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A. Joy, K. J. Al-Ghoul; Basal Fiber End Architecture in an in vitro Hyperglycemic Lens Culture Model. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4378.
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© ARVO (1962-2015); The Authors (2016-present)
Our laboratory has defined the progressive alteration of posterior fiber ends in a Streptozotocin (STZ)-induced diabetic rat model. The structural breakdown has been correlated with changes in blood glucose levels and the duration of hyperglycemic exposure. This study characterizes the direct effects of hyperglycemia on the basal ends of elongating fibers in an in vitro whole lens culture model.
Twenty-four Wistar rats were euthanized, lenses enucleated and incubated in one of four culture media: Control (<180 mg/dL), Mildly Hyperglycemic (180-260 mg/dL), Moderately Hyperglycemic (261-300 mg/dL) and Severely Hyperglycemic (301-340 mg/dL), for 24 and 48 hours. At the end of the culture period, lenses were processed either for structural analyses using scanning electron microscopy or labeled for F-actin and visualized using a laser scanning confocal microscope.
Lenses cultured in control media were comparable to normal Wistar rat lenses. Specifically, they were transparent, had tightly packed, ovoid basal fiber ends and F-actin was predominantly distributed at the periphery of the basal membrane complex (BMC) and along lateral membrane domains. As expected, lenses cultured in hyperglycemic media showed cellular swelling and extracellular space dilations. These changes were more severe as a function of increasing glucose levels. Discrete opacities were not observed during the limited culture period, although mild cloudiness was noted in a few lenses by 48 hours. Lenses cultured in moderate and severely hyperglycemic media exhibited sutural widening and slightly elongated ends. The actin configuration in experimental lenses showed characteristic features including, discrete foci at cell-cell vertices, prominent stress fiber formation in the BMC and phalloidin-labeled fragments within posterior fiber segments.
Structural alterations seen in the present study, such as fiber swelling/degeneration, fiber end elongation and actin stress fiber formation are consistent with those from STZ-induced diabetic rat lenses. This indicates that hyperglycemia has a direct adverse effect on some aspects of basal fiber end structure and its actin cytoskeleton, which in turn could influence migratory processes.
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