Mild restraint reduces the time hormonally primed rats spend with sexually active males.

The effect of 5 min of restraint on the time sexually-receptive females spend in the compartment of a sexually active male was examined. Ovariectomized females, hormonally primed with 10 microg estradiol benzoate and 500 microg progesterone (EP) or primed only with estradiol benzoate (EO) were used. After the restraint or home-cage experience, females were tested for 30 min in a chamber that allowed the female to escape to a small "burrow". Females, subjected to restraint, left the male's compartment faster and spent significantly less time in the male's compartment than did non-restrained females. This was true for both EP and EO females. When females were injected with the 5-HT(2B/2C)-receptor antagonist, SB 206553, 15 min before restraint, time spent in the male's compartment was even further reduced. However, additional studies indicated that it was the stress of the injection rather than the action of the drug that was responsible for the female's behavior. These findings are discussed in terms of their significance to the understanding of the female's reproductive response to stress and are compared to prior findings, where lordosis behavior was significantly reduced by restraint.