Studies on Cataractogenesis in Humans and in Rats with Alloxan-Induced Diabetes

Abstract

Changes in the cation balance cause hydration and initiate the process of lens opacification. Such alterations were studied in human cataractous lenses and during the development of alloxan-induced diabetic cataract in rats by biochemical and histochemical techniques. The development of alloxan-induced cataract in rats was examined in vivo which showed cortical opacities beginning after 32 days. These opacities did progress to maturity after 64 days and finally the lenses were completely opacified after 96 days of alloxan treatment. The histochemical localization of sodium-potassium-activated adenosine triphosphatase using three different methods provided information on the possible role of this enzyme in normal and cataractous lenses. In human cataractous lenses, sodium-potassium adenosine triphosphatase activity was found to be considerably decreased, whereas no activity of this enzyme was localized in human diabetic cataractous lenses. An animal model provided evidence that an apparent decrease of sodium-potassium adenosine triphosphatase may be involved in the initiation of alloxan-induced diabetic cataract in rats.

A proteomic approach to identify early molecular targets of oxidative stress in human epithelial lens cells

“…The incidence of cataract is increased in subjects with G6PDH deficiency [43]. Accordingly, human cataractous lenses showed a decrease in G6PDH activity [44]. Inactivation of these enzymes would slow down glycolysis and the tricarboxylic acid cycle.…”

The Contribution of Fluoride to the Pathogenesis of Eye Diseases: Molecular Mechanisms and Implications for Public Health

“…Previous studies have shown that inhibition of Na+, K+-ATPase activity has been found to accelerate depletion of adenosine triphosphate (ATP), induce mitochondrial depolarization, suppress reactive oxygen species (ROS) scavenging, and enhance ROS production and oxidative stress [122,123,124]. Loss of Na+, K+-ATPase activity is associated with cataract formation [125,126,127,128,129] and age-dependent degeneration in photoreceptors [130]; suggesting a link between loss of Na+, K+-ATPase and AMD.…”

“…The molecular mechanisms by which F inhibits Na+, K+-ATPase enzyme activity have recently been described [208]. As previously elucidated loss of Na+, K+-ATPase enzyme activity is associated with impaired ROS scavenging, enhanced ROS production [122,123,124], cataract formation [125,126,127,128,129] and age-dependent degeneration in photoreceptors [130]. It is long known that F is an inhibitor of the Na+, K+-ATPase enzyme activity [209,210,211,212,213,214,215,216,217,218,219,220].…”

Activities of NADPH-dependent reductases and sorbitol dehydrogenase in canine and feline lenses

“…In addition, it has been observed that in human patients with diabetes mellitus, activities of aldose reductase and sorbitol dehydrogenase vary with stage of the disease. 10,11 Aldose reductase activity is not increased in lenses from people with early-stage diabetic cataracts, 12,13 whereas in lenses from people with hypermature or senile diabetic cataracts, increased aldose reductase activity and decreased sorbitol dehydrogenase activity have been confirmed. 10,11 The purpose of the study reported here was to measure activity of NADPH-dependent reductases, which primarily reflects aldose reductase activity, 14 and sorbitol dehydrogenase activity in lenses from healthy dogs and cats.…”

“…10,11 Aldose reductase activity is not increased in lenses from people with early-stage diabetic cataracts, 12,13 whereas in lenses from people with hypermature or senile diabetic cataracts, increased aldose reductase activity and decreased sorbitol dehydrogenase activity have been confirmed. 10,11 The purpose of the study reported here was to measure activity of NADPH-dependent reductases, which primarily reflects aldose reductase activity, 14 and sorbitol dehydrogenase activity in lenses from healthy dogs and cats. We assumed that the ratio of NADPH-dependent reductases activity-to-sorbitol dehydrogenase activity would provide an estimation of the accumulation rate of sorbitol in the initial stages of hyperglycemia and hypothesized that the ratio for dogs would be significantly different from the ratio for cats.…”