Rodriguez P, Darmon N, Chappuis P, Candalh C, Blaton M A, Bouchaud C, Heyman M
Laboratoire de Cytologie, Université Paris VI, France.
Gut. 1996 Sep;39(3):416-22. doi: 10.1136/gut.39.3.416.
Zinc has been shown to have beneficial effects in vitro on epithelial barrier function, and in vivo to reduce intestinal permeability in malnourished children with diarrhoea.
To determine whether malnutrition alters intestinal paracellular permeability, and whether zinc prevents such alterations.
Guinea pigs were fed a normal protein diet (NP group), a low protein diet (LP group), or a low protein diet enriched with 1800 ppm zinc (LPZn group) for three weeks. Intestinal permeability was measured on jejunal segments mounted in Ussing chambers by measuring ionic conductance and mucosal to serosal fluxes of 14C-mannitol, 22Na, and horseradish peroxidase. Tight junction morphology was assessed on cryofracture replicas.
Mannitol and Na fluxes and ionic conductance increased in the LP group compared with the NP group but remained normal in the LPZn group. Accordingly, jejunal epithelia from the LP group, but not from the LPZn group, showed a small decrease in number of tight junctional strands compared with epithelia from the NP group. Neither malnutrition nor zinc treatment modified horseradish peroxidase fluxes.
Malnutrition is associated with increased intestinal paracellular permeability to small molecules, and pharmacological doses of zinc prevent such functional abnormality.
锌已被证明在体外对上皮屏障功能有有益作用，在体内可降低腹泻营养不良儿童的肠道通透性。
确定营养不良是否会改变肠道细胞旁通透性，以及锌是否能预防这种改变。
将豚鼠分为三组，分别给予正常蛋白质饮食（NP组）、低蛋白质饮食（LP组）或富含1800 ppm锌的低蛋白质饮食（LPZn组），持续三周。通过测量离子电导以及14C-甘露醇、22Na和辣根过氧化物酶的黏膜到浆膜通量，对安装在尤斯灌流小室中的空肠段的肠道通透性进行测量。在冷冻断裂复制品上评估紧密连接形态。
与NP组相比，LP组的甘露醇和钠通量以及离子电导增加，但LPZn组保持正常。因此，与NP组的上皮相比，LP组空肠上皮的紧密连接链数量略有减少，而LPZn组没有。营养不良和锌处理均未改变辣根过氧化物酶通量。
营养不良与肠道对小分子的细胞旁通透性增加有关，药理学剂量的锌可预防这种功能异常。
