Odor modulation of ventral scent gland marking in the Mongolian gerbil.

Gerbil odors were allowed to accumulate in individual home cages for several months in order to provide stable olfactory stimuli that might modulate the number of ventral scent gland marks produced by both male and female Mongolian gerbils. Male marking levels for most test conditions were 2-3 times larger than those in females. In general, the relative patterns of responsiveness to particular odors were similar in both sexes. The number of scent marks in home cages was significantly smaller than the number obtained in clean cages. This suppression was not strongly dependent on the odors emanating from an individual's own ventral gland sebum. Marking levels in the home cages of other gerbils were substantially higher than those seen in the test animal's own cage and were maximal in the home cages of other males. Behaviorally receptive females marked at significantly higher levels in home, clean, and conspecific cages than did nonreceptive females. Conspecific urine odors, especially those from females, increased marking levels significantly over those obtained in home cages. In males, home cage marking was significantly enhanced by the presence of a female. Females, on the other hand, marked at similar levels in home cages whether a potential mating partner was present or not. Both sexes showed significant reductions in marking levels in another's cage if the resident animal was present. These results suggest that when sufficient gerbil-related odors are available to a test animal, its rate of scent-marking is altered, depending on the particular odor environment. Some gerbil-related odors increase marking levels, whereas others decrease marking. Scent-marking then, like other olfactory guided behaviors and odor preferences, is context specific.