15. Cohabitation with a sick cage mate: Interaction between innate immunity and resistance to Ehrlich tumor growth in male mice

Abstract

Stress can modulate the immune response through hypothalamus–pituitary–adrenal axis and sympathetic autonomic nervous system activities. Recent studies of our group have shown that cohabitation with a sick conspecific (inoculated with Ehrlich tumor cells intraperitoneally) induces in female mice leukopenia, increases the susceptibility to the development of the same tumor, reduces the activity of neutrophils, decreases norepinephrine levels and increases this neurotransmitter turnover in the hypothalamus. The aim of the present study was to verify the possible occurrence of similar neuroimmune effects in male mice that lived with a sick cage mate. Specifically we looked now for effects of cohabitation on resistance to Ehrlich tumor growth and neutrophils phagocytosis and oxidative burst. Our results showed a reduction in the oxidative burst of neutrophils and an increased volume of the collected ascitic fluid after Ehrlich tumor induction. In all the cases, the results were considered significant at p < 0.05. In conclusion, our results suggest that male mice that lived with a sick animal presented as with female, a reduction in both host resistance to Ehrlich tumor growth and innate immunity. CAPES.