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Effects of olive and corn-oil enriched diets on tissue mineral content in regeneration liver and lymphatic tissue of partially hepatectomized mice

Injury or removal of liver tissue leads to fast growth of liver remnant, involving changes in gene expression, growth factor production and morphological structure. Important biological mediators in these events, might be tissue minerals, and mono- and polyunsaturated fatty acids, which are controlling processes of proliferation and apoptosis, affecting the mitogenesis, lipid peroxidation, antioxidant activities, activity of growth factors, hormones etc, as well as the lymphatic functions, responsible for the maintenance of immune surveillance and cytokine production. To elucidate some aspects of these events during the normal growth, in this study we analyzed the mineral content (zinc, iron, magnesium and calcium) in the liver, spleen and thymus of intact and partially hepatectomized (pHx) mice, which were over 21 days fed by diets enriched with olive or corn oil (5% addition to standard pellet, w/w). Namely, olive oil contains predominantly oleic acid (C18:1, n-9), and 0, 2-0, 7 % of squalene, while in corn oil prevails linoleic acid (C18:2, n-6). Analysis was done by microwave digestion and ICP spectrometry and tissue mineral content was analyzed from the second until 21st day after pHx. Mice in the control group were fed by standard laboratory food. The data have shown that tissue content of Zn, Fe, Mg and Ca is significantly affected by pHx, and additionally changed by the diets. In early phase of regeneration in the liver of control mice significantly increased the concentration of Zn and Ca. Simultaneously, the concentration of Zn, Ca and Mg decreased in the thymus and in the spleen. In the latter phase of regeneration (on the 7th and 21st p.o. day), however, a marked accumulation of Zn, Mg and Ca was noticed particularly in the thymus. In mice fed by olive and corn oil diet most of these changes were less expressed. Zn- accumulation in the liver was significantly lower, while in the thymus on the 2nd p. o. day the increased concentrations of Ca and Mg were noticed. The data also imply that olive-oil enriched diet had greater effects on Zn, Ca and Mg turnover in the thymus, in contrast to corn-oil diet, which more affected Zn and Ca content in the spleen. These changes probably explain the initially greater liver growth in mice on olive oil in comparison with those on corn-oil, but after 48h both diets decreased the weight of regenerating liver. The importance of Zn-dependent hepato-thymic axis in pHx mice was additionally emphasized by finding that in mice on corn-oil diet, the remnant liver mass was in high correlation with zinc concentration in the thymus, being negative at the beginning of regeneration (r = -0, 74 ; p<0, 002), and highly positive (r = 0, 81, p<0.05) at its end. The data imply that the binding affinity of hepatic metallothioneins play a role in liver regeneration, provoking direct or indirect changes also in lymphatic system, where mineral content might influence several aspects of immunity.

tissue metal content; partial hepatectomy; lymphatic organs

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