Diabetes Impairs Visual Function and Reduces Cytoprotective Nrf2 Protein Content in Retinas of Rats

Abstract

PurposeTo determine the effect of diabetes and metabolic stress on retinal nuclear factor E2‐related factor‐2 (Nrf2) protein content after light and dark adaptation, and its effect on vision in rats. Darkness was used as a stressor because the retina is more metabolically active in the dark.MethodsLong‐Evans and Sprague‐Dawley rats were made diabetic by streptozotocin (STZ) injection and compared to age‐matched controls (CNT). One group of STZ and CNT rats was sacrificed in light‐adapted conditions; the second group was sacrificed after 24 hr dark adaptation. Retinal Nrf2 protein was determined by immunoblot after 6 and 10 weeks of STZ‐diabetes. Behavioral optokinetic testing was used to measure visual function (spatial frequency threshold and contrast sensitivity) after 6 and 10 weeks of diabetes. Statistical analysis was by ANOVA and Newman‐Keuls test.ResultsThere was significantly less Nrf2 after 6 weeks of STZ‐diabetes (p<0.05), and visual function was also significantly reduced after 6 and 10 weeks of STZ‐diabetes compared to CNT (p<0.05).ConclusionDiabetes impairs visual function in rats and reduces retinal Nrf2 protein content under metabolic stress.