| 目的：众所周知，糖尿病视网膜病变的病理生理学特点是血管平滑肌细胞的渐进性功能障碍和死亡，然而导致该过程的潜在机制还不明确。已知PDGF是一种多功能肽血小板衍生生长因子,且在生理应激反应时，是血管细胞类生存的重要因子。但是PDGF的视网膜细胞来源仍属未知，因此了解糖尿病过程中这个重要生长因子的表达如何改变是非常有意义的。
方法：用链唑霉素诱导C57鼠建立糖尿病模型。症状维持8周后，摘除眼球并使用原位杂交分别对糖尿病组和非糖尿病对照组定位PDGF-A和PDGF-B链在视网膜上的表达。利用实时PCR对PDGF形式和它们的同源PDGF-α及PDGF-β受体的mRNA水平进行量化。
结果：原位杂交结果表明正常对照鼠和糖尿病鼠的PDGF-A和PDGF-B主要由神经纤维层中的视网膜神节细胞表达，而且这种定位模式不因糖尿病变化。PDGF-A受体只在视网膜神经节细胞层表达，而PDGF-B受体大多定位于内界膜的Muller细胞终足，而神经节细胞、内丛状层及内部中心层在该处只有微弱的免疫反应性。虽然PDGF-A和PDGF-α受体的mRNA水平在处理组之间保持不变，但是两种受体的视网膜免疫反应模式明显不同。而当与非糖尿病对照组进行比较时，尽管PDGF-α受体（插入片段空间）的表达没有明显的不同 ，但是在糖尿病组视网膜上PDGF-B的mRNA水平明显降低。
结论：1.神经节细胞是成熟视网膜PDGF的主要来源。2.PDGF-B的mRNA表达在糖尿病中明显降低，这对于血管在糖尿病视网膜病变进展中的生存有重要的意义。
Abstract
Purpose: Progressive dysfunction and death of vascular smooth muscle cells and pericytes is a pathophysiological hallmark of diabetic retinopathy, although the underlying mechanisms behind this process remain ill-defined. The multifunctional peptide platelet-derived growth factor (PDGF) is known to act as an important survival factor for both of these vascular cell-types at times of physiological stress. The retinal cell source(s) of PDGF remain unknown. It is important to understand how diabetes alters expression of this important growth factor.
Methods: Streptozotocin-diabetes was established in C57 mice. Following 8 weeks of sustained diabetes, the eyes were enucleated and in situ hybridization was used to localize expression of PDGF-A and PDGF-B chains in retina from both diabetic and non-diabetic controls. mRNA levels for both forms of PDGF, and their cognate PDGF-α and PDGF-β receptors, were also quantified using real-time PCR.
Results: In situ hybridization demonstrated that PDGF-A and PDGF-B were predominantly expressed by the retinal ganglion cells/nerve fibre layer in both normal and diabetic mice, and this localization pattern did not alter in diabetes. PDGF-A receptor was expressed exclusively in the ganglion cell layer of the retina while PDGF-B receptor was mostly localized to the Muller cell end-feet at the internal limiting membrane with lesser immunoreactivity in the ganglion cells, inner plexiform layer, and inner nuclear layer. PDGF-A and PDGF-α receptor mRNA expression levels remained unaltered between treatment groups, although retinal immunolocalization patterns between both receptors was distinct. However, there was a significant decrease of PDGF-B mRNA levels in diabetic retina when compared to non-diabetic controls (p<0.001), although there was no significant difference in PDGF-α receptor (insert space) expression.
Conclusions: Previous studies have shown PDGF expression in a range of cell-types during retinal development, but these results confirm ganglion cells as the principal PDGF source in mature retina. It may be significant that diabetes can reduce PDGF-B mRNA expression since this may have serious implications for vascular survival during diabetic retinopathy progression. |
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