Effects of Naoxintong on atherosclerosis and inducible nitric oxide synthase expression in atherosclerotic rabbit.

BACKGROUND: High levels of nitric oxide (NO) produced by inducible NO synthase (iNOS) have been associated with atherosclerosis processes. Naoxintong is a traditional Chinese medicine for treatment of cerebrovascular and cardiovascular disease. The aim of the present study was to detect and quantify changes of iNOS mRNA and NO levels in the vessel wall after the administration of Naoxintong in an atherosclerotic rabbit model. METHODS: Forty New Zealand white rabbits were randomly divided into five groups (n = 8). Rabbits were fed a standard diet (group A), an atherogenic diet consisting of 79% standard feed + 1% cholesterol + 5% lard + 15% egg yolk powder (group B), an atherogenic diet with Naoxintong 0.25 mg×kg(-1)×d(-1) (group C), an atherogenic diet with Naoxintong 0.5 mg×kg(-1)×d(-1) (group D), or atherogenic diet with Naoxintong 1.0 mg×kg(-1)×d(-1) (group E) for 12 weeks. RESULTS: Supplemented administration of Naoxintong led to a down-regulation of cholesterol (CHOL) (P < 0.001) and low-density lipoprotein (LDL) (P < 0.001). The trend became more notable as the dose of Naoxintong increased; group C vs. group B (CHOL, P = 0.568; LDL-cholesterol (LDL-C), P = 0.119), group D vs. group B (CHOL, P = 0.264; LDL-C, P = 0.027), group E vs. group B (CHOL, P = 0.028; LDL-C, P = 0.002). Atherosclerotic lesions in aorta were reduced in Naoxintong groups (groups C, D, E) compared to group B. Group B had higher iNOS mRNA (P = 0.001) and NO level (P < 0.001) than group A. Compared with the atherogenic diet fed-rabbits, Naoxintong supplements decreased the expression of iNOS mRNA (P < 0.001) and the NO level (P < 0.001) in the vessel wall. Groups given a higher Naoxintong dose exhibited greater benefits. iNOS mRNA and NO levels seemed to be reduced in group C, although the difference did not quite reach statistical significance (iNOS mRNA, P = 0.130; NO, P = 0.038). iNOS mRNA and NO levels significantly decreased in group D (iNOS mRNA, P = 0.019; NO, P = 0.018) and group E (iNOS mRNA, P = 0.004; NO, P < 0.001). CONCLUSION: Naoxintong has beneficial effects on atherosclerosis treatment by reducing expression of iNOS mRNA and the NO level in the vessel wall.