It is known that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) enhance the expression- of the low-density lipoprotein (LDL) receptor and lower the level of LDL cholesterol in the blood. But, a triglyceride (TG)-lowering effect is also observed during their administration. To clarify the possibility that statins enhance LPL activity and its mechanism, the effects of statins on the expression of LPL in adipocytes were studied. When statins (pravastatin, simvastatin, atorvastatin and pitavastatin) were added to the culture medium of mouse 3T3-L1 preadipocytes at final concentrations of 1 microM for 3 days, LPL activity increased. Pitavastatin increased the activity the most. Western and Northern blotting showed that LPL protein and m-RNA were strongly expressed on the addition of pitavastatin. With the addition of mevalonate (10 microM, 3 days), LPL activity weakened significantly. Statins, especially pitavastatin, increased the expression of LPL in 3T3-L1 preadipocytes. The TG-lowering effect of pitavastatin might be mediated by enhancement of LPL production in adipocytes.