Chronic treatment with recombinant human erythropoietin exerts renoprotective effects beyond hematopoiesis in streptozotocin-induced diabetic rat.
Recombinant human erythropoietin (rHuEPO), which has been used clinically for the management of renal anemia, is reported to exert pleiotropic beneficial properties against acute ischemic/reperfusion injury in various tissues. To investigate the hypothesis that chronic treatment with rHuEPO might ameliorate diabetic nephropathy beyond hematopoiesis, rHuEPO (150 U/kg, subcutaneously) was administered three times per week to the streptozotocin-induced diabetic rats for 4 weeks. Streptozotocin (65 mg/kg, intravenously) significantly increased urinary protein excretion and collagen deposition in glomerular and tubulointerstitial areas in the kidney, which were attenuated by rHuEPO. rHuEPO normalized the levels of creatinine clearance, serum creatinine, and blood urea nitrogen of diabetic rats. RT-PCR analysis revealed that the expressions of mRNA for transforming growth factor-beta, osteopontin and adhesion molecules were enhanced in the diabetic rat kidney and that the overexpression of these molecules was suppressed by rHuEPO. rHuEPO exerted antioxidant properties by inhibiting renal activation and overexpression of NADPH oxidase. We found the activation of the Akt signaling pathway by the increased expression of phosphorylated Akt and GSK-3beta and a reduction of TUNEL-positive apoptotic cell death in renal tissue from rHuEPO-treated diabetic group. We also demonstrated that rHuEPO restored the endothelial nitric oxide synthase (eNOS) content in the diabetic rat kidney. On the other hand, treatment with rHuEPO did not affect blood glucose level, blood pressure, or hematocrit in diabetic rats. These results suggest that chronic treatment with rHuEPO attenuated renal injury beyond hematopoiesis and regulated apoptosis and eNOS expression, which might be due to the activation of Akt pathway.
Department of Clinical Pharmacology, Division of Pathological Sciences, Kyoto Pharmaceutical University, Japan. toba@mb.kyoto-phu.ac.jp
Hiroe
H
Toba
Naoki
N
Sawai
Masayuki
M
Morishita
Shoko
S
Murata
Mamiko
M
Yoshida
Kohei
K
Nakashima
Yosuke
Y
Morita
Miyuki
M
Kobara
Tetsuo
T
Nakata
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001786:Blood Glucose / Q000032:analysis; D001806:Blood Urea Nitrogen; D016923:Cell Death / Q000187:drug effects; D003404:Creatinine / Q000097:blood / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy*; D004921:Erythropoietin / Q000235:genetics / Q000627:therapeutic use*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D006400:Hematocrit; D006410:Hematopoiesis / Q000187:drug effects*; D006801:Humans; D020287:In Situ Nick-End Labeling / Q000379:methods; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D053495:Osteopontin / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins; D015398:Signal Transduction / Q000187:drug effects; D013311:Streptozocin / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000378:metabolism
D001786:Blood Glucose; D012333:RNA, Messenger; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D053495:Osteopontin; D004921:Erythropoietin; D013311:Streptozocin; D003404:Creatinine; D019255:NADPH Oxidases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; C000605508:Gsk3b protein, rat; D051057:Proto-Oncogene Proteins c-akt; D038362:Glycogen Synthase Kinase 3