Stud male-originating chemosignals: a luteotrophic agent.

The chemosignals from mating male are found to be responsible for protecting his coital partner against pregnancy failure induced by strange male or food-deprivation. The stud male pheromone not only provides luteotrophic support in female of vulnerable condition but also exerts luteotrophic effect in pregnancy-blocked females by inducing pseudopregnancy. The luteotrophic stimulus rendered by stud male to prevent pregnancy failure is mediated through the main olfactory system, and not through the accessory olfactory system, since the accessory olfactory system is primarily involved in perceiving the luteolytic stimulus produced from strange male for causing pregnancy failure. It has been shown that pericopulatory period seems to be crucial in females in the formation of stud male chemosignals, and the olfactory luteotrophic memory of stud male is further proved to be a short-term one. The precise mechanism involved in accessing and retaining the stud male chemical cues is unclear. In this brief review an attempt has been made to bring out the luteotrophic process of stud male chemosignals, the olfactory pathway and critical period to access the signals. The possible neural mechanism and neural chemistry underlying the formation and recognition of mating male chemical cues are also highlighted.