Experimental Study Of PSK On Modulating Lipoidemia And Blunting Atherosclerosis In Rats And Rabbits

OBJECTIVES: To study the effects of PSK on hyperlipoidemia and atherosclerotic formation of rabbits after a preliminary research of PSKon modulating lipoidemia in rats.METHODS: Healthy New Zealand rabbits were randomized into 6 groups. Different feeds and treatments for each group were arranged as follow: normal group was on normal diet; control group was on high fat and high cholesterol diet; low dose PSK group, middle dose PSK group and high dose PSK group were on high fat and high cholesterol diet and treated with PSK 47mg/kg, 140mg/kg and 420mg/kg, once a day, respectively; lovastatin group was on high fat and cholesterol diet and treated with lovastatin 4mg/kg/d. After 100 days of feeding, the levels of plasma TC, LDL, TG, HDL and Lp- (a) were detected. Then animals were sacrificed for surveying lesion area in aortic arch and coronary arteries in heart wall with microscope. Percentages of plaque area in aorta, ratio of plaque formation at the artery opening in aorta, and degrees of stenosis of the branches of coronary arteries in heart wall were examined.RESULTS:Great increases of plasma TC and LDL levels were observed in experimental hyperlipoidemia rabbits and were decreased by treatments with different doses of PSK or locastatin. But only high dose PSK and lovastatin had significant effects on them (p<0.01). The effects of high dose PSK on plasma TC and LDL were less than that of lovastatin. Neither high dose PSK or lovastatin could recover plasma TC and LDL levels of experimental hyperlipoidemia rabbits to normal. There was alsogreat increase in plasma TG in experimental hyperlipoidemia rabbits, and both PSK and lovastatin could significantly decreased it (p<0.05). Plasma HDL in experimental hyperlipoidemia rabbits increased too and responded to PSK and lovastatin like plasma TG did. The same thing happened to plasma Lp-(a)(p>0.05), which was possibly involved in the atherosclerotic plaque formation of experimental hyperlipoidemia rabbits. The results of gross morphology survey on aorta were agreed with that of microscopic morphology survey on lesion area in aortic arch and on coronary arteries in heart wall. It was showed that the degree of lesion was the severest in experimental AS control group and was the lightest in lovastatin group, and gradually lessened with increase of dose of PSK; no lesion was found in normal group. The dose-effect relationship existed among different dose PSK groups. Decrease of the percentage of plaque area in aorta was the greatest in lovastatin group and was greater in high dose PSK group. The dose-effect relationship was showed among different dose PSK groups, but only high dose PSK and lovastatin could significantly decrease the percentage of plaque area in aorta (p<0.01), and the effect of high dose PSK was less than that of lovastatin (p<0.01). The ratio of plaque formation at the artery opening in aorta was reduced by different dose PSK as well as lovastatin. The effect of lovastatin on it was significant (p<0.01). The dose-effect relationship was revealed among different dose PSK groups. Only in high dose PSK group there was statistical difference (p<0.00625), compared with experimental AS control group. High dose PSK and lovastatin could significantly mitigate the stenosis degree of the branches of coronary arteries in heart wall (p<0.01). There was just only statistical difference in middle dose PSK group (p<0.05), compared with experimental AS control group. The effect of high dose PSK was less than that of lovastatin, but the significant difference between them failed to be found. CONCLUSION: All above indicates that either high dose PSK or lovastin has a benign effect on modulating hyperlipoidemia and blunting atherosclerosis in rabbits.