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PubMed1998

Neuroanatomical distribution and variations across the reproductive cycle of aromatase activity and aromatase-immunoreactive cells in the pied flycatcher (Ficedula hypoleuca).

The anatomical distribution and seasonal variations in aromatase activity and in the number of aromatase-immunoreactive cells were studied in the brain of free-living male pied flycatchers (Ficedula hypoleuca). A high aromatase activity was detected in the telencephalon and diencephalon but low to negligible levels were present in the optic lobes, cerebellum, and brain stem. In the diencephalon, most aromatase-immunoreactive cells were confined to three nuclei implicated in the control of reproductive behaviors: the medial preoptic nucleus, the nucleus of the stria terminalis, and the ventromedial nucleus of the hypothalamus. In the telencephalon, the immunopositive cells were clustered in the medial part of the neostriatum and in the hippocampus as previously described in another songbird species, the zebra finch. No immunoreactive cells could be observed in the song control nuclei. A marked drop in aromatase activity was detected in the anterior and posterior diencephalon in the early summer when the behavior of the birds had switched from defending a territory to helping the female in feeding the nestlings. This enzymatic change is presumably controlled by the drop in plasma testosterone levels observed at that stage of the reproductive cycle. No change in enzyme activity, however, was seen at that time in other brain areas. The number of aromatase-immunoreactive cells also decreased at that time in the caudal part of the medial preoptic nucleus but not in the ventromedial nucleus of the hypothalamus (an increase was even observed), suggesting that differential mechanisms control the enzyme concentration and enzyme activity in the hypothalamus. Taken together, these data suggest that changes in diencephalic aromatase activity contribute to the control of seasonal variations in reproductive behavior of male pied flycatchers but the role of the telencephalic aromatase in the control of behavior remains unclear at present.

Animals↗
PubMed2003

Hormonally derived sex pheromones in fish: exogenous cues and signals from gonad to brain.

Living in a medium that can limit visual information but readily exposes the olfactory organ to hormonal compounds released by conspecifics, fish throughout their long evolutionary history have had both clear cause and ample opportunity to evolve olfactory responsiveness to these potentially important chemical cues (hormonal pheromones). Indeed, water-borne steroids, prostaglandins, and their metabolites are detected with great sensitivity and specificity by the olfactory organs of diverse fishes, and exert important effects on reproductive behavior and physiology in major taxa including carps (goldfish), catfishes, salmon, and gobies. Best understood are goldfish, where periovulatory females sequentially release a preovulatory steroid pheromone and a postovulatory prostaglandin pheromone that dramatically affect male behavior, physiology, and reproductive fitness. Although the diverse array of hormonal products released and detected by fish indicates clear potential for species-specific hormonal pheromones, olfactory recordings showing similar patterns of hormone detection among closely related species provide little evidence of selection for specificity. By demonstrating that the actions of sex hormones and related products are not limited to reproductive synchrony within the individual, the relatively recent discovery of hormonal pheromones has considerably expanded our understanding of fish reproductive function, while providing valuable model systems for future study of olfactory function and pheromone evolution.

Animal Communication↗
PubMed1987

Endocrine events associated with spawning behavior in the sea lamprey (Petromyzon marinus).

Levels of estradiol, progesterone, and testosterone were determined in plasma of sea lamprey (Petromyzon marinus) undergoing certain behaviors associated with spawning in natural and artificial stream environments. Significantly higher levels of estradiol, progesterone, and testosterone were found in males than in females. In the artificial spawning channel, levels of estradiol were significantly higher in females exhibiting resting and swimming behaviors than in fanning, nest building, and spawning behaviors. No significant correlation was found with either progesterone or testosterone levels and the various reproductive behaviors. The data presented are the first experimental evidence that suggest gonadal steroids may be correlated with certain reproductive behaviors in the sea lamprey.

Aggression↗
PubMed1998

Prolactin (PRL) and its receptor: actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice.

PRL is an anterior pituitary hormone that, along with GH and PLs, forms a family of hormones that probably resulted from the duplication of an ancestral gene. The PRLR is also a member of a larger family, known as the cytokine class-1 receptor superfamily, which currently has more than 20 different members. PRLRs or binding sites are widely distributed throughout the body. In fact, it is difficult to find a tissue that does not express any PRLR mRNA or protein. In agreement with this wide distribution of receptors is the fact that now more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection. Clearly, a large proportion of these actions are directly or indirectly associated with the process of reproduction, including many behavioral effects. PRL is also becoming well known as an important regulator of immune function. A number of disease states, including the growth of different forms of cancer as well as various autoimmune diseases, appear to be related to an overproduction of PRL, which may act in an endocrine, autocrine, or paracrine manner, or via an increased sensitivity to the hormone. The first step in the mechanism of action of PRL is the binding to a cell surface receptor. The ligand binds in a two-step process in which site 1 on PRL binds to one receptor molecule, after which a second receptor molecule binds to site 2 on the hormone, forming a homodimer consisting of one molecule of PRL and two molecules of receptor. The PRLR contains no intrinsic tyrosine kinase cytoplasmic domain but associates with a cytoplasmic tyrosine kinase, JAK2. Dimerization of the receptor induces tyrosine phosphorylation and activation of the JAK kinase followed by phosphorylation of the receptor. Other receptor-associated kinases of the Src family have also been shown to be activated by PRL. One major pathway of signaling involves phosphorylation of cytoplasmic State proteins, which themselves dimerize and translocate to nucleus and bind to specific promoter elements on PRL-responsive genes. In addition, the Ras/Raf/MAP kinase pathway is also activated by PRL and may be involved in the proliferative effects of the hormone. Finally, a number of other potential mediators have been identified, including IRS-1, PI-3 kinase, SHP-2, PLC gamma, PKC, and intracellular Ca2+. The technique of gene targeting in mice has been used to develop the first experimental model in which the effect of the complete absence of any lactogen or PRL-mediated effects can be studied. Heterozygous (+/-) females show almost complete failure to lactate after the first, but not subsequent, pregnancies. Homozygous (-/-) females are infertile due to multiple reproductive abnormalities, including ovulation of premeiotic oocytes, reduced fertilization of oocytes, reduced preimplantation oocyte development, lack of embryo implantation, and the absence of pseudopregnancy. Twenty per cent of the homozygous males showed delayed fertility. Other phenotypes, including effects on the immune system and bone, are currently being examined. It is clear that there are multiple actions associated with PRL. It will be important to correlate known effects with local production of PRL to differentiate classic endocrine from autocrine/paracrine effects. The fact that extrapituitary PRL can, under some circumstances, compensate for pituitary PRL raises the interesting possibility that there may be effects of PRL other than those originally observed in hypophysectomized rats. The PRLR knockout mouse model should be an interesting system by which to look for effects activated only by PRL or other lactogenic hormones. On the other hand, many of the effects reported in this review may be shared with other hormones, cytokines, or growth factors and thus will be more difficult to study. (ABSTRACT TRUNCATED)

Animals↗
PubMed2005

Identification of roughskin newt medullary vasotocin target neurons with a fluorescent vasotocin conjugate.

Arginine8 vasotocin (AVT), a neurohypophyseal peptide in nonmammalian vertebrates, plays a key role in the regulation of social behaviors related to reproduction. In male roughskin newts (Taricha granulosa), AVT is an important facilitator of several reproductive behaviors, including courtship clasping of females. Although AVT is known to act in certain brain regions and AVT receptors have been localized to some extent, specific target neurons for this peptide have not been identified in any species. Internalization of a receptor-specific conjugate of AVT and the fluorescent dye Oregon green was used to identify AVT target cells in the medulla of male roughskin newts. Medullary neurons are of interest because they appear to mediate facilitation of clasping by AVT. Direct application of AVT-Oregon green to the fourth ventricular surface of the medulla in vivo resulted in conjugate internalization by a widespread population of medullary neurons, particularly in the medial reticular formation and nuclei of cranial nerves V, VII, VIII, IX, and X. Some fourth-ventricle ependymal cells were also labeled. Reticulospinal neurons, which play an important role in clasping, were identified by retrograde labeling with tetramethylrhodamine dextran amine. AVT-Oregon green was internalized by 72% of these neurons. These results show that AVT can directly affect a very large and diverse medullary neuronal population, which may underlie the peptide's role in multiple neuroendocrinological processes, including autonomic and behavioral regulation. Selectivity of the AVT action may arise through interactions between AVT and steroids such as corticosterone.

Animals↗
PubMed1997

Psychological factors affecting health after toxicological disasters.

Exposure to toxic substances in the environment is an ever more common event, that may cause physical as well as psychological harm. When an entire community is exposed, the term 'toxicological disaster' is used. The mere threat of such an event may be a source of stress, associated with changes in mental health, physical health, and changes in health-related behaviors. A review is presented of the literature about the effects of the stressful experience of toxicological disasters on health and health-related behaviors. Three questions are examined: (a) do toxicological disasters represent a specific type of stressor, different from other stressors?; (b) which stress-mediated health effects have been observed in the aftermath of toxicological disasters? and (c) is there evidence for a higher vulnerability in certain identifiable risk groups? On the basis of the available literature, it is concluded that toxicological disasters may have profound effects on subjective health, especially on symptom reporting, and on a number of psychophysiological parameters. Evidence for a substantial impact of disaster-related stress on either physical or psychiatric morbidity remains inconclusive. In this respect toxicological disasters do not appear to differ from other stressors. There is some evidence that toxicological disasters may have a more pronounced effect on health-related behaviors, especially on reproductive behavior (number of births and abortions). Women, and especially those who have young children to care for, appear to be more at risk for the observed health effects. The evidence for a higher vulnerability in other risk groups (e.g., former psychiatric patients remains inconclusive.

Adaptation, Psychological↗
PubMed1997

The health of Navajo women: findings from the Navajo Health and Nutrition Survey, 1991-1992.

Cancer-screening behaviors, reproductive history, risk behaviors during pregnancy and chronic disease risk factors were examined in a representative sample of 566 Navajo women residing on the Navajo Reservation in 1991-1992. Among all women 15 y and older, 59% were overweight, 4% were current smokers, 10% currently used smokeless tobacco and 12% were anemic. Seventy-one percent of Navajo women aged 18 and older reported ever having had a Pap smear, but only 35% of women aged 50 and over reported ever having had a mammogram. Among parous women, the prevalence of having received no prenatal care for any pregnancy declined from 60% among women 60 and older to 13% among women 20-29 y of age, and the prevalence of ever having had a child born at home declined from 82 to 2%. These data suggest marked secular improvement in these pregnancy-related risk behaviors. However, data on cancer-screening behaviors indicate opportunities to improve health of Navajo women by increasing their use of mammography and Pap smear screening services.

Adolescent↗
PubMed1980

Effect of transportation on sexual behavior of cats.

Transportation of an established feline colony approximately 1500 miles did not inhibit the resumption of behavioral reproductive cyclicity. Estrous behavior was observed as early as 18 days following shipment and mean duration of these first post-transfer estrous periods was normal. Relocation appeared to induce a synchronizing effect on behavioral cyclicity, since 76.2% and 42.9% of the population exhibited estrous onset during Days 18--31 and Days 24--26 respectively, following transport.

Animals↗
PubMed1992

Oxytocin--a neuropeptide for affiliation: evidence from behavioral, receptor autoradiographic, and comparative studies.

Oxytocin (OT) is a nine amino acid peptide synthesized in hypothalamic cells which project either to the neurohypophysis or to sites within the central nervous system. Although neurohypophyseal OT release has long been associated with uterine contraction and milk ejection, the function of intracerebral OT remains unclear. On the basis of behavioral, cellular, and comparative studies, this review suggests that brain OT influences the formation of social bonds. The first part of this review examines evidence linking central OT to several forms of affiliation. Central administration of OT induces maternal and reproductive behaviors in rats primed with gonadal steroids. OT antagonists and hypothalamic lesions block the initiation of maternal and reproductive behaviors but have no effects on these behaviors once established. Our new studies in rat pups demonstrate that central OT selectively decreases the separation response, an effect which mimics social contact. These studies of parental, reproductive, and attachment behaviors suggest that exogenous OT has "prosocial" effects and that endogenous OT may be essential for initiating social interaction. In a second series of experiments, we investigated the cellular mechanisms for OT's effects on social behavior by means of autoradiographic receptor binding. In the rat forebrain, OT receptors are expressed in several limbic regions believed to be involved in the integration of sensory processing. The regulation of these receptors is surprisingly resistant to either ablation of OT cells or repeated central administration of OT. However, receptors in two regions, the bed nucleus of the stria terminalis (BNST) and the ventromedial nucleus of the hypothalamus (VMN), appear selectively induced by exogenous or endogenous increases in gonadal steroids. At parturition, binding to OT receptors increases 84% in the BNST, and at estrus, binding increases 35% in the VMN. These results demonstrate that physiologic changes in gonadal steroids can alter receptor expression in anatomically discrete target fields and thereby direct responsiveness to endogenous neuropeptide release. A model for OT's effects on social behavior is proposed, which relies on the heterologous regulation of the brain OT receptor. A third series of experiments tested the hypothesis that brain OT influences affiliation by comparing prairie and montane voles, two closely related species with dichotomous systems of social organization. Although no differences appear in the presynaptic expression of the neuropeptide, OT receptors are distributed in complementary patterns in the two species. In the highly affiliative prairie vole, receptors are most evident in the BNST and one of its primary afferents, the lateral amygdala, highlighting a circuit previously implicated in maternal behavior.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

The effect of diabetes on sexual behavior and reproductive tract function in male rats.

The effect of streptozotocin induced diabetes and sabeluzole (SBZ) on sexual function was evaluated in male rats. SBZ is a benzothiazole derivative with antihypoxic and antiischaemic activities. Rats were rendered diabetic by intraperitoneal injection of streptozotocin, 60 mg./kg. body weight, and either left untreated or treated with 1.0 mg./kg. of SBZ. Two groups of control rats treated with or without SBZ were also evaluated. Seven weeks after the induction of diabetes, all rats were studied in vivo for mating behavior. Animals were sacrificed one week later, and detrusor strip response in vitro was evaluated. The reproductive organ weight, sperm content and motility as well as in vitro testosterone secretion and serum levels of LH and testosterone were determined. Diabetes induced significant reduction in mating behavior. The diabetic rats that received SBZ showed a significant improvement in mating behavior. The percentage of animals that exhibited ejaculation was 0% in the diabetic group compared to 70% in the controls and 38% in diabetic plus SBZ group. The strips of the detrusor muscle of the diabetic group showed a marked hypersensitivity to bethanechol HCL. In the diabetic plus SBZ group, the strips of the detrusor muscle showed a response similar to that of the control. The diabetic rats had significantly diminished reproductive organ weight, testicular sperm content, epididymal sperm content and sperm motility relative to the control. In addition, marked decrease in the serum level of testosterone and in vitro testosterone secretion was observed in diabetic rats. In the diabetic plus SBZ group, the reproductive organ weight, sperm content and motility as well as serum testosterone and in vitro testosterone secretion showed an improvement compared to diabetic rats. In summary, our data suggest that sex behavior and reproductive tract functions are markedly affected by streptozotocin induced diabetes. Sabeluzole treatment could be beneficial in reducing the deleterious effect of diabetes on sexual functions.

Animals↗
PubMed2005

A new model for sexual conditioning: the ring dove (Streptopelia risoria).

Sexual conditioning investigations have primarily used rats and domestic quail as subjects. Although much has been learned from such experiments, the relative simplicity of rat and quail reproductive behavior prohibits investigation of certain experimental questions about sexual conditioning. In contrast, the reproductive behavior of male and female ring doves (Streptopelia risoria) is complex, involving courtship, bonding, and parental care. In the present experiment, male ring doves that were presented with a visual conditioned stimulus paired with access to their pair-bonded mate (the unconditioned stimulus) showed sexual conditioned responding in the presence of the conditioned stimulus. These results represent the first evidence of sexual conditioning in ring doves and illustrate the potential of ring doves as a useful model for future sexual conditioning investigations.

Animals↗
PubMed2001

Dihydrotestosterone activates sexual behavior in adult male hamsters but not in juveniles.

The effect of an androgenic metabolite of testosterone, dihydrotestosterone (DHT), on reproductive behavior and brain androgen receptor (AR) immunoreactivity was compared in juvenile and adult male Syrian hamsters. Prepubertal and adult animals were castrated and treated with 0, 500, or 1000 microg of DHT daily for 1 week and then tested for their ability to engage in mating behavior. The 1000-microg dose of DHT activated intromissions in adult but not prepubertal males. Brains were collected immediately after the behavioral test to investigate whether the lack of a behavioral response to DHT prior to puberty is associated with fewer AR-immunoreactive (AR-ir) cells in the forebrain nuclei that mediate male sexual behavior. In four of the five nuclei within the behavioral circuit that were examined, the number of AR-containing cells was similar in prepubertal and adult males treated with 1000 microg of DHT. Only in the anterior medial amygdala (MeA) was there a greater number of AR-ir cells in adults. These data indicate that (1) DHT does not activate components of male reproductive behavior prior to puberty and (2) the lack of behavioral responsiveness to DHT in prepubertal males is most likely not related to an overall reduction in ARs within the forebrain circuit that mediates mating behavior.

Aging↗
PubMed1997

Sex differences in the vomeronasal system.

In the early eighties we found sex differences in the vomeronasal organ (VNO) and hypothesized that the vomeronasal system (VNS), a complex neural network involved in the control of reproductive behavior, might be sexually dimorphic. At that time sex differences had already been described for some structures that receive VNO input, such as the medial amygdala, the medial preoptic area, the ventromedial hypothalamic nucleus, and the ventral region of the premammillary nucleus. Since then, we have shown sex differences in the accessory olfactory bulb (AOB), the bed nucleus of the accessory olfactory tract (BAOT), and the bed nucleus of the stria terminalis (BST). When new VNS connections were found, all of them ended in nuclei that present sex differences. In general, sex differences in the olfactory system show two morphological patterns: one in which males present greater morphological measures than females, and just the opposite. To explain the morphometric measures of males in the latter, it has been hypothesized that androgens serve as inhibitors. Our work on the involvement of the GABA(A) receptor in the development of AOB and maternal behavior sex differences also suggests that neonatal changes in neuronal membrane permeability to the ion Cl- differences. This might be the first animal model to help us to understand the situation in which human genetic and gonadal sex do not agree with brain and behavioral sex. Finally, we stress that sex differences in the VNS constitute a neurofunctional model for understanding sex differences in reproductive behaviors.

Animals↗
PubMed2000

Estrogens, brain and behavior: studies in fundamental neurobiology and observations related to women's health.

Mechanisms and consequences of the effects of estrogen on the brain have been studied both at the fundamental level and with therapeutic applications in mind. Estrogenic hormones binding in particular neurons in a limbic-hypothalamic system and their effects on the electrophysiology and molecular biology of medial hypothalamic neurons were central in establishing the first circuit for a mammalian behavior, the female-typical mating behavior, lordosis. Notably, the ability of estradiol to facilitate transcription from six genes whose products are important for lordosis behavior proved that hormones can turn on genes in specific neurons at specific times, with sensible behavioral consequences. The use of a gene knockout for estrogen receptor alpha (ERalpha) revealed that homozygous mutant females simply would not do lordosis behavior and instead were extremely aggressive, thus identifying a specific gene as essential for a mammalian social behavior. In dramatic contrast, ERbeta knockout females can exhibit normal lordosis behavior. With the understanding, in considerable mechanistic detail, of how the behavior is produced, now we are also studying brain mechanisms for the biologically adaptive influences which constrain reproductive behavior. With respect to cold temperatures and other environmental or metabolic circumstances which are not consistent with successful reproduction, we are interested in thyroid hormone effects in the brain. Competitive relations between two types of transcription factors - thyroid hormone receptors and estrogen receptors have the potential of subserving the blocking effects of inappropriate environmental circumstances on female reproductive behaviors. TRs can compete with ERalpha both for DNA binding to consensus and physiological EREs and for nuclear coactivators. In the presence of both TRs and ERs, in transfection studies, thyroid hormone coadministration can reduce estrogen-stimulated transcription. These competitive relations apparently have behavioral consequences, as thyroid hormones will reduce lordosis, and a TRbeta gene knockout will increase it. In sum, we not only know several genes that participate in the selective control of this sex behavior, but also, for two genes, we know the causal routes. Estrogenic hormones are also the foci of widespread attention for their potential therapeutic effects improving, for example, certain aspects of mood and cognition. The former has an efficient animal analog, demonstrated by the positive effects of estrogen in the Porsolt forced swim test. The latter almost certainly depends upon trophic actions of estrogen on several fundamental features of nerve cell survival and growth. The hypothesis is raised that the synaptic effects of estrogens are secondary to the trophic actions of this type of hormone in the nucleus and nerve cell body.

Affect↗
PubMed2005

Maternal education and child nutritional status in Bolivia: finding the links.

This study models various pathways linking maternal education and child nutritional status in Bolivia, using a national sample of children. Pathways examined include socioeconomic status, health knowledge, modern attitudes towards health care, female autonomy, and reproductive behavior. The data come from the 1998 Bolivia Demographic and Health Survey. Logistic regression results suggest that socioeconomic factors are the most important pathways linking maternal education and child nutritional status, and that modern attitudes about health care also explain the impact of education. Health care knowledge accounts for less of the effect of maternal education on child nutritional status, with autonomy being the weakest pathway. Other pathways, such as reproductive behaviors, appear to influence nutritional status independent of maternal education. Overall, the pathways examined accounted for 60 percent of the effect of maternal education on child nutritional status.

Adolescent↗
PubMed1999

Interactions between behavior and plasma steroids within the scramble mating system of the promiscuous green turtle, Chelonia mydas.

We measured plasma androgen (combined testosterone and 5alpha-dihydrotestosterone) (A) and corticosterone (B) in the promiscuous green turtle (Chelonia mydas) during courtship in the southern Great Barrier Reef. This study examined if reproductive behaviors and intermale aggression induced behavioral androgen and adrenocortical responses in reproductively active male and female green turtles. Associations between reproductive behavior and plasma steroids were investigated in green turtles across the population and within individuals. Levels across a range of both asocial and social behaviors were compared including (a) free swimming behavior; (b) initial courtship interactions; (c) mounted behavior (male and female turtles involved in copulatory activities); (d) intermale aggression (rival males that physically competed with another male turtle or mounted males recipient to these aggressive interactions); and (e) extensive courtship damage (male turtles that had accumulated excessive courtship damage from rival males). Behavioral androgen responses were detected in male turtles, in that plasma A was observed to increase with both attendant and mounted behavior. Male turtles who had been subjected to intermale aggression or who had accumulated severe courtship damage exhibited significantly lower plasma A than their respective controls. No pronounced adrenocortical response was observed after either intermale aggression or accumulation of extensive courtship damage. Female turtles exhibited a significant increase in plasma B during swimming versus mounted behavior, but no change in plasma A. We discuss our results in terms of how scramble polygamy might influence behavioral androgen interactions differently from more typical combative and territorial forms of male polygamy.

Aggression↗