Poster Title

Effects of Testosterone on the Mammalian Immune System: Immunosuppression or Immunoredistribution?

Institution

Murray State University

Abstract

Testosterone is believed to be immunosuppressive in mammals. Recent research suggests, however, that testosterone may cause redistribution of leukocytes rather an actual reduction in leukocyte numbers. One hormone known to induce immunoredistribution is corticosterone. To investigate the effects of testosterone, we tested the null hypotheses that: 1) testosterone has no effect on corticosterone level and 2) testosterone has no effect on the distribution of leukocytes. We established four groups of adult male white-footed mice (Peromsycus leucopus): 1) control, 2) testosterone-treated, 3) immunochallenged, and 4) testosteronetreated and immunochallenged. Testosterone injections were given to mice for 10 days. The immunochallenged mice were treated with sheep red blood cells (SRBC) and phytohemagglutinin (PHA). To determine if immunoredistribution occurred, blood samples were taken from the heart and the retro-orbital sinus. There was no significant redistribution of leukocytes in any group of mice; however, the reaction to PHA was much greater in the control mice than the testosterone treated mice. Total white blood cell counts revealed no significant differences between the control group and testosterone treated group. Corticosterone levels were lowered by the testosterone injections so redistribution could not have occurred due to corticosterone. We concluded that testosterone does not raise corticosterone levels and is not related to immunoredistribution. Testosterone did lower the activity of leukocytes.

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Effects of Testosterone on the Mammalian Immune System: Immunosuppression or Immunoredistribution?

Testosterone is believed to be immunosuppressive in mammals. Recent research suggests, however, that testosterone may cause redistribution of leukocytes rather an actual reduction in leukocyte numbers. One hormone known to induce immunoredistribution is corticosterone. To investigate the effects of testosterone, we tested the null hypotheses that: 1) testosterone has no effect on corticosterone level and 2) testosterone has no effect on the distribution of leukocytes. We established four groups of adult male white-footed mice (Peromsycus leucopus): 1) control, 2) testosterone-treated, 3) immunochallenged, and 4) testosteronetreated and immunochallenged. Testosterone injections were given to mice for 10 days. The immunochallenged mice were treated with sheep red blood cells (SRBC) and phytohemagglutinin (PHA). To determine if immunoredistribution occurred, blood samples were taken from the heart and the retro-orbital sinus. There was no significant redistribution of leukocytes in any group of mice; however, the reaction to PHA was much greater in the control mice than the testosterone treated mice. Total white blood cell counts revealed no significant differences between the control group and testosterone treated group. Corticosterone levels were lowered by the testosterone injections so redistribution could not have occurred due to corticosterone. We concluded that testosterone does not raise corticosterone levels and is not related to immunoredistribution. Testosterone did lower the activity of leukocytes.