Abstract
P 088
Expression of aquaporins in the neuroretina and RPE of diabetic rats
Margrit Hollborn1, Sladjana Dukic-Stefanovic2, Thomas Pannicke2, Peter Wiedemann1, Andreas Bringmann1, Leon Kohen3
1Forschungslabor, Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Leipzig, Leipzig; 2Paul Flechsig Institute of Brain Research, Leipzig; 3Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Leipzig, Leipzig; 4Klinik für Augenheilkunde, HELIOS Klinikum Aue
Objective
Diabetic retinopathy is often associated with the formation of retinal edema which is a main reason of impaired vision. The disturbed balance between the fluid influx into the retinal parenchyma and the fluid absorption from the retinal tissue into the blood was suggested to underlie the development of edema. Aquaporins (Aqp) are integral membrane proteins; their main function is the transport of water and small solutes such as glycerol across membranes. Little is known regarding the role of Aqp in the retina and the retinal pigment epithelium (RPE) in diabetes. Therefore we investigated the Aqp mRNA and protein expression using an animal model of diabetic retinopathy.
Methods
Diabetes was induced by a single intravenous injection of streptozotocin (65 mg/kg body weight) in male Long Evans rats. 4 months after injection, the mRNA expression was analysed in isolated neuroretinas and RPE with real-time PCR. The localization of proteins was investigated by immunohistochemistry.
Results
Both the neuroretina and the RPE express mRNA for Aqp0, 1, 3, 4, 5, 6, 8, 9, and 11. Diabe-tes caused a significant up regulation of Aqp1 and a down regulation of Aqp6 and 11 in the neuroretina. Aqp5, 9, and 11 mRNA levels were increased in the RPE of diabetic animals as compared to control tissues, whereas Aqp0 mRNA was decreased. Increases in the immunoreactivity were observed for Aquaporins 3, 5 and 9 in the RPE. Aqp6 immunore-activity was decreased in the neuroretina. Furthermore the Vegfa mRNA was up regulated in the RPE but was unaltered in the neuroretina of diabetic animals.
Conclusions
Diabetes causes alterations of the Aqp expression in the neuroretina and RPE. Changes in Aqp expression may contribute to edema formation and/or resolution in the diabetic retina in dependence on the osmotic gradient between the retina and blood.
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