Proteolysis by calpain is an underlying mechanism for formation of sugar cataract in rat lens.
To confirm the effect of a new aldose reductase inhibitor (ARI), rat lenses were cultured with xylose. ARI prevented opacities and reduced lens hydration caused by xylose. Next, cataract was produced by feeding a diet containing 50% galactose. ARI was tested for amelioration of cataract. On day 19 after feeding of galactose, nuclear cataracts were visible in 75% of the animals receiving only galactose, while nuclear cataracts were not observed in animals treated with ARI. In galactose cataract, lens hydration and calcium were significantly increased. Calpain in soluble and insoluble fractions was decreased. Alpha- and beta-crystallins were proteolyzed. These changes were inhibited by administration of ARI. These results suggested that proteolysis by calpain is an underlying mechanism in formation of sugar cataract in rat lens.
Azuma
M
M
Department of Oral Molecular Biology, Oregon Health Sciences University, Portland 97201, USA.
Inoue
E
E
Oka
T
T
Shearer
T R
TR
D000449:Aldehyde Reductase / Q000037:antagonists & inhibitors; D000818:Animals; D052160:Benzothiazoles; D001834:Body Water / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002154:Calpain / Q000378:metabolism*; D002386:Cataract / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D003459:Crystallins / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D005690:Galactose; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D009924:Organ Culture Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D013843:Thiazines / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology; D014994:Xylose
D052160:Benzothiazoles; D003459:Crystallins; D013843:Thiazines; D013844:Thiazoles; C088258:SPR 210; D014994:Xylose; D000449:Aldehyde Reductase; D002154:Calpain; D002118:Calcium; D005690:Galactose