Zinc supplementation partially prevents renal pathological changes in diabetic rats.
We have demonstrated that Zn supplementation mediated up-regulation of cardiac metallothionein (MT) as a potent antioxidant prevented the development of diabetic cardiomyopathy. The present study was undertaken to test whether induction of renal MT synthesis by Zn supplementation protects the kidney from diabetes-induced damage. Streptozotocin-induced diabetic rats were treated with and without Zn supplementation at 5 mg/kg in drinking water for 3 months. Diabetic renal damage was detected by examining renal pathological alterations and 24-h urinary protein levels. Three-month Zn supplementation immediately after the onset of diabetes, partially but significantly, prevented the kidney from diabetes-induced increases in 24-h urinary proteins and pathological alterations. Diabetes-induced renal oxidative damage, inflammation and up-regulated expression of profibrosis mediator connective tissue growth factor (CTGF) were also markedly attenuated by Zn supplementation, along with significant increases in Zn levels concomitant with MT expression in renal tubular cells. Direct exposure of renal tubular (HK11) cells to high levels of glucose (HG) induced CTGF up-regulation predominantly through ERK (extracellular signal-regulated kinase)1/2-dependent, and partially through p38 mitogen-activated protein kinase (MAPK)-dependent pathways. Pretreatment of HK11 cells with Zn or cadmium induced MT expression and also significantly suppressed HG-induced CTGF expression. These results provide the first evidence for Zn supplementation to attenuate diabetes-induced renal pathological changes, likely through prevention of hyperglycemia-induced CTGF expression by Zn-induced MT in renal tubular cells.
The Chinese-American Research Institute for Diabetic Complications, The Wenzhou Medical College, Wenzhou, China.
Yunan
Y
Tang
Qin
Q
Yang
Jiayin
J
Lu
Xiaolin
X
Zhang
Di
D
Suen
Yi
Y
Tan
Litai
L
Jin
Jian
J
Xiao
Rujia
R
Xie
Madhavi
M
Rane
Xiaokun
X
Li
Lu
L
Cai
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002460:Cell Line; D055513:Connective Tissue Growth Factor / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced / Q000150:complications* / Q000473:pathology / Q000503:physiopathology; D003928:Diabetic Nephropathies / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000633:toxicity; D006801:Humans; D007668:Kidney / Q000737:chemistry / Q000187:drug effects* / Q000473:pathology; D007687:Kidney Tubules, Proximal / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity; D017395:Plasminogen Activator Inhibitor 1 / Q000378:metabolism; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011507:Proteinuria; D012333:RNA, Messenger / Q000378:metabolism; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013482:Superoxide Dismutase / Q000378:metabolism; D015032:Zinc / Q000032:analysis / Q000097:blood / Q000172:deficiency / Q000627:therapeutic use*
D001786:Blood Glucose; D017395:Plasminogen Activator Inhibitor 1; D020033:Protein Isoforms; D012333:RNA, Messenger; D055513:Connective Tissue Growth Factor; D008668:Metallothionein; D013482:Superoxide Dismutase; D005947:Glucose; D015032:Zinc