Abstract
Methods: :
Female heterozygous pigmented Zucker rats were used. To induce CNV in rats, we used argon laser (300 mW/ 100 micrometers/ 100 ms) creating four lesions around the optic disc. After 48 hours, the expression of sulfated glycosaminoglycans (sGAG) were evaluated in retina and choroid/sclera from animals metabolically labeled with [35S]-sulfate before and after CNV lesion in different animals, using agarose gel electrophoresis in PDA buffer. Similar analyses were performed for hyaluronan (HA), which was measured by fluorometric ELISA-like assay. Using serial cryosections (10µm), histochemistry for HA and immunofluorescence using antibodies against VEGF receptor (VEGFR) and syndecan4 (Syn4) were performed and analyzed by confocal microscopy.
Results: :
Retina and choroid presented different biosynthesis of sGAG. Heparan sulfate (HS), chondroitin sulfate (CS) and dermatan sulfate (DS) were found in retina. On the other hand, DS and HS were found in choroid/sclera. After laser induction of CNV lesion we could observe an increase of 3.9 and 1.4 times of total sGAG (CS+DS+HS) in retina and choroid/sclera, respectively. The CNV lesion leads an increase mainly in CS+DS in retina (ratio CNV/control: 4.8), whereas in choroid HS and DS increase proportionally (ratio CNV/control: 1.5). HA content was elevated in retina (ratio CNV/control: 3.5) and decreased in choroid (ratio CNV/control: 0.4). Using histochemistry HA was found in ECM of photoreceptors, internal plexiform and internal and external nuclear layers and a global increase of HA staining was found after laser induced CNV. Confocal analysis of retinal tissue showed Syn4 co-localizing with VEGFR.
Keywords: choroid: neovascularization • proteoglycans/glycosaminoglycans • extracellular matrix