抄録
Previous studies have demonstrated that zinc deficient rats drink 0.3M NaCl, avoided by normal animals, in preference to water. We investigated the participation of humoral factors in such salt intakes in zinc deficient rats by analyzing serum concentrations of aldosterone, angiotensin II and sodium. Animals were fed a zinc deficient diet (group 1) or the normal control diet (groups 2 and 3) ad libitum. Group 3 was pair fed with group 1. Serum constituents and preference for NaCl solutions (48-hr two-bottle choice test) were determined at one and four weeks after the onset of feeding. The intake of 0.3M NaCl solution in preference to water occurs in group 1, but not in groups 2 and 3, from one week after the onset of feeding. There was no significant difference in serum concentrations of sodium among all groups throughout experiments. However, estimates of group 1 tended to be lower than those of other two groups four weeks after the onset of feeding. Angiotensin II concentrations decreased significantly in group 1 compared with in two other groups, whereas aldosterone concentrations in group 1 were approximately two times as high as those of two other groups. These results suggest that in zinc deficient animals with low serum concentrations of sodium, aldosterone is upregulated through synthetic pathways different from rennin-angiotensin system. Increased central action of aldosterone may lead to increased sodium appetite. [J Physiol Sci. 2006;56 Suppl:S225]
