Renoprotective effects of a selective estrogen receptor modulator, raloxifene, in an animal model of diabetic nephropathy.

BACKGROUND/AIMS Our previous studies have shown that supplementation with 17beta-estradiol (E2) from the onset of diabetes attenuates diabetic nephropathy. However, E2 is accompanied by feminizing effects as well as adverse side effects on other organs. The current study examined the renoprotective effects of a selective estrogen receptor modulator, raloxifene (RAL), in an experimental model of diabetic nephropathy. RAL activates estrogen receptors and estrogen-receptor-mediated cellular events without the side effects of E2. METHODS The study was performed in Sprague-Dawley nondiabetic (ND), streptozotocin-induced diabetic (D) and streptozotocin-induced D + RAL rats (n = 6/group). RESULTS After 12 weeks of treatment, D was associated with increased urine albumin excretion (ND: 4.2 +/- 0.4; D: 41.3 +/- 9.0 mg/day), glomerulosclerosis [glomerulosclerotic index; ND: 0.26 +/- 0.04; D: 1.86 +/- 0.80 arbitrary units (AU)], tubulointerstitial fibrosis (tubulointerstitial fibrosis index; ND: 0.37 +/- 0.05; D: 2.12 +/- 0.50 AU), increased collagen type I [ND: 1.31 +/- 0.07; D: 4.65 +/- 0.09 relative optical density (ROD)], collagen type IV (ND: 0.64 +/- 0.03; D: 1.37 +/- 0.11 ROD) and transforming growth factor beta (TGF-beta) protein expression (ND: 0.65 +/- 0.08; D: 1.25 +/- 0.10 ROD), increased density of CD68-positive cells (ND: 1.37 +/- 3.02; D: 29.2 +/- 1.74 cells/mm2) and increased plasma levels of interleukin-6 (ND: 14.8 +/- 5.0; D: 51.3 +/- 14.0 pg/ml). Treatment with RAL partially or fully attenuated these processes (urine albumin excretion: 21.0 +/- 5.0 mg/day; glomerulosclerotic index: 0.40 +/- 0.06 AU; tubulointerstitial fibrosis index: 0.20 +/- 0.04 AU; collagen type I: 2.55 +/- 0.49 ROD; collagen type IV: 0.70 +/- 0.09 ROD; TGF-beta: 0.91 +/- 0.08 ROD; CD68: 6.03 +/- 2.38 cells/mm2; interleukin-6: 31.2 +/- 5.0 pg/ml). CONCLUSIONS Our data indicate that treatment with RAL attenuates albuminuria and renal structural changes associated with diabetes.