Estrus termination following copulation in female guinea pigs

In the female guinea pig, estrus is inhibited after copulation. This study explored the role of the endocrine status of the male on the termination of the lordosis response in females. Ovariectomized females were treated with estradiol benzoate and progesterone to induce estrus and were then mated with males when the males were intact, castrated, and castrated and treated with testosterone propionate (TP). Lordosis responses were recorded prior to and following mating. Females who received an ejaculation from a castrated male remained sexually receptive longer than the females mated with intact males, or those males that were castrated and treated with TP. These results support the hypothesis that the factor(s) responsible for termination of estrus in females are found in the ejaculate of the male and are testosterone dependent.