Mechanism study of chitosan on lipid metabolism in hyperlipidemic rats.

It has been reported that plasma and liver cholesterol concentrations decrease when animals are fed with chitosan, but the mechanism is unclear. Four wk old male SD (Sprague-Dawley) rats were fed a commercial rat diet (cholesterol-free diet, negative control, NC), cholesterol-enriched diet containing 5% of chitosan (CH) or cholesterol-enriched diet containing 5% of cellulose (CE) and 5% of lard for 12 weeks. We would investigated the effects of chitosan on plasma and liver cholesterol levels, liver weight, bile acids concentrations of fecal and hepatic LDL receptor mRNA expression. The results showed that chitosan could decrease levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) in plasma (p<0.05), and TC, total triglyceride (TG) in liver (p<0.05), and increase fecal bile acids excretion (p<0.05), but the levels of TG and HDL-C in plasma was unchanged (p>0.05). In addition, the result of RT-PCR test showed that saturated fat and cholesterol fed could significantly induce the reduction of LDL receptor mRNA levels, while chitosan could increase hepatic LDL receptor mRNA levels. This study suggested that chitosan improve lipid metabolism by regulating TC and LDL-C by upregulating of hepatic LDL receptor mRNA expression, increasing the excretion of fecal bile acids.