ABSTRACT
Experimentally induced chronic stress can produce severe retardation on the physical development of young animals. Moreover, the chronic stress and its associated secondary malnutrition cause a variable depression on immunity, whose pathogenesis has been related to the excessive production of cytokines and glucocorticoids. When stressful stimuli are excessive, animals increment their anorexia and express a progressively installed wasting syndrome, associated with hypozincemia and susceptibility to infections with high mortality rate. In this work, chronically stressed mice were studied to observe the prophylactic effect of a zinc treatment on the evolution of both their malnutrition and their immune competence. Stress was induced in newborn Balb/c mice by intraperitoneal (IP) injections with heat-killed bacteria for 4 weeks. Following this inductive period, almost all the stressed mice showed a transient wasting syndrome characterized by anorexia, deficient gain of corporal weight, diarrhea, skin infection, reduced antibody response against antigens of red blood sheep cells, and a decreased proliferative response in their Con-A stimulated splenic lymphocytes. However, when the stressed mice received an additional IP treatment with zinc acetate, their clinical condition showed a significant improvement and their immunocompetence was similar to that exhibited by non-stressed mice fron the control groups. The results suggest that zinc supplementation can ameliorate the effects of chronic stress on the growth, corporal weight, and immunocompetence of young mice