scholarly journals Scopoletin Inhibits Rat Aldose Reductase Activity and Cataractogenesis in Galactose-Fed Rats

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Junghyun Kim ◽  
Chan-Sik Kim ◽  
Yun Mi Lee ◽  
Eunjin Sohn ◽  
Kyuhyung Jo ◽  
...  
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Diabetic Patients ◽  
Membrane Rupture ◽  
Magnolia Fargesii ◽  
Sugar Cataract ◽  
Induced Changes ◽  
Rate Limiting ◽  
And Oxidative Stress

Cataracts are a major cause of human blindness. Aldose reductase (AR) is an important rate-limiting enzyme that contributes to cataract induction in diabetic patients. Scopoletin is the main bioactive constituent of flower buds fromMagnolia fargesiiand is known to inhibit AR activity. To assess scopoletin’s ability to mitigate sugar cataract formationin vivo, we studied its effects in a rat model of dietary galactose-induced sugar cataracts. Galactose-fed rats were orally dosed with scopoletin (10 or 50 mg/kg body weight) once a day for 2 weeks. Administering scopoletin delayed the progression of the cataracts that were induced by dietary galactose. Scopoletin also prevented galactose-induced changes in lens morphology, such as lens fiber swelling and membrane rupture. Scopoletin’s protective effect against sugar cataracts was mediated by inhibiting both AR activity and oxidative stress. These results suggest that scopoletin is a useful treatment for sugar cataracts.

scholarly journals Effect of Berberine on Glycation, Aldose Reductase Activity, and Oxidative Stress in the Lenses of Streptozotocin-Induced Diabetic Rats In Vivo—A Preliminary Study

2020 ◽  
Vol 21 (12) ◽  
pp. 4278
Author(s):  
Maria Zych ◽  
Weronika Wojnar ◽  
Magdalena Kielanowska ◽  
Joanna Folwarczna ◽  
Ilona Kaczmarczyk-Sedlak
Keyword(s):  
Oxidative Stress ◽  
Aldose Reductase ◽  
Soluble Protein ◽  
Reductase Activity ◽  
Thiobarbituric Acid ◽  
Isoquinoline Alkaloid ◽  
Diabetic Rats ◽  
Protein Sulfhydryl Groups ◽  
And Oxidative Stress

Diabetes mellitus affects the eye lens, leading to cataract formation by glycation, osmotic stress, and oxidative stress. Berberine, an isoquinoline alkaloid, is a natural compound that has been reported to counteract all these pathological processes in various tissues and organs. The goal of this study was to evaluate whether berberine administered at a dose of 50 mg/kg by oral gavage for 28 days to rats with streptozotocin-induced diabetes reveals such effects on the biochemical parameters in the lenses. For this purpose, the following lenticular parameters were studied: concentrations of soluble protein, non-protein sulfhydryl groups (NPSH), advanced oxidation protein products (AOPP), advanced glycation end-products (AGEs), thiobarbituric acid reactive substances (TBARS), and activities of aldose reductase (AR), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Diabetes induced unfavorable changes in the majority of the examined parameters. The administration of berberine resulted in an increased soluble protein level, decreased activity of AR, and lowered AOPP and AGEs levels. The results suggest that berberine administered orally positively affects the lenses of diabetic rats, and should be further examined with regard to its anticataract potential.

In vivo Nitrate Reductase Activity in Leaves of Pearl Millet, Pennisetum americanum (L.) Leeke

1987 ◽  
Vol 14 (2) ◽  
pp. 125 ◽  
Author(s):  
SV Chanda ◽  
AK Joshi ◽  
PN Krishnan ◽  
YD Singh
Keyword(s):  
Nitrate Reductase ◽  
Reductase Activity ◽  
Potassium Phosphate ◽  
Limiting Factor ◽  
Growth Stages ◽  
In Vivo Assay ◽  
Rate Limiting ◽  
Nr Activity

In the in vivo assay of nitrate reductase (NR) in P. americanum leaves, addition of 1% (v/v) Triton X-100, potassium phosphate buffer (80 mM, pH 7.4) and 1.13 mM NADH to the assay medium resulted in maximum activity. With increasing concentration of NADH, saturation-type kinetics were observed. Based on this data metabolic pool concentration for NADH and apparent Km for nitrate reductase were determined. In field studies with cultivars BJ-104, J-104 and 5141-A of P. americanum, the relative limitation of NO3-, NADH and nitrate reductase in NO3- assimilation was determined. NR activity was measured by four modifications of the in vivo assay technique (with NO3-, with NADH, without NO3- and NADH and with both NO3- and NADH additions to the reaction mixture) and with one in vitro technique. For all the cultivars, NADH was the major rate-limiting factor for in vivo assay during early growth stages, while at later stages, NO3- was limiting. At no stage was NR rate-limiting. It is concluded that NR activity alone may not serve as biochemical marker for improved efficiency of utilisation of nitrogen in P. americanum.

scholarly journals Osmotic stress, not aldose reductase activity, directly induces growth factors and MAPK signaling changes during sugar cataract formation

2012 ◽  
Vol 101 ◽  
pp. 36-43 ◽  
Author(s):  
Peng Zhang ◽  
Kuiyi Xing ◽  
James Randazzo ◽  
Karen Blessing ◽  
Marjorie F. Lou ◽  
...  
Keyword(s):  
Growth Factors ◽  
Osmotic Stress ◽  
Aldose Reductase ◽  
Reductase Activity ◽  
Mapk Signaling ◽  
Cataract Formation ◽  
Sugar Cataract

Perfused hearts from Type 2 diabetic (db/db) mice show metabolic responsiveness to insulin

2006 ◽  
Vol 290 (5) ◽  
pp. H1763-H1769 ◽  
Author(s):  
Anne Dragøy Hafstad ◽  
Geir Helge Solevåg ◽  
David L. Severson ◽  
Terje S. Larsen ◽  
Ellen Aasum
Keyword(s):  
Insulin Resistance ◽  
Glucose Uptake ◽  
Metabolic Response ◽  
Diabetic Patients ◽  
High Concentration ◽  
Isolated Cardiomyocytes ◽  
Isolated Hearts ◽  
Induced Changes

Diabetic ( db/db) mice provide an animal model of Type 2 diabetes characterized by marked in vivo insulin resistance. The effect of insulin on myocardial metabolism has not been fully elucidated in this diabetic model. In the present study we tested the hypothesis that the metabolic response to insulin in db/db hearts will be diminished due to cardiac insulin resistance. Insulin-induced changes in glucose oxidation (GLUox) and fatty acid (FA) oxidation (FAox) were measured in isolated hearts from control and diabetic mice, perfused with both low as well as high concentration of glucose and FA: 10 mM glucose/0.5 mM palmitate and 28 mM glucose/1.1 mM palmitate. Both in the absence and presence of insulin, diabetic hearts showed decreased rates of GLUox and elevated rates of FAox. However, the insulin-induced increment in GLUox, as well as the insulin-induced decrement in FAox, was similar or even more pronounced in diabetic that in control hearts. During elevated FA and glucose supply, however, the effect of insulin was blunted in db/db hearts with respect to both FAox and GLUox. Finally, insulin-stimulated deoxyglucose uptake was markedly reduced in isolated cardiomyocytes from db/db mice, whereas glucose uptake in isolated perfused db/db hearts was clearly responsive to insulin. These results show that, despite reduced insulin-stimulated glucose uptake in isolated cardiomyocytes, isolated perfused db/db hearts are responsive to metabolic actions of insulin. These results should advocate the use of insulin therapy (glucose-insulin-potassium) in diabetic patients undergoing cardiac surgery or during reperfusion after an ischemic insult.

Inhibition of 17β-hydroxysteroid-oxidoreductase activity in purified rat Leydig cells by single injection of human choriogonadotrophin

1984 ◽  
Vol 105 (4) ◽  
pp. 571-576 ◽  
Author(s):  
Nikolaus Kühn-Velten ◽  
Wolfgang Staib
Keyword(s):  
Leydig Cells ◽  
Time Course ◽  
Marked Decrease ◽  
Single Injection ◽  
Reductase Activity ◽  
Competitive Inhibitor ◽  
Oxidoreductase Activity ◽  
Rate Limiting

Abstract. A marked decrease of progesterone conversion to androgens in vitro by purified rat testis Leydig cells is observed from 1/2 to 3 days after treatment of the rats with 100 IU human choriogonadotrophin (hCG) in vivo. The maximal inhibition results 2 days after hCG injection and is denoted by a 72% reduction of androstenedione formation and a 78% reduction of testosterone formation from 2.5 μmol progesterone · l7#x2212;1. The testosterone/androstenedione ratio (about 0.4), however, is not changed after hCG treatment, indicating that the 17-ketosteroid-reductase activity is not rate-limiting under these conditions. Nevertheless, testosterone formation from 2.5 μmol androstenedione · l−1 is reduced by 67% and androstenedione formation from 2.5 μmol testosterone · l−1 is reduced by 79% 1 and 2 days after hCG treatment. The time-course of this hCG-induced decrease in both reductase and oxidase activities of the Leydig cell 17β-hydroxysteroid-oxidoreductase parallels the decrease of androgen formation from progesterone. Kinetic analyses reveal that the Vmax of the oxidase is reduced to a significantly (P < 0.05) greater extent than the Vmax of the reductase (79 and 62%, respectively), whereas the respective Km values remain unchanged. From these results it may be concluded that either a loss, or an inactivation of the enzyme protein, or the formation of non-competitive inhibitor occur during hCG action and that hCG may affect different enzyme activities involved in testicular androgen biosynthesis in a similar way.

Factors affecting the ratio of different organic osmolytes in renal medullary cells

1990 ◽  
Vol 259 (5) ◽  
pp. F847-F858 ◽  
Author(s):  
T. Moriyama ◽  
A. Garcia-Perez ◽  
M. B. Burg
Keyword(s):  
Tissue Culture ◽  
Aldose Reductase ◽  
Glucose Concentration ◽  
Reductase Activity ◽  
Renal Medulla ◽  
Organic Osmolytes ◽  
Factors Affecting ◽  
High Concentrations ◽  
Medullary Cells

Renal medullary cells contain high concentrations of sorbitol, inositol, glycerophosphorylcholine (GPC), and betaine, which balance the variably high osmolality of extracellular NaCl. We found that PAP-HT25 (rabbit renal medullary) cells in tissue culture increase their content of all four when medium osmolality is increased by adding NaCl and urea. However, this requires that betaine be added to medium in addition to customary constituents. Some factors affecting the mix of organic osmolytes in these cells during hypertonicity are as follows. 1) Urea in medium increases cell GPC and tends to decrease others, particularly betaine. 2) With small increases in medium NaCl, intracellular inositol is highest, whereas sorbitol predominates with large NaCl increases. 3) When osmolality is suddenly decreased, these four organic osmolytes exit rapidly from cells, but in differing relative amounts (betaine much greater than sorbitol greater than inositol much greater than GPC). 4) Altering cell betaine levels (by varying betaine in medium) causes reciprocal changes in cell sorbitol (by affecting aldose reductase activity) and vice versa, whereas inositol and GPC are less affected. 5) Raising medium glucose concentration (from which sorbitol is synthesized) increases cell sorbitol and decreases cell inositol and betaine. 6) Decreasing the amount of GPC in cells (by removing choline from medium) causes small changes in betaine and sorbitol, but not in inositol. Changing the amount of inositol does not affect the others. Similar interrelations may operate in vivo to vary the mix of organic osmolytes in renal medulla.

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