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Antennal-specific pheromone-degrading aldehyde oxidases from the moths Antheraea polyphemus and Bombyx mori.

Female moths produce blends of odorant chemicals, called pheromones. These precise chemical mixtures both attract males and elicit appropriate mating behaviors. To locate females, male moths must rapidly detect changes in environmental pheromone concentration. Therefore, the regulation of pheromone concentration within antennae, their chief organ of smell, is important. We describe antennal-specific aldehyde oxidases from the moths Antheraea polyphemus and Bombyx mori that are capable of catabolizing long chain, unsaturated aldehydes such as their aldehyde pheromones. These soluble enzymes are associated uniquely with male and female antennae and have molecular masses of 175 and 130 kDa, respectively. The A. polyphemus aldehyde oxidase has been localized to the olfactory sensilla which contain the pheromone receptor cell dendrites. These same sensilla contain a previously described sensilla-specific esterase that degrades the acetate ester component of A. polyphemus pheromone. We propose that sensillar pheromone-degrading enzymes modulate pheromone concentration in the receptor space and hence play a dynamic role in the pheromone-mediated reproductive behaviors of these animals.

Aldehyde Oxidase↗

Between nurture and nature: the shifting determinants of female fertility in Danish twin cohorts.

Behaviors related to fertility constitute primary candidates for investigating the relevance of evolutionary influences and biological dispositions on contemporary human behaviors. Using female Danish twin cohorts born 1870-1968, we document important transformations in the relative contributions of "nurture" and "nature" to within-cohort variations in early and complete fertility, and we point toward a systematic relation between the socioeconomic context of cohorts and the relevance of genetic and shared environmental factors. This transformation is most striking for early fertility where genetic factors strengthen over time and are consistent with up to 50 percent of the variation in early fertility in most recent cohorts. Understanding this emerging relevance of genetic factors is of central importance because early fertility constitutes an important determinant of complete fertility levels in low-fertility societies, and because teenage motherhood and early childbearing are often associated with negative life-cycle consequences. Moreover, our results emphasize the need for socially and contextually informed analyses of nature and nurture that allow both factors to influence human reproductive behavior over time.

Adult↗

Projections of luteinizing hormone-releasing hormone and vasotocin fibers to the anterior part of the preoptic nucleus in the toad, Bufo japonicus.

The anterior part of the preoptic nucleus (APON) is a crucial locus for triggering male mate calling behavior in anuran amphibia. The projections to this locus of luteinizing hormone-releasing hormone and vasotocin fibers were immunohistochemically demonstrated in the brain of the toad (Bufo japonicus) using the avidin-biotin-peroxidase complex method. Immunoreactive (ir)-LH-RH perikarya are localized in the nucleus medialis septi and the nucleus of the diagonal band of Broca. A part of ir-LH-RH fibers arising from these nuclei project to the lateral part of the APON, where the APON neurons form their dendritic field, and often protrude into its medial neuronal cell mass. Meanwhile, a considerable number of vasotocin fibers arising from the ventral magnocellular part of the preoptic nucleus project anterior to these loci. These observations indicate that the LH-RH and vasotocin fibers may form ordinary and/or en passant synapses with the APON neurons to transmit peptidergic neuronal signals which are concerned with initiation of seasonal reproductive behavior.

Animals↗

Implications of estrogen-dependent brain organization for gender differences in hypothalamo-pituitary-adrenal regulation.

Estrogens, derived from the aromatization of testosterone in the brain, account for sex-specific organization of neural circuits controlling gonadotropin release and sexual behavior. This study examines the possible organizing role of perinatal gonadal steroids in the manifestation of known, albeit unexplained, male-female differences in basal and stress-related adrenocortical secretion. We document here the existence of gender-specific differences in the gene expression of hypothalamic corticotropin-releasing hormone (CRH), and hippocampal and hypothalamic glucocorticoid receptors (GR), diurnal corticosterone secretion, as well as in the responsiveness of CRH and GR mRNA levels to exogenous estradiol. In addition, we report that neonatal estrogenization of female rats profoundly affects several regulatory substrates of the hypothalamo-pituitary-adrenal (HPA) axis, namely, the gene expression of CRH, arginine-vasopressin (AVP) and GR in the brain, and the responsiveness of these parameters to estrogen. The neonatal treatment appeared to "defeminize" a number of neuroendocrine mechanisms related to HPA function; these changes were reminiscent of those observed in earlier studies on sexual differentiation of reproductive behavior and hormonal secretion. The results indicate a pivotal role for estrogens during early development for the determination of gender-specific differences in HPA function in the mature animal and demonstrate for the first time that the brain-organizing actions of gonadal steroids may extend to nonreproductive neuroendocrine axes.

Adrenal Glands↗

Prenatal amphetamine exposure: ovulation, sexual behavior and hypothalamic monoamine content in rats.

Previous observations have pointed out that amphetamine treatment during pregnancy produces behavioral and neurochemical changes in the male offspring. The present study was undertaken in order to determine whether those findings could be extended to sexual behavior, reproductive function and hypothalamic monoamine metabolism in female rats. It was found that offspring of amphetamine treated rats have greater sensitivity to estrogen and estrogen-progesterone for the induction of sexual receptivity. 5-HT content in medial hypothalamus of estrogen-progesterone treated rats was decreased with respect to controls. On the other hand the content of 5-HIAA was not different; noradrenaline levels in hypothalamus were also normal. Sex cycle duration and ovulatory phenomena were not affected.

Amphetamine↗

Arginine vasotocin interacts with the social environment to regulate advertisement calling in the gray treefrog (Hyla versicolor).

Arginine vasotocin (AVT) has different effects on social behaviors across species with different social systems. However, less attention has been directed towards the way environmental stimuli interact with AVT to affect social behaviors. Previous work found that AVT affects the production of advertisement calls and the outcome of competitive interactions between male gray treefrogs (Hula versicolor). We conducted a field study to investigate how the presence of other males in a chorus influenced the production of advertisement calls in males treated with AVT or saline. After hormone treatment we placed individuals in call sites either within 50 cm of another calling male (proximate), or more than 2 m away from any calling male (distant). Males treated with AVT produced significantly longer calls with more pulses when placed at proximate call sites, but not distant call sites. Nonsignificant trends indicated that these increases in call length coincided with a decrease in call rate. There was no effect of call site distance on advertisement calls when males were treated with saline. These results indicate that the social environment can modulate the action of AVT on an important reproductive behavior, and that AVT does not influence call duration and pulse number unless another male is nearby. Understanding how social stimuli regulate the action of AVT on behavior could provide insight on the diversity of AVT function across species.

Animals↗

Predictors of repeat pregnancy among HIV-1-infected women.

BACKGROUND: In the Women and Infants Transmission Study (WITS), a prospective cohort study of HIV-infected pregnant women at six US mainland and Puerto Rican sites, changes in the HIV-1 epidemic have included higher income, better education, and better-controlled HIV disease among more recently enrolled women. Because these changes may alter the reproductive patterns of these women an awareness of these women's current reproductive behaviors is essential. We examined predictors of repeat pregnancy among HIV-1-infected women enrolled in the Women and Infants Transmission Study (WITS). METHODS: Women enrolled in WITS without a history of sterilization were included. Using bivariate and multivariate analyses, predictors of a repeat pregnancy were modeled. Changes in risk factors for repeat pregnancy over time were examined and important predictors of repeat pregnancy were determined. RESULTS: Of 2246 eligible women, 22% had more than one WITS-enrolled pregnancy. In bivariate analyses, risk of repeat pregnancy was associated with younger age, lower educational status, higher CD4%, and lower viral loads. There was little change in risk factors for repeat pregnancy over time. CONCLUSIONS: HIV-1-infected women who are younger and healthier are more likely to have more than one pregnancy. Factors associated with repeat pregnancy among HIV-1-infected women have remained stable over time. Awareness of these factors will better equip healthcare providers to address the reproductive needs of HIV-1-infected women.

Adult↗

Immunoreactive gonadotropin-releasing hormone (GnRHir) is associated with vestibular structures in the green anole (Anolis carolinensis).

The distribution of immunoreactive gonadotropin-releasing hormone (GnRHir) in relation to endocrine and behavioral pathways is not well established for lizards. To more completely understand the GnRHir distribution and its possible function in a lizard, we investigated the brain of Anolis carolinensis, a species whose visual courtship displays, mating postures and gonadal cycles are well known. Using antisera that recognize multiple GnRH forms, we observed no GnRHir cells or fibers in the forebrain. In the midbrain, however, GnRHir cells occurred along the medial border of the medial longitudinal fasciculus. These cells appeared to project GnRHir fibers to nuclei of cranial nerve III and IV. In the hindbrain, positive fibers were observed in the area of the vestibular nuclei and dorsal funiculus. These hindbrain fibers were followed to their terminals in the cerebellum. The GnRHir midbrain distribution suggests an association of GnRH with eye movements, whereas the hindbrain distribution suggests a GnRH-vestibular association. The lack of GnRHir in the forebrain of Anolis could reflect the minimal role of the vomeronasal system in mediating reproduction in this species. Thus, our study cannot verify hypothalamic GnRH control of the pituitary in A. carolinensis, but it does indicate GnRH control of oculomotor and vestibular nuclei, which might play a role in Anolis reproductive behaviors.

Animals↗

Cloning, characterization and tissue specific expression of Amur tiger (Panthera tigris altaica) IGF-I.

Insulin-like growth factor I (IGF-I) plays an important role in regulating gonad function, which is essential for normal reproduction in animals, especially in sexual receptivity and reproductive behavior. In this study, a cDNA encoding Amur tiger (Panthera tigris altaica) IGF-I was isolated from liver total RNA using RT-PCR. The IGF-I cDNA of Amur tiger (ATIGF-I) was highly homologous to that of other animals, 84.8% to rat, 93.7% to human and horse. Alignment analysis showed that the cysteine residues and many amino acid residues of putative mature ATIGF-I are highly conserved in mammalian species, confirming the high sequence homology observed in other species. DNA encoding the mature ATIGF-I peptide was ligated with pET-DsbA expression vector and highly expressed in Escherichia coli BL21 with IPTG induction. The recombinant proteins expressed existed mostly in the soluble protein fraction, and were purified with metal affinity resins. Western blotting confirmed that the recombinant proteins reacted with antibodies against IGF-I. The results obtained here should be useful for large-scale production of biological active ATIGF-I protein, as well as for further research on growth, development, and reproduction in the Amur tiger. Tissue specific expression of ATIGF-I mRNA in the Amur tiger was examined by reverse transcription-polymerase chain reaction (RT-PCR), The major ATIGF-I mRNA expression tissue was the liver, while medium signals were found in the uterus, ovary, and pituitary, and minor signals were detected in various tissues including the heart, spleen, pancreas, and kidney. The results indicate that IGF-I might play an important role in the reproductive system and in cub development in the Amur tiger.

Amino Acid Sequence↗

The synaptic organization of VMH neurons that mediate the effects of estrogen on sexual behavior.

Estrogen acts in the hypothalamic ventromedial nucleus (VMH) of female rats to promote sexual behavior, as typified by the lordosis response. Morphological changes in the VMH, such as increased synaptic profiles and increased dendritic spines, suggest that estrogen may modulate behavior by altering VMH synaptic organization. To understand the significance of these changes, this laboratory has been investigating the functional classes of lordosis-relevant neurons and their local connectivity. A neurotropic virus, pseudorabies virus (PRV), was used to transneuronally label the CNS network that controls the lordosis-producing muscles. When PRV was placed in the lumbar epaxial muscles, it was sequentially detected in the lumbar ventral horn, the medullary reticular formation, the periaqueductal gray, and finally the VMH. Subsequent analysis showed that the population of VMH neurons that were initially infected with PRV largely resided beyond the cluster of estrogen receptor-containing neurons. In a separate study, VMH neurons were visualized with Lucifer yellow, and their morphology was analyzed using confocal microscopy. Such analysis confirmed that estrogen treatment increased dendritic spines in the VMH. The particular VMH neurons in this study did not express nuclear estrogen receptor, which suggests that estrogen can increase spine density indirectly. These results represent initial steps toward unraveling the local circuit that mediates estrogenic action on a specific reproductive behavior.

Animals↗

Progesterone treatment increases Fos-immunoreactivity within some progestin receptor-containing neurons in localized regions of female rat forebrain.

In female rats, the sequential release of estradiol and progesterone from the ovaries is required for the expression of sexual behavior during the estrous cycle. Many of the neuronal effects of estradiol and progesterone involve estrogen and progestin receptors. Treatment with a behaviorally-effective dose of estradiol increases Fos expression, suggestive of neuronal response, and subsequent treatment with a behaviorally-effective dose of progesterone further increases Fos expression within a few hours in female rat brain. In order to determine if neurons that respond to progesterone with increase Fos expression also contain progestin receptors, we used a double-label immunofluorescent technique to label both progestin receptors and Fos protein following progesterone or vehicle treatment of estradiol-primed female rats. As shown previously, progesterone treatment increased Fos expression in progestin receptor-containing regions, such as the ventromedial nucleus of the hypothalamus and the medial preoptic area. In addition, progesterone treatment induced a statistically-significant increase in Fos-immunoreactivity within progestin receptor-containing cells in the medial preoptic area and the ventromedial nucleus of the hypothalamus, but not in the arcuate nucleus. Therefore, many but not all of the neurons that respond to progesterone with increased Fos expression also contain progestin receptor-immunoreactivity. The progesterone-induced Fos expression within progestin receptor-containing neurons may or may not be associated with the effects of progesterone on sexual or other reproductive behaviors, as it remains to be tested. However, the Fos expression provides a useful marker to aid in identification of neurons that respond to a behaviorally-relevant dose of progesterone.

Animals↗

Effects of pesticides and toxic substances on behavioral and morphological reproductive development: endocrine versus nonendocrine mechanisms.

Exposure to toxic substances or pesticides during critical perinatal developmental periods can alter reproductive and central nervous system (CNS) function in a manner that does not compromise the growth and viability of the fetus but causes functional alterations that become apparent later in life. While some "CNS/behavioral teratogens" are mutagenic or alter cell division, other chemicals produce alterations of CNS development via endocrine-mediated mechanisms. The following discussion will focus on studies conducted primarily in our laboratory that describe how pesticides and toxic substances alter development of the reproductive and central nervous systems as a consequence of organizational or activational exposures. Abnormal behavior and morphology can result from exposure to endocrine-disrupting toxicants by altering organization of the CNS during critical stages of life or activation of behavior after puberty. Some of the toxicants that alter rodent sexual differentiation include xenoestrogens, antiandrogenic pesticides, and dioxin-like toxic substances. Chemicals that alter sex-linked nonreproductive and reproductive CNS development via nonhormonal mechanisms are also discussed in order to demonstrate that multiple mechanisms of action are involved in the development of behavioral abnormalities in pre- and perinatally exposed offspring. The fact that reproductive function (behavioral, biochemical, and morphological) can be altered via such a wide variety of mechanisms indicates that hazard identification in this area cannot rely solely on the detection of endocrine activity.

Animals↗

Determinants of adolescent fertility and its consequences for maternal health, with special reference to rural Bangladesh.

The second section of this paper set forth a theoretical model relating adolescent growth and development to family formation patterns and their implications for maternal and child health. Subsequent sections of the paper examine the evidence to support specific relationships hypothesized in the model, focusing on longitudinal data from Matlab, Bangladesh. Despite the emphasis on developing country populations, literature from developed countries was also reviewed. The weight of the evidence suggests that in the developed countries, while there is a positive relationship between reproductive maturation and subsequent reproductive behavior, the negative effects of young maternal age on pregnancy outcome is confounded with socioeconomic factors. Teenage pregnancy, or at least teenage birth, occurs disproportionately among the socially and economically disadvantaged. Moreover, teenage childbearing in the U.S., especially when it occurs outside of marriage, violates social norms, at least in the white population. Poor diet may be a problem in the U.S. but it does not appear to result in notable delays in physical growth and development, delayed or compromised adolescent growth, or late age at menarche. Limited evidence suggests that early menarche may be associated with more rapid onset of mature menstrual cycle activity but these findings have not been replicated elsewhere. In developing countries the situation is quite different. First, early marriage and childbearing are desired and common across most segments of society. Second, malnutrition is widespread, and is sufficiently severe to delay the adolescent growth spurt and raise average age at menarche by two to three years compared with developed country populations. This is certainly the case in Bangladesh. In this setting, several observations regarding the relationship of nutritional status, adolescent development and reproduction have been made. First, undernutrition delays growth and reproductive maturation, and women who mature early (i.e., women with young age at menarche) marry at younger ages than later maturers. In addition, body weight appears to have an independent effect on age at marriage, net of age at menarche, such that relatively heavy women marry at younger ages than their lighter counterparts. Explanations for this finding include correlation between body weight and development of secondary sex characteristics, and perhaps a cultural perception that heavier (i.e., normal body weight) women are more attractive, or healthier, mates. The effect of menarche and nutritional status on marriage gives rise to concern that an improvement in nutritional status, and an increase in the age at menarche, would lead to younger marriage and first birth, and higher lifetime fertility.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

High fertility among Indochinese refugees.

From 1975 to 1988, nearly 900,000 Indochinese refugees were resettled in the United States. This paper examines patterns of fertility among these refugees from Cambodia, Laos, and Vietnam who have exhibited high levels of reproduction since their arrival. Data are drawn from sample surveys in San Diego and San Francisco, CA. Fertility levels were found to exceed five children per ever-married woman, a level that is consistent with perceptions of ideal family size in the homeland. Fertility levels were significantly higher among rural second-wave refugees than in the more urban first-wave groups. One explanation for the high fertility is that couples have migrated from areas where fertility is high, and they have not yet adapted their reproductive behavior to the low fertility environment of the United States. This possibility is reinforced by a general gender preference for boys and exacerbated by the fact that, while a majority of women are aware of methods of fertility control, access is still limited by cultural and financial barriers, and the motivation to use family planning still appears to be relatively low. The data suggest that this refugee population will continue to put pressure on maternal and child health resources, and that continued residence in the United States could lead to desires to limit family size, thus increasing demand for methods of fertility control.

Adult↗

Effects of pretreatment with adrenocorticotropin on endocrine and behavioral responses of bulls to sexual activity.

Peripheral concentrations of cortisol, growth hormone and testosterone were determined in two experiments which examined the endocrine and behavioral responses of sexually mature Angus bulls to an estrous female (Experiment 1) and to female exposure 5 hours following an adrenocorticotropin (ACTH) injection (Experiment 2). Sexual activity of bulls in Experiment 1 significantly increased levels of cortisol when compared with concentrations before exposure to a female. Administration of ACTH in Experiment 2 consistently elevated levels of cortisol by 30-fold (P<0.01) when compared with pre-ACTH concentrations. This heightened level of cortisol persisted throughout the period of exposure to an estrous cow, although a gradual decline in cortisol concentrations occurred over time (P<0.05). In Experiment 1, growth hormone profiles tended to increase in response to sexual activity (P<0.10), whereas in Experiment 2, growth hormone increased in response to ACTH administration (P<0.01) and to female exposure (P<0.01). Concentrations of testosterone were unaffected (P>0.10) by mating activity in Experiment 1. In Experiment 2, acute suppression (P<0.01) in testosterone concentrations 5 hours after ACTH administration coincided with the exposure period to the estrous female. Frequencies of mounting behavious (penis extension, mounting, intromission and ejaculation) exhibited by ACTH-treated bulls were significantly lower compared with the frequencies two days earlier. Exogenous ACTH administration suppressed reproductive behaviors of bulls and altered secretion of cortisol, growth hormone and testosterone. Furthermore, these data provide evidence that specific mating behaviors of the bull can be influenced by circulating steroids.

Journal Article↗

Sex differences in estrogenic regulation of preproenkephalin mRNA levels in the medial preoptic area of prepubertal rats.

Opioids have been implicated in sexual differentiation of the brain and in the regulation of reproductive behavior and endocrinology of mammals. Previous studies have indicated that estrogen administration in adults regulates preproenkephalin MRNA levels in several hypothalamic brain nuclei. We have determined preproenkephalin mRNA levels in estrogen-treated juvenile male and female rats to investigate the developmental pattern of estrogenic regulation of enkephalinergic neurons in the medial preoptic area. Rats were treated with estradiol benzoate (20 microgram/kg/day) or oil from day 21 to 23. Sections of the medial preoptic area (mPOA) were studied by in situ hybridization histochemistry at the single cell level and quantified with the assistance of an image analysis system. Our data indicate that males contain higher levels of preproenkephalin mRNA per neuron than females. In addition, our results indicate that estrogen causes an upward shift in the amount of mRNA expressed per cell, females demonstrating a greater response to estrogen than males. An increase in soma cell area following estrogen treatment was observed only in female mPOA enkephalinergic neurons. Taken together, these results indicate a sex difference in total preproenkephalin levels and in estrogenic regulation of preproenkephalin mRNA in the POA of juvenile rats. These results are discussed in relation to the differential role opioids may play in male and female reproductive physiology.

Animals↗

Anatomic relationships between aromatase and androgen receptor mRNA expression in the hypothalamus and amygdala of adult male cynomolgus monkeys.

This study mapped the regional locations of cells expressing cytochrome P450 aromatase (P450AROM) and androgen receptor (AR) mRNAs in the adult male macaque hypothalamus and amygdala by in situ hybridization histochemistry using monkey-specific cRNA probes. High densities of P450AROM and AR mRNA-containing neurons were observed in discrete hypothalamic areas involved in the regulation of gonadotropin secretion and reproductive behavior. P450AROM mRNA-containing neurons were most abundant in the medial preoptic nucleus, bed nucleus of the stria terminalis, and anterior hypothalamic area, whereas AR mRNA-containing neurons were most numerous in the ventromedial nucleus, arcuate nucleus, and tuberomamillary nucleus. Moderate to heavily labeled P450AROM mRNA-containing cells were present in the cortical and medial amygdaloid nuclei, which are known to have strong reciprocal inputs with the hypothalamus. Heavily labeled P450AROM mRNA-containing cells were found in the accessory basal amygdala nucleus, which projects to the cingulate cortex and hippocampus, areas that are important in the expression of emotional behaviors and memory processing. In contrast to P450AROM, the highest density of AR mRNA labeling in the temporal lobe was associated with the cortical amygdaloid nucleus and the pyramidal cells of the hippocampus. All areas that contained P450AROM mRNA-expressing cells also contained AR mRNA-expressing cells, but there were areas in which AR mRNA was expressed but not P450AROM mRNA. The apparent relative differences in the expression of P450AROM and AR mRNA-containing neurons within the monkey brain suggests that T acts through different signaling pathways in specific brain areas or within different cells from the same region.

Amygdala↗

Effect of lactation on hypothalamic preproenkephalin gene expression.

Enkephalin appears to modulate several aspects of reproductive function in female rats. The purpose of this study was to determine if lactation influences preproenkephalin gene expression in one or more hypothalamic nuclei known to be involved in maternal or reproductive behavior and prolactin secretion. Lactating rats were killed on day 3 (LAC 3) or day 10 (LAC 10) of lactation. Controls consisted of regular 4-day cycling rats that were killed on diestrous day 1, with 9 to 12 females per group. We used in situ hybridization histochemistry to assess preproenkephalin gene expression in individual cells in the medial preoptic nucleus, anterior, medial and posterior arcuate nucleus, magnocellular and parvocellular aspects of paraventricular nucleus, and ventromedial nucleus. Preproenkephalin mRNA in the anterior arcuate nucleus increased to reach significance (P < 0.05) at day 10 of lactation. Levels in the medial arcuate nucleus increased significantly (P < 0.001) by day 3 of lactation (LAC 3) and remained elevated on day 10 (LAC 10). No significant differences between lactating and control rats were detected in preproenkephalin mRNA levels in the posterior arcuate nucleus, medial preoptic nucleus or in the ventromedial nucleus. Substantial levels of preproenkephalin mRNA were found in the paraventricular nucleus, particularly in a limited region of the magnocellular portion. However, these levels did not change with lactation. These data provide evidence for differential regulation of the preproenkephalin gene during lactation. This change may contribute to lactational hyperprolactinemia and suppressed GnRH secretion, leading to reproductive acyclicity.

Animals↗