Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Reproductive Behavior”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed1989

Serum 11-ketotestosterone and testosterone concentrations associated with reproduction in male bluegill (Lepomis macrochirus: Centrarchidae).

Male bluegill (Lepomis macrochirus) display a complex reproductive behavior involving two alternative life history pathways: delay of sexual maturation to become "parentals" or precocious maturation as "cuckolders." The purpose of our study was to investigate the association of two androgens, 11-ketotestosterone (11KT) and testosterone (T), with reproduction in these two types of males. Radioimmunoassay techniques were used to measure daily levels of the two androgens in the blood serum of parental male bluegill captured during the prespawning, spawning, and nesting periods throughout the reproductive season. Dramatic changes in the levels of 11KT and T were observed among parental males during these periods. Peaks occurred at the onset of spawning activity during each breeding bout. Compared to spawning parental males, spawning cuckolder males had significantly lower serum levels of 11KT. In contrast, the serum levels of T among parental and cuckolder males were not significantly different. These findings suggest that the elevated levels of 11KT are associated with the behaviors displayed by spawning parental males. The levels of T, however, seem to be associated with the occurrence of a phenomenon common to both parental and cuckolder males, such as development of gonads and/or spermiation.

Animals↗
PubMed1990

Copulatory behavior is controlled by the sexually dimorphic nucleus of the quail POA.

The medial preoptic nucleus (POM) of the quail preoptic area is sexually dimorphic and testosterone sensitive. Stereotaxic implantation of needles filled with crystalline testosterone demonstrated that the POM is a critical site of steroid action in the control of copulatory behavior. Only implants located in the POM reliably restored the behavior in castrated birds. Implants around the nucleus weakly activated the behavior; those which were distant by more than 200 microns were totally inactive. Electrolytic lesions confirmed the role of the POM in the control of copulatory behavior. The percentage of the POM which was lesioned was highly correlated to the behavioral deficit while the absolute size of the lesion was not. Electrolytic lesions in or around POM also significantly decreased the volume of the nucleus suggesting that the afferents and efferents of the nucleus are required for its full development. The total volume of the POM was correlated with the sexual behavior of the birds. The morphological changes in POM observed following exposure to testosterone probably represent the signature of the behavioral effects of the steroid. The sexually dimorphic testosterone-sensitive POM is therefore an excellent animal model to study the brain-steroid interactions which mediate the activation of male reproductive behavior.

Animals↗
PubMed1986

Effects of testosterone, estradiol, and temperature on neurons in preoptic tissue slices.

Thermosensitive preoptic neurons have been implicated in the regulation of body temperature. Testosterone- and estrogen-sensitive preoptic neurons have been implicated in reproductive behavioral and endocrine responses. In this study, rat preoptic tissue slices were used to examine the specificity of these neurons by determining their individual firing rate responses to both temperature and reproductive steroids. Of the 180 neurons classified according to thermosensitivity, 37% were warm sensitive, 8% were cold sensitive, and 55% were temperature insensitive. Ninety-three neurons were tested for their responses to perfusion media containing either testosterone or estradiol (30 pg/ml). Of the cells tested with both steroids, testosterone or estradiol affected half of the thermosensitive neurons and one-third of the temperature-insensitive neurons. This indicates that the population of temperature-insensitive neurons does not contain the majority of the steroid-sensitive neurons. There was much specificity, however, between the two types of steroid-sensitive neurons; testosterone and estradiol rarely affected the same neuron. Although these findings do not indicate a strong specificity between thermosensitive and steroid-sensitive neurons, they do support previous studies suggesting interactions between thermoregulatory and reproductive systems.

Action Potentials↗
PubMed2006

Complicity or conflict over sexual cannibalism? Male risk taking in the praying mantis Tenodera aridifolia sinensis.

Male complicity versus conflict over sexual cannibalism in mantids remains extremely controversial, yet few studies have attempted to establish a causal relationship between risk of cannibalism and male reproductive behavior. We studied male risk-taking behavior in the praying mantid Tenodera aridifolia sinensis by altering the risk imposed by females and measuring changes in male behavior. We show that males were less likely to approach hungrier, more rapacious females, and when they did approach, they moved more slowly, courted with greater intensity, and mounted from a greater distance. Similarly, when forced to approach females head-on, within better view and better reach of females, males also approached more slowly and courted with greater intensity. Thus, males behaved in a manner clearly indicative of risk avoidance, and we support the hypothesis of sexual conflict over sexual cannibalism.

Animals↗
PubMed2005

Reproductive emergencies.

The emergency clinician is frequently called on to manage problems relating to the female reproductive tract. Because owners sel-dom have the medical knowledge needed to differentiate normal from abnormal reproductive behaviors, they frequently look to the emergency veterinarian for guidance and information during and after parturition. For this reason, it is essential that the veterinarian have a good understanding of the normal reproductive cycle as well as the common emergencies that may occur. This article reviews the events surrounding normal parturition in the dog and cat and the reproductive emergencies seen most commonly in practice.

Animals↗
PubMed2004

Characterization of a peptide from skin secretions of male specimens of the frog, Leptodactylus fallax that stimulates aggression in male frogs.

During the breeding season of the mountain chicken frog Leptodactylus fallax, fighting between males results in the emergence of dominant animals that subsequently attract females to nesting sites. A peptide, termed Leptodactylus aggression-stimulating peptide (LASP), was isolated from norepinephrine-stimulated skin secretions from male specimens of L. fallax that was not present in skin secretions obtained from females. The primary structure of the peptide was established as: Gly-Leu-Trp-Asp-Asp-Leu-Lys-Ala-Ala-Ala-Lys-Lys-Val-Val-Ser-Ser-Leu-Ala-Ser-Ala-Ala-Ile-Glu-Lys-Leu NH2. LASP had no pheromone-like action on females but had a chemoattractive effect on males and stimulated aggressive behaviors, such as rearing and leaping. It is suggested that this peptide may play an important role in initiating the competitive male-male interactions that are associated with the onset of reproductive behavior in L. fallax.

Aggression↗
PubMed1999

Seasonal plasticity of neuromuscular junctions in adult male Siberian hamsters (Phodopus sungorus).

Transfer of adult Siberian hamsters, Phodopus sungorus, from long day (16 h light and 8 h dark; 16L:8D) to short day (8L:16D) photoperiods induces an involution of the gonads and a cessation of reproductive behavior 8-10 weeks later. The motoneurons of the spinal nucleus of the bulbocavernosus and their target muscles, the bulbocavernosus and the levator ani, are sexually dimorphic and are necessary for successful reproduction by male mammals. We demonstrate that after transfer of adult male Siberian hamsters to short photoperiods, the bulbocavernosus motoneurons, their target muscles and neuromuscular junctions are all significantly smaller than those of males that remain under long day conditions. Photoperiod also affected the number of active zones within each neuromuscular junction, an apparent remodeling of these synapses. Thus, this neuromuscular system of adult Siberian hamsters demonstrates considerable seasonal plasticity in response to changes in photoperiod.

Animals↗
PubMed1998

Environmental toxicants and female reproduction.

OBJECTIVE: To review current knowledge on the potential effects of environmental toxicants on female reproduction in laboratory animals, wildlife, and humans. DESIGN: Published literature about the effects of endocrine disruptors, heavy metals, solvents, pesticides, plastics, industrial chemicals, and cigarette smoke on female reproduction. RESULT(S): Published data indicate that chemical exposures may cause alterations in reproductive behavior and contribute to subfecundity, infertility, pregnancy loss, growth retardation, intrauterine fetal demise, birth defect, and ovarian failure in laboratory animals and wildlife. Data on the association of chemical exposures and adverse reproductive outcomes in humans are equivocal and often controversial. Some studies indicate that chemical exposures are associated with infertility, spontaneous abortion, or reproductive cancer in women. In contrast, other studies indicate that there is no association between chemical exposures and adverse reproductive outcomes. The reasons for ambiguous findings in human studies are unknown but likely include the fact that many studies are limited by multiple confounders, inadequate methodology, inappropriate endpoints, and small sample size. The mechanism by which chemicals alter reproductive function in all species is complex and may involve hormonal and/or immune disruption, DNA adduct formation, altered cellular proliferation, or inappropriate cellular death. CONCLUSION(S): Studies are needed to clarify which toxicants affect human reproduction and by which mechanisms of action. Furthermore, methods should be developed to minimize exposure to known reproductive toxicants such as dioxins and cigarette smoke.

Environmental Exposure↗
PubMed1979

[Is increase of the population a moral value? [author's transl)].

There is no complementary action of the partial competition between economic, demographic and rational factors in free capitalistic societies. Natural increase of the population means an increase of economic and cultural vitality for a state but can also mean a weakening. Increase of the population is in itself no normal value. Modern technology has forced man into a new life cycle by confronting him with ecologic, economic, and demographic limits to growth. Man reacts by decreasing the birth rate or by discontinuing procreation completely. The responsibility for the reproductive behavior can only be taken over by the state as long as this responsibility is in agreement with the private interest of the person. Demographic and social politics should nd. In questions of reproductive behaviour the decision of the individual and his possibility for individual action should be supreme.

Germany, West↗
PubMed2000

Region-specific regulation of cytochrome P450 aromatase messenger ribonucleic acid by androgen in brains of male rhesus monkeys.

We demonstrated previously that testosterone regulates aromatase activity in the anterior/dorsolateral hypothalamus of male rhesus macaques. To determine the level of the androgen effect, we developed a ribonuclease protection assay to study the effects of testosterone or dihydrotestosterone (DHT) on aromatase (P450(AROM)) mRNA in selected brain areas. Adult male rhesus monkeys were treated with testosterone or DHT. Steroids in serum were quantified by RIA. Fourteen brain regions were analyzed for P450(AROM) mRNA. Significant elevations of its message over controls (P<0.05) were found in the medial preoptic area/anterior hypothalamus of both androgen treatment groups and the medial basal hypothalamus of the testosterone-treated males. Other brain areas were not affected by androgen treatment. We conclude that testosterone and DHT regulate P450(AROM) mRNA in brain regions that mediate reproductive behaviors and gonadotropin release. The P450(AROM) mRNA of other brain areas is not androgen dependent. Brain-derived estrogens may also be important for maintaining neural circuitry in brain areas not related to reproduction. The control of P450(AROM) mRNA in these areas may differ from what we report here, but it is equally important to understand the function of in situ estrogen formation in these areas.

Androgens↗
PubMed1997

Distinct promoter sequences of two precursor genes for salmon gonadotropin-releasing hormone in masu salmon.

Two types of genes encode salmon gonadotropin-releasing hormone (sGnRH), which is thought to act on both sexual maturation and reproductive behavior, in salmonids. We characterized the two sGnRH genes (sGnRH-I and -II) and their upstream regions in masu salmon, Oncorhynchus masou, since such information is a prerequisite for molecular approaches to salmon reproduction. The two genes have similar exon-intron structures composed of four exons and three introns. Sequence analyses of the two genes showed that coding regions are highly conserved, but upstream regions are distinctively divergent. In the upstream regions, only the sGnRH-II gene has a large palindromic sequence, which has been proposed to be involved in control of transcription via estrogen receptors. In contrast, the sGnRH-I gene is missing the large palindromic sequence, but has three distinct palindromes in the upstream region. These results may suggest divergent transcription regulatory mechanisms between the two sGnRH genes in masu salmon. The differences in the upstream regions of sGnRH genes in Atlantic salmon (Salmo salar), sockeye salmon (Oncorhynchus nerka) and masu salmon are discussed with respect to the evolution of sGnRH genes in salmonid fish.

Animals↗
PubMed1996

Courtship behavior and plasma levels of androgens and corticosterone in male marbled salamanders, Ambystoma opacum (ambystomatidae).

We measured plasma levels of testosterone, dihydrotestosterone (DHT), and corticosterone for male marbled salamanders (Ambystoma opacum) collected during the breeding season. Our goal was to ascertain whether steroid levels changed in response to particular reproductive behaviors or laboratory confinement. Six groups of salamanders were examined: (a) MIGRATING, males migrating toward the pond basin during the breeding season; (b) LABORATORY, males kept under confined conditions in the laboratory for 10 days; (c) LAB-FIELD, laboratory males that were later released into seminatural enclosures in the field; (d) COURTING, males from male-female pairs in which the male actively courted the female (and deposited at least one spermatophore); (e) SOLO, males that were individually isolated from conspecifics; and (f) MALE-MALE, males that were placed together in pairs, and in which one male actively courted the other male. In three groups (COURTING, SOLO, and MALE-MALE), salamanders were placed in containers for observation and each male was observed for at least 2 hr prior to a plasma sample being taken. Circulating levels of testosterone, DHT, and corticosterone did not differ significantly for males in these groups. The similarity of androgen levels among the three groups indicated a lack of behaviorally evoked change under experimental conditions designed to reveal a behavior-androgen response. Male A. opacum differ taxonomically from other amphibians showing a behavior-androgen response (three species of toads in the genus Bufo) and also lack amplexus and male-male combat during competition for mates. The effects of confinement were indicated by levels of testosterone and DHT in LABORATORY males that were significantly lower than average levels of males in the following groups: MIGRATING, LAB-FIELD, and MALE-MALE. We inferred that LAB-FIELD males, following their release to seminatural enclosures, were able to regain plasma androgen levels typical of migrating males. This increase is one of very few demonstrations for amphibians of an increase in androgen levels upon release from laboratory confinement. Levels of corticosterone did not differ significantly between males that were active in the field and males that were kept in the laboratory. The similarity of corticosterone levels among these groups differs from the typical pattern of elevated corticosterone and depressed androgen levels in captive amphibians. Maximal corticosterone levels in breeding male A. opacum may act differently than in other species in which chronic elevations inhibit the pituitary-gonadal axis.

Ambystoma↗
PubMedDate not supplied

Age-specific mortality costs of exposure to inbred Drosophila melanogaster in relation to longevity selection.

This article address the hypotheses that selection for early- or late-life fitness changes patterns of reproductive behavior, that this behavior may be dependent on the genetic makeup of the females, and that patterns of male mortality are strongly dependent on the type of females to which they are exposed. Flies selected for late-life reproduction and their associated stocks selected for early reproduction were exposed to flies of the opposite sex from either the same stock or a highly inbred stock. Males of both long- and short-lived stocks showed an increase in early mortality when exposed to inbred females. In addition, when males were exposed to inbred females early in life they showed a lower age-specific mortality rate late in life than males exposed to females from their own stock. Interestingly, females exposed to inbred males showed a significant reduction in mean longevity. Analysis of age-specific mortality revealed that this reduction was brought about as a result of increased early mortality. Interpretation of the results from an analysis of mean longevity not only fails to identify important information--as shown from a demographic analysis of age-specific mortality--but also presents a misleading description of mortality costs.

Animals↗
PubMed2002

Estradiol induces hypothalamic progesterone receptors but does not activate mating behavior in male hamsters (Mesocricetus auratus) before puberty.

This study investigated pubertal changes in neural and behavioral responses to estradiol. Gonadectomized pre- and postpubertal male hamsters (Mesocricetus auratus) were treated with 0.00, 0.05, 0.10, or 0.25 mg estradiol and tested 1 week later for sexual behavior with a receptive female. Estradiol activated behavior in postpubertal, but not prepubertal, males. In contrast, estrogen receptor alpha (ERalpha) and progesterone receptor (PR) immunoreactivity in forebrain nuclei that mediate mating behavior was similar in pre- and postpubertal males. Thus, absence of a behavioral response before puberty is not associated with reduced levels of steroid receptors. Because estradiol induced PR in prepubertal males, these data also suggest that ERa is functional before puberty. Therefore, gonadal steroids facilitate male reproductive behavior only after as-yet-unidentified developmental processes occur during puberty.

Animals↗
PubMed1990

Personality development in the evolutionary perspective.

A relationship between personality processes and evolution can be seen when behaviors associated with sexual maturation, mating, and parenting are examined. This article stipulates the types of proximal cues implicated in the shaping of personality variables that become important in the development of the individual's reproductive behavior.

Biological Evolution↗
PubMed1996

5-Methoxytryptophol and melatonin in children: differences due to age and sex.

It seems clear that the pineal hormone, melatonin (N-acetyl-5-methoxytryptamine), is involved in the reproductive behavior of several animal species including humans. Moreover, several data also support a role for 5-methoxytryptophol (ML), another pineal hormone, in the control of sexual processes. To test the role of ML in human reproductive axis, 128 healthy children, 68 boys and 60 girls, were studied. Each of these groups was divided in three age subgroups of 6, 11, and 14 years. A single blood sample (0900 hours) was obtained from each subject to determine melatonin, ML, FSH, LH, estradiol (girls), and testoterone (boys) by RIA. Statistical analysis of the data included ANOVA-II (factor I: age, factor II: sex) and an analysis of covariance with age as covariate. A similar plasma melatonin concentration, with a significant decrease between 6 and 11 years, was found in boys and girls. Melatonin concentrations correlate well with initiation of the pubertal development in these children, although no sex differences were found. Concentrations of ML are approximately 50% of those of melatonin. In contrast to melatonin, ML levels show significant age and sex differences. Plasma ML concentration significantly increased in boys (P < 0.001) and decreased in girls (P < 0.001) after 8 years of age. These results support the hypothesis that, besides melatonin, other pineal compounds such as ML may be involved in the maturation process in humans. The pineal indole ML may also be used as a marker of the different chronobiology in the pubertal development in boys and girls.

Adolescent↗
PubMed1994

GnRH cell size and number in a teleost fish with two male reproductive morphs: sexual maturation, final sexual status and body size allometry.

Gonadotropin releasing hormone-like immunoreactive (GnRH-ir) cells in both the ganglion of the terminal nerve (TN) and the preoptic area (POA) have been implicated in the development and maintenance of reproductive behavior and physiology in teleost fishes. One marine species, the plainfin midshipman, Porichthys notatus, exhibits two sexually mature male morphs (types I and II) which differ with respect to size at sexual maturation, gonad/body weight index, reproductive tactic and vocal motor traits. Type II males become reproductively active at a smaller body size than either females or type I males. Immunocytochemical techniques and quantitative analyses were used here to determine the size and number of GnRH-ir cells in the TN and POA amongst field collected juveniles, sexually mature females, and type I and II males. Mean GnRH-ir cell size and number in the TN did not vary across the entire range of specimens. However, mean GnRH-ir cell size and number in the POA were 50-100% greater in sexually mature adults compared to juveniles. Analyses of covariance indicated that increases in cell number, but not cell size, could be explained solely on the basis of changes in body size. However, regression analyses showed that body size had a significant influence on increasing cell number only in the juvenile-type I male transition and the juvenile-female transition, not in the juvenile-type II male transition. The latter suggests that type II males, unlike the other adult morphs, have 'escaped' from a body size constraint imposed on increasing GnRH-ir cell number in the POA. There were also significant differences among the adult morphs in the size of GnRH-ir POA cells that could not be explained on the basis of differences in body size but, rather, appear to reflect differences in the temporal onset of sexual maturation. Together, the data suggest that the timing of changes in POA phenotype may provide a proximate mechanism permitting the development of alternative male reproductive morphs.

Animals↗
PubMed2000

Sexual swellings in female hamadryas baboons after male take-overs: "deceptive" swellings as a possible female counter-strategy against infanticide.

In many primate species, male intanticide is assumed to pose a serious risk for infants, and therefore female counter-strategies are expected. These counter-strategies may include changes in the females' reproductive behavior and physiology, e.g., mating with multiple males and prolonged receptivity. Since the risk of infanticide is particularly high when a new male enters the group or when a male rises in rank, we studied the changes in female reproductive conditions, e.g., post-partum amenorrhea and interbirth intervals, following group take-overs by new males in a captive group of hamadryas baboons (Papio h. hamadryas). Following take-overs, five out of six lactating females immediately developed sexual swellings, thus shortening their post-partum amenorrhea. However, none of these females conceived during the first cycles after the take-over, their reproduction was not accelerated, and four out of five dependent infants survived. Thus, interbirth intervals did not decrease compared to times with no group take-overs. We therefore suggest that these situation-dependent swellings are used by female hamadryas baboons as a counter-strategy to reduce the risk of infanticide, which exists in this species after male take-overs. By offering new males mating opportunities without allowing them to reproduce, females may increase their infants' probability of survival and at the same time avoid the costs of being pregnant and lactating simultaneously.

Animals↗