Green tea extract selectively activates peroxisome proliferator-activated receptor beta/delta in cultured cardiomyocytes.
Hypoxia/reoxygenation is one of the causes of the increased expression of inducible NO synthase in cardiomyocytes. In a recent study we demonstrated that a single, high dose of green tea extract (GT) supplemented to the medium of cultured cardiomyocytes just before hypoxia/reoxygenation is able to prevent the increased expression of inducible NO synthase, therefore reducing NO overproduction. In the present study we investigated the mechanism by which GT reduces NO production. Since a molecular mechanism for polyphenol activity has been postulated, and PPAR activation is related to the transcription of the inducible NO synthase gene, we evaluated the activation of PPAR by GT. A moderate GT concentration, supplemented to the cardiomyocyte medium since the initial seeding, selectively activated the PPAR-beta/delta isoform. Furthermore, we observed a reduction in NO production and an increase in total antioxidant activity, indicating that GT components may act on both reactive oxygen species, via an antioxidant mechanism, and NO overproduction. PPAR-beta/delta activation could represent the key event in the reduction of NO production by GT. Although PPAR activation by GT was lower than activation by fenofibrate, it is very interesting to note that it was selective for the beta/delta isoform, at least in neonatal cardiomyocytes.
Danesi
Francesca
F
Research Centre on Nutrition and Vitamins, Department of Biochemistry G. Moruzzi, University of Bologna, Via Irnerio 48, Bologna 40126, Italy.
Di Nunzio
Mattia
M
Boschetti
Elisa
E
Bordoni
Alessandra
A
D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015687:Cell Hypoxia; D002478:Cells, Cultured; D004789:Enzyme Activation; D032383:Myocytes, Cardiac / Q000201:enzymology*; D009569:Nitric Oxide / Q000032:analysis / Q000378:metabolism; D047494:PPAR delta / Q000378:metabolism*; D048068:PPAR-beta / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013662:Tea
D000975:Antioxidants; D047494:PPAR delta; D048068:PPAR-beta; D010936:Plant Extracts; D013662:Tea; D009569:Nitric Oxide; D002392:Catechin; C045651:epigallocatechin gallate