Ultrasonic Communication and the Hormonal Modulation of Aggressive Behavior in the Female Hamster

<p>Female golden hamsters are unusual both in the high levels of aggression they exhibit on nonestrous days of the estrous cycle and in the dramatic decrease in aggressiveness apparent on estrous days. The results of studies using adrenalectomized-ovariectomized or hypophysectomized females have failed to reveal any individual ovarian or pituitary hormone that is required for the display of high levels of aggression. In contrast, it seems clear that a very specific combination of ovarian hormones normally accounts for the inhibition of fighting and stimulation of sexual receptivity seen on estrous days. Thus, while control adrenalectomized-ovariectomized females fought at high levels comparable to those seen in intact nonestrous females, treatment with a combination of 17β-estradiol benzoate and progesterone suppressed fighting completely, creating a situation identical to that typical of estrous day. The aggressiveness of male and female hamsters suggests the operation of a social system in which individuals live solitarily and depend on noncontact social signals for the initiation and coordination of reproductive behavior. In this regard, the studies detailed here show that hamsters of both sexes emit ultrasonic calls of 16-64 kHz and roughly 50 dB SPL. Ultrasounds by females encode information regarding reproductive state as well as location. In particular, female call rates are highest during estrus, suggesting that these signals function primarily as sexual attractants in the initiation of social contact. Once contact has been initiated, ultrasounds by males prolong lordosis, thus helping to structure the interaction so as to facilitate successful reproduction. As in the case of the aggressive responses described above, hamster ultrasounds seem well suited to a behavioral system that strives to coordinate crucial reproductive behaviors with reproductive (endocrine) state.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Thesis

Year

1974

Author dc:creator

• Floody, Owen Robert

Contributors dc:contributor

• Donald W. Pfaff

• hamsters
• aggression
• estrous cycle
• ovarian hormones
• sexual receptivity
• ultrasonic vocalizations
• reproductive behavior
• Life Sciences

Repository record dc:identifier

https://digitalcommons.rockefeller.edu/student_theses_and_dissertations/497

OAI identifier oai:identifier

oai:digitalcommons.rockefeller.edu:student_theses_and_dissertations-1501