Abstract
Purpose :
To investigate gamma-glutamyl transpeptidase (GGT, critical to glutathione recapture and cysteine-dependent cell proliferation), Xc- antiporter, (xCT, cysteine transporter), aldose reductase (AR, hyperglycemic oxidative stress marker), oxidized DNA [8-hydroxy-2’-deoxyguanosine (8-OHdG), and annexin V (marker of apoptosis) expression in streptozotocin (STZ)-induced diabetic cataractous and normal rat lens.
Methods :
Gross ocular examinations were performed, and blood glucose levels were determined on control and diabetic rats. Bilateral eye enucleations were performed post euthanasia at 8 weeks and the eyes placed in 70% ethanol. Histopathology was determined on paraffin-embedded sections stained with hematoxylin and eosin. DAPI-treated sections were reacted with antibody to AR, GGT, 8-OHdG, and/or annexin V. The lens distributions were visualized using the immunohistochemical and immunofluorescent antibody methods, and digital images captured for comparative analysis.
Results :
Cytopathological changes consistent with lens epithelial cells disorganization and lens cell hyperplasia were noted in hyperglycemic rat cataractous lenses. GGT was expressed by epithelial cells and diminished to undetectable levels within 1 mm of the control rat lens surface. AR and oxidized DNA (8-OHdG) were detected in normal lens beneath the lens cortex within lens fibers (1 mm from the surface). Xc-antiporter (xCT) expression was reduced in diabetic lens. Weak annexin V reactivity was detected in the lens epithelium. In the diabetic rat lens, GGT expression in epithelial cells was decreased, while GGT was detected on sub-capsular hyperplastic lens cells. Increased AR expression and oxidized DNA (8-OHdG) were detected in the sub-capsular hyperplastic lens fiber cells of diabetic rat lens. Oxidized DNA was detected in annexin V-positive lens epithelial cells of some diabetic lenses.
Conclusions :
The sub-capsular cataractogenic changes in STZ-induced hyperglycemic diabetic rats were associated with increased expression of AR and GGT with oxidized DNA-positive hyperplastic lens fiber cells. The results support hyperglycemia-induced inhibition of epithelial-to-mesenchyme lens fiber cell differentiation and oxidative epithelial cell death as evidenced by annexin V expression.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.