Bandopadhyay R, Orte C, Lawrenson J G, Reid A R, De Silva S, Allt G
Weston Institute of Neurological Studies, Windeyer Building, University College Medical School, Cleveland Street, London W1P 6DB, UK.
J Neurocytol. 2001 Jan;30(1):35-44. doi: 10.1023/a:1011965307612.
Evidence from a variety of sources suggests that pericytes have contractile properties and may therefore function in the regulation of capillary blood flow. However, it has been suggested that contractility is not a ubiquitous function of pericytes, and that pericytes surrounding true capillaries apparently lack the machinery for contraction. The present study used a variety of techniques to investigate the expression of contractile proteins in the pericytes of the CNS. The results of immunocytochemistry on cryosections of brain and retina, retinal whole-mounts and immunoblotting of isolated brain capillaries indicate strong expression of the smooth muscle isoform of actin (alpha-SM actin) in a significant number of mid-capillary pericytes. Immunogold labelling at the ultrastructural level showed that alpha-SM actin expression in capillaries was exclusive to pericytes, and endothelial cells were negative. Compared to alpha-SM actin, non-muscle myosin was present in lower concentrations. By contrast, smooth muscle myosin isoforms, were absent. Pericytes were strongly positive for the intermediate filament protein vimentin, but lacked desmin which was consistently found in vascular smooth muscle cells. These results add support for a contractile role in pericytes of the CNS microvasculature, similar to that of vascular smooth muscle cells.
来自各种来源的证据表明，周细胞具有收缩特性，因此可能在调节毛细血管血流中发挥作用。然而，有人提出收缩性并非周细胞的普遍功能，并且围绕真毛细血管的周细胞显然缺乏收缩机制。本研究使用了多种技术来研究中枢神经系统周细胞中收缩蛋白的表达。对脑和视网膜冰冻切片、视网膜整装片进行免疫细胞化学以及对分离的脑毛细血管进行免疫印迹的结果表明，在大量毛细血管中段周细胞中，肌动蛋白的平滑肌异构体（α-SM肌动蛋白）有强烈表达。超微结构水平的免疫金标记显示，毛细血管中的α-SM肌动蛋白表达仅见于周细胞，内皮细胞呈阴性。与α-SM肌动蛋白相比，非肌肉肌球蛋白的浓度较低。相比之下，平滑肌肌球蛋白异构体不存在。周细胞对中间丝蛋白波形蛋白呈强阳性，但缺乏在血管平滑肌细胞中始终存在的结蛋白。这些结果为中枢神经系统微血管周细胞中类似于血管平滑肌细胞的收缩作用提供了支持。
