sorbinil and Cataract

Aldose reductase (AR) is widely expressed aldehyde-metabolizing enzyme. The reduction of glucose by the AR-catalyzed polyol pathway has been linked to the development of secondary diabetic complications. Although treatment with AR inhibitors has been shown to prevent tissue injury in animal models of diabetes, the clinical efficacy of these drugs remains to be established. Recent studies suggest that glucose may be an incidental substrate of AR, which appears to be more adept in catalyzing the reduction of a wide range of aldehydes generated from lipid peroxidation. Moreover, inhibition of the enzyme has been shown to increase inflammation-induced vascular oxidative stress and prevent myocardial protection associated with the late phase of ischemic preconditioning. On the basis of these studies, several investigators have ascribed an important antioxidant role to the enzyme. Additionally, ongoing work indicates that AR is a critical component of intracellular signaling, and inhibition of the enzyme prevents high glucose-, cytokine-, or growth factor-induced activation of protein kinase C and nuclear factor-kappa-binding protein. Thus, treatment with AR inhibitors prevents vascular smooth muscle cell growth and endothelial cell apoptosis in culture and inflammation and restenosis in vivo. Additional studies indicate that the antioxidant and signaling roles of AR are interlinked and that AR regulates protein kinase C and nuclear factor-kappaB via redox-sensitive mechanisms. These data underscore the need for reevaluating anti-AR interventions for the treatment of diabetic complications. Potentially, the development of newer drugs that selectively inhibit AR-mediated glucose metabolism and signaling, without affecting aldehyde detoxification, may be useful in preventing inflammation associated with the development of diabetic complications, particularly micro- and macrovascular diseases.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Humans; Imidazolidines; Models, Molecular; Naphthalenes; Oxidation-Reduction; Oxidative Stress; Signal Transduction

Diabetes mellitus has an effect on many organ systems including the eye, kidney and peripheral nerve. Many of these complications develop in animal models of diabetes, which has allowed some of the mechanisms of damage in target organs to be studied. Aldose reductase, an intracellular enzyme, converts glucose to sorbitol, and it is the intracellular accumulation of sorbitol which is thought to result in irreversible damage. In the diabetic eye the increased sorbitol accumulation in both the lens and the retina has been implicated in the pathogenesis of cataract and retinopathy, the major ocular complications of diabetes. In those experimental models which demonstrate characteristic diabetic complications, pharmacological inhibition of the enzyme aldose reductase has resulted in prevention of target organ damage. This paper summarises the experimental evidence upon which the clinical trials of aldose reductase inhibitors in diabetic patients have been initiated and the results of published drug trials in these patients.

Topics: Aldehyde Reductase; Animals; Cataract; Clinical Trials as Topic; Corneal Diseases; Diabetes Mellitus, Experimental; Diabetic Retinopathy; Disease Models, Animal; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Phthalazines; Rats; Retinal Vessels

Aldose reductase inhibitors impede flux of glucose through the sorbitol pathway in diabetes mellitus. They therefore reduce the accumulation of the pathway metabolites, sorbitol and fructose, reduce the impact of the flux on the cofactors used by the pathway and reduce other derived phenomena, such as osmotic stress and myo-inositol depletion. As drugs, their targets are the chronic complications of diabetes--neuropathy, retinopathy, nephropathy and vasculopathy. In experimental models there is proof of activity against biochemical, functional and structural defects in all of the involved tissues, but we await full clinical verification of this potential.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Diabetes Mellitus; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Humans; Imidazoles; Imidazolidines

Topics: Aldehyde Reductase; Animals; Binding Sites; Blood Glucose; Cataract; Chemical Phenomena; Chemistry; Corneal Diseases; Diabetes Complications; Diabetes Mellitus; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Disease Models, Animal; Fluorenes; Galactose; Humans; Hydantoins; Imidazoles; Imidazolidines; Models, Molecular; Naphthalenes; Phthalazines; Rhodanine; Sorbitol; Structure-Activity Relationship; Substrate Specificity; Sugar Alcohol Dehydrogenases; Thiazolidines; Tissue Distribution

Medical treatment of cataract depends on understanding the mechanism of cataract formation. This is established in sugar cataract, in which sugar is metabolised to sugar alcohol. Sugar alcohol accumulates and the resultant osmotic stress is considered to cause lens fibre damage. The conversion of sugar to alcohol is effected by the enzyme aldose reductase and interest now centres around the use of aldose reductase inhibitors. A controlled clinical trial into the effect of the spirohydantoin Sorbinil in adult diabetic cataract has started at Oxford. Aldose reductase inhibitors may also act on non-diabetic cataract, which is supported by some clinical evidence. The biochemical basis of this and other possible treatments for cataract are outlined.

Topics: Adult; Aldehyde Reductase; Cataract; Clinical Trials as Topic; Diabetes Complications; Humans; Imidazoles; Imidazolidines; Random Allocation; Sugar Alcohol Dehydrogenases; Sugar Alcohols

Tissues of the eye affected by diabetes are the lens, cornea, and retina. The lens becomes cataractous through osmotic swelling of its cortical fibers. Sorbitol, formed in the presence of aldose reductase, accumulates in the lens during hyperglycemia. Dulcitol similarly accumulates in the presence of galactosemia. Cataractogenesis in both cases can be prevented by inhibitors of aldose reductase. The efficacy of synthetic inhibitors differs in various tissues and species, but they react with aldose reductase at a common structural site. The most promising inhibitor is sorbinil . Diabetic retinopathy is similarly related to sorbitol accumulation and may be prevented or reversed by inhibition of aldose reductase. Healing of corneal wounds in diabetes is facilitated by enzyme inhibition. Retinal vasculopathy of diabetes is due to selective loss of the intramural pericytes that normally form structural elements in the retinal capillary walls. The vulnerability of these cells is due to their aldose reductase content. Whether inhibition of aldose reductase will prevent retinopathy is being tested in a randomized trial conducted by the National Eye Institute.

Topics: Aldehyde Reductase; Animals; Axonal Transport; Cataract; Corneal Diseases; Diabetic Neuropathies; Diabetic Retinopathy; Disease Models, Animal; Galactosemias; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Osmolar Concentration; Peripheral Nerves; Rats; Sorbitol; Structure-Activity Relationship; Sugar Alcohol Dehydrogenases

An increased prevalence of cataract is associated with diabetes. Biochemical studies of diabetic lenses have revealed a variety of metabolic abnormalities including changes in the levels of electrolytes, glutathione, nucleotides and sugars. Similar biochemical changes have also been observed in cataracts associated with galactosaemia, suggesting that these sugar cataracts have a common biochemical aetiology. The common biochemical factor found to initiate both types of sugar cataract is the formation of sugar alcohols (polyols) from either glucose or galactose by the enzyme aldose reductase (alditol: NADP+ 1-oxidoreductase, EC 1.1.1.21). Increased intracellular levels of these polar alcohols have a hyperosmotic effect which leads to lens fibre swelling, vacuole formation and subsequent opacification. The process of sugar cataract formation in animals can be prevented by inhibiting aldose reductase.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Experimental; Galactose; Galactosemias; Glucose; Humans; Imidazoles; Imidazolidines; Intracellular Fluid; Lens, Crystalline; Mice; Osmosis; Rats; Sugar Alcohols

Aldose reductase (AR) appears to initiate the cataractous process in galactosemic and diabetic animals. Sugars in excess are converted to polyols by lens AR. In sugar cataracts, polyols accumulate to levels substantial enough to cause a hypertonicity leading to lens fiber swelling. All other changes appear secondary to polyol accumulation and lens swelling. The development of sugar cataracts can be duplicated in organ culture. In culture, the various changes that occur were minimized or did not occur when inhibitors of AR were included in the medium. Moreover, AR inhibitors were shown to effectively delay the onset of sugar cataract development in animals. A defect in the corneal epithelium of diabetics became apparent in vitrectomy. One manifestation of this problem was the delay in the reepithelialization of denuded corneas. In examining this problem experimentally, the epithelium was removed from the corneas of diabetic and normal rats. The regeneration of epithelium in corneas of diabetic rats required a longer period than in the normal. The possibility that AR, active in the epithelium, was involved in this phenomenon was investigated. The corneal epithelium was removed from both eyes of a diabetic rat. One eye was treated topically with the AR inhibitor CP-45,634 while the other served as control. The eye treated with CP-45,635 regenerated epithelium much more quickly than the untreated eye. Other AR inhibitors had similar beneficial effects.

Topics: Aldehyde Reductase; Animals; Cataract; Cattle; Chromans; Cornea; Diabetes Complications; Diabetic Retinopathy; Epithelium; Eye Diseases; Female; Galactitol; Galactose; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Mice; Mice, Obese; NADP; Polymers; Pregnancy; Rats; Regeneration; Retina; Rodentia; Sciatic Nerve; Sorbitol; Sugar Alcohol Dehydrogenases; Xylitol

Aldose reductase inhibitors impede flux of glucose through the sorbitol pathway in diabetes mellitus. They therefore reduce the accumulation of the pathway metabolites, sorbitol and fructose, reduce the impact of the flux on the cofactors used by the pathway and reduce other derived phenomena, such as osmotic stress and myo-inositol depletion. As drugs, their targets are the chronic complications of diabetes--neuropathy, retinopathy, nephropathy and vasculopathy. In experimental models there is proof of activity against biochemical, functional and structural defects in all of the involved tissues, but we await full clinical verification of this potential.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Diabetes Mellitus; Diabetic Angiopathies; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Humans; Imidazoles; Imidazolidines

Medical treatment of cataract depends on understanding the mechanism of cataract formation. This is established in sugar cataract, in which sugar is metabolised to sugar alcohol. Sugar alcohol accumulates and the resultant osmotic stress is considered to cause lens fibre damage. The conversion of sugar to alcohol is effected by the enzyme aldose reductase and interest now centres around the use of aldose reductase inhibitors. A controlled clinical trial into the effect of the spirohydantoin Sorbinil in adult diabetic cataract has started at Oxford. Aldose reductase inhibitors may also act on non-diabetic cataract, which is supported by some clinical evidence. The biochemical basis of this and other possible treatments for cataract are outlined.

Topics: Adult; Aldehyde Reductase; Cataract; Clinical Trials as Topic; Diabetes Complications; Humans; Imidazoles; Imidazolidines; Random Allocation; Sugar Alcohol Dehydrogenases; Sugar Alcohols

Cataracts are a leading cause of blindness worldwide. Surgical removal of cataracts is a safe and effective procedure to restore vision. However, a large number of patients later develop vision loss due to regrowth of lens cells and subsequent degradation of the visual axis leading to visual disability. This postsurgical complication, known as posterior capsular opacification (PCO), occurs in up to 30% of cataract patients and has no clinically proven pharmacological means of prevention. Despite the availability of many compounds capable of preventing early steps in PCO development, there is currently no effective means to deliver such therapies into the eye for a suitable duration. To model a solution to this unmet medical need, we fabricated acrylic substrates as intraocular lens (IOL) mimics scaled to place into the capsular bag of the mouse lens following a mock-cataract surgery. Substrates were coated with a hydrophilic crosslinked acrylate nanogel designed to elute Sorbinil, an aldose reductase inhibitor previously shown to suppress PCO. Insertion of the Sorbinil-eluting device into the lens capsule at the time of cataract surgery resulted in substantial prevention of cellular changes associated with PCO development. This model demonstrates that a cataract inhibitor can be delivered into the postsurgical lens capsule at therapeutic levels.

Topics: Actins; Animals; Cadherins; Capsule Opacification; Cataract; Cataract Extraction; Disease Models, Animal; Drug Carriers; Enzyme Inhibitors; Fibronectins; Gene Expression Regulation; Humans; Imidazolidines; Lens, Crystalline; Lenses, Intraocular; Mice; Nanogels; Signal Transduction; Vimentin

Aldose reductase (AR) in the lens plays an important role in the pathogenesis of diabetic cataract (DC) by contributing to osmotic and oxidative stress associated with accelerated glucose metabolism through the polyol pathway. Therefore, inhibition of AR in the lens may hold the key to prevent DC formation. Emodin, a bioactive compound isolated from plants, has been implicated as a therapy for diabetes. However, its inhibitory activity against AR remains unclear. Our results showed that emodin has good selectively inhibitory activity against AR (IC50 = 2.69 ± 0.90 μM) but not other aldo-keto reductases and is stable at 37 °C for at least 7 days. Enzyme kinetic studies demonstrated an uncompetitive inhibition against AR with a corresponding inhibition constant of 2.113 ± 0.095 μM. In in vivo studies, oral administration of emodin reduced the incidence and severity of morphological markers of cataract in lenses of AR transgenic mice. Computational modeling of the AR-NADP(+)-emodin ternary complex indicated that the 3-hydroxy group of emodin plays an essential role by interacting with Ser302 through hydrogen bonding in the specificity pocket of AR. All the findings above provide encouraging evidence for emodin as a potential therapeutic agent to prevent cataract in diabetic patients.

Topics: Aldehyde Reductase; Aldo-Keto Reductases; Animals; Cataract; Diabetes Complications; Diabetes Mellitus, Experimental; Emodin; Humans; Lens, Crystalline; Mice, Transgenic; Molecular Structure; Oxidative Stress; Structure-Activity Relationship

Aldose reductase (ALR2) inhibitors provide a viable mode to fight against diabetic complications. ALR2 exhibit plasticity in the active site vicinities and possible shifts in the nearby two supporting alpha helices. Therefore, a novel series of amino acid conjugates of chromene-3-imidazoles (13-15) were designed and synthesized based on natural isoflavonoids. The compounds were identified on the basis of spectral (

Topics: Aldehyde Reductase; Amino Acids; Animals; Benzopyrans; Blood Glucose; Catalytic Domain; Cataract; Diabetes Complications; Disease Models, Animal; Drug Design; Enzyme Activation; Enzyme Inhibitors; Imidazoles; Inhibitory Concentration 50; Molecular Docking Simulation; Rats; Stereoisomerism; Structure-Activity Relationship

Diabetes mellitus is a major threat to global public health that requires long-term medical attention. In view of the potentially devastating effects of diabetes on ocular health, it highlights the urgent need of therapeutic drugs for the prevention and treatment of the diabetic complications. The patent described in this evaluation (WO2015026380A1) claimed a topical composition for treating diabetic cataracts both in animals and human beings. The composition containing a therapeutic amount of the 2R-methyl sorbinil, one of aldose reductase inhibitors, delivered to the dog's eye can exert a preventive, inhibitory, or prophylactic effect on diabetic cataracts in a statistically significant portion of the population being studied. Thus methods and strategies using new formulations of known inhibitors are promising for future use in the treatment of diabetic complications.

Topics: Administration, Ophthalmic; Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Dogs; Enzyme Inhibitors; Humans; Imidazolidines; Patents as Topic

The acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested in vitro and in vivo as selective aldose reductase (ALR2) inhibitors. Compound PS11 showed highest inhibitory activity (IC(50)) 0.32 microM and was found to be effective in preventing cataract development in severely galactosemic rats when administered as an eyedrop solution. All the compounds investigated were selective for ALR2, since none of them inhibited appreciably aldehyde reductase, sorbitol dehydrogenase, or glutathione reductase.

Topics: Acetic Acid; Aldehyde Reductase; Animals; Benzimidazoles; Cataract; Disease Models, Animal; Enzyme Inhibitors; Galactosemias; Inhibitory Concentration 50; Molecular Structure; Naphthalenes; Ophthalmic Solutions; Rats

The purpose of this study was to evaluate the effect of aldose reductase (AR) inhibition on posterior capsular opacification (PCO) with the use of a pig eye capsular bag model.. Pig eye capsular bags were prepared by capsulorhexis and cultured in medium without or with AR inhibitors for 7 days. Immunostaining was performed in paraformaldehyde-fixed capsular bags to determine the expression of proliferating cell nuclear antigen (PCNA), alpha-smooth muscle actin (SMA), beta-crystallin, and intercellular adhesion molecule (ICAM)-1. The effect of AR inhibition on basic fibroblast growth factor (BFGF)-induced mitogenic signaling in cultured human lens epithelial cells (HLECs) was examined. Cell growth was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and cell counting, the expression of alpha-SMA, beta-crystallin, and ICAM-1 by Western blot and immunocytochemical analysis, protein kinases by Western blot analysis, and NF-kappaB activation by gel shift and reporter assays.. During culture of pig eye capsular bags, residual cells on both the anterior and the posterior capsule showed vigorous growth. Treatment with AR inhibitors significantly prevented the lens epithelial cell growth in capsular bags and expression of alpha-SMA, beta-crystallin, and ICAM-1. HLECs showed a dose-dependent response to BFGF, proliferation at lower concentrations (<20 ng/mL) and differentiation/transdifferentiation at higher concentrations (>50 ng/mL). Inhibition of AR also prevented the BFGF-induced activation of ERK1/2, JNK, and NF-kappaB in HLECs.. Results suggest that AR is required for lens epithelial cell growth and differentiation/transdifferentiation in the capsular bags, indicating that inhibition of AR could be a potential therapeutic target in the prevention of PCO.

Topics: Actins; Aldehyde Reductase; Animals; beta-Crystallins; Blotting, Western; Capsulorhexis; Cataract; Cell Count; Cell Differentiation; Cell Proliferation; Cells, Cultured; Electrophoretic Mobility Shift Assay; Enzyme Inhibitors; Epithelial Cells; Fibroblast Growth Factor 2; Imidazolidines; Immunoenzyme Techniques; Intercellular Adhesion Molecule-1; Lens Capsule, Crystalline; Microscopy, Fluorescence; NF-kappa B; Organ Culture Techniques; Proliferating Cell Nuclear Antigen; Signal Transduction; Swine

Cyano(2-oxo-2,3-dihydroindol-3-yl)acetic acid derivatives were synthesized and tested as a novel class of aldose reductase (ALR2) inhibitors. Each compound was evaluated as a diastereomeric mixture, due to tautomeric equilibria in solution. The parent compound 39 exhibited a good inhibitory activity with an IC(50) value of 0.85 microM, similar to that of the well-known ARI sorbinil (IC(50) 0.50 microM). The concurrent introduction of a halogen and a lipophilic group in the 5- and in the 1-positions, respectively, of the indole nucleus of 39, gave compound 55, cyano[5-fluoro-1-(4-methylbenzyl)-2-oxo-2,3-dihydroindol-3-yl]acetic acid, which displayed the highest activity (IC(50) 0.075 microM, very close to that of tolrestat IC(50) 0.046 microM), with a good selectivity toward ALR2 compared with aldehyde reductase (ALR1) (16.4-fold), and no appreciable inhibitory properties against sorbitol dehydrogenase (SD), or glutathione reductase (GR). The isopropyl ester 59, a prodrug of 55, was found to be almost as effective as tolrestat in preventing cataract development in severely galactosemic rats when administered as an eye drop solution. Docking simulation of 55 into a three-dimensional model of human ALR2 made it possible to formulate the hypothesis that the 2-hydroxy tautomer was the active species binding into the catalytic site of the enzyme. This was fully consistent with the structure-activity relationships within this series of cyanooxoindolylacetic acid derivatives.

Topics: Acetates; Aldehyde Reductase; Animals; Cataract; Enzyme Inhibitors; Galactosemias; Humans; Indoles; Models, Molecular; Ophthalmic Solutions; Rats; Rats, Sprague-Dawley; Stereoisomerism; Structure-Activity Relationship

Acetic acid derivatives of [1,2,4]triazino[4,3-a]benzimidazole (TBI) were synthesized and tested in vitro and in vivo as a novel class of aldose reductase (ALR2) inhibitors. Compound 3, (10-benzyl[1,2,4]triazino[4,3-a]benzimidazol-3,4(10H)-dion-2-yl)acetic acid, displayed the highest inhibitory activity (IC(50) = 0.36 microM) and was found to be effective in preventing cataract development in severely galactosemic rats when administered as an eyedrop solution. All the compounds investigated were selective for ALR2, since none of them inhibited appreciably aldehyde reductase, sorbitol dehydrogenase, or glutathione reductase. The activity of 3 was lowered by inserting various substituents on the pendant phenyl ring, by shifting the acetic acid moiety from the 2 to the 3 position of the TBI nucleus, or by cleaving the TBI system to yield benzimidazolylidenehydrazines as open-chain analogues. A three-dimensional model of human ALR2 was built, taking into account the conformational changes induced by the binding of inhibitors such as zopolrestat, to simulate the docking of 3 into the enzyme active site. The theoretical binding mode of 3 was fully consistent with the structure-activity relationships in the TBI series and will guide the design of novel ALR2 inhibitors.

Topics: Acetates; Aldehyde Reductase; Animals; Benzimidazoles; Binding Sites; Cataract; Enzyme Inhibitors; Galactosemias; Humans; Models, Molecular; Ophthalmic Solutions; Protein Binding; Rats; Stereoisomerism; Structure-Activity Relationship; Triazines

The effects of aldose reductase inhibitors on lens protein modifications induced by naphthalene-1,2-dihydrodiol were investigated in vitro to confirm the role of aldose reductase on naphthalene cataract formation. HPLC analysis of naphthalene-1, 2-dihydrodiol incubated with aldose reductase and NAD+indicated the formation of a metabolite peak corresponding to 1,2-naphthoquinone. Soluble proteins from rat lenses prepared by gel filtration of crude lens extracts through Sephadex PD-10, incubated with naphthalene-1, 2-dihydrodiol in the presence of NAD+displayed an absorbance ca 450 nm and their spectra were essentially identical to those of 1, 2-naphthoquinone-protein adducts. Similar spectra were also obtained from proteins isolated from the intact rat lens after in vitro incubation in medium containing naphthalene-1,2-dihydrodiol. The spectra obtained from lens proteins incubated with 1, 2-dihydroxynaphthalene were distinct from those of either naphthalene-1,2-dihydrodiol or 1,2-naphthoquinone. Aldose reductase inhibitors possessing either hydantoin or carboxylic acid groups prevented protein modification induced by naphthalene-1, 2-dihydrodiol but not protein modification induced by 1, 2-dihydroxynaphthalene or 1,2-naphthoquinone. Therefore, the metabolite formed from naphthalene-1,2-dihydrodiol by aldose reductase is 1,2-naphthoquinone. Lens proteins modified by naphthalene-1,2-dihydrodiol appear essentially identical to protein adducts formed with 1,2-naphthoquinone and their formation can be prevented by both hydantoin and carboxylic acid containing aldose reductase inhibitors.

Topics: Aldehyde Reductase; Animals; Cataract; Chromatography, High Pressure Liquid; Crystallins; Enzyme Inhibitors; Fluorenes; Hydantoins; Imidazoles; Imidazolidines; Lens, Crystalline; Naphthalenes; Naphthols; Naphthoquinones; Phthalazines; Rats; Spectrophotometry

Naphthalene-induced cataract in rat lenses can be completely prevented by AL01576, an aldose reductase inhibitor (ARI). In an attempt to understand the mechanism of this inhibition, several ARIs were examined to compare their efficacies in preventing naphthalene cataract, using both in vitro and in vivo models. Two classes of ARIs were tested: One group including AL01576, AL04114 (a AL01576 analog) and Sorbinil contained the spirohydantoin group, while Tolrestat contained a carboxylic acid group. Furthermore, to clarify if aldose reductase played a role in naphthalene-induced cataractogenesis in addition to its role in sugar cataract formation, a new dual cataract model was established for ARI evaluations. This was achieved by feeding rats simultaneously with high galactose and naphthalene or incubating rat lenses in culture media containing high galactose and naphthalene dihydrodiol. Under these conditions, both cortical cataract and perinuclear cataract developed in the same lens. It was found that at the same dosage of 10 mg/kg/day, both AL01576 and AL04114 completely prevented all morphological and biochemical changes in the lenses of naphthalene-fed rats. Sorbinil was less efficacious, while Tolrestat was inactive. AL01576 showed a dose-response effect in preventing naphthalene cataract and at 10 mg/kg/day, it was also effective as an intervention agent after cataractogenesis had begun. With the dual cataract model, Tolrestat prevented the high galactose-induced cortical cataract but showed no protection against the naphthalene-induced perinuclear cataract. AL01576, on the other hand, prevented both cataract formations. Results for dulcitol and glutathione levels were in good agreement with the morphological findings. AL04114, and ARI as potent as AL01576 but without its property for cytochrome P-450 inhibition, displayed similar efficacy in preventing naphthalene cataract. Based on these results, it was concluded that the prevention of the naphthalene cataract probably results from inhibition of the conversion of naphthalene dihydrodiol to 1,2-dihydroxynaphthalene and that the effect of the ARIs cannot be explained by their inhibition of the dihydrodiol dehydrogenase activity of aldose reductase.

Topics: Aldehyde Reductase; Animals; Cataract; Culture Techniques; Disease Models, Animal; Enzyme Inhibitors; Fluorenes; Galactose; Hydantoins; Imidazoles; Imidazolidines; Male; Naphthalenes; Rats; Spiro Compounds

Free radicals have extremely short half-lives and they readily oxidize lipids and initiate an autocatalytic chain reaction of lipid peroxidation, which leads to the formation of lipid peroxides. The lipid peroxides undergo degradation to form metastable lipid aldehydes such as 4-hydroxynonenal (HNE). We have shown earlier that under hyperglycemia, lipid peroxides increase; and aldose reductase, an enzyme that reduces glucose to sorbitol, efficiently reduces HNE. The purpose of the present studies was thus to investigate the role of HNE in hyperglycemic cataract and understand the mechanism(s) of its prevention by antioxidants and aldose reductase inhibitors. HNE and hyperglycemic cataract were developed by culturing rat lenses in TC-199 medium containing 50 microM HNE and 50 mM glucose, respectively. The effect of an anti-oxidant, trolox, and an aldose reductase inhibitor, sorbinil, on the progression of HNE and hyperglycemic cataract, evaluated by digital image analysis, was followed for 8 and 9 days, respectively. In lenses cultured with HNE, the decrease in transmitted light was 43, 65, and 87% on Days 3, 5, and 8, respectively. Trolox ameliorated the HNE cataract, whereas sorbinil accelerated the progression of HNE cataract and prevented the progression of hyperglycemic cataract. It is concluded that HNE formed under hyperglycemia may play a pivotal role in diabetic cataractogenesis.

Topics: Aldehyde Reductase; Aldehydes; Animals; Cataract; Chromans; Cross-Linking Reagents; Enzyme Inhibitors; Image Enhancement; Imidazoles; Imidazolidines; Rats

To determine if the retinal microangiopathies of the galactose-fed rat model of diabetic retinopathy can be prevented with the aldose reductase inhibitor sorbinil.. Sprague-Dawley rats were fed 50% d-galactose with or without sorbinil (0.05% wt/wt), mixed biweekly with fresh diet. Rats in each group were examined frequently by slit lamp and were killed after 8, 16, and 24 months. Computer-assisted morphometry was performed on wholemounts of elastase retinal digest preparations.. Cataracts developed in all galactose-fed untreated rats within 3 weeks but not in the sorbinil-treated rats even after 24 months. At 8 months, the galactose-fed untreated rats exhibited statistically significant increases in the mean capillary width, the percent of retinal area occupied by capillaries (capillary density), and the percent of microvascular area with capillaries > 20 microns wide (dilated channels), compared to controls. At 16 months, the galactose-fed untreated rats showed statistically significant increases over controls in both total mean capillary length and density, and two of the four rats examined had microaneurysms. At 24 months, all the galactose-fed untreated rats had microaneurysms and extensive areas with hypercellular meshworks composed of dilated channels characteristic of intraretinal microvascular abnormalities (IRMA). By contrast, galactose-fed, sorbinil-treated rats, at 24 months, had no IRMA and showed no statistically significant differences from control rats in any of the parameters measured morphometrically.. All the galactose-induced retinal microangiopathies were prevented with sorbinil. Aldose reductase inhibitors may be beneficial in ameliorating the similar vascular lesions characteristic of human diabetic retinopathy, though the mechanism remains obscure.

Topics: Aldehyde Reductase; Animals; Capillaries; Cataract; Diabetic Retinopathy; Disease Models, Animal; Enzyme Inhibitors; Galactose; Image Processing, Computer-Assisted; Imidazoles; Imidazolidines; Male; Rats; Rats, Sprague-Dawley; Retinal Vessels

The suitability of the galactose-fed rat as a model of diabetic retinopathy was examined in nondiabetic rats fed diets enriched with either 30% or 50% galactose for up to 2 years.. Retinal capillaries were examined by light and electron microscopy, and the prevalence or severity of diabetic-like lesions was quantitated.. Histologic evaluation of trypsin digests of retina revealed significantly greater than normal frequencies of pericyte ghosts and acellular capillaries at both 15 and 23 months receiving a 50% galactose diet. Similar lesions were observed in rats receiving a 30% galactose diet for 23 months. Capillary basement membrane thickening, dilated hypercellular capillaries (or intra-retinal microvascular abnormalities), and foci of vascular cells appeared in rats fed 50% galactose, but saccular microaneurysms characteristic of retinopathy in diabetic patients, diabetic dogs, and experimentally galactosemic dogs were not observed. Administration of the aldose reductase inhibitor, Sorbinil, to rats fed 50% galactose resulted in a significant inhibition of cataract and of galactitol accumulation in nerve and blood (by more that 90%) and retina (by 62%), but did not inhibit development of the retinal microvascular lesions.. Two years of galactosemia in rats seems to reproduce only a portion of the lesions characteristic of diabetic retinopathy in patients or dogs. Nevertheless, lesions characteristic of at least the early stages of retinopathy clearly do develop in this galactosemic rat model, and are not restrained by inhibition of retinal polyol accumulation by 62%.

Topics: Aldehyde Reductase; Animals; Basement Membrane; Capillaries; Cataract; Diabetic Retinopathy; Disease Models, Animal; Erythrocytes; Galactitol; Galactose; Galactosemias; Imidazoles; Imidazolidines; Male; Rats; Rats, Sprague-Dawley; Retina; Retinal Vessels; Sciatic Nerve

Diabetic retinopathy, the leading cause of blindness among young adults in the developed world, is characterized by vascular changes of the retinal capillary bed. Beagles fed a diet containing 30% galactose develop retinal vascular lesions that are similar to those observed in diabetics. These progress from initial retinal changes which include aldose-reductase-linked formation of pericyte ghosts and the subsequent development of acellular capillaries, microaneurysms, and intraretinal hemorrhages to the appearance of occluded vessels, areas of nonperfusion, and intraretinal microvascular abnormalities (IRMA) and in the final stages, the formation of fibrovascular membranes on both the retinal surface and the posterior hyaloid membrane. In prevention studies utilizing 0.5, 5.0, 10, and 16 mg/kg/day of the aldose reductase inhibitor M79175 (2-methyl-6-fluoro-spirochroman-4-5'-imidazolidine-2',4'-dione), pericyte ghost formation, and the subsequent appearance of microaneurysms, intraretinal hemorrhages, acellular capillaries associated with background retinopathy were arrested in a dose-dependent manner. Similar dose-dependent changes in the appearance of cataracts were also observed. The dog represents the first animal model to demonstrate all of the clinical and histological retinal vessel changes observed in human diabetics.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetic Retinopathy; Dogs; Dose-Response Relationship, Drug; Galactose; Imidazoles; Imidazolidines; Male; Retina; Retinal Vessels

Topics: Aldehyde Reductase; Animals; Cataract; Diabetic Retinopathy; Dogs; Galactosemias; Imidazoles; Imidazolidines; Research Design

We reported that in utero galactose-induced cataracts could be inhibited if aldose reductase inhibitors (ARIs) were included in the galactose diet of pregnant rats. These studies involved morphological and cytochemical approaches. We undertook this investigation to evaluate the effects of ARIs in preventing the formation, accumulation and depletion of dulcitol in lenses of in utero galactose exposed neonates and in mothers during and following pregnancy. Sprague Dawley rats were fed Purina Rat Chow with 50% galactose either with or without 15mg Sorbinil or 1mg Eisai compound E-0722/day/Kg body weight during and following pregnancy. The lenses of neonates and mothers were processed to determine dulcitol concentrations. At parturition there was a significant amount of dulcitol in the lenses of pups and their mothers, which reduced rapidly in the lenses of pups regardless of the diet fed to the nursing mother. While galactose had a cross-placental but not a milk-mediated effect, the ARIs had both cross-placental and milk-mediated effects on dulcitol accumulation and depletion, respectively. The galactose feeding of mothers post-parturition maintained the high lenticular dulcitol concentration and the absence of galactose led to a reduction in lenticular dulcitol. The correlation between dulcitol accumulation and cataract development is discussed.

Topics: Aldehyde Reductase; Animals; Animals, Newborn; Cataract; Female; Galactitol; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Maternal-Fetal Exchange; Pregnancy; Rats; Rats, Sprague-Dawley

Retinal vessel changes in 36-month 30% galactose-fed beagles treated with or without aldose reductase inhibitors were quantified using an Olympus Cue-3 color image analysis system. Individual maps of the intact retinal vasculature, isolated by trypsin-digestion, were divided into 24 distinct subregions and measurements of either the endothelial cell to pericyte (E/P) ratio or cell densities, expressed as pericytes per mm capillary length or endothelial cells per mm capillary length, were conducted in 0.1 mm2 areas surrounding the midpoints of 12 subregions associated with the highest incidence of microaneurysms. Significantly increased E/P ratios and decreased pericyte densities were observed with the duration of galactose-feeding. These retinal changes were reduced by aldose reductase inhibitor treatment. Correlations between the E/P ratio and either number of microaneurysms or cataract severity were also observed. These data support the dose-dependent effects of aldose reductase inhibitors in preventing pericyte degeneration and subsequent formation of microaneurysms (Archives Ophthalmol. 108:1301, 1990).

Topics: Aldehyde Reductase; Animals; Cataract; Cell Count; Diabetic Retinopathy; Dogs; Endothelium, Vascular; Galactose; Image Processing, Computer-Assisted; Imidazoles; Imidazolidines; Male; Retinal Vessels

We have shown that galactose cataract development is delayed or inhibited with the administration of aldose reductase inhibitors (ARIs). Dulcitol forms and accumulates in the lens of rats fed galactose. We undertook investigations to study the effectiveness of ARIs in preventing the formation and accumulation of dulcitol in the lens. Young Sprague Dawley rats were fed Purina Rat Chow with 50% galactose either with or without 15 mg sorbinil, 0.15, 0.5, or 1.0 mg E-0722/day/Kg body weight. At desired intervals following the initiation of diets, the lenses were processed for the determination of galactose and dulcitol levels. The lenticular dulcitol increased significantly in all animals fed galactose reaching a maximum level by approximately 15 days with comparatively lower levels in the groups fed ARIs with galactose; this increase was dose dependent in the groups fed E-0722. There was a subsequent, rapid drop in lenticular dulcitol by 18 days in all dietary groups. Interestingly, a second peak of increased lenticular dulcitol was observed in all groups. The correlation between dulcitol accumulation and cataract development is discussed.

Topics: Aldehyde Reductase; Animals; Cataract; Dietary Carbohydrates; Galactitol; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Rats; Rats, Sprague-Dawley

Young beagle dogs were fed a 30% galactose diet, with or without the aldose reductase inhibitors sorbinil or M79175. Cataract formation was monitored by indirect ophthalmoscope and hand-held slit-lamp microscopy and documented by retroillumination photography. In these dogs, the first sign of cataract development was an accentuation of the anterior and posterior lens sutures (1 month after feeding), then the appearance of cortical vacuoles (3 months after feeding), and finally, the formation of predominantly equatorial cortical opacities toward the posterior cortices (4-6 months after feeding). After long-term galactose feeding, a progressive, irregular, clear zone formed at the cortical equatorial regions. Light microscopic examination of these lenses shows that the cataracts are osmotic, many of the lens fibers appear to be swollen or ruptured, and vacuoles are seen near the bow region. Moreover, these histologic changes were reduced in a dose-dependent manner in galactose-fed dogs concomitantly treated with the aldose reductase inhibitors sorbinil or M79175. The osmotic nature of these cataracts and the observation that their formation can be reduced in a dose-dependent manner by aldose reductase inhibitors are consistent with the concept that the aldose-reductase catalyzed formation of polar sugar alcohols (polyols) initiates sugar cataract formation in the dog.

Topics: Aldehyde Reductase; Animals; Cataract; Dietary Carbohydrates; Disease Models, Animal; Dogs; Dose-Response Relationship, Drug; Galactose; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Photography; Random Allocation; Rats; Rats, Inbred Strains

Properties and efficacies of novel aldose reductase (AR) inhibitors, M16209 (1-(3-bromobenzo[b]furan-2-ylsulfonyl)hydantoin) and M16287 (1-(3-chlorobenzo[b]furan-2-ylsulfonyl)hydantoin), were examined in vitro and in vivo, compared with known AR inhibitors, ONO-2235 and sorbinil. These four compounds inhibited partially purified aldose reductases from various origins, and the potencies of M16209 and M16287 were on the whole similar to ONO-2235, and were greater than that of sorbinil. The IC50 values of the four AR inhibitors did not substantially depend on the substrate used. Kinetic studies of inhibition of partially purified bovine lens (BLAR) revealed that M16209, M16287 and sorbinil were uncompetitive with glyceraldehyde and noncompetitive with nicotineamide adenine dinucleotide phosphate (NADPH), whereas ONO-2235 was noncompetitive with both glyceraldehyde and NADPH. Aldose reductase became less sensitive to the four inhibitors as enzyme purification progressed, although the susceptibility to inhibition was partially reversed by incubation with dithiothreitol. In addition, the four compounds slightly affected those enzymes of carbohydrate and glutathione metabolism which were tested. M16209 and M16287 prevented sorbitol accumulation in isolated rat tissues as potently as ONO-2235 and sorbinil. M16209 and M16287 were effective in the prevention of galactosemic cataracts and amelioration of diabetic neuropathy with almost the same potency, while ONO-2235 was effective only in neuropathy, and sorbinil was effective in galactosemic cataracts and diabetic neuropathy with a different potency. These results indicate that M16209 and M16287 are potent aldose reductase inhibitors, which could be applicable to treatment for diabetic complications.

Topics: Aldehyde Reductase; Animals; Benzofurans; Cataract; Cattle; Diabetic Neuropathies; Hydantoins; Imidazoles; Imidazolidines; In Vitro Techniques; Male; Rats; Rats, Inbred Strains; Rhodanine; Sorbitol; Thiazolidines

It has been suggested that sugar cataracts associated with diabetes mellitus result from the accumulation of excess sorbitol within lens fibrils. Swelling of lens fibrils occurs when water moves in to maintain osmotic balance; the excess water causes disruption of fibrils and cataract formation. Other studies have indicated that more than sorbitol-induced osmotic stress is involved. Our study used lenses collected from rats after 21 or 44 d of streptozotocin diabetes. Cataracts formed in untreated 44-d streptozotocin diabetic rats, but were not apparent in the 21-d untreated diabetic animals. Lens sorbitol increased in the diabetic animals both before and after cataract formation. Lens taurine varied inversely with the sorbitol content in a fashion that resulted in no net change in total lens osmoles. Lens water did not increase in the diabetic animals with or without cataracts. The aldose reductase inhibitor Sorbinil prevented the increase in lens sorbitol in both the 21- and 44-d streptozotocin diabetic rats; cataract formation was prevented in the 44-d diabetic animals. The lens water in untreated diabetic animals with cataracts did not differ from lens water in the Sorbinil-treated diabetic animals that did not develop cataracts. Sorbinil treatment of diabetic animals was associated with normalization of both lens sorbitol and taurine levels. Taurine has been shown to serve both as an osmoregulator and as an antioxidant. The apparent increase in lens osmolality attributed to sorbitol was counterbalanced by an equimolar reduction in taurine concentration. The reciprocal relationship between taurine and sorbitol reduces the likelihood of an osmotic mechanism for sugar cataractogenesis; the reduced lens taurine, however, may increase the risk of lens protein oxidation and subsequent cataract formation. Thus in vivo sugar cataract formation may be an oxidative process rather than an osmotic phenomenon.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus, Experimental; Imidazoles; Imidazolidines; Inositol; Lens, Crystalline; Male; Rats; Rats, Inbred Strains; Sorbitol; Streptozocin; Sugar Alcohol Dehydrogenases; Taurine

Kidney cortex sialic acid level, sialidase and sialyltransferase activities have been measured in spontaneously diabetic BB rats and in streptozotocin-diabetic rats (STZ). In untreated diabetic BB rats, at the onset of the disease, sialidase specific activity was found to be increased by 21% when compared with diabetes-resistant BB controls (P less than 0.05) whereas sialyltransferase activity was not significantly modified and bound sialic acid concentration was diminished (P less than 0.05). In diabetic BB rats submitted to a minimal insulin therapy, during 3 months of disease, sialidase activity and sialic acid concentration were similar to those of Wistar age-matched controls. In STZ-diabetic Wistar rats, sialidase specific activity was increased by 76% after 5 months of disease when compared to age-matched Wistar controls (P less than 0.01); in contrast, specific sialyltransferase activity was decreased by 21% (P less than 0.05); these enzymatic alterations were associated with a decrease in bound sialic acid concentration (P less than 0.01); 1 month's insulin therapy, started 4 months after onset of the disease, normalized sialidase activity but had no effect on sialyltransferase activity and sialic acid concentration; treatment with sorbinil prevented cataract development but had no effect on sialidase activity whereas it emphasized the decrease in sialyltransferase activity and sialic acid concentration. The disturbances in the enzyme activities concerned with sialoglycoconjugate metabolism observed in experimental and spontaneous diabetes may be responsible for the decreased bound sialic acid content observed in the rat kidney cortex.

Topics: Animals; beta-D-Galactoside alpha 2-6-Sialyltransferase; Cataract; Diabetes Mellitus, Experimental; Imidazoles; Imidazolidines; Insulin; Kidney; Kidney Cortex; N-Acetylneuraminic Acid; Neuraminidase; Organ Size; Rats; Rats, Inbred BB; Sialic Acids; Sialyltransferases

The Octodon degus has been reported to have higher aldose reductase activity in the lens compared to the gerbil and rat. When made diabetic the degus develop cataracts within 4 weeks. We have been able to completely prevent cataract formation in diabetic degus using Pfizer's sorbinil for up to 6 months. This is further evidence of the role of aldose reductase in the formation of cataracts in diabetes.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus, Experimental; Disease Models, Animal; Imidazoles; Imidazolidines; Lens, Crystalline; Rodentia; Streptozocin; Sugar Alcohol Dehydrogenases

Our previous studies have shown that the aldose reductase inhibitor (ARI), sorbinil, prevents galactose-induced alterations and cataracts in rat lenses. We have now used sorbinil as well as another ARI, Eisai compound E-0722, to determine their potency in inhibiting aldose reductase- and galactose-induced alterations in lens morphology and Na+-K+-ATPase activity. Young Sprague Dawley rats were fed Purina Rat Chow plus 50% galactose, with or without 15 mg sorbinil, 0.15, 0.5 or 1.0 mg of E-0722/kg body weight per day. Controls were given Purina Rat Chow with or without ARIs. Lenses were studied for up to 60 days following the initiation of the diet using morphological, cytochemical and biochemical approaches to assess any alterations in the lens. While galactose-induced damage and cataracts were delayed by low doses (0.15 mg and 0.5 mg) of E-0722, they were completely prevented by the administration of 15 mg of sorbinil or 1 mg of E-0722/kg body weight per day. This study further showed that just 1 mg of E-0722 was more effective in preventing cataracts than 15 mg sorbinil. Thus it appeared that E-0722 was a more potent inhibitor of aldose reductase than sorbinil.

Topics: Aldehyde Reductase; Animals; Cataract; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Rats; Rats, Inbred Strains; Sodium-Potassium-Exchanging ATPase; Sugar Alcohol Dehydrogenases; Time Factors

Fresh intact human cataracts (derived from patients with mature-onset diabetes mellitus and from nondiabetic patients), normal human lenses between 2 and 71 years old and lenses derived from 1.5- to 5-kg rabbits were incubated in Earle's media containing enriched 13C-glucose (5 and 15 mM). 31P NMR organophosphate profiles were obtained at the start and end of each incubation. Sorbinil was added to one of each pair of selected lenses, both incubated with 13C-glucose. All the lenses were frozen after 4h of incubation and were subsequently assayed by 13C NMR spectroscopy. The results demonstrate significant sorbitol generation only in young lenses which can be inhibited by Sorbinil. None of the older normal and cataractous human lenses or the mature-onset diabetic cataracts were capable of generating measurable sorbitol levels although they all showed active glucose metabolism and their organophosphate profiles demonstrated normal high-energy phosphate levels. Increased sugar phosphate levels were usually found in the mature-onset diabetic cataracts. Although our NMR spectroscopy is only sensitive to 10(-3) M levels, such concentrations of sorbitol are required to exert their osmotic effects. These data indicate that high sorbitol levels can only be generated in young human and rabbit lenses and correlate well with the age-related changes in aldose reductase activity in these lenses.

Topics: Adolescent; Adult; Aged; Animals; Cataract; Child; Child, Preschool; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Magnetic Resonance Spectroscopy; Middle Aged; Rabbits; Sorbitol

When rat lens is incubated in 30 mM galactose overnight, the extent of accumulation of rubidium ions (Rb) and myoinositol (MI) are affected, as well as the Na-K ATPase activity. Rb accumulation and Na-K ATPase activity are only slightly affected compared to the dramatic drop in MI accumulation. These changes are completely abolished by sorbinil, which blocks polyol formation, or by rendering the galactose medium hypertonic to offset the osmotic effect of polyol formation. On the other hand, the addition of excess MI to the galactose medium had no effect on correcting these changes. The results obtained are consistent with the polyol-osmotic theory of sugar cataract formation.

Topics: Aldehyde Reductase; Animals; Cataract; Galactose; Hypertonic Solutions; Imidazoles; Imidazolidines; Inositol; Lens, Crystalline; Male; Radioisotopes; Rats; Rubidium; Sodium-Potassium-Exchanging ATPase

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus; Dogs; Glyceraldehyde; Humans; Imidazoles; Imidazolidines; L-Iditol 2-Dehydrogenase; Lens, Crystalline; Rabbits; Rats; Sugar Alcohol Dehydrogenases

Diabetic cataractogenesis, a multifactorial process, was examined with nuclear magnetic resonance (NMR). P-31 NMR spectroscopic studies showed substantial alteration of both energy and membrane metabolism in the diabetic lens. Findings from a C-13 NMR spectroscopic determination of the sorbitol pathway flux in lenses incubated in 35.5 mmol/L glucose revealed that (1) one-third of total glucose consumed was channeled through this pathway, and (2) the turnover rate of NADPH to NADP was 3,000%/hr. Furthermore, a competition for NADPH between aldose reductase and glutathione reductase was demonstrated. It is important to note that all metabolic changes in hyperglycemic/diabetic lenses can be prevented by aldose reductase inhibitors, eg, sorbinil.

Topics: Adenosine Triphosphate; Aldehyde Reductase; Animals; Cataract; Cell Membrane; Diabetes Complications; Glucose; Glycerophosphates; Humans; Imidazoles; Imidazolidines; Lens, Crystalline; Magnetic Resonance Spectroscopy; NADP; Oxidation-Reduction; Rats; Sorbitol; Sugar Alcohol Dehydrogenases

Cataracts associated with diabetes and galactosemia are characterized by their rapid onset and bilateral appearance. These cataracts display similar morphology and histology and have common biochemical mechanisms initiating the cataractous processes. An understanding of these biochemical mechanisms have been aided both by the ability to reproduce these cataracts in various animal models and by the development of potent inhibitors of aldose reductase. This is a US government work. There are no restrictions on its use.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Diabetes Mellitus, Experimental; Imidazoles; Imidazolidines; L-Iditol 2-Dehydrogenase; Lens, Crystalline; Mice; NADP; Osmotic Pressure; Oxidation-Reduction; Rabbits; Rats; Rodentia; Sorbitol; Sugar Alcohol Dehydrogenases

The isolated cultured rat lens has been used to examine the effects of the aldose reductase inhibitor sorbinil on lenticular polyol accumulation and sugar cataract formation. Lenses incubated in medium containing 35 mmol/L glucose accumulated sorbitol over a seven-day period without the appearance of overt opacities. Sorbitol accumulation was inhibited in a dose response fashion by sorbinil with an IC50 of 3.1 X 10(-6) mol/L. In lenses incubated in the presence of 29.5 mmol/L xylose, xylitol accumulation was accompanied by an increase in the water content of the lens and the development of a classical sugar cataract. All of these effects could be prevented by the addition of sorbinil to the culture medium. Complete inhibition of cataract formation required greater than an 80% inhibition of the xylitol accumulation. Reversal of a preformed xylose cataract by sorbinil could be achieved if the inhibitor was added at the stage of cortical opacities (20 h). Cataract progression proceeded normally over the next 48 hours and then the lens slowly began to clear. The rate of the reversal was dependent on the dose of sorbinil.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Complications; Hyperglycemia; Imidazoles; Imidazolidines; Lens, Crystalline; Male; Organ Culture Techniques; Rats; Rats, Inbred Strains; Sorbitol; Sugar Alcohol Dehydrogenases; Xylitol

Nephropathy is a serious complication of Type I or insulin-dependent diabetes mellitus (IDDM) with a poor prognosis after the onset of proteinuria. Since aldose reductase may be implicated in the pathogenesis of proteinuria, onset and reversal studies were performed with sorbinil at a dose of 20 mg/kg to determine whether inhibition of this enzyme promoted either diminution or reversal of the appearance of urinary proteins. In the onset study, age-matched control, streptozotocin-diabetic, and sorbinil-treated diabetic rats were maintained for ten weeks; their 24-hour urine samples were analyzed weekly for volume, glucose, ketones, total protein, and individual protein components with molecular weights between 15,000 and 120,000 daltons. These last were examined by polyacrylamide gel electrophoresis and quantitated by laser densitometric analysis. Results indicated that sorbinil administered daily for ten weeks effectively diminished total protein excretion throughout this period primarily by protecting against appearance of abnormal urinary proteins that characterized the untreated diabetic state; the latter exhibited albuminuria, numerous newly detected proteins between 30,000 and 65,000 daltons, and an additional 4 to 5 proteins between 70,000 and 120,000 daltons. These findings closely resembled protein patterns exhibited by 54-week spontaneously diabetic BB rats, another model for IDDM. In the reversal study, age-matched control and streptozotocin-induced diabetic rats were maintained for four weeks, and weekly 24-hour urine analyses were performed as previously described.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Nephropathies; Electrophoresis, Polyacrylamide Gel; Humans; Imidazoles; Imidazolidines; L-Iditol 2-Dehydrogenase; Proteinuria; Rats; Rats, Inbred BB

Topics: Aldehyde Reductase; Body Water; Cataract; Collagen; Diabetes Complications; Diabetes Mellitus; Diabetic Neuropathies; Hand; Humans; Imidazoles; Imidazolidines; Joint Diseases; Models, Biological

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus, Experimental; Glucose; Imidazoles; Imidazolidines; Lens, Crystalline; Rats; Sorbitol; Sugar Alcohol Dehydrogenases

Aldose reductase is implicated in the pathogenesis of diabetic cataracts; therefore, inhibition of this enzyme subsequent to cataractogenesis may represent a therapeutic approach for restoration of lens physiology. In the present study, the effect of aldose reductase inhibition subsequent to stage I cataract formation was investigated in the streptozocin-induced diabetic rat. Our results indicated that the aldose reductase inhibitor sorbinil, a spirohydantoin, arrested further progression and promoted a reparative process despite continuation of hyperglycemia and elevated lens glucose. Quantitative analysis of scanning electron micrographs indicated that the afflicted lens regions were contained and their cellular components stabilized with regard to fiber hydration and interdigitation. The reparative process included: normalization of lens sorbitol, gradual recovery of existing fiber contour and interdigitation, production of new fibers, and partial restoration of lens myo-inositol content.

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus, Experimental; Glucose; Imidazoles; Imidazolidines; Inositol; Lens, Crystalline; Microscopy, Electron, Scanning; Rats; Rats, Inbred Strains; Sorbitol; Sugar Alcohol Dehydrogenases

Previous cytochemical and biochemical studies have shown an increase in the activity of acid phosphatase and arylsulfatase during the induction of galactose cataracts in rat lenses. It was postulated that these enzymes may be involved in lens fiber degradation observed during cataractogenesis, however, the role of these enzymes in the repair process was not ruled out. The present investigation has evaluated the level of acid phosphatase activity in lenses in which the induction of opacity is inhibited with the aldose reductase inhibitor sorbinil and during the recovery of galactose induced opacity. Sprague-Dawley rats received 50% galactose diet, or galactose diet with sorbinil, or laboratory chow diet. Following 20 days on this diet all rats received lab chow plus 50 mg kg-1 sorbinil (recovery diet). The lenses were removed at desired intervals following the initiation of the above three diets and following the transfer of animals to the recovery diet. Cytochemical localization and biochemical quantitation of acid phosphatase activity were performed with methods previously reported. Most of the enzyme activity was localized within the epithelial cells and superficial cortical fibers. In the epithelial cell layer, the enzyme activity was primarily localized in lysosomes and at extracellular sites near the epithelial cell membrane which abut each other and cortical fibers. In cortical fibers the enzyme activity was observed at various extracellular sites between the cell membranes of neighboring fibers. The effect of sorbinil, if any, and the possible role of acid hydrolases in the repair process during cataract reversal is discussed.

Topics: Acid Phosphatase; Aldehyde Reductase; Animals; Cataract; Female; Galactose; Histocytochemistry; Imidazoles; Imidazolidines; Lens, Crystalline; Lysosomes; Microscopy, Electron; Rats; Rats, Inbred Strains

Aldose reductase is implicated in the pathogenesis of sugar cataracts; therefore, inhibition of this enzyme subsequent to cataractogenesis may represent a therapeutic approach for the restoration of lens physiology despite the persistence of diabetes or galactosemia. In the present study, the effect of aldose reductase inhibition subsequent to stage-I cataract formation was investigated in the galactose-maintained rat. Our results indicated that despite continuation of galactose feeding the aldose reductase inhibitor, Sorbinil, a spirohydantoin, arrested further progression and promoted a reparative process. Quantitative analysis of scanning electron micrographs indicated that the afflicted lens regions were contained and their cellular components stabilized with regard to fiber hydration and interdigitation. The reparative process involved: decrease in lens dulcitol, gradual recovery of fiber thickness and partial restoration of lens myo-inositol content. At this stage of cataractogenesis, despite continuance of galactose feeding, the effects of Sorbinil treatment were comparable to the reparative process achieved by restoration of a normal diet.

Topics: Aldehyde Reductase; Animals; Cataract; Diet; Female; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Rats; Rats, Inbred Strains; Sugar Alcohol Dehydrogenases

Sorbinil, an aldose reductase inhibitor, in combination with diet normalization, arrested stage-II galactose cataract and restored lens transparency. During the reversal process, determination of lens dry weight, dulcitol and myo-inositol content as well as individual fiber cell ultrastructure offered a comprehensive index of lens integrity. In this study, young rats received a 50% galactose diet for 10 days to produce a stage-II sugar cataract. Then they were placed on one of the following diets: 50% galactose and Sorbinil (20 mg/kg); 50% galactose; normal diet, normal diet and Sorbinil (20 mg/kg). From each group, equal numbers were sacrificed at 5, 10 and 20 days. Although differences were obtained after 5 and 10 days, the 20-day reversal period provided the most significant findings. Only the combination of Sorbinil and normal diet restored lens transparency, normalized lens myo-inositol content and dry weight and partially restored fiber cell integrity as evidenced by diminished granulation and increased fiber synthesis. Neither Sorbinil treatment during galactose administration nor normal diet alone were sufficient to protect against further cataractogenesis, thus indicating a synergistic effect of Sorbinil in combination with normal diet.

Topics: Aldehyde Reductase; Animals; Cataract; Combined Modality Therapy; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Male; Rats; Rats, Inbred Strains; Sugar Alcohol Dehydrogenases

We have demonstrated an increase in activity of arylsulfatase A and B during galactose induced cataract development in rats. Our recent investigation shows that acid phosphatase activity, which increases substantially during galactose cataract development in rats, could be contained to near normal level if Sorbinil, an aldose reductase inhibitor, was fed along with galactose to the rat. We have observed that the activity of other lysosomal enzymes, arylsulfatase A and/or B, also increases during galactose cataractogenesis. In the present report, we provide information with regards to the effect of Sorbinil on the activity of these enzymes during cataractogenesis. A modified Hopsu-Havu and Helminen method (1974) with p-nitrocatecholsulfate as substrate was used for localization of both arylsulfatase A and B; and the method of Hara et al. (1979) was utilized to obtain quantitative data on the level of arylsulfatase A and B activity. Ultrastructural cytochemistry shows that arylsulfatase activity in all lenses was primarily localized in epithelial cells in lysosomes with very little or no activity in cortical fibers. The number of arylsulfatase positive lysosomes and the activity level of these enzymes increased with the progression of cataract development. Galactose induced damage to lens morphology and increase in activity of arylsulfatase A and B was inhibited by inclusion of 50mg/Kg (diet) Sorbinil in the galactose containing cataractogenic diet. However, Sorbinil had no significant effect on the enzyme activity following the establishment of mature cataracts.

Topics: Animals; Arylsulfatases; Cataract; Epithelium; Female; Galactose; Imidazoles; Imidazolidines; Kinetics; Lens, Crystalline; Lysosomes; Microscopy, Electron; Rats; Rats, Inbred Strains; Sulfatases; Wound Healing

Rats fed a 50% galactose diet were treated topically in one eye with 1% Sorbinil . The eye treated with Sorbinil remained clear during the following 4-week period. Unexpectedly, the lens of the untreated eye also maintained transparency. Histologically both lenses remained normal. Moreover, the reduced dulcitol levels in the lenses of both eyes were identical. These findings suggest that the effect of topically administered Sorbinil in galactosemic rats was mainly systemic rather than local. Confirmation of this came from the observations that the extent of inhibition of polyol synthesis in these rats was found to be similar in the sciatic nerve, blood, and lens. A reversal of the galactose cataracts also was affected by Sorbinil eye drop treatment.

Topics: Animals; Cataract; Galactosemias; Imidazoles; Imidazolidines; Rats; Rats, Inbred Strains

Lens ultrastructure and Na- K-ATPase activity in the lenses of rats fed galactose and a galactose + sorbinil diet (aldose reductase inhibitor) were studied. Lenses of rats on the galactose diet exhibited development of peripheral opacity within 3-4 days. This opacity progressed with the continuation of the galactose feeding, and by 20 days mature cataracts were observed in these animals. The formation of vacuoles, cysts, membrane disruption in the epithelium and fibers, and swelling of fibers accompanied the development of opacity. With the progression of opacity there was a considerable drop in lens Na- K-ATPase activity in the galactose-fed animals. However, the lenses of rats that were treated with sorbinil did not show any of the alterations in the ultrastructure of the epithelium and fibers that accompany galactose cataractogenesis. The level of Na-K-ATPase activity in the sorbinil-treated animals was similar to that found in lenses from the laboratory chow-fed group of rats. These observations further substantiate the role of aldose reductase in sugar-cataract development.

Topics: 4-Nitrophenylphosphatase; Aldehyde Reductase; Animals; Cataract; Female; Galactose; Imidazoles; Imidazolidines; Lens, Crystalline; Microscopy, Electron; Rats; Rats, Inbred Strains; Sodium-Potassium-Exchanging ATPase

Sorbinil, a potent aldose reductase inhibitor, can effectively block the progression of a galactose cataract even though the cataractous process is well underway. The prevention of dulcitol accumulation by Sorbinil is just as effective in reversing the cataract as the removal of galactose from the diet. The progression and reversal of the cataract were followed by ophthalmoscopy and histology. The results also further support the concept that in galactosemia the cataract is not caused by the toxic effects of galactose per se but by the consequence of the aldose reductase reaction.

Topics: Animals; Cataract; Galactosemias; Imidazoles; Imidazolidines; Rats; Rats, Inbred Strains

Cataract formation in galactosemic rats was studied by ophthalmoscopy, slit-lamp biomicroscopy, and by light microscopy using plastic embedding with methacrylate. Untreated rats developed nuclear cataracts by 14 days and mature cataracts by 21 days. However, rats treated with the aldose reductase inhibitor sorbinil did not develop any cataractous change for up to 8 months of 50% galactose feeding and could not be distinguished from normal controls. This strongly suggests that aldose reductase is the common factor involved in the formation of sugar cataracts.

Topics: Aldehyde Reductase; Animals; Cataract; Galactose; Imidazoles; Imidazolidines; Male; Rats; Rats, Inbred Strains; Sugar Alcohol Dehydrogenases

Topical application of Sorbinil, a potent aldose reductase inhibitor, preserved lens growth, cell hydration and protein components--alpha, beta and gamma crystallins. The concomitant protective effects of Sorbinil were established on the three lenticular parameters because their quantitation offered a comprehensive index of lens integrity during galactose cataractogenesis. The fused eyelids of the rat neonate provided a natural delivery chamber, an orbital pouch, for topical administration of inhibitor to the treated lens; the contralateral pouch served as an untreated control. Protein preservation was determined by gel filtration chromatography. In galactose-maintained neonates, untreated lenses exhibited only 50% of the normal fraction-II component, whereas Sorbinil treatment maintained 95% of the protein. Likewise, quantitative analysis of scanning electron micrographs indicated that Sorbinil protected lenses against both intra- and extracellular fluid accumulation as determined by measurements of individual fiber cell thickness, density (the number of cells/10 micrometer cortex), and interdigitation. In addition, Sorbinil-treatment maintained normal growth as evidenced by radius and dry weight measurements. In normal neonates, Sorbinil had no effect on these parameters. These results indicate that changes in lens growth, fiber ultrastructure and protein components respond to aldose reductase inhibition by Sorbinil, thereby diminishing cataractogenesis.

Topics: Aldehyde Reductase; Animals; Cataract; Crystallins; Diabetic Retinopathy; Imidazoles; Imidazolidines; Lens, Crystalline; Proteins; Rats; Sugar Alcohol Dehydrogenases

Topics: Aldehyde Reductase; Animals; Cataract; Diabetes Mellitus; Humans; Imidazoles; Imidazolidines; L-Iditol 2-Dehydrogenase; Lens, Crystalline; Rats; Sorbitol; Sugar Alcohol Dehydrogenases

The susceptibility of human lens aldose reductase (HLAR), human placental aldose reductase (HPAR), and rat lens aldose reductase (RLAR) to inhibition by 10 structurally diverse inhibitors is compared. Significant differences in the susceptibility of these enzymes was observed; however, no trends could be predicted. In general, HPAR appeared to be less susceptible to inhibition than either HLAR or RLAR, with the susceptibility of HLAR being more similar to RLAR than to HPAR. These findings indicate that the evaluation of aldose reductase inhibitors for potential clinical use may require the use of human aldose reductase from the appropriate target tissue.

Topics: Aldehyde Reductase; Animals; Cataract; Chromones; Female; Humans; Imidazoles; Imidazolidines; Isoquinolines; Lens, Crystalline; Placenta; Pregnancy; Quercetin; Rats; Sugar Alcohol Dehydrogenases; Sugar Alcohols

Topics: Animals; Cataract; Disease Models, Animal; Galactose; Galactosemias; Glycoproteins; Imidazoles; Imidazolidines; Lens, Crystalline; Proteins; Rats

In some tissues containing aldose reductase, increased flux through the polyol pathway has been implicated as being causative in diabetic complications (e.g., cataracts, peripheral neuropathy). We have found CP-45,634 (d-6-fluoro-spiro[chroman-4,4'-imidazolidine]-2',5'-dione) to be a highly potent, structurally novel, uncompetitive inhibitor of calf lens aldose reductase (IC50 approximately 5 X 10(-7)M). In a system in which sorbitol accumulation in isolated rat sciatic nerves was monitored in the presence of high (50 mM) glucose concentrations, CP-45,634 produced inhibition of polyol accumulation at levels as low as 1 X 10(-6)M. To determine if in vitro activity would translate to in vivo models, sorbitol accumulation in rat sciatic nerves was measured 27 hr after induction of diabetes with streptozotocin. Orally administered CP-45,634 was effective at dose levels as low as 0.25 mg/kg, t.i.d., and at 0.75 mg/kg produced an 85% inhibition of sorbitol accumulation. Two weeks after induction of diabetes by streptozotocin, sorbitol levels in rat lens and the sciatic nerve rose to 21,203 nmole/gm and 1,161 nmole/gm, respectively. Subsequent oral administration of CP-45,634 (2.5 mg/kg, b.i.d.) for 1 wk reduced these levels by 92% in nerves and 90% in lenses. In galactosemic rats, CP-45,634 inhibited the rise in lens galactitol and effectively delayed cataract formation at oral doses as low as 5 mg/kg/day. These high levels of in vivo activity suggest that CP-45,634 has potential for assessing the role of the polyol pathway in diabetic complications.

Topics: Aldehyde Reductase; Animals; Benzopyrans; Cataract; Chromans; Diabetes Mellitus, Experimental; Galactitol; Galactose; Galactosemias; Imidazoles; Imidazolidines; Kinetics; Lens, Crystalline; Male; Polymers; Rats; Sciatic Nerve; Sorbitol; Sugar Alcohol Dehydrogenases