Social hierarchies are crucial for a group's survival and can influence the way an individual behaves and relates to a given social context. The study of social rank has been classically based on ethological and observational paradigms, but it recently has taken advantage of the use of other approaches, such as the tube test that measures territorial dominance without the display of in situ aggression and is executable in group-living animals. However, little is known about how previous basal individual differences affect the development of dominance hierarchy measured in the tube test. We have analyzed in male mice body weight, locomotion, anxiety, and serum corticosterone both before and after the tube test, as well as adult hippocampal neurogenesis and transcriptome in the prefrontal cortex after the hierarchy had been established. We found differential gene expression between dominants and subordinates but no association between the other parameters and social status, neither pre- nor posttest. Our findings reveal that social rank in mice is stable along time and is not related to basal differences in stress, mood, or physical features. Lastly, real-time quantitative PCR analysis confirmed differential expression of vomeronasal and olfactory receptors in the cerebral cortex between dominant and subordinate individuals, suggesting that differential brain gene expression in the medial prefrontal cortex could potentially be used as a biomarker of social dominance.-Pallé, A., Zorzo, C., Luskey, V. E., McGreevy, K. R., Fernández, S., Trejo, J. L. Social dominance differentially alters gene expression in the medial prefrontal cortex without affecting adult hippocampal neurogenesis or stress and anxiety-like behavior.
Keywords: corticosterone; dominance hierarchy; elevated plus maze; tube test; vomeronasal/olfactory receptors.