Neuroimunes aspects of mice kept in a stable social relation / Aspectos neuroimunes de camundongos mantidos em uma relação social estável

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The objective of the present work was to investigate the repercussions of a stable social relationship on different parameters of the behavior, neurochemical and immune activity of dominant and submissives mice. Adult males (with approximately 90 days of age) kept in pairs since wean it, had been determined as dominant or submissives, after three consecutive evaluations of the behavior, where presences or absences of attacks or escapes and positions of submission had been observed. In some experiments, groups of five animals kept in one same box had been used to compare the results gotten between these and the animals coexisting in pairs. The pairs had been used only where the social hierarchy clearly was observed. The results had shown that the submissives animals in relation to the dominant ones had presented: 1) reduction in the time spent in the central zone of the open field; 2) reduction in the number of entrances in the open arms and reduction in the time spent in the exploration of the open arms of the plus maze; 3) increase in the time spent in the exploration of the closed arms of the plus maze; 4) reduction in the number of entrances and time spent in the exploration of the final third of the closed arms of the plus maze; 5) increase in the turnover of dopamine in the hypothalamus; 6) reduction in the turnover of dopamine in the corpus striatum; 7) increased number of metastasis in the lungs induced by murino melanoma experimental B16F10; 8) increase of the percentage of cells T CD8+ in the thymus after 14 days of inoculation of the same melanoma; 9) reduction in the basal oxidative burst of neutrophil and monocytes sanguine, but not in the induced by bacteria; 10) decreased NK cells activity measured in the blood and spleen. In relation to the animals kept in number of five, the submissives animals had presented: 11) reduction in the percentile of NK cells in the blood. While the dominant animals had presented in relation to the animals kept in groups: 1) increase in the turnover of norepinephrine in hypothalamus; 2) increase in the turnover of dopamine in the fluted body; 3) reduction in the percentile of NK cells in the blood. The social status, however, did not provoke differences: 1) in the absolute levels of dopamine, norepinephrine and serotonin; 2) in the metabolites of serotonin; 3) in the serum levels of corticosterone; 4) in the weight and number of cells of the spleen and thymus; 5) in the percentage of cells T CD4+ and CD8+ in the spleen and 6) in the percentage of lymphocytes, neutrophil and monocytes in the blood. Together, the results obtained had shown that dominants and submissives animals kept 90 days living in a stable social hierarchy had presented behavior and neurochemical differences, and had answered of different form to one same immune stimulation, in this case, the induced development of metastasis in the lungs for experimental melanoma murino B16F10, where the submissives had been more susceptible than the dominant ones. This results suggest that other mechanisms, different of HPA activation, may be involved with the decreased resistance of submissive mice to B16F10 tumor dissemination

ASSUNTO(S)

estresse corticosterona stress tumor dominância neuroimunomodulação neuroimmunomodulation dominance corticosterone tumor

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