Abstract: Objective To observe effects of leptin on acyl Co A carboxy lase(ACC)and adenosine mono phosphate activated prote in kinase(AM PK)1 mRN A expression in cultured ratadipocytes in vitro.Methods Epididymal adiposetis sues from 3 male Wistar rats were dige sted and adiposetissue derived stromal cells were separated and cultured for adipogenic differentiation.Differentiated cells were incubated with ratrecom binant leptin of 50 nmol/L for 6 hr and expressions of ACC and AMPKα1mRNA were measured with semi quantitive reverse transcript polymerase chain reaction(RT-PCR).Results Ratprimary adiposetissue derived stromal cells could differentiate to adipocytes.The expression of ACC mRNA of leptin treated adipo cytes(0.39±0.29)was significantly lower than that of control(0.75±0.50,P<0.05).However,no significant difference was observed on the expression of AM PKα1 mRN A between two groups(P>0.05).Conclusion Rat recom binant leptin caninhibit fatty acid synthesis of cultured rat adipocytes in vitro,which may be unrela ted to AMPKα1.