Abstract | AIMS: MAIN METHODS: Diabetes was induced by streptozotocin in 42 male Sprague-Dawley rats. Sixteen weeks after diabetes induction, animals were divided into four groups: diabetic animals without intervention (D), diabetic animals with administration of sirolimus (D+SRL), diabetic animals with administration of rosiglitazone (D+RGT), and diabetic animals with administration of sirolimus and rosiglitazone (D+SRL+RGT). KEY FINDINGS: At a 30-day follow up, diabetic rats showed higher kidney weight, mean glomerular volume, mesangial expansion and albuminuria compared with non-diabetic rats. mTOR downstream proteins, p-T389-S6K and p-T37/46-4EBP1, were higher in diabetic than non-diabetic kidneys, whereas p-S473-AKT was not, suggesting that hyperglycemia mainly activated the mTORC1 pathway in vivo. Moreover, the catalytic subunit of protein phosphatase 2A (PP2Ac) was down-regulated in the diabetic kidney. Sirolimus inhibited the mTORC1 pathway, while the PPAR-gamma agonist rosiglitazone enhanced PP2Ac and reduced p70S6K. Both drugs were associated with a reduction in albuminuria, renal enlargement and mesangial expansion, but without any improvement in glycemic control. Sirolimus and rosiglitazone in combination down-regulated the mTORC1 pathway and over-activated PP2Ac in diabetic kidney. This effect may account for the synergistic reduction of renal hypertrophy, albuminuria and renal TGF-beta1 observed in diabetic rats treated with SRL+RGT. SIGNIFICANCE:
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Authors | Maria Flaquer, Núria Lloberas, Marcella Franquesa, Joan Torras, August Vidal, Jose Luis Rosa, Immaculada Herrero-Fresneda, Josep M Grinyó, Josep M Cruzado |
Journal | Life sciences
(Life Sci)
Vol. 87
Issue 5-6
Pg. 147-53
(Jul 31 2010)
ISSN: 1879-0631 [Electronic] Netherlands |
PMID | 20600147
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Copyright | Copyright 2010 Elsevier Inc. All rights reserved. |
Chemical References |
- Crtc1 protein, rat
- Hypoglycemic Agents
- Immunosuppressive Agents
- Thiazolidinediones
- Transcription Factors
- Transforming Growth Factor beta1
- Rosiglitazone
- Protein Phosphatase 2
- Sirolimus
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Topics |
- Albuminuria
(drug therapy)
- Animals
- Diabetes Mellitus, Experimental
(complications)
- Diabetic Nephropathies
(drug therapy, physiopathology)
- Down-Regulation
(drug effects)
- Drug Synergism
- Drug Therapy, Combination
- Hypoglycemic Agents
(administration & dosage, pharmacology)
- Immunosuppressive Agents
(administration & dosage, pharmacology)
- Male
- Protein Phosphatase 2
(drug effects, metabolism)
- Rats
- Rats, Sprague-Dawley
- Rosiglitazone
- Sirolimus
(administration & dosage, pharmacology)
- Thiazolidinediones
(administration & dosage, pharmacology)
- Transcription Factors
(genetics, metabolism)
- Transforming Growth Factor beta1
(drug effects)
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