Effects of (-)-epigallocatechin-3-gallate on pancreatic beta-cell damage in streptozotocin-induced diabetic rats.
Oxygen free radicals, which are produced as a result of chronic hyperglycemia, are implicated in many diabetic complications. (-)-Epigallocatechin-3-gallate (EGCG), a green tea polyphenol, has been shown to have both antioxidant and pro-oxidant activities, but its effect on oxidative stress of pancreatic beta cells in vivo is unclear. Here we evaluated the effects of nanomolar concentrations of EGCG on beta-cell survival and the response to high glucose loading in streptozotocin-induced diabetic rats. A 4-day intraperitoneal treatment with EGCG (5 mg/kg/day) further impaired the beta-cell response to high glucose in the diabetic rats. EGCG exacerbated the loss of islet cell mass and insulin-immunoreactivity in beta cells. These results suggest that, even at nanomolar plasma concentrations, EGCG acts as a pro-oxidant rather than an antioxidant, at least in beta cells in vivo.
Yun
Seung-Young
SY
Department of Physiology and Chronic Disease Research Center, Keimyung University School of Medicine, 194, Dongsan-Dong, Jung-Gu Daegu, 700-712, South Korea.
Kim
Sang-Pyo
SP
Song
Dae-Kyu
DK
D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D002452:Cell Count; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000473:pathology / Q000503:physiopathology*; D004305:Dose-Response Relationship, Drug; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D007150:Immunohistochemistry; D007274:Injections, Intraperitoneal; D007328:Insulin / Q000032:analysis / Q000097:blood; D050417:Insulin-Secreting Cells / Q000737:chemistry / Q000187:drug effects* / Q000473:pathology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology; D014815:Vitamins / Q000008:administration & dosage / Q000494:pharmacology
D000975:Antioxidants; D007328:Insulin; D014815:Vitamins; D014810:Vitamin E; D002392:Catechin; C045651:epigallocatechin gallate; D005947:Glucose