Current eye research
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Current eye research · Apr 2009
Elevated Expression of indoleamine 2,3-dioxygenase (IDO) and accumulation of kynurenic acid in the pathogenesis of STZ-induced diabetic cataract in Wistar rats.
Glycated lens proteins are capable of producing reactive oxygen species (ROS), which, in turn, can oxidize tryptophan (Trp) into kynurenines. Indoleamine 2,3-dioxygenase (IDO), which is expressed in many tissues and which is inducible by interferon-gamma (IFN-gamma), is able to oxidize Trp into kynurenines. These kynurenines can modify lens proteins and, in fact, kynurenine adducts are markedly increased in lenses with age-related nuclear cataract. Therefore, it has been suggested that lenticular IDO is involved in diabetic cataractogenesis. The aim of the present study was to examine the possible role(s) of IDO in streptozotocin (STZ)-induced diabetic cataract in rats. ⋯ Production of IDO was induced in STZ-induced diabetic cataractous lenses, possibly by locally produced IFN- gamma. IDO-mediated oxidation of Trp may partly explain the increase in lens KYNA and may thus be implicated in cataractogenesis in concert with the non-enzymic oxidation of Trp by glycated lens proteins.