Modulation of marble-burying behavior in adult versus adolescent C57BL/6J mice of both sexes by ethologically relevant chemosensory stimuli.

The marble-burying test is a pharmacologically validated paradigm used to study anxiety-like behaviors in laboratory rodents. Our laboratory has employed this assay as part of a behavioral screen to examine drug-induced negative affective states. Historically, the majority of our prior binge alcohol-drinking studies employed male subjects exclusively and reliably detected adolescent-adult differences in both basal and alcohol withdrawal-induced negative affect. However, age-related differences in marble-burying behavior were either absent or opposite those observed in our prior work when female subjects were included in the experimental design. As chemosensory cues from females are reported to be anxiolytic in males, the present study examined how odors from adult members of the opposite and same sex (obtained from soiled bedding) influence marble-burying behavior in adult, as well as adolescent, mice. Control studies examined the responsiveness of mice in the presence of novel neutral (vanilla) and aversive (tea tree) odors. Adult males exhibited reduced signs of anxiety-like behavior in the presence of female-soiled bedding, while adult females and adolescent mice of both sexes increased marble-burying behavior in the presence of both male- and female-soiled bedding. All mice exhibited increased burying in the presence of an aversive odor, while only adolescents increased marble-burying in response to the novel neutral odor. These data indicate sex by age interactions in the effects of volatile and nonvolatile odors from sexually-naive adult conspecifics on indices of anxiety-like behavior in the marble-burying test of relevance to the experimental design and procedural timing of experiments including sex as a biological variable.