The molecular basis of Chinese herbs (Astragali and Angelica) on increasing serum albumin synthesis in nephrotic rats

Our previous studies have shown that two Chinese herbs, Astragali and Angelica, combined with an adequate protein intake can ameliorate the reduction in serum albumin, and improve the ratio of protein synthesis to catabolic rate without significant influence on urinary protein in both nephrotic patients and rats. This study was designed to investigate mechanisms by studying the effect of Astragali and Angelica on albumin synthesis in experimental nephrotic syndrome (NS), measuring the effect on hepatic albumin mRNA expression and gene transcription, Male Sprague-Dawley (SD) rats were divided into eight groups: (1) normal control, C; (2) nephrotic control, NC; (3) treated with Astragali and Angelica, Ast & Ang; (4) treated with Astragali alone, Ast; (5) treated with Angelica alone, Ang; (6) treated with Astragali polysaccharide I, Ast I (MW. 36 000); (7) treated with Astragali polysaccharide II, Ast II (MW. 12 500); (8) treated with Astragali glucoside, Ast G. Nephrotic syndrome in rats was induced by accelerated nephrotoxic nephritis. The herb extracts were force-fed daily for 14 days, the animals were then sacrificed, and the serum and liver collected. The level of serum albumin, albumin mRNA and its gene transcription activity were measured using biochemistry, Northern blot analysis, run-on assay and quantity in laser density screening. In the NC group, the level of serum albumin was significantly lower, the level of albumin mRNA in the liver was significantly higher and the activity of albumin gene transcription was increased compared with normal controls. In the Ast & Ang group, the urinary protein was not different to that in the NC group, while the level of serum albumin was significantly higher and both the level of albumin mRNA and the activity of albumin gene transcription were significantly higher. In each component therapy group, the effect of increasing the level of serum albumin, the levels of albumin mRNA and activities of albumin gene transcription were no different compared with the NC group. Our results suggest that Astragali and Angelica increase albumin synthesis in the nephrotic rat by increasing liver albumin mRNA expression, at least in part by improving the activity of gene transcription. The extract of Astragali and Angelica was better effect than any components tested.