Effects of Pueraria mirifica on isolated aorta in high cholesterol-fed rats and ovariectomized rabbits

Abstract

Pueraria mirifica (White Kwao Keur) is an indigenous herb of Thailand which possess estrogenic-like activity. Experiments were designed to study the effects of p. mirifica on lipid profile and endothelium-dependent vascular response in hypercholesterolemic rats and ovariectomized rabbits. Part 1: 30 male Wistar rats were randomly assigned to three groups. The rats were fed normal diet serve as control group. The other 2 groups, rats were fed diet containing 1% cholesterol (cholesterol group) and 1% cholesterol supplemented with p. mirifica 100 mg/kg/day (cholesterol+p. mirifica group). After 90 days, blood samples were obtained for the evaluation of total cholesterol, triglyceride, HDL-C and LDL-C. The aortas were removed, cut into ring and measured for isometric tension. Total cholesterol, LDL-C, HDL-C and triglyceride were significantly decreased in the cholesterol+P. mirifica group compared with cholesterol group (p<0.05). In addition, supplementation with 100 mg/kg/day P. mirifica significantly improved HDL/LDL ratio. There was no significant different in the contraction response to noradrenaline (10-9 to 10-4 M) in all experimental groups. The endothelium-dependent relaxation to acetylcholine (10-9 to 10-4 M) was impaired in the cholesterol group and restored in cholesterol+P. mirifica group, whereas, endothelium-independent relaxation to sodium nitroprusside (10~9 to 10‘4 M) was not significantly different between all experimental groups. Part 2 : 20 ovariectomized (OVX) rabbits were randomly assigned to four groups. The normal rabbits were orally administered with double distilled water. The other 3 groups, OVX rabbits were orally administered with double distilled water (ovariectomized group), 17 β -estradiol 4 mg/kg/day (OVX+Estrogen group) and P. mirifica 100 mg/kg/day (OVX+P.mirifica group). Blood sample were obtained every 4 week for analysis of blood biochemistry and serum lipid parameters. After 90 days, the aortas were measured for vascular function and pathologic examination of endothelial cell. Total cholesterol, LDL-C,HDL-C and triglyceride were not significantly different between all group. There was no significant different in the contraction response to NA and the endothelium-independent relaxation to SNP, whereas, endothelium-dependent relaxation to Ach was impaired in ovariectomized group and improved in OVX+Estrogen and OVX+P. mirifica group. Maintained pathologic of endothelial in OVX+Estrogen group and OVX+P. mirifica group as control. In contrast, vessel from cholesterol group demonstrated a loss of endothelial cell. Adherent of a large number of WBC are clustered on the surface of the endothelium. These results indicated that p. mirifica had beneficial effects on cardiovascular system in cholesterol-fed rats by cholesterol lowering effect and maintained endothelial cell and vascular function in OVX rabbits.