high concentration of IGF-1 receptors in the duodenal mucosa compared to other parts of the camel gut. It also possesses a higher concentration of the receptor in its mucosa compared to the muscle layer. We speculate that this might be a significant feature necessary for the regenerative ability of the duodenal mucosa in the one-humped camel.
通过免疫组织化学和定量受体放射自显影技术，研究了单峰骆驼（骆驼属双峰驼）肠道中胰岛素样生长因子-1（IGF-1）及其受体的分布。IGF-1免疫反应细胞主要出现在小肠的固有层和上皮中，而在大肠中，在结肠腺上皮层的柱状细胞中可见阳性细胞。在肠道的外肌层中也可辨别出IGF-I。放射自显影显示，与肌肉层相比，黏膜中的受体浓度更高。就黏膜而言，十二指肠中受体密度最高。免疫组织化学显示，受体的主要部位是固有层、肠隐窝和绒毛的上皮。用针对IGF-I及其受体的联合抗血清进行的双重免疫荧光研究表明，配体及其受体通常出现在黏膜中的同一细胞内。少数形态各异的细胞对配体或受体有免疫反应，但对两者都无反应。形态各异的细胞对肌肉层中的受体抗血清有免疫反应，但对配体无反应。因此，IGF-1可能在骆驼黏膜中通过自分泌和旁分泌方式作用于其受体。在肌层中，IGF-1可能通过不同机制起作用。我们的数据表明，与所有其他已研究的哺乳动物不同，与骆驼肠道的其他部分相比，骆驼十二指肠黏膜中含有高浓度的IGF-1受体。与肌肉层相比，其黏膜中受体浓度也更高。我们推测，这可能是单峰骆驼十二指肠黏膜再生能力所必需的一个重要特征。
