CHANGE IN SOCIAL STATUS OF DOMINANT MALE MICE SUBSEQUENT TO GONADECTOMY: A MULTIVARIATE APPROACH
The present research investigated the effects of castration on the social status of dominant male mice. Male mice achieve dominance with aggressive behavior, and aggression is viewed as covarying with many behaviors related to survival. Since testosterone is known to modulate aggression castration should lower the dominant male's aggressive behavior. Consequently, castrated dominant males should evidence a change social status.^ SJL/J mice were randomly selected and assigned to 30 colonies. Animals were approximately 65 days old and were maintained on a reverse (12:12 hr) light-dark cycle. Each of six testing arenas consisted of one large Habitrail unit connected to two smaller Habitrail units. Four male and two female mice were introduced into the large unit. Behavioral testing began the following day and continued for 10 consecutive days. These daily observations started approximately one hour into the animals' dark cycle and totaled 30 minutes per day. Two observers recorded the frequencies of all behaviors emitted by all animals. On Day 5, the dominant male was identified. This animal was either castrated (n = 15) or given sham surgery (n = 15) and returned to the colony.^ Previous research has revealed that mice establish a society consisting of dominant, subordinate, and female animals. In this study, neither Factor Analysis nor Hierarchical Cluster Analysis could delineate these three social groups. However, an exploratory Stepwise Discriminant Analysis did support the existence of three social groups on Day 5. The ANOVA statistic revealed that dominant males emitted most behaviors, and that these animals showed a lowered frequency of behaviors following surgery. Behaviors of castrated and sham treated males were similar subsequent to surgery. (Abstract shortened with permission of author.) ^
HANDS, CAROL, "CHANGE IN SOCIAL STATUS OF DOMINANT MALE MICE SUBSEQUENT TO GONADECTOMY: A MULTIVARIATE APPROACH" (1985). ETD Collection for Fordham University. AAI8521390.