Zinc administration prevents wasting in stressed mice

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 from 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.