Effect of Shunyo Rice Protein on Cholesterol Metabolism in Adult Rats

To elucidate the effect of Shunyo rice protein,with high prolamin content,on cholesterol metabolism in adult rats.20-week-old male Wistar rats were fed with Shunyo rice protein(RP),soy protein(SP) and casein(CAS) ad libitum for 2 weeks(CP as 14%),respectively.Similar growth performance and protein efficiency ratio were observed in all groups.Compared with CAS,RP and SP both produced marked hypocholesterolemic action,reflecting in the significant reduction of total cholesterol(TC),low density lipoprotein cholesterol(LDL-C) and very low density lipoprotein cholesterol(VLDL-C)(P0.05),as a result,the atherogenic index(AI) of adult rats fed with RP was lower than those fed with CAS.The liver accumulations of total lipids,cholesterol(total cholesterol,free cholesterol and cholesterol ester) and triglyceride were significantly decreased in RP and SP when compared with CAS(P0.05).The dramatic decrease of apparent cholesterol absorption(P0.05) and cholesterol esterified ratio(P0.05) were also observed both in this study.The similar stimulation in excretion of fecal neutral sterol and fecal cholesterol were observed both in adult rats fed with RP and SP(P0.05).SP increased fecal bile acids excretion,whereas RP did not.Results suggested that Shunyo rice protein,with high prolamin content,efficaciously lowered plasma and liver cholesterol level in adult rats,showing a similar cholesterol-lowering effect with soy protein.The mechanism of cholesterol-lowering effects induced by Shunyo rice protein cannot be explained by the result of a simple diversion of bile acids toward fecal excretion.Inhibition of intestinal cholesterol absorption may be the primary mechanism due to the poor digestibility of prolamin.