title: The reduction of hypoxia-induced and reoxygenation-induced apoptosis in rat islets by epigallocatechin gallate.
abstract: The survival of transplanted tissue is affected by the detrimental consequences of hypoxia followed by reoxygenation. The majority of transplanted cells undergo apoptosis due to hypoxia and reoxygenation (H/R) injury, but protection from H/R has been less examined. In this study, we examined whether epigallocatechin gallate (EGCG) protected rat islets from H/R injury. Rat islets, freshly prepared from F344 rat strain by collagenase digestion and density centrifugation, were seeded in triplicate at concentrations of 100 per well in 24-well plates for culture under normoxia. The cells were then exposed to hypoxia for 14 hours with or without EGCG, after which they were reoxygenated for 72 hours in a humidified oxygenated CO(2) incubator at 37 degrees C. Apoptosis, lactate dehydrogenase (LDH), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) were evaluated according to the manufacturer's instructions. The H/R induced apoptosis in the islets that was reduced in dose-dependent manner by EGCG treatment. The viability of islets exposed to H/R was assessed by LDH release. H/R reduced viability compared with the controls, while the viability of the islets improved upon EGCG treatment. The secretion of insulin was also decreased by H/R, as well as the dose dependent EGCG protective ability on insulin secretion. The content of 8-OHdG in islets from H/R was also reduced by EGCG. Our results indicated that apoptosis and the decline in insulin secretion by H/R were inhibited by EGCG treatment. EGCG may be considered useful for protection of islets from oxidative injury associated with the transplantation procedure.
authors.affiliation: Laboratory of Transplantation Immunology and National Research Institute for Child Health and Development, Tokyo, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Hara
authors.forename: M
authors.initials: M
authors.lastname: Fujino
authors.forename: K
authors.initials: K
authors.lastname: Adachi
authors.forename: X-K
authors.initials: XK
authors.lastname: Li
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016381:Islets of Langerhans Transplantation / Q000473:pathology / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000032:analysis; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D002392:Catechin; C045651:epigallocatechin gallate; D007770:L-Lactate Dehydrogenase