Scent marking behavior in male C57BL/6J mice: sexual and developmental determination

Abstract

The present study investigated urinary scent marking behavior in male C57BL/6J (C57) mice as olfactory social signaling. In Experiment 1, when compared scent marking toward adult males, C57 males showed substantial scent marking toward CD-1 males and even toward the odor alone of CD-1 males, but not toward C57 males. Experiment 2 explored scent marking in C57 males of different ages to males and females, and juveniles and adults of the same strain. C57 males deposited more marks than control conditions only toward an adult C57 female when tested at 100 days of age, but not at 60 days of age. Development of urine marking behavior was investigated in C57 males at the ages of 30, 60, 90, and 120 days in Experiment 3. When tested alone (control) or confronted with a C57 male, C57 males showed diminished scent marks throughout development. Compared to controls, marking toward a CD-1 male increased after the age of 60 days, while marks toward an adult female showed significant increases after the age of 90 days. This difference in scent marking depending on the sex of the stimulus animal is likely to be associated with development of sexual behavior, in which males need to set up territories against other males prior to advertising to females. Although highly inbred strains have similar odor components, C57 males are able to detect and deposit urine marks after puberty as social communication depending on age, sex, and genetic differences in the opponents.

Fig. 1

Total number of squares with urine marks for C57 males (N=12) during 20 min exposed singly (S), or with a C57 male (C57), a CD-1 male (CD1), or odor of CD-1 male (OD1 odor). Data are expressed as mean (± S.E.M.). * indicates significant differences between groups compared to Group S, p<.05.

Fig. 2

Total number of squares with urine marks for C57 males aged 60 days (left panel) and 100 days (right panel) (each N=12) during 20 min exposure singly (S), or with an adult C57 male (AM), an adult C57 female (AF), a juvenile C57 male (JM), or a juvenile C57 female (JF). Data are expressed as mean (± S.E.M.). * indicates significant differences between groups compared to Group S, p<.05.

Fig. 3

Total number of squares with urine marks for C57 males aged 30, 60, 90, and 120 days (each N=12) during 20 min exposure singly (S), or with a C57 male (C57m), with an adult C57 female (C57f), or an adult CD-1 male (CD1m). Data are expressed as mean (± S.E.M.). * indicates significant differences between groups compared to Group S, p<.05.