EFFECT OF ZINC DEFICIENCY ON THE APOPTOSIS OF IMMUNOCYTES IN THREE WEEKS OLD RATS / 营养学报

Objective: To observe the effects of dietary zinc deficiency on the apoptosis of immunocytes in 3 weeks old rats and study the underlying mechanism. Methods: A zinc-deficient growing rat model was developed. Using TUNEL(terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) method, the apoptosis of thymocytes and spleen lymphocytes was checked. The expression of bcl-2, bax mRNA in thymus and spleen was detected by RT-PCR. Results: Compared with zinc adequate(ZA) and paired-fed(PF) groups, the percentage of apoptosis cells in thymus and spleen of zinc-deficient(ZD) rats was obviously higher, and the thymus and spleen of ZD rats had a higher expression of bax mRNA. Zinc supplementation could reverse these changes. Conclusion: Dietary zinc deficiency leads to the increase of apoptosis of lymphocytes in thymus and spleen. One important mechanism is that the thymus and spleen have higher expression of bax mRNA, which causes the decrease of bcl-2/bax ratio.

THE EFFECT OF ZINC DEFICIENCY ON THE PHENOTYPES AND SUBSETS OF PERIPHERAL BLOOD LYMPHOCYTES IN GROWING RATS / 营养学报

Objective: To observe the effects of zinc deficiency on peripheral blood lymphocyte phenotypic distribution and the balance between Th1 and Th2 cells in growing rats. Methods: Two-color cytofluorometric analysis was used. Results: Compared with zinc adequate (ZA) and paired-fed (PF) groups, peripheral blood lymphocytes in zinc deficient (ZD) rats had higher percentage of CD8+ cells (cytolytic T cells), lower percentage of CD4+ cells (T helper cells) and lower percentage of CD45RA+ cells (pure B lymphocytes).In addition, zinc deficiency selectively caused reduction of Th1-like CD45RC+CD4+ cells , but Th2-like CD45RC-CD4+cells had no significant changes in weanling rats. Zinc supplementation could reverse these changes. Conclusion: Dietary zinc deficiency leads to changes of lymphocyte phenotypic distribution and the imbalance of Th1 and Th2 subsets. These changes are reversible.

ZINC METABOLIC POOL SIZE--A RELIABLE INDEX FOR THE ASSESSMENT OF ZINC NUTRITURE / 营养学报

Zinc metabolism was determined with 88Zn and 70Zn, stable isotopes of zinc, in two volunteers who went through different levels of zinc nutriture for 15 weeks. It was shown that zinc metabolic pool size could correctly reflect zinc nutriture. The difference between fasting and postprandial plasma zinc concentration was more reliable than fasting plasma zinc concentration alone. The sense of daily urinary and fecal zinc excretion were rather limi ted. In a certain sense, fecal endogenous zinc excretion was valuable for establishing recommendation dietary allowance of zinc.