Co-housing in a stable hierarchical group is not aversive for dominant and subordinate individuals.

The behavior of individuals and their responses to external stimuli are controlled by the microsocial environment, which for most mammals is associated with dominant-subordinate relationships. Physiological and behavioral differences between dominant and subordinate individuals may be 'primary' (genetically determined) or 'secondary' (due to position in the group's hierarchical structure). A series of experiments was conducted to investigate the physiological (pain response threshold), immunological (thymus, spleen weights, primary immune response), and behavioral (motor activity, behavior in a shuttle box test) characteristics of dominant and subordinate individuals in groups of three laboratory mice formed on the basis of linear hierarchy. Assessment of the effects of group conditions was made using a conditioned reflex location preference test. The results showed: 1) there are no statistically significant differences in physiological and behavioral (except for motor activity) parameters between dominant and subordinate mice; 2) co-housing of dominant and subordinate individuals in groups with stable hierarchical relationships was not aversive for them.