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Diabetes. 2010 Dec;59(12):3208-15. doi: 10.2337/db10-0552. Epub 2010 Sep 17.

Candesartan attenuates diabetic retinal vascular pathology by restoring glyoxalase-I function.

Author information

  • 1Oxidative Stress Laboratory, Diabetes Division, Baker IDI Heart and Diabetes Institute, Melbourne, Australia. antonia.miller@monash.edu

Abstract

OBJECTIVE:

Advanced glycation end products (AGEs) and the renin-angiotensin system (RAS) are both implicated in the development of diabetic retinopathy. How these pathways interact to promote retinal vasculopathy is not fully understood. Glyoxalase-I (GLO-I) is an enzyme critical for the detoxification of AGEs and retinal vascular cell survival. We hypothesized that, in retina, angiotensin II (Ang II) downregulates GLO-I, which leads to an increase in methylglyoxal-AGE formation. The angiotensin type 1 receptor blocker, candesartan, rectifies this imbalance and protects against retinal vasculopathy.

RESEARCH DESIGN AND METHODS:

Cultured bovine retinal endothelial cells (BREC) and bovine retinal pericytes (BRP) were incubated with Ang II (100 nmol/l) or Ang II+candesartan (1 μmol/l). Transgenic Ren-2 rats that overexpress the RAS were randomized to be nondiabetic, diabetic, or diabetic+candesartan (5 mg/kg/day) and studied over 20 weeks. Comparisons were made with diabetic Sprague-Dawley rats.

RESULTS:

In BREC and BRP, Ang II induced apoptosis and reduced GLO-I activity and mRNA, with a concomitant increase in nitric oxide (NO(•)), the latter being a known negative regulator of GLO-I in BRP. In BREC and BRP, candesartan restored GLO-I and reduced NO(•). Similar events occurred in vivo, with the elevated RAS of the diabetic Ren-2 rat, but not the diabetic Sprague-Dawley rat, reducing retinal GLO-I. In diabetic Ren-2 rats, candesartan reduced retinal acellular capillaries, inflammation, and inducible nitric oxide synthase and NO(•), and restored GLO-I.

CONCLUSIONS:

We have identified a novel mechanism by which candesartan improves diabetic retinopathy through the restoration of GLO-I.

PMID:
20852029
[PubMed - indexed for MEDLINE]
PMCID:
PMC2992784
Free PMC Article
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