Endothelial F-actin cytoskeleton in the retinal vasculature of normal and diabetic rats.
OBJECTIVE
The purpose of this study was to characterize the endothelial (EC) F-actin cytoskeleton at different orders of the retinal microvasculature in the normal and diabetic rat and determine if changes in F-actin are associated with different stages of diabetes.


METHODS
The EC F-actin cytoskeleton distribution, nuclei shape, and capillary diameter in the retinal vasculature of rats after 5 and 28 weeks of streptozotocin (STZ)-induced diabetes were compared to those in age-matched controls. The eyes were enucleated, arterially perfused, and labeled for F-actin cytoskeleton and nuclei (YO-PRO-1) or microvascular leakage (FITC-dextran). Retinal whole mounts were then examined by confocal microscopy.


RESULTS
The EC F-actin distribution and nuclear size and shape were highly dependent on the location down the vascular tree. The retinal arterial system in the rat shows a high level of F-actin stress fibre (SF) staining. Peripheral border (PB) staining was present in the ECs of all vessels. Diffuse F-actin staining was observed in endothelial cytoplasm in capillaries, venules, and veins. EC nuclei became distinctly less elongated down the vascular tree. In diabetic rats at 5 weeks, at the capillary level the F-actin staining was more diffuse, and areas of F-actin loss were evident. Both dot-like and diffuse leakage was detected in retinal capillaries, and these leakage types were closely associated with the degree of F-actin changes. In diabetic rats at 28 weeks, there was an increased level of SF staining in the arterial system in addition to capillary F-actin changes.


CONCLUSIONS
The EC F-actin cytoskeleton and nuclei shape retinal microvasculature of the normal rat change with location along the vascular tree. In the early stages of diabetes, there are changes to the F-actin cytoskeleton that are clearly associated with microvascular leakage. F-actin distribution could indicate important structural changes in the pathogenesis of diabetic retinopathy.
Yu
Paula K
PK
Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia 6009.
Yu
Dao-Yi
DY
Cringle
Stephen J
SJ
Su
Er-Ning
EN
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001813:Blood-Retinal Barrier; D002196:Capillaries; D002199:Capillary Permeability; D003599:Cytoskeleton / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology; D004730:Endothelium, Vascular / Q000378:metabolism*; D008297:Male; D018613:Microscopy, Confocal; D051381:Rats; D017207:Rats, Sprague-Dawley; D012171:Retinal Vessels / Q000378:metabolism* / Q000473:pathology
D000199:Actins