Abstract: Objective:To study the effect of excited dopamine type I receptor on the production of nitric oxide/nitric oxide synthase(NO/NOS)in ox-LDL activated THP-1 cells and the possible mechanism. Methods:Cultured THP-1 cells activated by PMA were randomly assigned in the following groups:control group (control), oxidized low density lipoprotein group (ox-LDL), dopamine receptor 1(DR1) agonist group (SKF), DR1 antagonist group (SCH), ERK blocker group (PD98059). Oil Red O staining was used to identify the accumulation of cellular lipid. The levels of NO and NOS in the supernatant of THP-1 were assayed by nitrate reductase method. The protein expression of DR1, p-ERK and ERK were obtained by Western blot and immunity fluorescence. Results:After 48 h of incubation of ox-LDL, accumulation of lipid in the cytoplasm was found in most THP-1 cells. Compared with control group, DR1 protein expression was reduced in ox-LDL-induced cells(P<0.01). Activation of DR1 agonist decrease the production of NO and iNOS(P<0.01), and PD98059 partly reversed the above effect. Conclusion:Activation of DR1 can inhibit the production of NO/NOS in ox-LDL-induced THP-1 cells, which may be related with ERK pathway.

Key words: dopamine receptor(DR), foam cells, nitric oxide(NO), THP-1 cells, LDL