Abstract
Purpose: :
The mechanism of action of limited grid laser in reducing diabetic macular oedema is poorly understood. We propose that the effect is due to the induction by laser treatment of a diffusible factor that stabilises the blood–retinal barrier. We have employed 2–dimensional gel electrophoresis and mass spectroscopic techniques to examine the proteome changes two months after laser in experimental diabetic retinopathy.
Methods: :
Dark agouti rats received either sham or limited grid argon laser to one eye four weeks after hyperglycaemia was induced with streptozotocin. Eight weeks later the neuroretinae of the two groups were excised and solubilized for isoelectric focusing on 17cm pH 4.0 – 7.0 immobilized pH gradient strips. Proteins separated for the second dimension by 19 cm 8 – 18 % SDS – PAGE were Sypro Ruby stained for image analysis. Protein spots of interest were then excised for MALDI–TOF–TOF analysis.
Results: :
Differential image analysis of triplicate gels revealed 9 protein spots with increased expression in lasered gels. Identifications included isovaleryl con–enzyme A dehydrogenase and alpha A crystallin. There were 24 spots with decreased expression on lasered gels including Wnt– 5b, LEK– 1, and SPIN– 2. Four uniquely expressed proteins in lasered gels included rRNA promoter binding protein. Of 13 proteins absent from lasered gels and uniquely expressed on non–lasered gels, Claudin– 12 and ATP–synthase beta unit were identified.
Conclusions: :
Using proteomic techniques we have identified previously unknown protein changes attributable to limited laser treatment in diabetic retinopathy. This knowledge aids development of therapies for disorders of the blood–retinal–barrier.
Keywords: proteomics • laser • retina