Aim To investigate the effect of adrenaline on the expression of ATP binding cassette transporter A1 (ABCA1) mRNA and scavenger receptor AI(SR-AI) mRNA in THP-1 macrophages and to identify its possible mechanism mediated byβ-adrenoceptor.Methods THP-1 derived macrophages were preincubated for an hour with aβ1-adrenoceptor antagonist metoprolol(10 nmol/L to 100μmol/L) and aβ2-adrenoceptor antagonist butoxamine(2.5 nmol/L to 25μmol/L),respectively,before treatment with 1μmol/L adrenaline for 24 h.Then ABCA1 and SR-AI mRNA expression were determined by RT-PCR.Results RT-PCR analysis showed that compared with control(without adrenaline),1μmol/L adrenaline significantly decreased ABCA1 mRNA expression and significantly increased SR-AI mRNA expression (P<0.05).These stimulatory effects of adrenaline on ABCA1 mRNA and SR-AI mRNA expression in THP-1 macrophages were reversed by theβ1-adrenoceptor antagonist metoprolol or theβ2-adrenoceptor antagonist butoxamine in a concentration -dependent manner.Furthermore,the effect of theβ2-adrenoceptor antagonist butoxamine reached a platform at the concentration of 2.5μmol/L.Conclusion Adrenaline up-regulates SR-AI mRNA expression and down-regulates ABCA1 mRNA expression,probably being mediated viaβ1-adrenoceptor orβ2-adrenoceptor activation.