ZINC ADMINISTRATION PREVENTS WASTING IN STRESSED MICE

Experimentally induced chronic stress can produce severe retardation o n the physical development of young animals. Moreover, the chronic str ess and its associated secondary malnutrition cause a variable depress ion on immunity, whose pathogenesis has been related to the excessive production of cytokines and glucocorticoids. When stressful stimuli ar e excessive, animals increment their anorexia and express a progressiv ely installed wasting syndrome, associated with hypozincemia and susce ptibility to infections with high mortality rate. In this work, chroni cally stressed mice were studied to observe the prophylactic effect of a zinc treatment on the evolution of both their malnutrition and thei r immune competence. Stress was induced in newborn Balb/c mice by intr aperitoneal (IP) injections with heat-killed bacteria for 4 weeks. Fol lowing this inductive period, almost all the stressed mice showed a tr ansient wasting syndrome characterized by anorexia, deficient gain of corporal weight, diarrhea, skin infection, reduced antibody response a gainst antigens of red blood sheep cells, and a decreased proliferativ e response in their Con-A stimulated splenic lymphocytes. However, whe n the stressed mice received an additional IP treatment with zinc acet ate, their clinical condition showed a significant improvement and the ir immunocompetence was similar to that exhibited by non-stressed mice from the control groups. The results suggest that zinc supplementatio n can ameliorate the effects of chronic stress on the growth, corporal weight, and immunocompetence of young mice.