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PubMed2001

Vomeronasal organ: electrical stimulation activates Fos in mating pathways and in GnRH neurons.

Electrical stimulation of the vomeronasal organ in male hamsters activated Fos expression in neurons of the chemosensory pathways, as in experiments where animals were stimulated with female chemical stimuli. Fos was also activated in gonadotropin hormone releasing hormone (GnRH, or LHRH) neurons in the rostral medial preoptic region of the brain, a possible substrate for GnRH influence on chemosensory-dependent reproductive behavior.

Animals↗
PubMed2003

The influence of ovariectomy with or without estrogen replacement on responses of rat gracile nucleus neurons to stimulation of hindquarter skin and pelvic viscera.

Responses of neurons in the gracile nucleus (NG) of female rats to tactile and visceral stimulation change across the estrous cycle [J. Neurosci. 20 (2000) 7722]. To investigate estrogen's role in these changes, responses of NG neurons to tactile and visceral stimuli were examined in three groups: ovariectomized (OVX), OVX with estrogen replacement (OVX+E2), or sham OVX (tested in diestrus; shamOVX-D). The stimuli were: gentle brushing of hindquarter skin, pressure on the cervix, and distention of the uterus, vagina, or colon. After OVX, the magnitude of multi-unit responses to brushing the perineum, hip and tail, but not the foot and leg, were significantly reduced relative to shamOVX-D. OVX+E2 restored this magnitude to the same level as shamOVX-D, but not, as expected, to levels as large as previously observed in proestrus. After OVX, responses of single neurons to stimulation of the uterus, cervix, and colon were more likely to be excitatory (versus inhibitory) than they had been in cycling rats in proestrus (uterus, cervix) or diestrus (colon); OVX+E2 did not restore the inhibitory responses. In contrast, whereas all responses to vaginal distention after OVX were also excitatory, OVX+E2 in this case significantly restored the inhibitory responses. These findings provide further support for the conclusion that response characteristics of NG neurons are influenced by the rat's hormonal milieu, but also indicate that the influences are not a simple reflection of estrogen levels. The findings further suggest that NG is a component of neural systems that contribute to both reproductive behaviors and vaginal nociception.

Animals↗
PubMed1996

NADPH diaphorase activity and nitric oxide synthase immunoreactivity in lordosis-relevant neurons of the ventromedial hypothalamus.

The distribution of the enzymes NADPH diaphorase and nitric oxide synthase in the ventromedial nucleus of the hypothalamus of cycling and ovariectomized/estrogen-treated and control female rats was demonstrated using histochemical and immunocytochemical methods. Serial section analysis of vibratome sections through the entire ventromedial nucleus showed that NADPH diaphorase cellular staining was localized primarily in the ventrolateral subdivision. NADPH diaphorase staining was visible in both neuronal perikarya and processes. Light microscopic immunocytochemistry using affinity-purified polyclonal antibodies to brain nitric oxide synthase revealed a similar pattern of labelling within the ventromedial nucleus and within neurons of the ventrolateral subdivision of the ventromedial nucleus. Control experiments involved omitting the primary antibodies; no labelling was visible under these conditions. Some, but not all, neurons in the ventrolateral subdivision of the ventromedial nucleus contained both NADPH diaphorase and brain nitric oxide synthase as demonstrated by co-localization of these two enzymes in individual cells of this area. That NADPH diaphorase and brain nitric oxide synthase were found in estrogen-binding cells was shown by co-localization of NADPH diaphorase and estrogen receptor and brain nitric oxide synthase and estrogen receptor at the light and ultrastructural levels, respectively. Our studies suggest that brain nitric oxide synthase is present and may be subject to estrogenic influences in lordosis-relevant neurons in the ventrolateral subdivision of the ventromedial nucleus. The hypothalamus is a primary subcortical regulatory center controlling sympathetic function. Therefore, not only is nitric oxide likely to be important for reproductive behavior, but also for the regulation of responses to emotional stress and other autonomic functions.

Animals↗
PubMed1998

Induction of fos-like immunoreactivity in musk shrews after mating.

In many mammalian species the neuroendocrine regulation of male and female reproductive behavior is sexually dimorphic. By contrast, many features of female sexual behavior in the musk shrew (Suncus murinus) more closely resemble those of males than of females of other species. Female musk shrews require testosterone (T), which is neurally aromatized to estrogen, to induce sexual behavior. Aromatization occurs in the medial preoptic area (MPOA), and this region is critical for the expression of female receptivity. To compare neural responses to sexual behavior in females and males, we compared the number of Fos-like immunoreactive (Fos-ir) neurons after mating in musk shrews. In both males and females the number of Fos-ir neurons was increased by mating activity in the granule layer of the accessory olfactory bulb (gr-AOB), the bed nucleus of the stria terminalis (BNST), MPOA, the medial amygdala (MeA), and the region corresponding to the midbrain central tegmental field (CTF). Although Fos was induced by mating in several regions, this response was only dimorphic in the ventral medial nucleus of the hypothalamus (VMN), where mating significantly increased Fos-ir in females, but not in males. In both sexes, only the gr-AOB displayed an increase in Fos-ir after exposure to chemosensory cues alone. Thus, the pattern of Fos expression in the brain after mating is only sexually dimorphic in one region, the VMN. Further, in spite of past behavioral studies done in this species, which show a role for pheromones in induction of receptivity, these data show that exposure to pheromones does not induce Fos in structures caudal to the olfactory bulbs.

Animals↗
PubMed1998

Distribution and regulation of aromatase activity in the ram hypothalamus and amygdala.

Conversion of androgen to estrogen within the brain by cytochrome P450 aromatase is a component of the system controlling the display of normal male reproductive behavior and negative feedback inhibition of LH secretion in rams. In the present study, we used the highly sensitive 3H2O assay to measure aromatase activity in microdissected regions of the basal diencephalon and amygdala of intact and castrated rams. We found that aromatase activity was heterogeneously distributed. The highest activity was found in the medial amygdala, cortical amygdala, and bed nucleus of the stria terminalis. Intermediate levels of aromatase activity were found within the medial preoptic area/anterior hypothalamus, periventricular preoptic area, lateral preoptic area/anterior hypothalamus, ventromedial hypothalamus, and lateral hypothalamus. The lowest activity was present in the septum, infundibulum/median eminence, and dorsal medial hypothalamus. After castration, aromatase was significantly reduced in the medial preoptic area/anterior hypothalamus, periventricular preoptic area, lateral preoptic area/anterior hypothalamus, and infundibular nucleus/median eminence. In contrast, levels in castrate rams were unchanged in several other regions, most notably the bed nucleus of the stria terminalis and medial and cortical amygdala. These results provide a quantitative profile of aromatase activity in discrete regions of the ram hypothalamus and limbic system. They also demonstrate that aromatase activity is reduced in some, but not all brain regions after castration which suggests that different regulatory mechanisms control aromatase within different neuronal populations of the ram.

Amygdala↗
PubMed1985

Influence of levonorgestrel contraceptive implants, NORPLANT, initiated early postpartum upon lactation and infant growth.

This study was undertaken to investigate the effect of use of levonorgestrel contraceptive implants, NORPLANT, by breastfeeding mothers on lactational performance and infant growth. NORPLANT implants were inserted between days 30 and 42 postpartum in 50 lactating women. Two control groups of breastfeeding mothers, 50 each, were studied in parallel: the first used an intrauterine device (Cu T380-Ag) and the second used either barrier or no contraception. There was no difference in lactational performance among the three groups. The increments in infant weight and height in the three groups were within the normal range for Egyptian infants. However, the rates of weight and height gain in the early postpartum months were slightly, but significantly, lower in the NORPLANT group than in the two control groups. However, by the sixth postpartum month, there were no significant group differences in these growth parameters. The possible confusing effect of supplementary feeding is discussed.

Adult↗
PubMed2003

FSH and LH-beta subunits in the preoptic nucleus: ontogenic expression in teleost.

In the present study we cloned, sequenced, and confirmed the presence of mRNAs of gonadotropins (FSH-beta, LH-beta subunits) from the brain and pituitary of tilapia, Oreochromis niloticus. Further, we examined the spatio-temporal expression pattern of FSH-beta and LH-beta in the brain and pituitary of two species of teleost (tilapia, O. niloticus; sockeye salmon, Oncorhynchus nerka), using in situ hybridization and immunological methods. The expression of FSH and LH immunoreactivity appeared simultaneously in the brain and pituitary (tilapia, 14 days; sockeye, 51 days after fertilization). In the pituitary, FSH mRNA and peptide expressing cells were distinct from LH expressing cells located in the ventral proximal pars distalis. In the brain, FSH and LH immunoreactivity was co-localized in cells of the preoptic nucleus parvocellularis, magnocellularis, and gigantocellularis. Fibers immunoreactive to FSH and LH antisera were seen along the forebrain-hypothalamus and in the neurohypophysis of the pituitary. Double-label immunofluorescence revealed FSH and LH immunoreactivity co-localized in arginine vasotocin synthesizing preoptic neurons. Our results show that FSH and LH-producing cells have developmental origins in the brain as well as in the pituitary. In addition, we propose that the brain-derived gonadotropins may function as hypophysiotropic hormones that regulate pituitary cells and along with arginine vasotocin could act as neuromodulators of reproductive behaviors.

Age Factors↗
PubMed2003

Rapid corticosterone-induced impairment of amplectic clasping occurs in the spinal cord of roughskin newts (taricha granulosa).

Courtship clasping, a reproductive behavior in male roughskin newts (Taricha granulosa), is rapidly blocked by an action of corticosterone (CORT) at a specific neuronal membrane receptor. The CORT-induced impairment of clasping in behaving newts appears to be mediated partly by an elimination of clasping-related activity in medullary reticulospinal neurons. Previous studies of rapid CORT actions in Taricha have focused on the brain, so existence of CORT action in the spinal cord or peripheral nervous system has not been assessed. The present study used newts with a high cervical spinal transection to examine potential spinal or peripheral CORT effects on clasping by the hindlimbs in response to pressure on the cloaca. Spinal transection causes clasps elicited by cloacal stimulation to be very sustained beyond the termination of the eliciting stimulus. In spinally transected newts, CORT caused a dose-dependent depression in the duration as well as quality of the clasp that appeared within 10 min of injection. CORT selectively impaired the usual sustained maintenance of a clasp after termination of cloacal stimulation, but not clasp elicitation during stimulation. These effects were not produced by dexamethasone, a synthetic glucocorticoid that binds poorly to the CORT membrane receptor. The CORT effect on clasp maintenance but not clasp elicitation implies selective action on an intraspinal generator for clasping but not on sensory or efferent neuromuscular aspects of the response. These results indicate the presence in the newt spinal cord of the CORT membrane receptor that exerts functional effects distinctly different from those on the brainstem.

Animals↗
PubMed1997

Impact of roles of women on health in India.

India's population has more than doubled since 1961. Although India has been a leader in developing health and population policies, there have been major implementation problems due to poverty, gender discrimination, and illiteracy. Yet, three-quarters of the food produced annually in India is because of women. In 1991, only 39.3% of Indian women were literate. The literacy level of women can affect reproductive behavior, use of contraceptives, health and upbringing of children, proper hygienic practises, access to jobs and the overall status of women in the society. Early marriage and childbirth was a major determinant of women's health and was also responsible for the prevailing socioeconomic underdevelopment in India. The overall maternal mortality for India is 572.3 per 100,000 births, ranging from 14.9% in Bihar to 1.3% in Kerala. Anemia is an indirect factor in 64.4% of the maternal deaths. Trained birth attendants currently assist in about 60-80% of all births in women at the time of delivery. Socioeconomic factors are responsible for maternal deaths to a large extent - money in 18.3%, transport in 13.7%. When the mother dies it doubles the chances of death of her surviving sons and quadruples that of her daughters. Among the avoidable factors in maternal deaths, lack of antenatal care is the most important. Women, if educated and aware, can improve the health of their children by simple measures like good hygiene, exercise and dietary habits. Because of poverty, many of the young children, especially girls living on streets are easy prey for criminal prostitution rings, drug trafficking and consequences of HIV infection, and severe emotional and mental disturbances. Women are responsible for 70-80% of all the healthcare provided in India. Female healthcare providers can play an important role in educating society to recognize their health and nutrition needs. Women professionals and empowerment of women at all levels are required for improvement of the health and nutrition structure in India.

Family Health↗
PubMed2002

Sexual dimorphism in the central nervous system of marsupials.

It is now evident that gonadal steroids, acting within a limited critical period during fetal or neonatal life, bring about sexual differentiation of both the reproductive tract and the central nervous system (CNS) in eutherians. This results in structural dimorphism in several regions of the brain and spinal cord and the programming of future patterns of adult reproductive behavior. At birth the CNS of marsupials is very underdeveloped and debate continues as to the importance of hormones in its sexual differentiation. Nevertheless, some sexually dimorphic regions have been identified, including the lateral septal nucleus in the hypothalamus and the spinal nucleus of the bulbocavernosus and dorsolateral nucleus in the spinal cord, but interestingly not the cremasteric nucleus, which is dimorphic in eutherians. To date, no apparent sex differences in estrogen and androgen receptor-immunoreactive structures have been detected in the marsupial brain; however, higher levels of aromatase activity during early development in male opossums have been reported. Sex differences have been identified in the localization of cholecystokinin-immunoreactive structures in the marsupial brain indicating that the expression of this neuropeptide is differentially regulated in each sex. A sex difference also exists in the density of arginine vasopressin-immunoreactive fibers. Arguments continue as to whether sexually dimorphic behavior in marsupials, as in eutherians, is largely predetermined by hormones acting on the CNS early in development or if it is entirely dependent on the adult steroid hormonal environment.

Animals↗
PubMed2006

Vomeronasal versus olfactory epithelium: is there a cellular basis for human vomeronasal perception?

The vomeronasal organ (VNO) constitutes an accessory olfactory organ that receives chemical stimuli, pheromones, which elicit behavioral, reproductive, or neuroendocrine responses among individuals of the same species. In many macrosmatic animals, the morphological substrate constitutes a separate organ system consisting of a vomeronasal duct (ductus vomeronasalis, VND), equipped with chemosensory cells, and a vomeronasal nerve (nervus vomeronasalis, VNN) conducting information into the accessory olfactory bulb (AOB) in the central nervous system (CNS). Recent data require that the long-accepted dual functionality of a main olfactory system and the VNO be reexamined, since all species without a VNO are nevertheless sexually active, and species possessing a VNO also can sense other than "vomeronasal" stimuli via the vomeronasal epithelium (VNE). The human case constitutes a borderline situation, as its embryonic VNO anlage exerts a developmental track common to most macrosmatics, but later typical structures such as the VNN, AOB, and probably most of the chemoreceptor cells within the still existent VND are lost. This review also presents recent information on the VND including immunohistochemical expression of neuronal markers, intermediate filaments, lectins, integrins, caveolin, CD44, and aquaporins. Further, we will address the issue of human pheromone candidates.

Animals↗
PubMed2001

Peripartum plasticity within the hypothalamo-pituitary-adrenal axis.

The hypothalamo-pituitary-adrenal (HPA) axis plays important roles in the adaptive changes in physiology that occur during pregnancy and lactation. Although the axis still exhibits a pulsatile pattern of secretion, the normal diurnal rhythm of pulse amplitude is lost during lactation, such that mean basal levels remain constant throughout the day. In addition, the peripartum period is associated with a remarkable plasticity in stress-induced HPA activity, in that the increase of HPA activity normally seen in response to either physical or psychological stresses in the non-reproductive state become severely attenuated or absent in the lactating animal. This stabilization of both basal and stress-induced HPA activity may be important for maintaining a constant endocrine environment, thereby preventing any programming effects on the developing offspring. Attenuation of the stress response is initiated in late pregnancy and is temporally associated with luteolysis, indicating possible steroid hormone involvement. Indeed, mimicking the luteolytic changes in oestrogen and progesterone levels in non-pregnant animals induces a similar attenuation of the stress response. Furthermore down-regulation of the stress response is, at least in part, centrally mediated since in the period following luteolysis rats will show a decreased level of stress-induced neuronal activation of the PVN, as measured by the expression of either c-fos or CRH mRNAs. Persistence of this adapted state is dependent upon the continued suckling stimulus, as removal of the offspring litter rapidly leads to resumption of HPA responses to and the appearance of an exaggerated diurnal rhythm. The underlying mechanisms responsible for this stress hyporesponsiveness may include plasticity of noradrenergic and oxytocin pathways. In view of its role in other reproductive behaviors, a stress-inhibiting effect of oxytocin may reflect a more widespread co-ordinating role in the peripartum animal.

Animals↗
PubMedDate not supplied

Unintended pregnancy. Consequences and solutions for a worldwide problem.

Unintended pregnancy is a worldwide problem that affects women, their families, and society. Unintended pregnancy can result from contraceptive failure, non-use of contraceptive services, and, less commonly, rape. Abortion is a frequent consequence of unintended pregnancy and, in the developing world, can result in serious, long-term negative health effects including infertility and maternal death. In many developing countries, poverty, malnutrition, and lack of sanitation and education contribute to serious health consequences for women and their families experiencing an unintended pregnancy. Regardless of the cause, unintended pregnancy and its negative consequences can be prevented by access to contraceptive services including emergency contraception, safe and legal abortion services, and a society that allows women to determine their own reproductive choices. Addressing unintended pregnancy and its substantial human and dollar costs should be a priority in every country. The availability of reliable contraception for all, regardless of age or ability to pay, is an essential first step. Women and adolescents require access to age-appropriate and culturally sensitive reproductive health care services, including emergency contraception. Access to safe, legal abortion services is necessary to impact the staggering maternal mortality rates worldwide. Midwives throughout the world provide the majority of care for women of reproductive age. It is essential to identify those at risk for unintended pregnancy, provide the services they require, and remain diligent to ensure that those women and their families have safe options to consider when faced with an unintended pregnancy. In 1920, Magaret Sanger said, "No women can call herself free who does not control her own body." Although great strides have been made to improve the health and status of women since Ms. Sanger spoke those words, there remains much work to be done.

Contraception↗
PubMed1998

Preventing teenage pregnancy.

Teenage pregnancy is still a medical and economic concern. Early anticipatory counseling with an emphasis on abstinence is helpful. Contraception information and sexually transmitted disease prevention should be part of the counseling. This article reviews common contraception methodology.

Adolescent↗
PubMed1980

Return of fertility after discontinuation of depot medroxyprogesterone acetate and intra-uterine devices in Northern Thailand.

796 Thai women who stopped using the long-acting injectable contraceptive 'Depo-Provera' (medroxyprogesterone acetate) and 125 women who had an intra-uterine device removed to have a planned pregnancy were followed-up to ascertain the delay between conception and the end of contraception, and to determine the proportion of women who did not conceive in the 2 years after discontinuation. The median delay before conception was 5.5 months plus the estimated duration of the effect of the last injection of depo-provera and 4.5 months after discontinuing the IUD. Since depo-provera acts for approximately 15 weeks, women can except a median delay to conception of around 9 months after their last injection. The proportions of women who did not conceive within 1 year and within 2 years of stopping contraception by the two methods were similar. There was no evidence to suggest that prolonged use of depo-provera increases the delay before conception, and the return of fertility among never pregnant ex-users resembled that of ever pregnant ex-users.

Delayed-Action Preparations↗
PubMed2000

Spatial ability of XY sex-reversed female mice.

Perinatal gonadal hormones significantly affect subsequent sex differences in reproductive and non-reproductive behaviors in rodents. However, the influence of the sex chromosomes on these behaviors has been largely ignored. To assess the influence of the non-pseudoautosomal region of the Y chromosome, C57BL/JEi male and female mice and mice from the C57BL/6JEi-Y(POS) consomic strain were given behavioral tests known to distinguish males from females. The C57BL/6JEi-Y(POS) strain contains sex-reversed XY-females which, when compared to their XX-female siblings, allow assessment of the influence of the Y chromosome in a female phenotype. XX-females and XY-females did not differ on open-field activity, the Lashley maze, or active avoidance learning, but XY-females were significantly better than XX-females on the Morris hidden platform spatial maze. These findings suggest that males may have both a genetic and a hormonal mechanism to ensure visuospatial superiority.

Animals↗
PubMed2002

Estrogen's effects on activity, anxiety, and fear in two mouse strains.

Estrogen has effects on activity levels and emotional reactivity in both humans and rats. In a recent study conducted in ovariectomized (OVX) C57BL/6 (C57) mice we found that treatment with estradiol benzoate (EB) increased anxiety, fear learning, and running wheel activity relative to vehicle control (Veh). The present study was conducted to examine the stability of these findings across mouse strains (C57 and Swiss-Webster; SW), to get a better sense of the magnitude of the anxiety response by reducing baseline anxiety levels, and to discover if EB affects activity levels in a safe environment other than the home-cage running wheel. Mice of both strains treated with EB (s.c. implant, 25 microg in sesame oil, which enters the body over 5 weeks) were more anxious than Veh animals in the open field, elevated plus, and dark-light transition tests. SW animals were less anxious than C57 in the elevated plus. EB-treated animals of both strains were more active in the running wheel than Veh animals, and more active in the test of spontaneous activity in the home cage. EB-treatment also increased fear learning in a step-down avoidance task. EB appears to have a consistent but moderate effect in elevating anxiety and in increasing fear learning in two strains of mice. It is also involved in increasing activity in two different types of locomotion in the safer home cage. We conclude that these results of increased anxiety/fear and increased activity are suggestive of a general increase in arousal, with both sets of responses increasing the likelihood of reproductive behaviors occurring only when the environment predicts success.

Animals↗