Diabetic eNOS-knockout mice develop accelerated retinopathy.
OBJECTIVE
Dysfunction of endothelial nitric oxide synthase (eNOS) has been implicated in the pathogenesis of diabetic vascular complications. This study was undertaken to determine the role of eNOS in the development of diabetic retinopathy (DR), by investigating the functional consequences of its deficiency in the diabetic state.


METHODS
Diabetes was induced in eNOS-knockout (eNOS(-/-)) and C57B/6 mice by streptozotocin (STZ) injection. Retinal vasculature was evaluated by albumin extravasation, to quantitatively measure vascular permeability, and by trypsin-digested retinal vascular preparations, to quantify acellular capillaries. Gliosis was evaluated by immunofluorescent techniques. Retinal capillary basement membrane thickness was assessed by transmission electron microscopy. Total retinal nitric oxide level was assessed by measuring nitrate/nitrite using a fluorometric-based assay, iNOS expression was examined by real-time PCR.


RESULTS
Diabetic eNOS(-/-) mice exhibit more severe retinal vascular permeability than age-matched diabetic C57BL/6 mice, detectable as early as 3 weeks after diabetes induction. Diabetic eNOS(-/-) mice also show earlier onset and an increased number of acellular capillaries, sustained gliosis, and increased capillary basement membrane thickness. Total nitric oxide (NO) level was also increased, concomitant with elevated iNOS expression in diabetic eNOS(-/-) retina.


CONCLUSIONS
Diabetic eNOS(-/-) mice exhibit A significantly wider range of advanced retinal vascular complications than the age-matched diabetic C57BL/6 mice, supporting the notion that eNOS-derived NO plays an essential role in retinal vascular function. This mouse model also faithfully replicates many of the hallmarks of vascular changes associated with human retinopathy, thus providing a unique model to aid in understanding the pathologic mechanisms of and to develop effective therapeutic strategies for diabetic retinopathy.
Li
Qiuhong
Q
Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, Florida 32610-0284, USA. qli@ufl.edu
Verma
Amrisha
A
Han
Ping-Yang
PY
Nakagawa
Takahiko
T
Johnson
Richard J
RJ
Grant
Maria B
MB
Campbell-Thompson
Martha
M
Jarajapu
Yagna P R
YP
Lei
Bo
B
Hauswirth
William W
WW
D000418:Albumins / Q000378:metabolism; D000818:Animals; D002199:Capillary Permeability; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology* / Q000503:physiopathology; D003930:Diabetic Retinopathy / Q000201:enzymology* / Q000503:physiopathology; D005260:Female; D005451:Fluorescein Angiography; D019084:Fluorescent Antibody Technique, Indirect; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005911:Gliosis / Q000175:diagnosis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000502:physiology; D052247:Nitric Oxide Synthase Type II / Q000235:genetics; D052250:Nitric Oxide Synthase Type III / Q000502:physiology*; D012160:Retina / Q000201:enzymology* / Q000503:physiopathology; D012171:Retinal Vessels / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000418:Albumins; D005904:Glial Fibrillary Acidic Protein; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496317:Nos2 protein, mouse; C496315:Nos3 protein, mouse