Splenomegaly and other hematological parameters in the socially dominant mouse.

Within a social dominance hierarchy, subordinate mice show hematological changes such as increased erythropoiesis and splenomegaly. The present experiment demonstrates similar findings for the unwounded dominant mouse. In addition, total serum protein, serum albumin and plasma fibrinogen were measured. Male DBA/2j mice were placed into social triads for three 24 hr periods. The resultant dominant and subordinate mice were compared with isolated control mice. Splenomegaly, thymus involution, decreased hematocrit, and increased fibrinogen levels were found in dominant mice. Subordinate mice demonstrated the same changes to a greater extent, as well as an increased reticulocyte count. Only dominant mice showed a reduction in total serum protein. Wounding-independent processes must be involved in these cellular and non-cellular hematological effects of psychosocial stress.