Abstract
Abstract: :
Purpose: To detect alterations in gene expression in neural retinal tissue in rats with a genetic form of diabetes or with dietary galactosemia, which produces a diabetic-like retinopathy, after 8 mo. of metabolic abnormality. Methods: Male rats of the BBZDR strain, a genetic model of diabetes, were maintained either in "poor" blood glucose control for 8 mo., or in good control using insulin for the same period, or in poor control for 4 mo. followed by good control for 4 mo. These were compared to females of the same strain which do not become diabetic. They were also compared to male Sprague Dawley rats, either controls, rats fed a 30% galactose diet for 8 mo., or rats fed 30% galactose for 4 mo. followed by a standard diet for 4 mo. Animals were killed, the retinas excised, total RNA isolated, reverse transcribed to cDNAs, and the cDNAs applied to Affymetrix chips containing 5,000 rat genes for microarray analysis. Raw data were processed using GeneData Analyst software. Results: Several different methods of hierarchical clustering showed close correlations in gene expression between non-diabetic control BBZ and Sprague Dawley animals, compared to well controlled diabetic rats; between Sprague Dawley rats fed galactose for 8 mo. compared to those fed galactose for 4 mo. followed by a normal diet for 4 mo., and between poorly controlled diabetic BBZDR compared to BBZDR rats that were poorly controlled for 4 mo. then well controlled for 4 mo. We identified 254 genes that showed significant (p < 0.05, t-test) alterations in expression in diabetic or galactosemic rats (including those that were "tightly" controlled only for the last 4 mo.) by comparison with control animals, or diabetic rats maintained in "tight" blood glucose control. Conclusions: Chronic diabetes and galactosemia produce virtually identical retinopathies that are critically influenced by the metabolic abnormalities of these disorders. There is evidence that both diabetes and galactosemia act in large part through altering the expression of critical genes, and that both types of retinopathy continue to progress long after the carbohydrate abnormalities have been eliminated. This suggests that the alterations in retinal gene expression are similarly long-lived. We report here that the expression of 254 retinal genes is significantly altered by chronic diabetes or galactosemia in rats, and we propose that among these are genes that may be critical to the pathogenesis of diabetic/galactosemic retinopathy.
Keywords: 388 diabetic retinopathy • 476 molecular biology • 316 animal model