Behavioral effects of testosterone in relation to social rank in the male rabbit

The role of gonadal androgens in favoring the adaptation to environmental pressure, including social organization, is well known. In the rabbit, testosterone administration increases marking behavior, and its level can be affected by agonistic interaction. In this experiment, we studied the effect of subcutaneous administration of testosterone propionate (TP) (3 mg/d for 6 days) in male rabbits belonging to the same social group (6 groups of 4 animals). In 2 additional groups (4 animals each), males were injected with almond oil. The animals were observed for 6 days in seminatural conditions, then treated with TP (or oil) and observed for another 6 days. The dominant/subordinate frequency ratio of behavioral patterns was used to rank the animals. The testosterone plasma concentration was correlated with agonistic behavior after the first period of social interaction. A significant increase of marking, digging, and defensive activity was observed after TP administration in all animals independent of rank, whereas this increase was not present in animals treated with oil. Agonistic and interactive behaviors increased significantly after TP treatment only in the first-ranking animals. This indicates the influence of social rank in the modification of behaviors involving interactions among subjects © Wiley-Liss, Inc.