Immunochemical Analysis of Parvalbumin Immunoreactivity in the Rat Retina During Experimental Diabetes

Abstract

Abstract: : Purpose: To investigate the alteration of parvalbumin immunoreactivity in the chemically induced diabetic rat retina. Methods: Experimental diabetes was induced by a single intravenous injection of streptozotocin in a dose of 60 mg/kg body weight. Diabetic rats showing high blood glucose levels (above 300 mg/dl) were cared for 1, 4, 12 and 24 weeks, respectively. The retinas at each time point were processed for immunohistochemistry and Western blotting using anti–parvalbumin antibody. Results: In the normal retina, parvalbumin immunoreactivity appeared in AII amacrine cells, amacrine cells of a wide–field type and displaced amacrine cells. A few bipolar cells are also showed the reactivity. During diabetes, the intensity of parvalbumin immunoreactivity is decreased especially in the AII amacrine cells. The cell number of the parvalbumin expressing neurons has showed no large changes throughout the diabetes, except the bipolar cells. That of bipolar cells has increased remarkably at later diabetic periods. The protein level of parvalbumin decreased to lower than that of normal at later diabetic periods. Conclusions: These results suggest that the calcium buffering activity of parvalbumin is shifted from AII amacrine cells to bipolar cells in response to diabetes.

Keywords: retina • diabetic retinopathy • amacrine cells