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At least 1,531 records · Page 85Linked to original sources
PubMed1984

The effect of Aroclor 1254 (PCB) on the physiology of reproduction in the female rat--I.

Daily oral exposure of rats to 30 mg/kg of Aroclor 1254 for 1 month caused deleterious effects on the reproductive process, which were reflected in a decrease in the reproductive potential. The following disturbances were observed: prolongation of the estrous cycle; decrease in sexual receptivity; delay in timing of copulation; vaginal bleeding during gestation; decrease in litter size and delay in the time of parturition. The offspring, whether exposed to PCBs either prenatally and/or postnatally, showed a slower rate of body weight gain than controls. This was accompanied by high mortality until weaning of treated pups. Vaginal opening in the PCB-treated (as young) females occurred precociously, while other reproductive parameters were not affected at adulthood. Discontinuance of PCB treatment reversed the above symptoms.

Animals↗
PubMed1989

Sexual behavior suppresses the primary antibody response in the golden hamster.

The possibility that sexual behavior triggers neural or endocrine events that influence immune function was explored in male Golden Hamsters (Mesocricetus auratus). Sexually experienced males showed a 62.8 and 64.9% decrease in antibody response to TNP-ovalbumin compared to virgin and sham-mated males, respectively, as measured by ELISA. Antibody deficiency was associated with copulation on the day of immunization and was highly correlated with ejaculatory behavior and the incidence of prolonged intromissions, an indicator of sexual satiety. Although a single sexual encounter was not sufficient to inhibit antibody levels, prolonged intromissions were inversely correlated with titers. Changes in antibody production were not related to plasma levels of cortisol, corticosteroid-binding globulin activity, or testosterone. These results suggest that sexual behavior is immunosuppressive and may play a role in the communicability of sexually transmitted diseases.

Animals↗
PubMed2005

Methylation changes of H19 gene in sperms of X-irradiated mouse and maintenance in offspring.

The nature of imprinting is just differential methylation of imprinted genes. Unlike the non-imprinted genes, the methylation pattern of imprinted genes established during the period of gametogenesis remains unchangeable after fertilization and during embryo development. It implies that gametogenesis is the key stage for methylation pattern of imprinted genes. The imprinting interfered by exogenous factors during this stage could be inherited to offspring and cause genetic effect. Now many studies have proved that ionizing irradiation could disturb DNA methylation. Here we choose BALB/c mice as a research model and X-ray as interfering source to further clarify it. We discovered that the whole-body irradiation of X-ray to male BALB/c mice could influence the methylation pattern of H19 gene in sperms, which resulted in some cytosines of partial CpG islands in the imprinting control region could not transform to methylated cytosines. Furthermore, by copulating the interfered male mice with normal female, we analyzed the promoter methylation pattern of H19 in offspring fetal liver and compared the same to the pattern of male parent in sperms. We found that the majority of methylation changes in offspring liver were related to the ones in their parent sperms. Our data proved that the changes of the H19 gene methylation pattern interfered by X-ray irradiation could be transmitted and maintained in the first-generation offspring.

Animals↗
PubMed2004

Neural substrates for sexual and thermoregulatory behavior in the male leopard gecko, Eublepharis macularius.

The preoptic area-anterior hypothalamus (POAH) continuum is critical for the integration of environmental, physiological, and behavioral cues associated with reproduction in vertebrates. In the present study, radiofrequency lesions in the POAH abolished sexual behavior in the leopard gecko (Eublepharis macularius). Furthermore, results suggest a differential effect of POAH lesions on those behaviors regarded as appetitive (tail vibration and grip) and those regarded as consummatory (mounting and copulation), with consummatory behaviors being affected to a greater extent. E. macularius is an ectothermic vertebrate that modulates body temperature behaviorally relative to ambient temperature. In vertebrates, the POAH is also an important integrator of thermoregulation. Thus, the present study investigated whether lesions that disrupt reproductive behavior also disrupt body temperature regulation. While virtually all males displayed diurnal rhythms in thermoregulatory behavior prior to surgery, this pattern was abolished in a small proportion of animals bearing POAH lesions. Lesions that abolished thermoregulatory rhythms involved the suprachiasmatic nucleus (SCN), whereas lesions confined to the POAH, while dramatically influencing sexual behavior, did not affect thermoregulatory rhythms or temperature set point. Together, these findings identify the POAH as an important neural locus regulating sexual behavior but not thermoregulation and suggest that the SCN acts as a pacemaker controlling daily behavioral temperature regulation in this species.

Animals↗
PubMed2006

Behavioral effects of pubertal anabolic androgenic steroid exposure in male rats with low serotonin.

The goal of this study was to assess the interactive effects of chronic anabolic androgenic steroid (AAS) exposure and brain serotonin (5-hydroxytryptamine, 5-HT) depletion on behavior of pubertal male rats. Serotonin was depleted beginning on postnatal day 26 with parachlorophenylalanine (PCPA 100 mg/kg, every other day); controls received saline. At puberty (P40), half the PCPA-treated rats and half the saline-treated rats began treatment with testosterone (T, 5 mg/kg, 5 days/week). Behavioral measures included locomotion, irritability, copulation, partner preference, and aggression. Animals were tested for aggression in their home cage, both with and without physical provocation (mild tail pinch). Brain levels of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were determined using HPLC. PCPA significantly and substantially depleted 5-HT and 5-HIAA in all brain regions examined. Chronic T treatment significantly decreased 5-HT and 5-HIAA in certain brain areas, but to a much lesser extent than PCPA. Chronic exposure to PCPA alone significantly decreased locomotor activity and increased irritability but had no effect on sexual behavior, partner preference, or aggression. T alone had no effect on locomotion, irritability, or sexual behavior but increased partner preference and aggression. The most striking effect of combining T+PCPA was a significant increase in attack frequency as well as a significant decrease in the latency to attack, particularly following physical provocation. Based on these data, it can be speculated that pubertal AAS users with low central 5-HT may be especially prone to exhibit aggressive behavior.

Aggression↗
PubMed2005

Ejaculation induces long-lasting behavioural changes in male rats in the forced swimming test: evidence for an increased sensitivity to the antidepressant desipramine.

Copulation to exhaustion induces a sexual inhibitory state featured by a decreased motivation. Since diminished motivation is a key symptom of depression, we analysed if sexually exhausted animals showed increased levels of depressive-like behaviour in the forced swimming test (FST). Besides, sexual activity has been reported to have reinforcing properties. Thus, we analysed whether different levels of sexual activity modified the development of the behavioural despair in the FST. Finally, the effect of a sub-threshold dose of desipramine (DMI, 2.5mg/kg) was evaluated in animals with different sexual conditions. Male adult rats were divided into: (a) naive rats and (b) animals executing one intromission (1-INTR) or (c) one ejaculation (1-EJ) and (d) sexually satiated rats, classified as sexually responsive (R) and non-responsive (NR). No differences were found in immobility behaviour between sexually exhausted and naive rats. In the pre-test sessions of the FST males attaining ejaculation (1-EJ, R and NR) had lower levels of immobility or showed a tendency towards such a diminution, while animals with sexual activity not involving ejaculation did not. Data suggest a "protective" effect of ejaculation against the development of depressive-like behaviour. Finally, the sub-effective dose of DMI produced an antidepressant-like action in all animals that ejaculated. In conclusion, sexual experience involving ejaculation modifies the behavioural expression of rats in the FST and their sensitivity to antidepressant drugs like DMI. Both responses reflect brain plastic changes induced by ejaculation.

Analysis of Variance↗
PubMed2004

Reproductive consequences of population divergence through sexual conflict.

Sexual-selection research increasingly focuses on reproductive conflicts between the sexes. Sexual conflict, divergent evolutionary interests of males and females, can cause rapid antagonistic coevolution of reproductive traits and is a potentially powerful speciation engine. This idea has theoretical and comparative support but remains controversial. Recent experimental evidence from Sepsis cynipsea indicates that populations with greater sexual conflict diverged more quickly; females were less likely to mate with males from other populations when flies had evolved under high levels of sexual conflict. The consequences of this divergence have not been addressed, so here we assess two female fitness surrogates after 44 generations of evolving (and diverging) under three different levels of sexual conflict. Longevity after copulation was negatively associated with the degree of sexual conflict under which flies evolved, and housing females with males also reduced female longevity. Female lifetime reproductive success (LRS) also tended to decrease with increasing conflict. However, there was evidence of either sexual-selection fitness benefits at intermediate levels of sexual selection and conflict or inbreeding depression in the smallest populations (those with the lowest levels of conflict). Nevertheless, the results indicate that there can be a fitness load associated with sexual selection and support claims that sexual conflict can lead to reproductive isolation.

Animals↗
PubMed2004

Evolution: sperm ejection near and far.

In promiscuous fruit flies, the last male to inseminate a female has a fertilising advantage. Recent evidence indicates that this happens because females eject previously stored semen after a new copulation, revealing female bias in sperm use and the resulting battle of the sexes over fertilisation.

Animals↗
PubMed2005

Drosophila sex-peptide stimulates female innate immune system after mating via the Toll and Imd pathways.

Insect immune defense is mainly based on humoral factors like antimicrobial peptides (AMPs) that kill the pathogens directly or on cellular processes involving phagocytosis and encapsulation by hemocytes. In Drosophila, the Toll pathway (activated by fungi and gram-positive bacteria) and the Imd pathway (activated by gram-negative bacteria) lead to the synthesis of AMPs. But AMP genes are also regulated without pathogenic challenge, e.g., by aging, circadian rhythms, and mating. Here, we show that AMP genes are differentially expressed in mated females. Metchnikowin (Mtk) expression is strongly stimulated in the first 6 hr after mating. Sex-peptide (SP), a male seminal peptide transferred during copulation, is the major agent eliciting transcription of Mtk and of other AMP genes. Both pathways are needed for Mtk induction by SP. Furthermore, SP induces additional AMP genes via the Toll (Drosomycin) and the Imd (Diptericin) pathways. SP affects the Toll pathway at or upstream of the gene spätzle, the Imd pathway at or upstream of the gene imd. Mating may physically damage females and pathogens may be transferred. Thus, endogenous stimulation of AMP transcription by SP at mating might be considered as a preventive step to encounter putative immunogenic attacks.

Animals↗
PubMed2005

Mate choice: been there, done that.

Females may benefit from mating with several males, but how can they avoid mating with the same male repeatedly? A new study of crickets has found that females mark their mates to avoid repeat copulations.

Animals↗
PubMed2006

Administration of the anabolic androgenic steroid nandrolone decanoate to female rats causes alterations in the morphology of their uterus and a reduction in reproductive capacity.

OBJECTIVE: The aim of the present investigation was to characterize the effects of supraphysiological doses of the anabolic androgenic steroid nandrolone decanoate (ND) on the fertility of female rats, as well as on the morphology of their uterus. STUDY DESIGN: Female Wistar rats (n=15) received a subcutaneous injection of ND (15 mg/kg) once daily during a 2-week period, while the control animals (n=10) were administered vehicle alone (arachidis oleum) in the same manner. Estrus behavior was evaluated 4 weeks after termination of this treatment and in cases where signs of receptivity were present, the female rat was given the opportunity to copulate with a male. After breeding, the female animals were sacrificed and their uteri examined histomorphologically. RESULTS: All ND-treated animals exhibited abnormal vaginal smears, whereas all of the control smears were normal. Most (73%) of the treated females demonstrated normal estrus behavior (i.e., willingness) on the day of mating, but none got pregnant; whereas all of the control rats became pregnant. The female rats receiving the ND showed an enhanced rate of weight gain and the myometrium thickness of their uteri was significantly increased, while the endometrium was significantly thinner. Furthermore, ND caused a significant proportion of the treated animals to display tortuous and irregularly branching endometrial glands, as well as a lack of the physiologically normal infiltration of eosinophilic leukocytes into the endometrium (endometrial eosinophilic homing), a finding that has not been reported previously. CONCLUSION: The present findings indicate that high doses of ND cause morphological and physiological alterations in the uterus of female rats that are associated with a suppression of their reproductive capacity.

Anabolic Agents↗
PubMed2006

Morphologic, endocrinologic and natural pregnancy assessment of allogeneic ovarian orthotopic transplantation without a vascular pedicle in rabbits.

OBJECTIVE: The objective was to assess the natural pregnancy of rabbits subjected to bilateral oophorectomy and orthotopic allogeneic intact and sliced ovarian transplantation without a vascular pedicle, and to determine the morphofunctional aspects of the transplanted ovaries. STUDY DESIGN: Thirty-two female rabbits were studied. The ovaries were removed and orthotopically transplanted without vascular anastomoses between the two breeds of rabbits. In Group 1 (n=8), only laparotomy and laparorrhaphy were performed, in Group 2A (n=8) intact ovaries were transplanted on both sides, in Group 2B (n=8) both ovaries were sliced and orthotopically transplanted, and in Group 2C (n=8) an intact ovary was transplanted on one side and a sliced ovary on the other side. Three months later, the animals were paired with males for copulation. Estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone levels were assessed. A histologic study was carried out and the numbers of pregnancies and litters were also determined. RESULTS: Pregnancies occurred in seven rabbits in Group 1, 37.5% of rabbits in Group 2A, 50% in Group 2B, and 62.5% in Group 2C. Hormone levels and histology confirmed the vitality and function of all ovaries. CONCLUSIONS: Intact or sliced orthotopic allogeneic ovarian transplantation without a vascular pedicle is viable in rabbits, and preserves their hormonal and fertile functions.

Animals↗
PubMed2006

Estradiol-associated variation in responses of rostral medullary neurons to somatovisceral stimulation.

The lordosis posture and cervix stimulation during copulation are important reproductive events involving complex neural circuitries that are under hormonal influence. An important component of this circuitry, neurons within the medullary reticular formation (MRF), was examined in the present study using electrophysiological techniques. Single unit extracellular recordings were performed in the MRF of 27 urethane-anesthetized female rats. Using bilateral electrical stimulation of the dorsal nerve of the clitoris as the search stimulus, a detailed examination of the somatovisceral convergent responses of 585 individual MRF neurons was made. A total of 7 different groups of cycling and ovariectomized/hormone-supplemented rats were examined and their neuronal response properties to mechanical stimulation of various pelvic organs (cervix pressure, vaginal distension, colon distension) compared. The results indicate the existence of complex response properties as well as several variations in MRF response characteristics that are hormone-dependent. Specifically, estradiol is associated with hyposensitivity to cervix pressure and hypersensitivity to stroking the face. These opposing effects of estradiol in the same subset of neurons likely relate to lordosis behavior which can be either disrupted or elicited, depending on the area being stimulated (upper versus lower parts of the body, respectively).

Animals↗
PubMed2005

Comparison of embryo implantation in Wistar rats that underwent ovarian stimulation using exogenous gonadotropins associated with cetrorelix acetate or leuprolide acetate.

OBJECTIVE: To compare embryo implantation in Wistar rats submitted to ovarian stimulation using recombinant FSH (rFSH) with cetrorelix acetate or leuprolide acetate. DESIGN: Experimental study. SETTING: Faculty of medicine animal facility. PATIENT(S): Fifty-six female Wistar rats with normal estrus cycles and 30 male. INTERVENTION(S): Ovarian stimulation and laparotomy (by the day 13 of gestation). MAIN OUTCOME MEASURE(S): Embryo implantation. RESULT(S): The female rats were subdivided into four groups: group 1, medicated with rFSH, hCG, and cetrorelix acetate; group 2, medicated with rFSH, hCG, and leuprolide acetate; group 3, medicated with rFSH and hCG; and group 4, in which only saline solution was administered. The female rats were mated with fertile male rats on the day of hCG administration with copulation confirmed through cytologic vaginal analysis. The females were killed on the 13th day of gestation. After laparotomy, comparison and identification was done regarding the numbers of corpora lutea and embryo implantations and gestation rates. Group 1 presented lower numbers of corpora lutea and embryo implantations in comparison to the other groups (P<.05). A difference was not found in the gestation rates between the groups. CONCLUSION(S): The number of embryo implantations in Wistar rats medicated with rFSH and cetrorelix acetate is lower than that of rats medicated with rFSH and leuprolide acetate.

Animals↗
PubMed2005

Mutations in the desat1 gene reduces the production of courtship stimulatory pheromones through a marked effect on fatty acids in Drosophila melanogaster.

In Drosophila melanogaster, desat1 is involved in the synthesis of fatty acids (FAs), some of which are precursors in the production of unsaturated hydrocarbons (HCs) in position 7 (7-HC) that play an important role in mating behaviour. Three GS lines with P-element insertion in the desat1 promoter showed more or less decrease in 7-HC, depending on the site of insertion. The forced transcription of genomic 5'P-flanking sequence led to opposite effects upon 7-HC, depending on the orientation of the insertions. Homozygous GS12251 flies showed particularly low 7-HC levels and severely affected courtship parameters (courtship latency doubled, number of copulation attempts decreased by half). After transposon excision, the HC phenotype was reversed in most lines, showing that the location of the transposon was responsible for the mutant phenotype. In homozygous GS12251 flies, the amounts of FAs and desat1 transcripts were reduced by half, compared to the amounts in heterozygous or wild-type flies. Relative proportions among FAs were quite similar to those of wild-type, with the exception of a slight decrease in myristoleic, palmitoleic and vaccenic acid. As the reduction of desat1 activity in the mutant resulted in a large decrease in both unsaturated and saturated FAs, it could impair FA and lipid metabolism, as it is known in vertebrates.

Animals↗
PubMed2005

Female choice and the MHC.

In animals, it is the female that typically selects a mating partner. This decision can occur before, during and after copulation. Here, recent evidence for the involvement of genes within the MHC in female choice is reviewed and the roles of MHC I and II antigens, various types of chemoreceptors, as well as MHC-encoded transcription factors, in securing an optimal genetic constitution of the offspring are discussed. Some particularly interesting and as yet unanswered questions are raised and some experiments that could provide deeper insight into the molecular mechanisms underlying female choice are suggested.

Animals↗
PubMed2005

Effect of host size on male fitness in the parasitoid wasp Dinarmus basalis.

The effect of host size on male fitness was tested in the parasitoid wasp Dinarmus basalis (Hymenoptera, Pteromalidae) using hosts of different fresh weight. Fitness was measured as the sperm stock in seminal vesicles, and the ability to access females in single or competition situations. Both body size and sperm in seminal vesicles increased with host fresh weight. Males from small hosts had a reduced size and sperm stock compared to those from larger hosts. In single situations, males from both small and large hosts had similar reproductive capacities, whereas in multiple mating or competition situations, males from small hosts were at a disadvantage, inseminating fewer females and copulating less frequently. However, females did not appear to choose between males, and no effect on sperm stored in the spermatheca was observed. Being small does not prevent a D. basalis male mating and producing progeny in single situations, although more offspring could be expected from larger males because of their better competitive abilities.

Animals↗
PubMed2006

Infection of Harmonia axyridis (Coleoptera: Coccinellidae) by Hesperomyces virescens (Ascomycetes: Laboulbeniales): role of mating status and aggregation behavior.

The ectoparasitic fungus Hesperomyces virescens was studied on Harmonia axyridis in North Carolina, in the southeastern United States. A primary goal was to investigate transmission of the disease by examining the correlation between the pattern of fungal infection and seasonal change in host behavior. Beetles were collected as they arrived at their winter quarters at two sites; in one site they were also subsampled at mid- and late winter. Insects were sexed and weighed, fungal thalli were counted, and their location on the host body mapped; spermathecae of females were examined for sperm. Infection levels varied between sites, differed significantly between the sexes in one site but not the other, and increased by approximately 40% during winter. The distribution of thalli on the body changed seasonally, in concert with behavioral changes in the host. At fall flight, thalli were found most often on the posterior elytra of mated females, virgin females, and males. This is suggestive that the disease had been spread among both sexes via successful and failed copulation attempts; however, the relatively low incidence of infection on the male venter does not fit the sexual transmission scenario. During winter, thallus location shifts in concert with beetle aggregation behavior, with infections more often located on the head and legs. Fresh weight of beetles decreased by approx. 20% during winter, but was not affected by disease status. Prior to spring flight, uninfected females were preferred as mating partners, but the probable relationship between female age and infection status complicates interpretation of the data.

Animals↗