Alterations of short-term tastant-containing fluid intake in zinc deficient adult rats.

Previous studies have demonstrated that zinc deficient rats have elevated taste preferences for tastant-containing solutions normally preferred or rejected by zinc sufficient rats when tested in a two-bottle, 24-hour procedure. Since that test does not control for postingestional determinants upon fluid consumption, we employed a two-bottle, 1-hour test combined with a restricted 3-hour eating period to evaluate taste preferences in seven rats fed a zinc deficient (1.3 ppm zinc) diet and nine rats pair-fed a zinc sufficient diet (100 ppm zinc). After 31 days of feeding, all rats were tested for 2 days (1 hour/day) with a choice between water and each of the following solutions: 0.15 M sodium chloride (NaCl), 2.5 X 10(-3) M Hydrochloric acid (HCl), 0.15 M NaCl, 2.5 X 10(-3) M HCl, 1.28 X 10(-6) M quinine sulfate (QS), 0.30 M NaCl and 1.28 X 10(p6) M QS. The zinc deficient rats demonstrated significantly greater preferences for all of the tastant-containing solutions but showed both significant increases and decreases in total volume intakes. Analysis of the individual water and tastant-containing fluid intakes demonstrated that the zinc sufficient rats consumed significantly more water but significantly less tastant-containing fluid than the zinc deficient rats. These results demonstrate that the increased preferences of zinc deficient rats may be related to preingestional, i.e., taste, rather than postingestion cues.