Ovarian Hormones Influence Odor Stimulated Flank Marking Behavior In The Hamster (Mesocricetus-Auratus)

The effect of ovarian hormones on the frequency of female flank marking in response to the odors of male hamsters was examined. The amount of flank marking differed significantly (p less than 0.01) among the days of the estrous cycle, with the lowest levels of flank marking occurring on estrus. Ovariectomy (OVX) eliminated the 4 day rhythm, and significantly (p less than 0.01) reduced the total amount of flank marking. Implantation of Silastic capsules containing estradiol benzoate (EB) in OVX hamsters increased flank marking by approximately two-fold when compared to hamsters implanted with blank Silastic capsules. In a second series of experiments, OVX hamsters given EB flank marked significantly (p less than 0.01) more than those with blank capsules. Subcutaneous injection of progesterone (P) into OVX-EB treated hamsters 6 hr prior to testing significantly reduced flank marking when compared to OVX-EB treated hamsters given oil. No differences were observed in flank marking between groups of OVX hamsters with blank capsules and injected with P or oil. In summary, these data indicate that the four day rhythm of odor stimulated flank marking in intact female hamsters may be the result of the 4 day fluctuations of estrogen and progesterone that occur during the estrous cycle.