ATP-binding cassette transporters (ABCs) belong to a large family and include 49 mammalian transmembrane transporters that transfer a variety of substrates across the lipid bilayers in an energy-dependent manner. ABCA1 is a member of this family which plays a crucial role in plasma HDL-C remodeling. The purpose of this study was to investigate liver ABCA1 expression and plasma HDL level in response to treadmill running program in rats. Ten adult Wistar male rats (12-14 weeks old, 200-220 g) were used for this study. Animals were divided into control (Con, n = 5) and Training TR, n = 5) groups. Training group was given exercise on a motor-driven treadmill at 25 m/min (0% grade) for 90 min/day, 5 days/week for 6 weeks. Rats were sacrificed 24 h after the last session of exercise portion of the liver was excised, immediately washed in ice-cold saline, and frozen in liquid nitrogen for extraction of ABCA1 mRNA. Plasma was collected for HDL-C, LDL, TC, TG, and VLDL-C measurements. Liver ABCA1 mRNA expression was significantly (P < 0.001) higher in trained rats compared to control rats. Plasma HDL-C, LCAT, pre-beta-HDL concentrations were significantly higher (P<0.01, P < 0.001, P < 0.028, respectively) in trained rats at the end of treadmill exercise. However, plasma lipids, other lipoproteins and TC/HDL and LDL/HDL ratio were unchanged. In conclusion, a treadmill running-induced elevated plasma HDL-C concentration was accompanied with a higher liver ABCA1 mRNA expression and increased in LCAT and pre-beta-HDL levels. (C) 2007 Elsevier Inc. All rights reserved.