HORMONES AND BEHAVIOR, 5, 303-315 (1974) Ovarian Hormones and the Duration of Sexual Receptivity in the Female Golden Hamster’ CAROL SUE CARTER2 and STEPHEN W. PORGES Departments of Ecology, Ethology and Evolution, and Psychology University of Illinois, Urbana-Champaign, Illinois The induction of sexual receptivity and its maintenance after copula- tion in ovariectomized female golden hamsters (Mesocricetus aura&s) was found to be a function of the levels of ovarian hormones administered. Various combinations of estradiol benzoate (between 0.6 and 666 pg) and progesterone (between 0.05 and 5.0 mg) were administered in two experi- ments. Although some animals responded at 0.6 pg, higher levels of estradiol benzoate (l-6 r.rg or more) were more effective in inducing levels of lordosis equivalent to those seen in intact females in natural estrus. After mating, a depression in lordosis was observed in both ovariectomized and intact females. However, in ovariectomized females (excluding animals that did not respond initially) the duration of postcopulatory receptivity was a function of the level of progesterone administered. High levels of progesterone tended to prolong slightly the duration of postcopulatory receptivity. Although hormone-induced estrus in the female hamster (Mesocricetus auratus) has been reported to last approximately 12-18 hr (Ciaccio and Lisk, 1971a; Kent, 1968) mating may dramatically abbreviate behavioral receptivi- ty. Previous research has shown that intact females become almost totally unreceptive 2-4 hr after copulation (Carter and Schein, 1971; Carter, 1973). Depressions in female receptivity associated with mating have been observedin several other species including the rat (Hardy and Debold, 1972), ewe (Fletcher and Lindsay, 1971), guinea pig (Goldfoot and Goy, 1970), albino mouse (Edwards, 1970), rice rat (Dewsbury, 1970), chinchilla (Bignami and Beach, 1968) and cat (Whalen, 1963). 1This research was supported by U.S.P.H.S. Grants HD 07496-01, MH 20292-01, and MH 21444-01 and the Illinois Department of Mental Health. Hormones used in this study were generously provided by Dr. Preston Perlman of the Schering Co. Bloomfield, N.J. The authors gratefully acknowledge the critical comments offered on an earlier version of this manuscript by William Greenougk 2Requests for reprints should be sent to C. S. Carter, Department of Psychology, University of Illinois, Champaign, Illinois 61820. 303 Copyright @ 1974 by Academic Press, Inc. All rights of reproduction in any form reserved.