Effects of stobadine and vitamin E in diabetes-induced retinal abnormalities: involvement of oxidative stress.
BACKGROUND
Because hyperglycemia-induced oxidative stress may be a cause of retinopathy, this study examined the hypothesis that administration of exogenous antioxidants, stobadine (ST) and vitamin E (vitE), can restore retinal abnormalities in experimental diabetes.


METHODS
Normal and streptozotocin (STZ)-induced male Wistar rats received daily intraoral doses of ST (24.7 mg/kg) and vitE (alpha-dl-tocopherol acetate, 400-500 IU/kg) individually or in combinations for 8 months. The biochemical parameters including aldose reductase enzyme (AR) activity and lipid peroxidation (MDA), and histopathological changes such as retinal capillary basement membrane thickness (RCBMT) and vascular endothelial growth factor (VEGF) expression were evaluated.


RESULTS
A 37.99% increase in RCBMT was observed in rats after 8 months diabetes duration. The increase in RCBMT was 12.34% in diabetic rats treated with ST and 23.07% in diabetic rats treated with vitE. In diabetic rats treated with antioxidant combination, just a 4.38% increase was observed in RCBMT. The excess VEGF immunoreactivity and increased MDA and AR activity determined in diabetic retina were significantly attenuated by individual antioxidant treatments. Although both antioxidants decreased blood glucose, HbA1c, fructosamine and triglyceride levels in diabetic rats, poor glycemic control was maintained in all experimental groups during the treatment period. However, the antioxidant combination led to almost complete amelioration in retinal MDA and RCBMT in diabetic rats.


CONCLUSIONS
The ability of antioxidant combination to arrest retinal abnormalities and lipid peroxidation even in the presence of poor glycemic control might advocate the key role of direct oxidative damage and the protective action of antioxidants in retinal alterations associated with diabetic retinopathy.
Yülek
Fatma
F
Department of Ophthalmalogy, Gazi University, Besevler, Ankara, Turkey.
Or
Meral
M
Ozoğul
Candan
C
Isik
Asli Ceylan
AC
Ari
Nuray
N
Stefek
Milan
M
Bauer
Victor
V
Karasu
Cimen
C
D000449:Aldehyde Reductase / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D001786:Blood Glucose; D002243:Carbolines / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000097:blood / Q000188:drug therapy / Q000378:metabolism*; D016228:Endothelial Growth Factors / Q000378:metabolism; D007150:Immunohistochemistry; D008297:Male; D008315:Malondialdehyde / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000737:chemistry / Q000201:enzymology / Q000473:pathology; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology*
D000975:Antioxidants; D001786:Blood Glucose; D002243:Carbolines; D016228:Endothelial Growth Factors; D014810:Vitamin E; D008315:Malondialdehyde; D000449:Aldehyde Reductase; C100106:dicarbine