Objective To investigate the effect of peroxisome proliferator-activated receptor-α（PPARα） and PPARγactivators on tumor necrosis factor-α（TNFα） expression in neonatal rat cardiac myocytes. Methods Primary cultures of cardiac myocytes from 1- to 3-day-old Wistar rats were prepared

and myocytes were ex-posed to lipopolysaccharide （LPS） and varying concentrations of PPARαor PPARγactivator （fenofibrate or pioglitazone）.RT-PCR and ELISA were used to measure TNFα

PPARα

and PPARγexpression in cultured cardiac myocytes. Transient tr-ansfection of TNFαpromoter with or without nuclear factor-kappaB （NF-κB） binding site to cardiac myocytes was performed. Results Pretreatment of cardiac myocytes with fenofibrate or pioglitazone inhibited LPS-induced TNFαmRNA and protein expression in a dose-dependent manner. However

no significant changes were observed on PPARαor PPARγmRNA expression when cardiac myocytes were pretreated with fenofibrate or pioglitazone. Proportional suppression of TNFαpromoter activity was observed when myocytes was transiently transfected with whole length of TNFαpromoter （-721/+17） after being stimulated with LPS and fenofibrate or pioglitazone

whereas no change of promoter activity was observed with transfection of TNFαreporter construct in deletion of NF-κB binding site （-182/+17）. Conclusions PPARαand PPARγactivators may inhibit cardiac TNFαexpression but not accompanied by change of PPARαor PPARγmRNA expression. Therefore PPARαand PPARγactivators appear to play a role in anti-inflammation. The mechanism may partly be involved in suppression of the NF-κB pathway.