Spironolactone prevents early renal injury in streptozotocin-induced diabetic rats.
BACKGROUND
Glomerular and tubulointerstitial injury leads to chronic impairment of renal function, and thus, reversal of the injury may improve renal function and survival. The present study investigated whether and how mineralocorticoid receptor antagonist spironolactone ameliorates early renal injury in streptozotocin-induced diabetic rats.


METHODS
Streptozotocin (65 mg/kg, single intraperitoneal injection)- or vehicle-administered rats were used as diabetic or control rats, respectively. The streptozotocin-administered rats were treated with spironolactone (50 mg/kg/day sc) for 3 weeks. Among the 3 groups of rats, we compared renal fibrosis and renal hypertrophy, using picro-sirius red staining and immunohistochemistry of ED-1 macrophage marker, plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor (TGF)-beta1.


RESULTS
Three weeks after administration of streptozotocin, rats exhibited increased collagen deposition in glomerular, tubulointerstitial, and perivascular areas in the kidney, which was completely attenuated by spironolactone treatment. In rats given streptozotocin alone, there were increases in ED-1-positive cell, PAI-1 expression, and TGF-beta1 expression in glomeruli and tubulointerstitiums, which were also suppressed by spironolactone treatment. Maximal glomerular and proximal tubular areas were not significantly different among the 3 groups. Rats given streptozotocin alone revealed an increase in proximal tubule wall-to-lumen ratio that was not influenced by treatment with spironolactone.


CONCLUSIONS
Streptozotocin-induced renal fibrosis, PAI-1 expression, TGF-beta1 expression, and macrophage infiltration occur via mineralocorticoid receptor, and spironolactone ameliorates renal fibrosis presumably via the inhibition of macrophage infiltration, PAI-1 expression, and TGF-beta1 expression in streptozotocin-induced early diabetic injury.
Divisions of Endocrinology, Department of Internal Medicine, Jichi Medical School, Minamikawachi, Tochigi, Japan. genrfjs@attglobal.net
Genro
G
Fujisawa
Koji
K
Okada
Shigeaki
S
Muto
Nobuya
N
Fujita
Naoki
N
Itabashi
Eiji
E
Kusano
Shun
S
Ishibashi
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000150:complications*; D003928:Diabetic Nephropathies / Q000188:drug therapy* / Q000473:pathology / Q000517:prevention & control*; D005355:Fibrosis; D006984:Hypertrophy; D007150:Immunohistochemistry; D007668:Kidney / Q000378:metabolism / Q000473:pathology; D008297:Male; D000451:Mineralocorticoid Receptor Antagonists / Q000494:pharmacology*; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013148:Spironolactone / Q000494:pharmacology*; D013194:Staining and Labeling; D016212:Transforming Growth Factor beta / Q000378:metabolism; D053773:Transforming Growth Factor beta1
D000451:Mineralocorticoid Receptor Antagonists; D017395:Plasminogen Activator Inhibitor 1; C508962:Tgfb1 protein, rat; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D013148:Spironolactone