Maternal influences on the sexual behavior and reproductive success of the female rat

In many species, including humans, there is evidence for parental effects on within-sex variations in reproductive behavior. In the present studies we found that variations in postnatal maternal care were associated with individual differences in female sexual behavior in the rat. Females born to and reared by dams that showed enhanced pup licking/grooming (i.e., High LG mothers) over the first week postpartum showed significantly reduced sexual receptivity and alterations in the pacing of male mounting (i.e., longer inter-intromission intervals) observed in a paced mating test. There were minimal effects on the sexual behavior of the male offspring. The female offspring of High LG mothers showed a reduced lordosis rating, a decreased mount:intromission ratio, received fewer ejaculations and were less likely to achieve pregnancy following mating in the paced mating context. The data suggest maternal influences on the sexual development of the female rat that are functionally relevant for reproductive success. Together with previous studies these findings imply that maternal care can ‘program’ reproductive strategies in the female rat.     

Effect of estrogen deprivation on the reproductive physiology of male and female primates

The availability of CGS 16949A, CGS 20267 and CGP 47645, a series of aromatase inhibitors (AIs) having high specific activity and specificity, made possible this study wherein the need for estrogen (E) for regulating (a) follicular maturation/ovulation, luteal function and pregnancy establishment, and (b) testicular function of the bonnet monkey (Macaca radiata) has been examined. Generally these compounds, used in the range of 500 μg to 2.5 mg/day did not inhibit follicular maturation although they did reduce E levels. Although low doses had no effect on ovulation it appears that relatively high doses of CGS 20267 and CGP 47645 could be inhibiting it. Three oral doses of letrozole (CGS 20267, each dose of 2 mg) during the follicular phase resulted in the formation of multiple follicles in cycling females, and these could be ovulated by exogenous hCG (1000 IU) treatment. Although administration of AI during the early luteal phase had no effect on progesterone (P) production, it prevented pregnancy establishment. Whereas AI administration in the female had no significant effect on luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels (except at high drug dosages), it significantly increased serum testosterone (T) levels in the male. Sustained high levels of T (30–50 ng/ml) could be maintained for 100 days by administering 2.5 mg of CGP 47465 orally once in 5 days. Blockade of E synthesis in the male led to the disruption of testicular germ cell transformation, which in turn resulted in a significant reduction in sperm production. These studies with aromatase inhibitors in the monkey suggest that these compounds have a potential for use as fertility regulating agents in both the male and female primate.     

Aetiological approach of female reproductive physiology in lactational amenorrhoea.

The duration of postpartum amenorrhea and return of ovulation varies on an individual and population basis. In 1980, in Senegal, the relationship of chronic malnutrition and female fertility was investigated for 2 years. The stability of the female body regarding weight and arm circumference despite a heavy annual workload was a surprising finding. The mean female body mass index was higher for lactating women in amenorrhea than required for restoring menstruation in European women. The mean duration of postpartum amenorrhea was 18.2 +or- .6 months. The difference between those who resumed menstruation (20.9 +or- .9 months) and who still had amenorrhea (25.4 +or- 2.2 months) was significant. The duration of breast feeding determined the duration of amenorrhea. Studies have found a link between ovarian dysfunction and women in harsh third world environments and sportswomen under intensive training with both showing irregular menstruation and amenorrhea. Long duration of cycles in New Guinean women, high amount of anovulation in Zairian forest women, and suppression of testosterone and estradiol levels in hunter-gatherers were found. In affluent Europeans and urbanized women in developing countries postpartum amenorrhea dropped drastically. Long distance runners are often vegetarians with low calorie consumption and with a high degree of menstrual trouble owing to low body fat and weight-for-height. The role of beta-endorphins in the hypothalamic blockade of the gonadotropin releasing hormone pulse generator and high stress or physical training is proven. The functioning of the hypothalamo-pituitary-ovarian axis can be hurt by intensive training. Short-term fasting also suppressed the pulsatile luteinizing hormone and testosterone secretion. The protocol and methodology of an etiological study is outlined regarding the factors of this hypothesis on amenorrhea.     

Myo-inositol in the reproductive tract of the female rat

• 1.1. myo-Inositol concentrations in oviduct, ovary and uterus were many-fold those of blood serum during all four stages of the estrous cycle of the female rat.
• 2.2. Inositol concentration was higher in oviduct than in ovary or uterus and was lower in uterine fluid than in uterus.
• 3.3. Estrus uteri had higher inositol concentrations than uteri in other phases of the cycle.
• 4.4. In order to measure dynamic aspects of the distribution of inositol. the distribution of radioactivity among organs of the reproductive tract of mature female rats was measured 45 min after i.p, injection of [2-³H]myo-inositol.
• 5.5. These organs concentrated inositol from the blood, and the tissue radioactivity (expressed as dpm/mg wet wt of tissue) increased in the sequence: vagina < cervix < uterus < ovary < oviduct.
• 6.6. The uterus and ovary concentrated myo-inositol more strongly during proestrus than during metestrus. diestrus or estrus.
• 7.7. The contents of proestrus follicles were more highly radioactive than was the ovary itself, whereas proestrus uterine fluid was less radioactive than the uterine tissue.

     

Roles of insulin-like growth factor Ⅱ in regulating female reproductive physiology

The number of growth factors involved in female fertility has been extensively studied, but reluctance to add essential growth factors in culture media has limited progress in optimizing embryonic growth and implantation outcomes, a situation that has ultimately led to reduced pregnancy outcomes. Insulin-like growth factor Ⅱ(IGF-Ⅱ) is the most intricately regulated of all known reproduction-related growth factors characterized to date, and is perhaps the predominant growth factor in human ovarian follicles. This review aims to concisely summarize what is known about the role of IGF-Ⅱ in follicular development, oocyte maturation, embryonic development, implantation success, placentation, fetal growth, and in reducing placental cell apoptosis, as well as present strategies that use growth factors in culture systems to improve the developmental potential of oocytes and embryos in different species. Synthesizing the present knowledge about the physiological roles of IGF-Ⅱ in follicular development, oocyte maturation, and early embryonic development should, on the one hand, deepen our overall understanding of the potential beneficial effects of growth factors in female reproduction and on the other hand support development(optimization) of improved outcomes for assisted reproductive technologies.     

Role of vocalizations in the reproductive cycle of ring doves (Streptopelia risoria): effects of hypoglossal nerve section on the reproductive behavior and physiology of the female

The role of vocalizations in the reproductive cycle of female ring doves was investigated. Two-stage bilateral hypoglossal nerve section (HNS) was performed on adult females to alter their cooing and they were observed for courtship behavior with the same stimulus males used in preoperation behavioral tests. The HNS females showed a reduction in both the vocalization and wing flipping components of nest-coos but no changes in other female courtship behaviors. In addition, the HNS females failed to show the typical male courtship-induced follicular growth observed in sham-operated females. The behavior of stimulus males did not differ between groups and therefore could not account for the failure of follicular growth in the HNS females. These data suggest that the female's performance of nest-coos, or factors associated with it, may stimulate her own follicular growth.     

Consequences of acute stress and cortisol manipulation on the physiology, behavior, and reproductive outcome of female Pacific salmon on spawning grounds

Life-history theory predicts that stress responses should be muted to maximize reproductive fitness. Yet, the relationship between stress and reproduction for semelparous salmon is unusual because successfully spawning individuals have elevated plasma cortisol levels. To tease apart the effects of high baseline cortisol levels and stress-induced elevation of cortisol titers, we determined how varying degrees of cortisol elevation (i.e., acute and chronic) affected behavior, reproductive physiology, and reproductive success of adult female pink salmon (Oncorhynchus gorbuscha) relative to different states of ovulation (i.e., ripe and unripe). Exhaustive exercise and air exposure were applied as acute stressors to manipulate plasma cortisol in salmon either confined to a behavioral arena or free-swimming in a spawning channel. Cortisol (eliciting a cortisol elevation to levels similar to those in post-spawn female salmon) and metyrapone (a corticosteroid synthesis inhibitor) implants were also used to chemically manipulate plasma cortisol. Cortisol implants elevated plasma cortisol, and impaired reproductive success; cortisol-treated fish released fewer eggs and died sooner than fish in other treatment groups. In contrast, acute stressors elevated plasma cortisol and the metyrapone implant suppressed plasma cortisol, but neither treatment significantly altered reproductive success, behavior, or physiology. Our results suggest that acute stressors do not influence behavior or reproductive outcome when experienced upon arrival at spawning grounds. Thus, certain critical aspects of salmonid reproduction can become refractory to various stressful conditions on spawning grounds. However, there is a limit to the ability of these fish to tolerate elevated cortisol levels as revealed by experimental elevation of cortisol.     

Reproductive disruption in adult female and male rats prenatally exposed to mesquite pod extract or daidzein

Phytoestrogens are considered to be endocrine disruptors, since they can alter the endocrine system, thus disturbing many reproductive events. The intake of diets containing a high content of phytoestrogens has increased worldwide in human populations and in domestic animals. Phytoestrogens in maternal blood can pass through the placenta to the fetus in high amounts and can have long-term organizational effects. Mesquite (Prosopis sp) is a leguminous plant widely used to feed several livestock species, and is also used in the human diet. In this study we assessed the effects of exposure to mesquite pod extract during the periconception and pregnancy periods on the reproduction of male and female descendants. The females of three experimental groups received one of the following treatments: 1) vehicle injection; 2) mesquite pod extract or 3) the isoflavone daidzein during the periconception and pregnancy periods. Estrous cyclicity, sexual behavior and hormones, as well as uterine and vaginal epithelia were evaluated in the female descendants. In the males, sexual behavior and hormones, apoptosis in testicular cells and sperm quality were evaluated. In females the following was observed: alterations in estrous cycles, decreased sexual behavior, estradiol and progesterone levels, increased uterine and vaginal epithelia. In males, we observed a decrease in sexual behavior, testosterone and sperm quality, and apoptosis increased in testicular cells. All these effects were similar to those caused by daidzein. These results indicate that prenatal exposure to mesquite pod extract or daidzein, administered to females before and during pregnancy, can disrupt normal organizational-activational programming of reproductive physiology in female and male descendants.     

Neonatal manipulation of oxytocin influences female reproductive behavior and success

During early neonatal development, oxytocin (OT) may influence the expression of adult behavior and physiology. Here we test the prediction that early postnatal exposure to OT or an oxytocin antagonist (OTA) can affect the subsequent expression of sexual receptivity and reproductive success of females. To test this hypothesis, female prairie voles (Microtus ochrogaster) received one of four treatments within 24 h of birth. Three groups received an intraperitoneal injection of OT, OTA, or isotonic saline. A fourth group was handled, but not injected. Around 75 days of age, females were paired with sexually experienced males for 72 h and sexual activity was recorded. Treatment had no effect on the probability of mating. Injection, regardless of treatment, reduced latency to mate compared with handled controls. OT and OTA treatment decreased mating bout frequency compared to saline and handled controls, while OTA treatment increased reproductive success, probability of successfully producing a litter. The results suggest that neonatally OT, both endogenous and exogenous, can affect the expression of adult female reproductive activity and that blocking the effects of endogenous OT during neonatal development can affect female reproductive success. Finally, the results suggest that a number of aspects of reproduction are regulated by OT during the postnatal period, but that the mechanism of action may differ depending upon the reproductive activity.     

Social status modifies estradiol activation of sociosexual behavior in female rhesus monkeys

Estrogen (E2) has activational effects on sexual motivation and mitigating effects on anxiety-like behaviors that can be attenuated with chronic exposure to psychosocial stress. Some studies suggest that this attenuation can be overcome by higher doses of E2, while others show that chronic psychosocial stress may alter the mechanisms of E2 function, thus reducing any positive benefit from higher doses of E2. To determine the interaction between psychosocial stress and E2 dose on behavior, we examined the scope of attenuation across a suite of socioemotional behaviors, including reproduction, affiliation, aggression, submission, and anxiety-like behaviors on 36 ovariectomized female rhesus monkeys. Females were exposed to graded psychosocial stress, established by an intrinsic female dominance hierarchy, where subordinate animals receive high amounts of harassment. Our data show that E2 dose-dependently increased sexual motivation and male-affiliation in dominant (e.g. low-stress) females, while subordinate females showed no positive effects of E2, even at higher doses. In addition, contact aggression was attenuated in dominant females, while non-contact aggression was attenuated in both dominant and middle-ranking females. These results suggest that the stress-induced attenuation of E2's activational effects on sexual behavior and affiliation with males may not be overcome with higher doses of E2. Furthermore, the observed behavioral consequences of psychosocial stress and E2 dose may be dependent on the behaviors of all the females in the social-group, and better resolution on these effects depends on isolating treatment to individuals within the group to minimize alterations in social-group interactions.     

Effects of perinatal polychlorinated biphenyls on adult female rat reproduction: development, reproductive physiology, and second generational effects

Perinatal exposures to endocrine-disrupting chemicals, such as polychlorinated biphenyls (PCBs), can cause latent effects on reproductive function. Here, we tested whether PCBs administered during late pregnancy would compromise reproductive physiology in both the fetally exposed female offspring (F1 generation), as well as in their female offspring (F2 generation). Pregnant Sprague-Dawley rats were treated with the PCB mixture, Aroclor 1221 (A1221; 0, 0.1, 1, or 10 mg/kg), on Embryonic Days 16 and 18. Somatic and reproductive development of F1 and their F2 female offspring were monitored, including ages of eye opening, pubertal landmarks, and serum reproductive hormones. The results showed that low doses of A1221 given during this critical period of neuroendocrine development caused differential effects of A1221 on F1 and F2 female rats. In both generations, litter sex ratio was skewed toward females. In the F1 generation, additional effects were found, including a significant alteration of serum LH in the 1 mg/kg A1221 group. The F2 generation showed more profound alterations, particularly with respect to fluctuations in hormones and reproductive tract tissues across the estrous cycle. On proestrus, the day of the preovulatory GnRH/gonadotropin surge, F2 females whose mothers had been exposed perinatally to A1221 exhibited substantially suppressed LH and progesterone concentrations, and correspondingly smaller uterine and ovarian weights on estrus, compared with F2 descendants of control rats. These latter changes suggest a dysregulation of reproductive physiology. Thus, low levels of exposure to PCBs during late fetal development cause significant effects on the maturation and physiology of two generations of female offspring. These findings have implications for reproductive health and fertility of wildlife and humans.     

Age at pollination modifies relative male and female reproductive success in a monoecious fig tree

Plants that depend on a single species of insect pollinator must often contend with infrequent and unpredictable visitation. Prolongation of floral receptivity comes at the cost of reduced male and/or female reproductive success among older flowers. Fig trees (Ficus spp.) have a highly specific pollination symbiosis and individual inflorescences (syconia) that remain receptive for days or weeks. Reproductive success in monoecious fig trees involves production of both seeds and fig wasp offspring. We assessed whether the reproductive output of individual syconia changes with the length of time they waited for pollination, and whether the relative female and male reproductive success also changes. A pollination experiment was conducted in an SE Asian monoecious fig tree Ficus curtipes, in which receptive syconia were covered with mesh bags to exclude wasps and pollinated by single pollinators of this fig tree at their different receptive ages. When the syconia matured their size and contents were recorded. Seed quality was also assessed. The results showed that pollinators entered syconia that had been waiting for up to 36?days. The frequencies of abortions among syconia pollinated at different ages were low throughout. The number of un-utilised flowers increased progressively in older syconia. Seed production was highest in syconia entered on the first day of receptivity, whereas pollinator production peaked in syconia pollinated on day 12, then declined in older syconia. Consequently, overall reproductive efficiency declined with syconium age and floral sex allocation became more male-biased in older syconia. Older syconia also produced lighter seeds. These results suggest that un-pollinated syconia of F. curtipes can remain receptive for several weeks. This makes pollination of each syconium more likely, but at the cost of reduced productivity and with more ovules allocated to male function. However, the prolongation of floral receptivity has significance for the co-adaptation between syconia and fig wasps and for the evolution of the fig tree-fig wasp symbiosis.     

Social status modifies estradiol activation of sociosexual behavior in female rhesus monkeys

Estrogen (E2) has activational effects on sexual motivation and mitigating effects on anxiety-like behaviors that can be attenuated with chronic exposure to psychosocial stress. Some studies suggest that this attenuation can be overcome by higher doses of E2, while others show that chronic psychosocial stress may alter the mechanisms of E2 function, thus reducing any positive benefit from higher doses of E2. To determine the interaction between psychosocial stress and E2 dose on behavior, we examined the scope of attenuation across a suite of socioemotional behaviors, including reproduction, affiliation, aggression, submission, and anxiety-like behaviors on 36 ovariectomized female rhesus monkeys. Females were exposed to graded psychosocial stress, established by an intrinsic female dominance hierarchy, where subordinate animals receive high amounts of harassment. Our data show that E2 dose-dependently increased sexual motivation and male-affiliation in dominant (e.g. low-stress) females, while subordinate females showed no positive effects of E2, even at higher doses. In addition, contact aggression was attenuated in dominant females, while non-contact aggression was attenuated in both dominant and middle-ranking females. These results suggest that the stress-induced attenuation of E2's activational effects on sexual behavior and affiliation with males may not be overcome with higher doses of E2. Furthermore, the observed behavioral consequences of psychosocial stress and E2 dose may be dependent on the behaviors of all the females in the social-group, and better resolution on these effects depends on isolating treatment to individuals within the group to minimize alterations in social-group interactions.     

Endocrinology of human female sexuality,mating, and reproductive behavior

Hormones orchestrate and coordinate human female sexual development, sexuality, and reproduction in relation to three types of phenotypic changes: life history transitions such as puberty and childbirth, responses to contextual factors such as caloric intake and stress, and cyclical patterns such as the ovulatory cycle. Here, we review the endocrinology underlying women's reproductive phenotypes, including sexual orientation and gender identity, mate preferences, competition for mates, sex drive, and maternal behavior. We highlight distinctive aspects of women's sexuality such as the possession of sexual ornaments, relatively cryptic fertile windows, extended sexual behavior across the ovulatory cycle, and a period of midlife reproductive senescence—and we focus on how hormonal mechanisms were shaped by selection to produce adaptive outcomes. We conclude with suggestions for future research to elucidate how hormonal mechanisms subserve women's reproductive phenotypes.     

GABAergic drugs and lordosis behavior in the female rat

Agents modifying GABAergic neurotransmission were administered to ovariectomized rats treated with different doses of estradiol benzoate (EB) + progesterone (P) or with EB alone. Hormone treatments were designed to induce an intermediate level of receptivity in order to be able to observe both stimulatory and inhibitory effects on lordosis behavior. Both the GABAA receptor agonist THIP and the GABAB receptor agonist baclofen inhibited lordosis behavior at doses from 20 and 5 mg/kg, respectively. The GABA transaminase inhibitor gamma-acetylen GABA (GAG) and the GABA agonist 3-aminopropanesulfonic acid had no effects, even when high doses were administered. The GABAA receptor antagonist bicuculline had no effect by itself nor did it block the effects of THIP. It is therefore suggested that the GABAA receptor is of slight importance in the control of lordosis behavior. No evidence could be found supporting the hypothesis that an interaction between P and GABA is important for hormone-induced receptivity. It does not appear likely that motor disturbances are responsible for the inhibitory effects of baclofen and THIP. The exact mechanism by which these drugs inhibit lordosis behavior is not clear at present.     

日本食蚧蚜小蜂的交配行为及雌蜂生殖系统观察

日本食蚧蚜小蜂Coccophagus japonicus Compere是橡副珠蜡蚧Parasaissetia nigra Nietner的优势寄生蜂之一,为明确其交配行为及雌蜂生殖系统构成,本研究在室内观察了该蜂的交配行为、雄蜂交配能力、雌蜂生殖系统等。结果表明:日本食蚧蚜小蜂的交配过程可分为交配前行为、交配、交配后行为3个阶段,整个交配过程平均时间为76.2 s,其中,交配时间为20.6 s;小蜂羽化当天即可交配,雌、雄蜂具有多次交配的习性,雄蜂的交配能力随其日龄的增加而减弱,1日龄的雄蜂交配能力最强,为6.3次/d,雄蜂一生平均能交配36.9次;雌蜂的生殖系统由1对卵巢、1对侧输卵管、1条中输卵管、1个受精囊和外生殖器等组成,卵巢管数量存在变异,其中95.78%雌蜂卵巢具6(3+3)条卵巢管,2.78%雌蜂卵巢具5(3+2)条卵巢管,1.22%的雌蜂卵巢具7(3+4)条卵巢管,0.22%的雌蜂卵巢是具4(2+2,1+3)条卵巢管,还有极个别的雌蜂仅有1个卵巢,由3条卵巢管组成。研究结果表明日本食蚧蚜小蜂有多次交配习性,卵巢存在一定变异。