Different recovery responses from dietary zinc-deficiency in the distribution of rat granulocytes

The purpose of this study was to elucidate the effects of the recovery from dietary zinc-deficiency on the number of total white blood cells (WBCs), neutrophils, eosinophils and basophils, and plasma zinc and corticosterone concentrations in weanling male Sprague Dawley rats. Rats (n=34) of the zinc-deficient diet (0.6 mg zinc/kg diet) and control diet (35.2 mg zinc/kg diet) groups were fed for 4 wk, and then rats of both groups were fed with the control diet for 3 wk. Zinc-deficiency increased duration-dependently and clearly the number of total WBCs, neutrophils and eosinophils, and the increased numbers of these cells recovered to the control levels in week 2 of the recovery. On the other hand, the number of basophils increased by the zinc-deficiency recovered to the control levels in week 1 of the recovery. Zinc-deficiency significantly decreased plasma zinc concentrations by 85%, and markedly increased plasma corticosterone concentrations by 317%, as compared with the control group. In the recovery period, plasma zinc and corticosterone concentrations recovered to the control levels in week 2 of the recovery. These results suggest that zinc-deficiency and its recovery responses in the number of granulocytes and total WBCs are reversible, and their recovery rates depend on the subsets of granulocytes in rats.