By Timothy Philbeck
Faculty Mentor: Parrish Waters
Mice are social animals, and interactions among individuals can provide valuable information related to behavioral and physiological processes. To better understand social relationships in mice, the Tube-Test was developed to easily measure behavioral dominance in cohorts of mice; although this method is not universally accepted as a reliable measure of social dominance, it holds the benefit of being rapid, low stress, and providing an objective measure of dominance. To address the controversial validity of the Tube-Test and to enhance our ability to discriminate dominant mice in social groups, I compared results from the Tube-Test to home-cage behavior, preputial gland size, and steroid hormone levels, all of which are more universally accepted (but more labor intensive) indicators of social dominance in mice.
I housed mice in dyads and assigned them social ranks (i.e. dominant or subordinate) based on their proportion of wins during the Tube-Test (n = 6 dyads). Social rank influenced the duration of total aggression (t = -18.42, df = 4, p ≤ 0.05), although subordinate mice exhibited higher levels of aggression. I used Wilcoxon rank sum tests to compare corticosterone concentration and preputial gland size. Social rank did not influence either of these measures (corticosterone: W = 6, p = 0.7; preputial gland: W = 3, p = 0.7). My results from this pilot study suggest that the Tube-Test does not represent an effective method to measure dominance-like behavior or physiological changes in laboratory mice, although I am continuing this work with an additional cohort of mice.