10923641

pubmed:Citation

8

The development and progression of diabetic nephropathy is dependent on glucose homeostasis and many other contributing factors. In the present study, we examined the effect of nitecapone, an inhibitor of the dopamine-metabolizing enzyme catechol-O-methyl transferase (COMT) and a potent antioxidant, on functional and cellular determinants of renal function in rats with streptozotocin-induced diabetes. Administration of nitecapone to diabetic rats normalized urinary sodium excretion in a manner consistent with the dopamine-dependent inhibition of proximal tubule Na,K-ATPase activity. Hyperfiltration, focal glomerulosclerosis, and albuminuria were also reversed by nitecapone, but in a manner that is more readily attributed to the antioxidant potential of the agent. A pattern of elevated oxidative stress, measured as CuZn superoxide dismutase gene expression and thiobarbituric acid-reactive substance content, was noted in diabetic rats, and both parameters were normalized by nitecapone treatment. In diabetic rats, activation of glomerular protein kinase C (PKC) was confirmed by isoform-specific translocation and Ser23 phosphorylation of the PKC substrate Na,K-ATPase. PKC-dependent changes in Na,K-ATPase phosphorylation were associated with decreased glomerular Na,K-ATPase activity. Nitecapone-treated diabetic rats were protected from these intracellular modifications. The combined results suggest that the COMT-inhibitory and antioxidant properties of nitecapone provide a protective therapy against the development of diabetic nephropathy.

eng

AIM

MEDLINE

0012-1797

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NLM

1381-9

pubmed-meshheading:10923641-Animals, pubmed-meshheading:10923641-Antioxidants, pubmed-meshheading:10923641-Benzazepines, pubmed-meshheading:10923641-Catechol O-Methyltransferase, pubmed-meshheading:10923641-Catechols, pubmed-meshheading:10923641-Diabetes Mellitus, Experimental, pubmed-meshheading:10923641-Diabetic Nephropathies, pubmed-meshheading:10923641-Enzyme Inhibitors, pubmed-meshheading:10923641-Glomerular Filtration Rate, pubmed-meshheading:10923641-Isoenzymes, pubmed-meshheading:10923641-Kidney, pubmed-meshheading:10923641-Male, pubmed-meshheading:10923641-Oxidative Stress, pubmed-meshheading:10923641-Pentanones, pubmed-meshheading:10923641-Protein Kinase C, pubmed-meshheading:10923641-Rats, pubmed-meshheading:10923641-Rats, Sprague-Dawley, pubmed-meshheading:10923641-Sodium, pubmed-meshheading:10923641-Sodium-Potassium-Exchanging ATPase, pubmed-meshheading:10923641-Superoxide Dismutase

Combined antioxidant and COMT inhibitor treatment reverses renal abnormalities in diabetic rats.

Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't