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At least 991 records · Page 55Linked to original sources
PubMed1995

The loss of female sex pheromone after mating in the corn earworm moth Helicoverpa zea: identification of a male pheromonostatic peptide.

Female moths often become depleted of sex pheromone after mating as the various components of virgin behavior are switched off. In examining a potential male contribution to these events in the corn earworm moth Helicoverpa zea, we have characterized a basic polypeptide from the tissues producing (accessory glands) and storing (duplex) the seminal fluids. The peptide evokes the depletion of sex pheromone when injected into virgin females. This pheromonostatic peptide (PSP) is 57 amino acids long and contains a single disulfide bridge. It is blocked at the N terminus with pyroglutamate and at the C terminus by amidation. As little as 23 ng of peptide evokes the near-complete depletion of pheromone in decapitated (neck-ligated) females that had been injected with pheromone biosynthesis-activating neuropeptide. Activity is approximately 15-fold less in intact virgins, showing that the head limits the expression of activity in these injected females. Females mated to surgically impaired males, capable of producing a spermatophore but not transferring spermatozoa or seminal fluids, are depleted of pheromone by injected peptide. Females whose abdominal nerve cords have been severed are not depleted of pheromone after mating. Thus, neural signals either descending or ascending via the nerve cord are required for the depletion of pheromone after mating. PSP, from the seminal fluids, may participate in this process by direct or indirect action on the glandular tissue; if so, it represents an unusual mechanism in insects for the regulation by seminal fluids of postmating reproductive behavior.

Amino Acid Sequence↗
PubMed2006

Plasticity in the expression of the steroid receptor coactivator 1 in the Japanese quail brain: effect of sex, testosterone, stress and time of the day.

Analysis of nuclear receptor action on the eukaryotic genome highlights the importance of coactivators on gene transcription. The steroid receptor coactivator-1 in particular is the focus of an intense research and physiological or behavioral studies have confirmed that it plays a major role in the modulation of steroid and thyroid receptors activity. However, little is known about the regulation of steroid receptor coactivator-1 expression the brain. The goal of this study was to determine the potential factors modulating steroid receptor coactivator-1 synthesis in Japanese quail by quantification of its mRNA with real time quantitative polymerase chain reaction and of the corresponding protein via Western blotting. Contrary to previously published results from our laboratory [Charlier TD, Lakaye B, Ball GF, Balthazart J (2002) The steroid receptor coactivator SRC-1 exhibits high expression in steroid-sensitive brain areas regulating reproductive behaviors in the quail brain. Neuroendocrinology 76:297-315], we found here that sexually mature females had a higher concentration of steroid receptor coactivator-1 in the preoptic area/hypothalamus compared with males. Steroid receptor coactivator-1 expression in the male preoptic area/hypothalamus was up-regulated by testosterone and tended to be decreased by stress. We also identified a significant correlation between the time of the day and the expression of the coactivator in the optic lobes, hippocampus, telencephalon and hindbrain but the pattern of changes in expression as a function of the time of the day varied from one brain area to another. Together, these data support the idea that steroid receptor coactivator-1 is not constitutively expressed but rather is finely regulated by steroids, stress and possibly other unidentified factors.

Animals↗
PubMed2004

Induced ovulation and egg deposition in the direct developing anuran Eleutherodactylus coqui.

This study investigates ovulation and egg deposition behaviors in the anuran Eleutherodactylus coqui from Puerto Rico in response to stimulation with gonadotropin and gonadotropin releasing hormones. Five hormones were tested by injection over a range of doses, including mammalian LHRH, avian LHRH, fish LHRH, D-Ala6, des-Gly10 ethylamide LHRH and hCG. We report a low level of ovulation and egg deposition in response to all hormones, with the most complete and consistent results from the non-natural D-Ala6, des-Gly10 ethylamide LHRH derivative. To confirm the viability of eggs produced in this manner we performed in vitro fertilization experiments that resulted in the development of normal frogs. Reproductive behaviors in E. coqui are apparently not controlled by a mammalian form of LHRH as reported in other common laboratory anuran species. D-Ala6, des-Gly10 ethylamide LHRH induces ovulation and deposition of mature and fertilizable eggs in E. coqui.

Animals↗
PubMed1999

Reproductive health risk behavior survey of Colombian high school students.

PURPOSE: To establish rates of potentially risky sexual behaviors among Colombian adolescent students. METHODS: A total of 230 9th and 11th graders at a Colombian high school (69% of enrolled students) were anonymously surveyed about selected reproductive health behaviors using the Centers for Disease Control and Prevention's self-administered Youth Risk Behavior Survey. RESULTS: The response rate was >90%. The group was demographically representative of students. Twenty-nine percent of the group had engaged in intercourse (13% of 9th and 43% of 11th graders). Male gender [beta = 0.7873; odds ratio (OR) = 2.09; 95% confidence interval (CI) = 1.57-3.08] and increasing age (beta = 0.3413; OR = 1.41; 95% CI = 1.02-1.93) were each significantly correlated with prior sexual activity. Compared with females, males initiated intercourse at a significantly earlier age (beta = 0.284; p < .001) but did not report significantly more partners (means 2.1 vs. 1.4; chi2 = 1.25; p = .262). Forty-eight percent of respondents used contraception during their last encounter. Sixty-three percent used oral contraceptives or condoms, while the remainder used less effective methods. Contraceptive use did not correlate with gender or age. Age was significantly and positively correlated with use of alcohol prior to sexual activity (B = 1.28; OR = 3.6; 95% CI = 1.49-8.44). CONCLUSIONS: Compared with U.S. populations of similar ages, the Colombian group surveyed had fewer sexually active members, reported fewer partners, and used contraception with lower frequency.

Adolescent↗
PubMed2001

Identification and synthesis of male-produced sex pheromone components of the stink bugs Chlorochroa ligata and Chlorochroa uhleri.

The reproductive behaviors of the stink bugs Chlorochroa ligata and C. uhleri were studied in the laboratory. Adults of both species became sexually mature about 12-14 days after the final molt, and both sexes mated multiple times during their lifetimes. The mean duration of copulation was 54 +/- 24 min for virgin bugs and 46 +/- 33 min for experienced bugs for C. ligata and 78 +/- 55 min for field-collected C. uhleri of unknown mating status. Male C. ligata were found to transfer a significant fraction of their body mass (19%) to females during mating. Sexually mature C. uhleri males produced three sex-specific compounds, methyl (R)-3-(E)-6-2,3-dihydrofarnesoate, methyl (2E,6E)-farnesoate, and methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate, in a ratio of 100:0.9:0.6. These three compounds were also produced by sexually mature male C. ligata in a ratio of 100:0.5:0.4. Identifications of the compounds were confirmed by synthesis. Production of the male-specific compounds peaked in late afternoon to early evening, coincident with the peak period of reproductive activity. Laboratory and field bioassays demonstrated that female bugs were attracted to odors from live males and to reconstructed blends of the male-specific compounds.

Animals↗
PubMed2006

Neurons containing tuberoinfundibular peptide of 39 residues are activated following male sexual behavior.

Tuberoinfundibular peptide of 39 residues (TIP39)-immunoreactive (IR) neurons are present in the medial subdivision of the parvocellular subparafascicular thalamic nucleus (mSPFp) where ejaculation-specific Fos expression is localized. The mSPFp is reciprocally connected to the medial preoptic area (MPOA), bed nucleus of the stria terminalis (BNST) and the medial nucleus of the amygdala (Me), all of which are critical for the regulation of male sexual behavior. The mSPFp also receives galanin and enkephalin containing projections from a region in the lumbar spinal cord, thought to be a central ejaculation center. Therefore, we hypothesized that TIP39 neurons in the mSPFp may be part of the neuronal circuitry activated by male sexual behavior. To test this hypothesis, we examined induction of Fos in TIP39 containing neurons in the mSPFp following male sexual behavior. Mating-induced Fos expression was evaluated in sexually experienced male rats under four experimental conditions: animals that (1) remained in their home cage without any interaction with females, (2) interacted with stimulus females and displayed intromission without ejaculation, (3) displayed one ejaculation, or (4) displayed 2 ejaculations. We found that Fos was induced in TIP39-IR neurons in the mSPFp in male rats following ejaculation but much less so following intromission without ejaculation. This suggests that TIP39-IR neurons in the mSPFp are part of the afferent circuits that process genital-somatosensory information related to ejaculation, and which contribute to mating and mating-induced changes in reproductive behavior.

Amygdala↗
PubMed2006

Female odors stimulate CART neurons in the ventral premammillary nucleus of male rats.

Olfactory information is known to influence both male and female sexual behavior. Chemosensory compounds known as pheromones activate distinct brain pathways, inducing innate and stereotyped behaviors, as well as hormonal changes. Studies have shown that female odors induce Fos expression in various brain nuclei of conspecific males, including the ventral premammillary nucleus (PMV). Although poorly investigated, previous studies have suggested that the PMV plays a role in aggressive and sexual behavior. In this study, we used Fos protein expression as a marker for neurons responsive to female odors in sexual inexperienced male rats exposed to soiled bedding. We observed that female odors induced intense Fos immunoreactivity throughout the PMV. Most of these neurons also express cocaine- and amphetamine-regulated transcript (CART) immunoreactivity. In addition, we used in situ hybridization and observed that, following exposure to female odors, CART mRNA increased only in the ventral PMV. Our results suggest that female odors stimulate CART production in the PMV of inexperienced males. Considering that the PMV CART neurons also express the leptin receptor, as well as the fact that they project to areas related to reproduction, we hypothesize that PMV CART neurons integrate nutritional and environmental (olfactory) information, being apt to modulate male reproductive behavior.

Animals↗
PubMed2003

Brain mast cells are influenced by chemosensory cues associated with estrus induction in female prairie voles (Microtus ochrogaster).

Historically, the brain has been viewed as protected from the infiltration of peripheral hematopoietic cells by the blood-brain barrier. However, numerous immune cell types have been found in the central nervous system (CNS). Mast cells, granulocytic immune cells, are found in the CNS of birds and mammals and their numbers and location are influenced by both extrinsic and intrinsic factors, including reproductive behavior and endocrine status. The present study used female prairie voles (Microtus ochrogaster) to investigate the interactions between brain mast cells and stimuli associated with estrus induction. Unlike spontaneous ovulators such as rats and mice, female prairie voles are induced into estrus by chemosensory stimuli present in conspecific male urine. Prior to estrus induction, female voles have undetectable concentrations of estrogen that rise rapidly following exposure to a male or male urine. In the first experiment, we examined whether mast cells may be influenced by estrus induction. Female voles exposed to conspecific male urine had increased numbers of mast cells in the main olfactory bulbs and epithalamus (medial habenula), but not the thalamus or median eminence, relative to control groups. Next, to determine if this mast cell increase was the result of elevated estrogen concentrations, female voles were injected with estradiol or vehicle and brain mast cell numbers analyzed. No differences in brain mast cell numbers were observed between estradiol-injected and control females in any brain area investigated. Together, these results lend further support to the contention that mast cell numbers and/or distribution can be influenced by reproductively relevant stimuli and underscore the utility of this vole model for delineating the function of brain mast cells.

Animals↗
PubMed2002

Avian reproductive anatomy, physiology and endocrinology.

Although many environmental cues influence reproductive activity, the seasonal breeder responds most strongly to long day length. THE MALE BIRD: Testicular interstitial cells secrete testosterone, which influences reproductive behavior such as territorial aggression and song. Other changes observed in seasonal breeders include testicular hypertrophy and enlargement of the ductus deferens and seminal glomus. THE FEMALE BIRD: Early changes associated with rising estrogen levels in the hen include osteomyelosclerosis and hypercalcemia. Ovulation is then induced by LH, which is followed by eggshell calcification, which is under the control of progesterone. Sources of calcium for shell production include intestinal absorption from the diet, renal control of calcium levels, and mobilization of bone calcium stores. During oviposition, PGF2 alpha and vasotocin stimulate powerful uterine contractions [32] in the presence of calcium. Incubation is associated with falling LH levels and rising prolactin levels. If the hen actually enters reproductive quiescence at this time, then molt will follow. Molt is associated with the total regression of the reproductive tract.

Animals↗
PubMed1985

Evidence for peripeduncular neurons having a role in the control of feminine sexual behavior in the rat.

In order to test the hypothesis that peripeduncular nucleus (PPN) cells are essential for normal sexual behavior, synaptic blockade in the chronically implanted awake animal was attempted by means of the local injection of pentobarbital (PB) at a concentration which may interfere with synaptic transmission without affecting conduction in fibers. Ovariectomized, female rats were chronically implanted with cannulae directed to the PPN or the dorsal midbrain. After adequate estrogen priming, rats were injected with 22 mM pentobarbital (PB) or artificial cerebrospinal fluid (ACSF). Seven min after PB injection in PPN lordosis quotient was significantly lowered, whereas PB in dorsal midbrain or ACSF in PPN had no effect. It is concluded that PPN neurons themselves may have a functional role in the control of lordosis and that loss of PPN neurons may account for impairment of reproductive behavior observed after lesions in the ventrolateral midbrain.

Animals↗
PubMed1998

Intraventricular injection of neuropeptide Y antisera curbs weight gain and feeding, and increases the display of sexual behaviors in obese Zucker female rats.

Obese Zucker rats are hyperphagic, overweight, and infertile. It has been postulated that neuropeptide Y (NPY) overproduction may contribute to obesity and infertility in these animals. To test this hypothesis, ovariectomized, adult obese Zucker rats were implanted with cannulae in the third ventricle and subsequently injected with NPY antisera or normal rabbit sera (NRS) 6, 4 and 2 h before experimental observation. Steroid-treated females injected with NPY antisera were significantly more receptive and were more likely to show proceptive behaviors than after treatment with NRS (e.g., lordosis quotient: NPY antisera, 65.5+/-6.9%; NRS, 30.9+/-11.6%, P < 0.02; 91% displaying proceptivity after NPY antisera injection vs. 36% after NRS, P < 0.03). Injection of NPY antisera also curbed food intake and weight gain (24 h food intake: NPY antisera, 10.5+/-2.1 g; NRS, 20.5+/-1.7 g, P < 0.01; 24 h weight gain: NPY antisera, -5.4+/-2.2 g; NRS, 5.8+/-0.7 g, P < 0.01). Locomotor activity was similar after NRS and NPY antisera treatment (P > 0.5) suggesting that general malaise was not responsible for the effects of NPY antisera on food intake or body weight. These data suggest that endogenous neuropeptide Y contributes to excessive feeding and weight gain, and suppressed reproductive behaviors in obese Zucker female rats.

Animals↗
PubMed1999

A pilot study of mammographic density patterns among Japanese women.

Mammographic density patterns, which refer to the distribution of fat, connective, and epithelial tissue in the healthy female breast, have been shown to be related to breast cancer risk. We used a quantitative method to assess mammographic densities in 41 mammograms from women in Japan without a diagnosis of breast cancer. Information about reproductive behavior and family history for breast cancer was available from a questionnaire. The statistical analysis applied Spearman correlation coefficients and multiple linear regression. The breast size as measured on the cranio-caudal view of the mammogram was approximately 12% larger, the size of the dense areas was 20% smaller, and the mean percent mammographic densities were 30% greater among premenopausal than among postmenopausal women. We found a strong relation between age at menarche and mammographic densities in premenopausal women and significant associations for age, family history of breast cancer, and age at menopause with mammographic densities in postmenopausal women. These preliminary data will be used to plan a future study that will compare mammographic density patterns and the relative importance of dietary, reproductive, and anthropometric factors between women in Japan and in the United States.

Adult↗
PubMed2005

Organization of electrically and chemically evoked defensive behaviors within the deeper collicular layers as compared to the periaqueductal gray matter of the rat.

Stimulation of the periaqueductal gray matter (PAG) and the deeper layers of superior colliculus (SC) produces both freezing (tense immobility) and flight (trotting, galloping and jumping) behaviors along with exophthalmus (fully opened bulging eyes) and, less often, micturition and defecation. The topography of these behaviors within the distinct layers of SC remains unclear. Therefore, this study compared the defensive repertoire of intermediate (ILSC) and deep (DLSC) layers of SC to those of dorsolateral periaqueductal gray matter (DLPAG) and lateral periaqueductal gray matter (LPAG) [Neuroscience 125 (2004) 71]. Electrical stimulation was carried out through intensity- (0-70 microA) and frequency-varying (0-130 Hz) pulses. Chemical stimulation employed a slow microinfusion of N-methyl-d-aspartic acid (NMDA, 0-2.3 nmol, 0.5 nmol/min). Probability curves of intensity-, frequency- and NMDA-evoked behaviors, as well as the unbiased estimates of median stimuli, were obtained by threshold logistic analysis. Compared with the PAG, the most important differences were the lack of frequency-evoked jumping in both layers of SC and the lack of NMDA-evoked galloping in the ILSC. Moreover, although galloping and jumping were also elicited by NMDA stimulation of DLSC, effective doses were about three times higher than those of DLPAG, suggesting the spreading of the injectate to the latter structure. In contrast, exophthalmus, immobility and trotting were evoked throughout the tectum structures. However, whatever the response and kind of stimulus, the lowest thresholds were always found in the DLPAG and the highest ones in the ILSC. Besides, neither the appetitive, nor the offensive, muricide or male reproductive behaviors were produced by any kind of stimulus in the presence of appropriate targets. Accordingly, the present data suggest that the deeper layers of SC are most likely involved in the increased attentiveness (exophthalmus, immobility) or restlessness (trotting) behaviors that herald a full-blown flight reaction (galloping, jumping) mediated in the PAG.

Aggression↗
PubMed1991

Testosterone in MPOA elicits behavioral but not neuroendocrine responses in ferrets.

The amount of time male ferrets were engaged in neck gripping, mounting, and thrusting was quantified in 30-min tests with a receptive female before and after castration. Bilateral cannulae containing a total of approximately 2 mg testosterone propionate (TP) in cocoa butter were then stereotaxically aimed at the medial preoptic area (MPOA). Tests for sexual behavior were conducted on days 3, 7, 14, and 21 postimplantation. Ferrets were histologically categorized as either 1) Miss (implants not in MPOA), 2) Unilateral implant in MPOA, or 3) Bilateral implants in MPOA. The mean amount of time spent neck gripping, mounting, and thrusting increased significantly over castrate levels on postimplantation day 14 in the Bilateral group, but not in the Miss or Unilateral groups. In all groups, mean plasma testosterone concentrations were below or near the lower limit of detectability on the day before TP implantation and on postimplantation test days. In the same plasma samples, luteinizing hormone concentrations were within the normal range of castrated ferrets, and did not significantly decline after TP implantation. These results suggest that the MPOA is a neural site for androgen activation of certain components of reproductive behavior but not for negative feedback on gonadotropin secretion in male ferrets.

Animals↗
PubMed1998

Parasite manipulation of insect reproduction: who benefits?

Host fertility is often curtailed as a result of parasitic infection. The hypothesis that this may confer an adaptive advantage upon the symbionts if nutrients are directed from reproduction and made available for host/parasite maintenance is explored. The suggestion is made that an understanding of the mechanisms underlying the pathophysiology of fecundity reduction may shed light upon the evolutionary implications of this strategy for both parasite and host. To illustrate this the down-regulation of egg production is explored with reference to a particular model system, the association between metacestodes of the rat tapeworm, Hymenolepis diminuta and the mealworm beetle, Tenebrio molitor. Several aspects of host reproductive behavior and physiology are affected by infection in this association, including vitellogenesis. Metacestodes directly inhibit the fat body synthesis of vitellogenin in a stage-specific, density-dependent manner. This inhibition is likely to be orchestrated by a modulator molecule, produced by the parasite. In the ovarian follicles, juvenile hormone III binding to a specific follicular membrane-binding protein is inhibited in infected beetles, resulting in the down-regulation of a cascade of events which enables vitellogenin to pass into the developing oocyte. Data to support the proposed existence of a parasite-induced antigonadotrophin, of host origin, are discussed. Evidence that similar mechanisms operate in Plasmodium-infected anopheline mosquitoes and Onchocerca-infected blackflies is presented in support of the possibility that a parasite-induced reduction in host reproductive fitness is an adaptive strategy and an assessment of who is manipulating whom is made.

Animals↗
PubMed1990

Seasonal changes in and effect of castration/androgen replacement on the plasma levels of five androgens in the male three-spined stickleback, Gasterosteus aculeatus L.

The seasonal changes in plasma levels of the androgens 11-ketotestosterone (OT), testosterone (T), 11 beta-hydroxytestosterone (OHT), 11-ketoandrostenedione (OA), and 11 beta-hydroxyandrostenedione (OHA) were measured in the male three-spined stickleback (Gasterosteus aculeatus L). OT was the dominant plasma androgen in the breeding season in summer and was the only androgen that peaked during this period. The levels of OT correlated closely with the development of male secondary sexual characters and reproductive behavior. T and OHT were low in all seasons, whereas OHA and OA displayed the highest levels in early winter. During the postbreeding period, the time of active spermatogenesis, all measured steroids were low. Castration resulted in an almost complete loss of plasma OT and reduced T, whereas OHT, OHA, and OA were not reliably influenced. Androstenedione implants in castrated fish increased plasma T and OA implants increased plasma OT, suggesting a nontesticular site of conversion.

Androgens↗
PubMed2003

In vivo and in vitro assessment of the androgenic potential of a pulp and paper mill effluent.

The androgenic potential of a New Zealand pulp and paper mill effluent was measured by applying a combination of in vitro and in vivo bioassays with mosquitofish (Gambusia affinis) and goldfish (Carassius auratus). The in vivo method assessed the rate of gonopodial development (masculinization) and alterations from normal reproductive behavior in adult female mosquitofish exposed for 21 d to untreated or secondary-treated pulp mill effluent. A second in vivo mosquitofish exposure tested the effect of glass-fiber (type C) filtration of secondary-treated effluent on rates of expression of the same endpoints. Extractable organics analyses of effluents and extracts thereof were conducted. Mosquitofish demonstrated significant masculinization on exposure to either treated or untreated effluent; the frequency of gonopodial development was reduced with effluent secondary-treatment. Male mating behavior was observed in the masculinized adult females. Glass-fiber (type F) filtration of the treated effluent eliminated the masculinizing effect, suggesting that the bioactive compounds were associated with the suspended solids. The in vitro method measured the binding of compounds within a treated thermomechanical/bleached kraft effluent extract to androgen receptors contained in goldfish testis cytosol. Exposure to extracts of either the particulate (glass-fiber filtered) or the dissolved organic fraction of the effluent produced significant binding (as indicated by the displacement of radiolabeled testosterone) to the androgen receptor in goldfish gonadal tissue. Thus, the dissolved organics extract of the treated effluent contained compounds androgenic to goldfish in vitro but not to mosquitofish in vivo. The combined in vitro and in vivo data suggest that the effluent in question could exert effects on the reproductive physiology of fishes through an androgenic mechanism. The androgenic compounds androstenedione and testosterone were not detected in the extracts used for the in vitro component of this study.

Androgens↗
PubMed1987

Castration reversibly alters levels of cholecystokinin immunoreactivity within cells of three interconnected sexually dimorphic forebrain nuclei in the rat.

Three sexually dimorphic cell groups in the forebrain of the rat--the central part of the medial preoptic nucleus, the encapsulated part of the bed nucleus of the stria terminalis, and the posterodorsal part of the medial nucleus of the amygdala--are larger in males, contain a high density of gonadal-steroid-concentrating cells, and are thought to play important roles in the control of reproductive behavior and physiology. Since each of these regions contains a large number of cholecystokinin-immunoreactive cells, we used an indirect immunohistochemical method to examine the possibility that levels of this peptide are modulated by circulating gonadal steroids in adult male rats. Rats were castrated at 60 days of age, and one group each was pretreated with colchicine and then killed 3, 7, and 14 days after gonadectomy. Castration clearly decreased CCK immunoreactivity within cells of each region, with the most dramatic effects occurring 7 and 14 days after gonadectomy, and these effects were reversed by treatment with testosterone over a 14-day period. The results suggest that CCK levels within individual cells in each of the interconnected sexually dimorphic nuclei examined here are regulated by circulating gonadal steroids and may be related to the hormonal modulation of reproductive functions thought to be mediated by these cell groups.

Animals↗