Cataracts Research Today is a free monthly online journal that collates and summarizes the latest research about Cataracts, including details on surgical procedures, outcomes, causes, treatment.

Up-regulation of P-glycoprotein expression by osmotic stress in rat sugar cataract.

Miyazawa T, Kubo E, Takamura Y, Akagi Y

Department of Ophthalmology, Faculty of Medical Science, University of Fukui, 23-3 Shimoaizuki, Matsuoka, Fukui 910-1193, Japan.

P-glycoprotein (P-gp), a plasma membrane protein, is thought to function in the export of cytotoxic drugs and to act as a modulator of chloride channels that regulate cell volume in many cell types. P-gp has been shown to play a role in lens volume regulation and initiation of osmotic cataract. We investigated the lenticular expression levels of P-gp in galactose-fed rats, an experimental model of sugar cataract. P-gp was overexpressed in lenses from galactose-fed rats with cortical sugar cataract, and in rat lens epithelial cells cultured in high-glucose medium. However, application of aldose reductase (AR) inhibitor was able to reverse the changes in P-gp levels in the lenses of galactose-fed rats, confirming the role of AR and involvement of the polyol pathway in cataract formation. Our findings suggest that P-gp may be induced by AR over-expression and/or osmotic stress, thus playing a regulatory role in maintaining lenticular osmotic balance in sugar cataract.

Published 25 December 2006 in Exp Eye Res, 84(2): 246-53.
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