椰油和牛脂对大鼠血脂浓度的影响及可能机制的初步探讨

目的观察椰油和牛脂对大鼠血脂浓度的影响并初步探讨其可能机制。方法选取18只Wistar雄性大鼠，实验分2组，分别喂饲含10％椰油或牛脂的纯合成饲料21d。实验开始和结束时，测血浆总胆固醇(STC)、总甘油三脂(STG)、低密度脂蛋白胆固醇(LDLC)、高密度脂蛋白胆固醇(HDLC)、载脂蛋白A(ApoA)和载脂蛋白B(ApoB)浓度。实验结束前，收集3d粪便，测定脂肪、钙、磷、镁消化率、粪胆汁酸排出量。结果同实验开始时相比，牛脂组的大鼠血浆总胆固醇浓度显升高(P＜0．05)，而椰油组大鼠却不明显；两组大鼠ApoA浓度均显升高，HDLC、STG和ApB浓度显降低(P＜0．01)；椰油组大鼠的LDLLC/HDLC比值显降低(P＜0．01)。同椰油组相比，牛脂组大鼠的脂肪、钙和镁的消化率显降低(P＜0．01)，粪胆汁酸浓度显下降(P＜0．01)。结论同摄入椰油相比，摄入牛脂可明显升高大鼠血浆总胆固醇浓度。其机制可能为组成椰油和牛脂的脂肪酸碳链长度不同导致了胆汁酸肠肝循环的速率不同，从而，引起粪胆汁酸排出量的变化，进而调整了血浆胆固醇浓度。因此，摄入含有大量中短链脂肪酸的油脂(如椰油)有利于心血管疾病的预防。

Effect of Coconut Oil and Tallow on the Concentration of Serum Lipids and a Preliminary Study on a Possible Mechanism

Objective To investigate the effects of coconut oil and tallow on the concentration of serum lipids and to explore the possible mechanism preliminarily Methods 18 male rats were divided into 2 groups and were fed purified diets containing 10% of coconut oil or tallow for 21 days,respectively Fast blood samples were collected at the beginning and the end of the experimental period Serum total cholesterol(STC),serum total triglycerides(STG),low-density lipoprotein cholesterol(LDLC),high-density lipoprotein cholesterol(HDLC),apolipoprotein A(ApoA),and apolipoprotein B(ApoB)were measured Feces were collected during the last 3 days of the trial,apparent digestibility of fat,calcium,phosphorus and magnesium was measured Fecal bile acid excretion was determined Results Comparing with the baseline,STC in tallow group was increased significantly( P <0 05)at the end of the experiment;ApoA was increased,but HDLC,STG and ApoB were decreased significantly( P <0 05)in both groups LDLC/HDLC in coconut oil group was declined markedly( P <0 01) Compared with rats in coconut oil group,digestibility of fat,calcium and magnesium of rats in tallow group was significantly low( P <0 01) Also,the concentration of fecal bile acid of rats was low( P <0 01) Conclusion Comparing with coconut oil,intake of tallow increased STC markedly in rats A possible mechanism may due to the difference of carbon chain length in fatty acids between coconut oil and tallow,that induces a different enterohepatic circulation frequency and leads to a change of fecal bile acid excretion,thus,concentration of STC may be regulated Therefore,intake of fat containing a great proportion of short chain length of fatty acids benefits prevention of cardiovascular disease