Receptivity

Abstract: Behavioral receptivity, as indicated by the presence of the lordosis reflex, could be elicited from spayed rats after implantation of estradiol in the medial-basal preoptic and anterior hypothalamic regions. Hormone implants elsewhere in the hypothalamus or blank tubing implants throughout the hypothalamus did not produce this effect. Subcutaneous implants were equally ineffective for producing behavioral receptivity.

Abstract: The involvement of indole- and catecholamines in the hormonal regulation of sexual receptivity has been investigated in ovariectomized female rats. Drugs that reduce 5-hydroxytryptamine, dopamine, and adrenaline or increase noradrenaline neurotransmission tended to facilitate the occurrence of estrous behavior in estrogen-treated females, and drugs having opposite effects tended to inhibit receptivity induced by estrogen and progesterone. Estrogen decreased noradrenaline turnover in cortex and brain stem; progesterone enhanced this effect in brain stem but prevented it in cortex. Both hormones tended to block noradrenaline uptake in hypothalamus in vitro. In a schedule used to induce receptivity, estrogen accelerated serotonin turnover, an effect prevented by progesterone. Thus a number of monoamines may be involved in the control by hormones of estrous behavior. Furthermore, hormones affect both amine turnover and uptake mechanisms.

Abstract: One of the most important, robust and evolutionarily conserved functions for neural estrogen receptor (ER) is as a mediator of female sexual behavior. Using homozygotic ER knockout (ERKO) mice we tested the hypothesis that ER controls female receptivity. Females with either two normal copies of the ER gene (wild-types), or an insertational disruption (knockouts) of the ER were ovariectomized. Each female was treated with 17 beta-estradiol (EB) alone, and with EB in combination with progesterone, prior to tests for behavioral receptivity. Under both hormonal conditions female ERKO mice did not display sexual receptivity whereas wild-type litter-mates were receptive to males. Male behavior indicated that females of both genotypes were equally attractive. Brain tissues were examined with immunocytochemical methods showed that ERKOs had greatly reduced levels of ER immunoreactivity in hypothalamus. In sum, the data show that ER is required for the display of sexual receptivity, but is not essential for female attractivity.

Abstract: Young and his co-workers1-3 have reported that although estrogen may induce heat behavior in spayed female rats, the administration of progesterone to estrogen-treated animals markedly increases sexual receptivity. Ball4, 5 was unable to confirm these results. She was of the opinion that her failure may have been due to peculiarities in the strain of rats used. In all of the studies listed the behavior of females has been recorded as nonreceptive, slightly receptive or receptive.In the course of a longer experiment we have collected some data which tend to resolve some of the differences between the findings of Ball and those of Young and his co-workers. Further, our results include complete and sensitive records of different degrees of receptivity in treated females.Procedure. Virgin female rats were raised in segregation and ovariectomized at 3 or 4 months of age. Hormone injections and mating tests were initiated approximately 3 weeks after castration.The effects of 3 types of injections upon sexual re...