Estradiol benzoate facilitates lordosis and ear wiggling of 4- to 6-day-old rats.

The effects of exogenous and endogenous steroids on components of female sexual behavior of neonatal male and female rats were investigated. In Experiment 1, 4-day-old rats were treated with 0, 0.1, 1.0, 10, or 100 μg/10 g body weight estradiol benzoate (EB) and were tested 44 hr later. In Experiment 2, male rats castrated within 24 to 48 hr of birth were compared with sham operated controls and castrates given steroid replacement. The results indicated that most 6-day-old pups will display lordosis and ear wiggling, therefore, the display of these responses is not dependent upon exogenous steroids. However, a fine-grain behavioral analysis revealed that EB treatment increased the frequency, duration, and intensity of lordosis and the frequency of ear wiggling in infant females, and it increased lordosis duration in males. Castration of infant males decreased the likelihood that male infants would display lordosis, whereas testosterone replacement restored behavior to control levels. These data question the concept that organizational and activational actions of estrogens occur during completely separable times in development and should provide new insights into the development of estrogen receptor function and the process of sexual differentiation of brain and behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vaginal stimulation in rats induces prolonged lordosis responsiveness and sexual receptivity.

Conducted 2 experiments, using a total of 131 female Sprague-Dawley rats. Sexual receptivity to males resulted from stimulation of the vagina with a glass rod in previously unreceptive ovariectomized, estrogen-treated Ss. Several minutes of rejection behavior preceded the receptivity. In Exp II manual palpation was used to determine the duration of the lordosis response facilitation. Initially, all Ss were unresponsive to manual flank-perineum stimulation (palpation). Vaginal stimulation plus palpation, which together elicited lordosis, facilitated subsequent lordosis responses to palpation. This effect persisted for several hours after the vaginal stimulation was applied. Vaginal stimulation alone, which was ineffective in eliciting lordosis, also facilitated lordosis in response to subsequent palpation. Repeated palpation did not facilitate lordosis. These prolonged effects were independent of hormone treatment. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Receptivity of the female rat (Rattus norvegicus) after male devocalization: A ventral perspective.

Male rats (Rattus norvegicus) emit at least two patterns of vocalization during copulation, the mating call and the pre-ejaculatory call. Both calls promote immobility of the female during lordosis, but the pre-ejaculatory calls are more effective. We undertook, through ventral observations of the mating pair, to determine if the female failed to assume or maintain the lordosis posture when mounted by a devocalized male and also to determine if the devocalized male was providing adequate stimulation to induce receptive behavior. Females were more likely to move away from the devocalized males before assuming the full lordosis posture. Furthermore, they were more likely to move away before the males had a chance to engage in intromissive behavior. However, when the females remained immobile along enough for the males to achieve a mount or intromission, there was little difference in the behavior of either animal that resulted from the devocalization of the male. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of the interintromission interval on lordotic response and attack latency in golden hamsters (Mesocricetus auratus).

After 12–25 ejaculatory series, each consisting of several short intromissions (2- to 3-s vaginal penetration) and an ejaculation, male golden hamsters adopt an altered copulatory pattern consisting of long intromissions (5- to 25-s penetration with intravaginal thrusting). Receptivity declines and the tendency for the female to attack the male increases at about the time of this shift in copulatory pattern. Because the mean interintromission interval (III) between short intromissions is about 8 s compared to 100 s between long intromissions, it is possible that females detect this difference and adjust their mating accordingly. When the III between short intromissions from a rested male experimentally increased to 100 s by use of a halter and lead device, the duration of lordosis was significantly less than that displayed by females paired with control males (8-s III) and virtually the same as that displayed by females paired with males that produced only long intromissions. This suggests that the female uses the temporal patterning of intravaginal stimulation as one criterion for terminating mating with a particular male. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of repeated testing on sexual behavior of the female rat.

Investigated effects of stimulation during repeated testing, using 24 female Sprague-Dawley rats in which intromission was prevented by a vaginal mask. Ss were ovariectomized and administered 1 mg of estradiol benzoate (EB) daily for 10 days (Exp I) or 5 mg of EB for 2 days (Exp II). Behavioral indices included lordosis quotient (a measure of sexual receptivity) and rejection quotient (a measure of social rejection of the male). Intensity and duration of lordosis gave additional measures. In Exp I hourly testing increased lordosis quotient and duration, especially in Ss receiving EB for 5 days; no effects of daily testing were shown. Exp II compared the behavior of Ss that were either handled hourly and tested hourly with the male rat or only handled hourly to the behavior of Ss that were tested and handled only once. Repeated testing and/or handling facilitated sexual responsiveness, while Ss that received neither treatment were sluggish in their social response to the male rat when they were tested, and were not sexually receptive. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Somatosensory determinants of lordosis in female rats: Behavioral definition of the estrogen effect.

By coating the ventral surface of 16 Sprague-Dawley male rats with a dye, regions of contact between males and females ( n = 76) during male mounting were recorded precisely on the female's hair and skin. Film analyses showed that the male's paws and pelvic thrusting stimulated the female's skin with dominant frequencies between 10 and 20/sec. Somatosensory stimuli were then applied to the female skin locations contacted by the male. Deflection of hair on the flanks or perineum alone did not cause lordosis. Light stimulation simultaneously on flanks and perineum caused lordosis only in some females given high estrogen dosages supplemented by progesterone. When flank stimuli were followed by pressure on the rump, tailbase, and perineum, lordosis was triggered reliably in hormone-treated females. In this case, the estrogen-dependence of the reflex was shown, and progesterone synergized with the estrogen effect. Among lordosis components, rump and head elevations in response to pressure stimuli on the rump, tailbase, and perineum appear to be hormone-sensitive. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypophysectomy facilitates sexual behavior in female rats

Lordosis was elecited in 49% of 87 hormonally untreated, hypophysectomized-ovariectomized (hypox-ovx) female rats in response to palpation of the flanks and perineum (vaginal stimulation was not applied). By contrast, only 12% of 113 hormonally untreated ovariectomized (ovx) rats showed lordosis in response to such stimulation. Subsequently, hypox-ovx and ovx-only rats were given daily injections of 1 mug/kg estradiol benzoate (EB) and tested for sexual receptivity with males. Teh estrogen-treated hypox-ovx females became sexually receptive significantly earlier, and exhibited higher lordosis quotients and more soliciting behavior, than the estrogen-treated ovx-only rats. The increased sexual responsiveness in the hypox-ovx rats could be due to increased LRH activity. To test this, we treated hypox-ovx rats with dihydrotestosterone propionate (DHT-P), which suppresses plasma LH levels but is relatively ineffective in inducing sexual receptivity, and found a significant depression of lordosis responsiveness. These experiments suggest that hypox-ovx females show a heightened responsiveness to hormonal and/or sensory factors that induce a lordosis response, possibly because of increased LRH activity.     

Effects of coital stimulation upon behavior of the female rat.

Tested the importance of vagino-cervical stimulation during coitus in 2 experiments, using 16 intact and 48 ovariectomized Sprague-Dawley female rats, in which intromission was prevented by a vaginal mask. The behavior of Ss was compared to that of unmasked females. Behavioral indices included lordosis quotient, a measure of sexual responsiveness, and rejection quotient, a measure of social response toward the males. The rating of lordosis intensity on a 3-point scale provided a mean lordosis intensity. Exp. I investigated long-term effects of coital stimulation by repeated testing of Ss in natural and hormone-induced heat. Coital stimulation generally decreased the probability of subsequent lordosis and increased display of rejection. Exp. II studied the short-term effects of coital stimulation using single 50-mount tests. Coital stimulation decreased intensity as well as probability of subsequent lordosis. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mate choice and mate competition influence male body size in Japanese medaka

A sexual size dimorphism usually occurs when size-dependent reproductive advantages exist in only one sex. Studies on Japanese medaka, Oryzias latipes, have demonstrated reproductive size advantages in females but not in males, even though males and females are similar in body size. We conducted mate-choice and mate-copying tests in which a female could first associate with, then mate with, either a large (>/=1 sd+X standard length) or a small male (相似文献   

Mating-induced inhibition of receptivity in the female golden hamster (Mesocricetus auratus): II. Stimuli mediating short-term effects.

In the female golden hamster, mating with an intact male results in reduced receptivity toward a second male. In Experiment 1, females received various types of mating stimuli (e.g., mounts from an aproned male, intromissions from a vasectomized male, a simulated copulatory plug, a male in a hardware cloth cylinder, or several of these stimuli in combination). Although stimuli associated with male intromissions appeared to be most effective in altering the female's responsiveness to a subsequent male, treatments that included intromissive stimuli also resulted in the longest periods of lordosis. In Experiment 2 we found a highly significant inverse relation between the duration of lordosis in the presence of a male enclosed in a hardware cloth cylinder and lordosis duration with a second male that was free to copulate. In Experiment 3 we further showed that it was not the presence of a male in the cylinder that was the essential stimulus for producing this effect but rather the act of lordosis itself. By varying lordosis time and the number of intromissions independently (Experiment 4), we convincingly showed that short-term inhibition of receptivity in the hamster is attributable to lordosis duration per se rather than to male intromissions, as had been previously reported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of ovarian secretions on female behavioral potentiality in the rat.

Measured receptivity in female Sprague-Dawley rats ovariectomized at 5 ages, in neonatally gonadectomized females and males implanted with ovaries, and in neonatally castrated males injected with estradiol benzoate (EB) or oil. Mean receptivity, darting, and lordosis scores were higher during the 1st 4-5 mating tests in females and males having ovaries prepubertally. In amounts greater than .01 mg., EB inhibited female behavior. Even after ovariectomy, body weight was lightest in males and females having ovaries for 60 days. Progesterone and EB decreased weight gain faster in Ss gonadectomized prepubertally. Results indicated that physiological amounts of ovarian hormones, while not necessary for development of female potentiality, permanently influence it by modifying rate of utilization of estrogen circulating during adulthood. (24 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of mate competition and mate choice on eastern tiger salamanders

Male tiger salamanders, Ambystoma tigrinum tigrinumare slightly larger in body size and have considerably higher and longer tails than females. To determine how these dimorphic traits affected reproductive performance and success, we conducted breeding trials using 12 males and six females per trial and monitored male-female and male-male interactions. Larger males had an advantage in most aspects of mate competition investigated. Males with higher tails had no advantage in either mate competition or mate choice. Males with longer tails also had no advantage in mate competition but were preferred as mates by females. Larger males interrupted courting males more often than smaller males did. The form of male-male interference was conditional on body size and not on either tail dimension. If the intruder was larger than the courting male, it would shove the female away from the courting male and initiate courtship; if the intruder was smaller, it adopted a female mimicry tactic in which it positioned itself between the courting male and female and performed female behaviours to the courting male while simultaneously courting the female. Our trials indicated that the two components of sexual selection may influence the evolution of different male morphological traits in tiger salamanders. Mate competition may favour increased male body length; mate choice may select for greater male tail length.     

Individual variation in male vocal traits and female mating preferences in Bufo americanus

We investigated the amount of variation in mating behaviour between and within individual male and female American toads, because both sources of trait variation can influence the course of sexual selection. Males varied in all four call parameters investigated (dominant call frequency, pulse rate, call rate and call duration). Individual males lowered the dominant frequency of their call when they interacted vocally with nearby males. Dominant call frequency was more highly correlated with body size in vocally interacting males than in non-interacting males. Pulse rate of calls primarily varied with water temperature. Call rate and call duration showed the most variation of the four call properties, but this variation was unrelated to male morphology or social interactions. Females varied in three aspects of mating behaviour: two measures of pair formation and their preference for dominant frequency of male calls. The body size of paired males varied between females both in pairings initiated by either sex and in pairings initiated only by females. Males chosen by females were usually larger than average, although age and prior breeding experience of females did not affect mate choice. Playback experiments indicated that female preference for calls of low dominant frequency depended on the temporal patterning of alternative calls presented. Each of the four male vocal properties showed significant repeatability, but only one of the three aspects of female mating behaviour was repeatable. We discuss how different degrees of repeatability in sexual traits of males and females may influence the action and detection of sexual selection in this and other species. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Interactive effects of fluid deprivation and testosterone on the expression of a sexually dimorphic conditioned taste aversion.

Conducted 3 experiments with 96 Wistar and 72 Sprague-Dawley rats to investigate the effects of fluid deprivation on the sexually dimorphic rate of extinction of a conditioned taste aversion. Under ad lib water conditions, males extinguished a conditioned taste aversion more slowly than females. However, when rats were fluid deprived, there was no difference in the extinction rates of females and males even when the more sensitive 2-bottle test was used. This absence of the sexual dimorphism was due to a differential effect of deprivation on females and males. Fluid deprivation increased the rate of extinction of the male but had no effect on the rate of the female. It is proposed that the more rapid extinction rate of the deprived male could be accounted for by a deprivation-induced change in a testosterone-dependent mechanism. This proposal was supported by demonstrating that injections of testosterone propionate blocked the effects of fluid deprivation on rate of extinction in the male rat. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assuring quality, information, and choice in managed care

The aim of the study was to determine whether there is an increase in responsiveness to estrogen stimulation of maternal behavior and lordosis responsiveness during pregnancy. Using separate groups of pregnancy-terminated females, we measured the initial maternal responsiveness of hysterectomized-ovariectomized (HO) females and their responsiveness to estrogen stimulation. Maternal behavior latencies were studied in females HO on the 8th, 10th, 13th, 16th, or 19th day of pregnancy (8HO-19HO) and in nonpregnant HO (NPHO) females. Groups were injected sc with estradiol benzoate (EB) in doses ranging from 0 to 200 microgram(s)/kg and tested for maternal behavior (retrieving, crouching, and licking pups). In addition, we investigated whether there is an increase during pregnancy (following HO) in lordosis responsiveness to estrogen stimulation. Lordosis behavior was studied in pregnant HO females (days 8, 16, and 22) and NPHO females given 0 to 200 microgram(s)/kg EB. There was an increase in maternal responsiveness in oil-treated HO females starting around midpregnancy. From early pregnancy on there was also an increase in maternal responsiveness to 20 microgram(s)/kg EB. In late pregnant females (16HO) there was a further increase with 50 microgram(s)/kg EB. There was no increase in lordosis responsiveness to EB stimulation during pregnancy; pregnant and nonpregnant HO females had the same EB threshold for stimulating lordosis behavior. The results of both studies were related to increases during the latter half of pregnancy in nuclear estrogen receptor concentrations in the MPOA, an area that mediates estrogen stimulation of maternal behavior, and the absence of such increases during pregnancy in the VMH, an area that mediates estrogen stimulation of lordosis behavior.     

Effects of olfactory cues on sexual behavior in the brown lemming, Lemmus trimucronatus..

Tested 3 groups of 12 female lemmings each to determine the effects of odor familiarity on measures of reproductive behavior. A familiar odor (FO) group was exposed to the bedding of a particular male for 1 wk, then tested with that male. A 2nd female group (unfamiliar odor; UO) was exposed to the bedding of a male for 1 wk, then tested with a different male. A 3rd group (control; CO) was not exposed to male bedding prior to being tested with a male. The FO females engaged in higher frequencies of contact social behaviors than did UO and CO females. Males with FO females ejaculated more frequently than did the males with UO and CO females. Latencies to first display of sexual behaviors (female:lordosis; male:mount, thrust, and ejaculation) were lower for FO pairs. Results suggest that previous exposure of females to the odor of a given male facilitates sexual behaviors when such females are later paired with that male. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Physical attractiveness, physical effectiveness, and self-concept in late adolescents

The differential role of various body attitudes in predicting the self-concepts of late adolescents (124 males and 218 females), enrolled in introductory psychology courses, was assessed. Subjects rated 24 body characteristics in terms of 1) how physically attractive they assumed these parts of their bodies were, and 2) how physically effective they assumed them to be; subjects also responded to a short self-concept scale. In accordance with the theory of Erikson (1968) and of McCandless (1970), it was expected that attractiveness attitudes should contribute more to the self-concepts of females than should effectiveness attitudes, while a reverse pattern of interrelatedness was expected for males. Results indicated a higher correspondence between what are seen as attractive body parts and what are viewed as effective body components for males than for females. Moreover, findings from step-wise multiple regression analyses of each sex group's ratings of the body parts for attractiveness and effectiveness, respectively, each with the criterion variable constituting mean self-concept score, were consistent with expectations. For females, the multiple correlation between attractiveness ratings and self-concept was greater than the multiple correlation between effectiveness ratings and self-concept, and more attractiveness variables than effectiveness variables were significant predictors of self-concept. The converse of these findings were obtained with the males' data. The relevance of these results for theories of personality development were discussed.     

Multiple open forms of ribose-binding protein trace the path of its conformational change

Spawning success of males and its correlates were investigated in a natural colony of whitebelly damselfish, A. leucogaster (Pomacentridae), to explore the criteria that females use in choosing mates. The mating success of individual males was variable, with some males acquiring as few as 5000 eggs and others as many as 450 000 eggs during a breeding season. Male spawning success was not correlated with body size, territory size, nest site parameters or parental care behaviour. Egg hatching success was not related to either male size or egg clutch size, and all males were capable of rearing eggs to hatching. The temporal sequence of choices by females indicated non-independent choice by females, such that males chosen by females on the first spawn of the day were also chosen by females that spawned later in the day. Field observations indicated that, in the absence of male courtship, females preferentially visited males that had eggs in their nest site. Males that had recently mated were preferred by females over those males with either late-stage eggs or no eggs in the nest. This female preference did not appear to be related to increased paternal care or egg clutch survival. Given that the mating system is promiscuous and non-resource based, and that there appears to be little difference among males in body size, females may be mating non-independently by mimicking the choice of other females. Copyright 1998 The Association for the Study of Animal Behaviour Copyright 1998 The Association for the Study of Animal Behaviour.     

Testosterone and persistence of social investigation in laboratory rats.

In 5 experiments 92 mature male and 44 mature female Long-Evans rats were individually exposed in their home cages to sexually immature conspecifics. A prominent sex difference was observed in duration of social investigation prior to a criterion of neglect. When pups were 5 days of age, no sex difference was observed, but when pups were 8 days of age and older, mature males consistently investigated them for significantly longer intervals than did mature females. Furthermore, intact males investigated prepuberal conspecifics for significantly longer intervals than did castrated males, castrated females, or intact females; none of the latter 3 groups differed significantly from each other. Following testosterone treatment, castrated males investigated unfamiliar, prepuberal conspecifics for a significantly longer duration than did untreated castrated control Ss. Combined results support the conclusion that gonadal testosterone effects a greater perseveration of social investigation in males. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender-related differences in bile acid and sterol metabolism in outbred CD-1 mice fed low- and high-cholesterol diets

These studies were undertaken to determine whether in young adult outbred CD-1 mice there were any gender-related differences in basal bile acid metabolism that might be important in determining how males and females in this species responded to a dietary cholesterol challenge. When fed a plain cereal-based rodent diet without added cholesterol, 3-month-old females, compared with age-matched males, manifested a significantly larger bile acid pool (89.1 vs. 54.1 micromol/100 g body weight), a higher rate of fecal bile acid excretion (13.6 vs. 8.5 micromol/d/100 g body weight), a more efficient level of intestinal cholesterol absorption (41.1% vs. 25. 3%), and a lower rate of hepatic sterol synthesis (338 vs. 847 nmol/h/g). Similar results were found in C57BL/6 and 129Sv inbred mice. In matching groups of CD-1 mice fed a diet containing 1% cholesterol for 21 days, hepatic cholesterol levels increased much more in the females (from 2.4 to 9.1 mg/g) than in the males (from 2. 1 to 5.2 mg/g). This occurred even though the level of stimulation of cholesterol 7-hydroxylase activity in the females (79%) exceeded that in the males (55%), as did the magnitude of the increase in fecal bile acid excretion (females: 262% vs. males: 218%). However, in both sexes, bile acid pool size expanded only modestly and by a comparable degree (females: 19% vs. males: 26%) so that in the cholesterol-fed groups, the pool remained substantially larger in the females than in the males (102.3 vs. 67.6 micromol/100 g body weight). Together, these data demonstrate that while male and female CD-1 mice do not differ qualitatively in the way cholesterol feeding changes their bile acid metabolism, the inherently larger bile acid pool in the female likely facilitates the delivery of significantly more dietary cholesterol to the liver than is the case in males, thereby resulting in higher steady-state hepatic cholesterol levels.