Effects of osthol on blood pressure and lipid metabolism in stroke-prone spontaneously hypertensive rats

Osthol, a coumarin compound, was isolated from the dried fruits of Cnidium monnieri (Umbelliferae) and the effect of dietary osthol on hypertension and lipid metabolism was examined in stroke-prone spontaneously hypertensive rats (SHRSP). Six-week-old male SHRSP were fed the experimental diet containing 0.05% osthol by weight for 4 weeks with free access to the diet and water. Elevation of systolic blood pressure was significantly suppressed on and after 3 weeks. In addition, significant decreases in cholesterol and triglyceride contents in the liver were recognized without any significant changes in serum lipids profiles. A comparative study on hepatic mRNA expression indicated that osthol induced a significant increase in 3-hydroxy-3-methylglutaryl coenzymeA (HMG-CoA) reductase mRNA expression, which may lead to decrease in hepatic cholesterol pool through inhibition of the enzyme activity. Moreover, osthol induced a significant increase in acyl-CoA oxidase mRNA expression associated with an increase in carnitine palmitoyl transferase 1a mRNA expression, which suggests the acceleration of β-oxidation of hepatic fatty acids. This may be responsible, at least in part, for the reduction of hepatic triglyceride content in SHRSP. These beneficial effects of osthol could be useful for both prevention of atherosclerosis and suppression of hepatic lipid accumulation.