OBJECTIVETo study the effect of soy isoflavones (SI) on ATP binding cassette A1 (ABCA1) expression in rats without ovary with atherosclerosis.

METHODSAfter they were raised for a week by given basic feed, the ovaries of 50 12-week old SPF rats were removed. The rats were randomly divided into groups by weight. Ten rats were selected as the basic control group (A) that basic feed was given all through the research. The other 40 rats were given high-fat diets and at the end of 4 weeks, these rats were randomly divided into four groups by blood lipid level: atherosclerotic model group (B) that was given high-fat diets through the research, low isoflavones group (C) that was given high-fat diets plus 30 mg/kg SI, middle isoflavones group (D) that was given high-fat diets plus 90 mg/kg SI, and high isoflavones group (E) that was given high-fat diets plus 270 mg/kg SI. After 22 weeks, all rats were executed to measure morphological change on the aorta wall, assessing the ABCA1 gene expression in aorta wall by real-time PCR and protein expression by Western blotting in aorta wall, small intestine and liver.

RESULTSSerum lipid level of A, B, C, D, E groups: TC levels were (6.82 +/- 0.22), (15.73 +/- 1.51), (10.77 +/- 1.12), (9.95 +/- 1.18), (9.11 +/- 1.12) mmol/L respectively (F = 72.882, P < 0.01); TG levels were: (2.49 +/- 0.24), (0.78 +/- 0.13), (0.39 +/- 0.08), (0.29 +/- 0.09), (0.24 +/- 0.09) mmol/L respectively (F = 378.515, P < 0.01); LDL-C levels were (1.29 +/- 0.08), (14.76 +/- 1.23), (8.18 +/- 0.80), (7.85 +/- 0.72), (7.16 +/- 0.64)mmol/L respectively (F = 320.936, P < 0.01); HDL-C levels were (1.94 +/- 0.18), (1.04 +/- 0.10), (1.55 +/- 0.14), (1.88 +/- 0.17), (2.11 +/- 0.22) mmol/L respectively (F = 49.450, P < 0.01). ABCA1 protein expression in intestine, liver and aorta: for A, B, C, E groups in intestine were 96.577 +/- 9.743, 5.218 +/- 2.048, 18.060 +/- 5.179, 54.725 +/- 8.960, respectively (F = 172.272, P < 0.01); ABCA1 protein expression in liver of groups of A, B, C, E were: 13.657 +/- 2.397, 1.361 +/- 0.266, 7.069 +/- 2.264, 11.793 +/- 2.515 respectively (F = 37.383, P < 0.01); ABCA1 protein expression in aorta of groups A, B, C, E were: 6.756 +/- 1.310, 0.027 +/- 0.006, 0.035 +/- 0.002 and 7.479 +/- 1.520 respectively (F = 91.999, P < 0.01). Compared to basic control group, atherosclerotic plaque could be observed in atherosclerotic model group, and it could be partially reversed by isoflavones addition.

CONCLUSIONSoy isoflavones treatment might inhibit atherosclerotic progression by lowering the level of blood lipid and increasing ABCA1 expression.