缺乏赖氨酸对大鼠血清氨基酸含量和肠道氨基酸通透性的影响

目的通过饲喂大鼠赖氨酸(L-lysine,Lys)缺乏日粮,研究其对血清氨基酸(amino acid,AA)含量及对空肠和回肠上皮组织Lys及其它AA吸收的影响。方法体重240±20g的成年SD大鼠16只,随机分为2常规日粮(对照)和玉米醇溶蛋白日粮(Lys缺乏试验日粮)2组,试验期21d。实验末大鼠称重采血,断头处死,采集空肠和回肠样品,测定血清AA含量,尤斯灌流系统(Ussing Chamber)测定肠道转运AA变化及Lys的转运能力。结果试验组大鼠生长呈负增长,血清Lys、精氨酸(Arg)含量较对照组分别降低61.93%和33.08%(P<0.01),亮氨酸(Leu)和酪氨酸(Tyr)分别提高111.48%和63.43%(P<0.05),其他AA含量受Lys缺乏的影响不明显;试验组由扩散池经空肠或回肠向接收室的转运过程中Lys的消耗比率达到46.55%或51.28%,与对照组相比,分别显著增加了28.06%(P=0.006)或51.74%(P=0.001);在一定时间(60min)内,对照组和试验组Lys的转运经回肠吸收的累计透过量显著高于空肠(P<0.05),并伴随有其他AA的变化。结论日粮缺乏Lys导致大鼠生长性能降低,同时使空肠Lys通透率降低,而回肠Lys通透率提高。该结果为研究Lys等内源性AA的代谢机制提供了基础。

EFFECTS OF DIETS WITHOUT L-LYSINE ON SERUM AMINO ACIDS CONCENTRATION AND INTESTINAL EPITHELIAL AMINO ACID PERMEABILITY IN RATS

Objective To determine the effects of diets without L-lysine(Lys) on serum amino acids concentration and absorption of Lys and other amino acids of jejunum and ileum epithelial tissue in SD rats.Method Sixteen Sprague-Dawley rats weighing 240±20g were randomly divided into two groups:normal diet(the control group),zein diet(diet without lysine,the experimental group).The experiment lasted 21 d.At the end of the experiment,all the rats were weighed,and then killed for blood and tissue collection,which were used to determine serum amino acid(AA) concentration,transfer ability and permeability of AA in intestinal mucosa by Ussing Chamber technology.Results The results showed that rats with zein diet appeared negative growth.Compared with the control group,serum Lys and Arg concentration in the experimental group was significantly decreased by 61.93%(P<0.01) and 33.08%(P<0.01) respectivaly,while Leu and Tyr concentration was significantly increased by 111.48%(P< 0.05) and 63.43%(P<0.05) respactively.There was no significant difference in other amino acids concentrations between two groups.In the experimental group,Lys penetrated the jejunum or ileum epithelium from the diffusion pool to the receiving room with the consumption rate of 46.55% or 51.28%,which was increased by 28.06%(P=0.006) and 51.74%(P=0.001) respectively when compared with the control group.During 60 min,the amount of cumulative Lys transported through ileum mucosa in the absorptive direction was significantly higher than that from jejunum(P<0.05),and meanwhile,other amino acids also appeared the same.Conclusion The diet without Lys caused retardation of growth in SD rats.Lys permeability was decreased in jejunum,but increaced in ileum in the exprimental group.This study provides foundation for further research about the mechamism of endogenous amino acid matabolism,especially Lys.