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At least 811 records · Page 45Linked to original sources
PubMed1996

Fertility and general reproduction studies in rats with the HMG-CoA reductase inhibitor, atorvastatin.

Fertility and reproduction studies were conducted in rats with the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, atorvastatin. Male rats received vehicle (0.5% methylcellulose) or atorvastatin at 20, 100, or 175 mg/kg by oral gavage for 11 weeks prior to mating with untreated females; treatment continued throughout mating and until necropsy on Day 115. An untreated control group of males was also included in the same procedures. Dose-related body weight gain suppressions of 17 and 25%, and food consumption suppressions of 7 and 16%, occurred during the 11-week premating treatment period at 100 and 175 mg/kg, respectively, compared with vehicle controls. There were no treatment-related effects on testes, epididymides, or accessory organs weights, testicular or epididymal sperm counts, sperm motility, or sperm morphology during Week 15 of treatment. Plasma drug concentrations during Week 15 increased with dose to a Cmax of 1820 +/- 1020 ng eq/ml at 175 mg/kg. There were no effects on copulation or fertility indices, number of days to mating, or female reproductive parameters (number of implants, live fetuses, or pre- and postimplantation loss). In the female fertility study, female rats received vehicle (0.5% methylcellulose) or atorvastatin at 20, 100, or 225 mg/kg by oral gavage for 2 weeks prior to mating with untreated males; treatment continued throughout mating and until Gestation Day 7. Sperm-positive females were sacrificed on presumed Gestation Day 13 to 15 for evaluation of reproductive parameters. Body weight gain in atorvastatin groups was comparable to controls during the premating period, but was suppressed by 35% at 225 mg/kg during the treatment period of gestation (Days 0-8), and was significantly increased at 225 mg/ kg during the posttreatment period of gestation (Days 8-13). Plasma drug concentrations on premating treatment Day 14 increased with dose to a Cmax of 7030 +/- 3680 ng eq/ml at 225 mg/ kg. The mean number of estrous cycles, copulation and fertility indices, number of days to mating, and number of viable litters were comparable between groups. In addition, term sacrifice parameters (number of corpora lutea, implants, live fetuses, pre- and postimplantation loss) were not significantly different between groups. Thus, these studies demonstrate no adverse effects of atorvastatin on fertility and reproduction in rats at doses up to 175 and 225 mg/kg in males and females, respectively, and 20 mg/kg was a no-effect dose.

Animals↗
PubMed1996

Frank A. Beach award. Homologies of animal and human sexual behaviors.

Theoretical models of animal and human sexual behavior have evolved from two very different literatures, yet they contain many common behavioral components that may reflect the action of similar neuroendocrine and neurochemical systems. The study of animal sexual behavior has been largely concerned with mechanisms that underlie the pattern of consummatory behaviors observed during copulation, behaviors that tend to be highly stereotyped, sexually differentiated, and species-specific. There are important species differences in the behavioral topography, endocrine control, and neural substrates of consummatory behaviors, which tend to be extreme when comparing animals and humans. Although this has led to an increased interest in comparative animal behavior, it has also helped to foster a general perception that animals and humans are fundamentally different. In contrast to consummatory behaviors, appetitive behaviors (which serve to bring animals and humans into contact with sexual incentives) are more flexible, less sexually differentiated, and less species-specific and span a variety of situations other than sexual interactions. Appetitive behaviors are thus viewed as "sexually specific" when they are displayed under sexual circumstances and reinforced by sexual incentives. Interestingly, an appetitive/consummatory dichotomy has emerged in the human literature which distinguishes measures of sexual desire or arousal from "performance" measures of masturbation or copulation. In fact, sexual desire, which reflects fantasy and behavioral excitement, has been further differentiated from sexual arousal, which reflects genital blood flow. The present analysis attempts to pull together these seemingly disparate literatures into a coherent theoretical framework that emphasizes similarities and differences in the structure of sexual behavior across rats and humans.

Animals↗
PubMed1996

Seasonal testicular function in male rhesus monkeys.

Some studies report seasonal patterns of testicular function in male rhesus monkeys even when they are housed away from females, while others suggest that exposure to sexually active females is essential for male seasonality. We conducted the present experiment (1) to test claims that seasonal testicular activation occurs in the absence of females and (2) to determine whether regular exposure to and copulation with females enhances, or is without effect upon, seasonal increases in testicular function. We studied two groups of male monkeys housed in a colony room containing no females. Males in the Female Exposure group (n = 7) were paired twice weekly with estradiol-implanted females and copulated vigorously. Males in the second group (n = 7) were placed in the same test chamber (at least 16 h after it had been scrubbed with disinfectant) but were never exposed to females. Serum testosterone levels and testis volume were monitored for both groups. Each group displayed a seasonal pattern of testosterone and of testis volume comparable in timing and magnitude to seasonal increases previously reported in group-housed males, but the two groups did not differ from each other. Our findings confirm that seasonal changes in testosterone and testis size occur in the absence of sexual interaction and demonstrate that moderate levels of sexual activity do not enhance this response.

Animals↗
PubMed1997

The effects of testicular tissue and prehatching inhibition of estrogen synthesis on the development of courtship and copulatory behavior in zebra finches.

As in many mammalian and avian species, testicular androgens or their metabolites activate courtship and copulatory behaviors in adult male zebra finches. However, studies of sexual differentiation of these behaviors and related anatomical structures provide conflicting results. For example, posthatching estradiol can both masculinize courtship and the neural structures involved in song in females and inhibit the development of masculine copulation in males. These and other results have led to the hypotheses that (1) testicular androgens are converted to estradiol in the brain of developing males, and estradiol serves to masculinize the song system, whereas (2) estradiol secretion by the female ovary allows feminine rather than masculine copulatory behavior to develop. Treating embryonic zebra finches with the estrogen synthesis inhibitor fadrozole causes functional testicular tissue to develop in genetic females. The present study investigated the effects of such treatment on the development of singing and copulatory behavior as well as song system anatomy in males and females. While exogenous testosterone facilitated the display of sexual behaviors in adult males, the testicular tissue in females had no masculinizing effect on the production of audible courtship song or copulation. Their song control nuclei were also not masculinized, even in individuals lacking ovarian tissue. In contrast, embryonic inhibition of estrogen synthesis in males significantly stimulated song production. These results suggest that while manipulations of steroid hormone exposure can influence the display of sexual behaviors, gonadal secretions may not be required for normal sexual differentiation of the song system in zebra finches.

Animals↗
PubMed1979

Temperature sensitivity of flocculation induction, conjugation and sporulation in fission yeast.

Homothallic cultures of Schizosaccharomyces pombe, anaerobically grown to stationary phase in broth at 32 degrees C, were induced by aeration to flocculate. Flocculation was followed by copulation, conjugation, zygote formation, meiosis and sporulation. Cultures grown to stationary phase at 32 degrees C and then aerated at 37 degrees C did not sporulate. Grown to stationary phase at 37 degrees C, cultures were not immediately inducible when aerated at 32 degrees C. To identify which events in the developmental sequence were thermosensitive, we grew and induced cultures at 32 degrees C and then shifted them at various times to 37 degrees C. We observed the following events to be thermosensitive: development of respiratory sufficiency, readiness (inducibility of a culture within 1 h), flocculation induction, copulation, conjugation and early sporulation (including meiosis). Respiration, flocculation and spore maturation were thermoresistant. Conjugation-induced lysis and postdevelopmental deflocculation were enhanced at 37 degrees C.

Ascomycota↗
PubMed1977

Behavioral role of the sexcombs in Drosophila melanogaster and Drosophila simulans.

The sexcombs were amputated from males of three strains of Drosophila melanogaster and one strain of D. simulans in order to assess the importance of these structures in the sexual behavior of these species. In D. melanogaster the sexcombs are important in attempts to copulate with the female. Their removal delays copulation but does not suppress it entirely. Other aspects of courtship are not influenced by removal of the sexcombs. Strain differences in quanitative aspects of courtship were found, and also in the insemination rates of females by males without sexcombs. The present evidence suggests that the sexcombs are primarily structures adapted to grasping the female securely during the act of intromission.

Animals↗
PubMed1995

Sex without emotional involvement: an evolutionary interpretation of sex differences.

Two samples of male (n = 243) and female (n = 298) college students completed sexual surveys, and in-depth, oral interviews were conducted with 28 highly sexually active female college students. Findings supported five predictions derived from evolutionary (parental-investment) theory. Even when females voluntarily engaged in low-investment copulation, coitus typically caused them to feel emotionally vulnerable, and to have thoughts expressing anxiety about partners' willingness to invest. For females, increasing numbers of partners correlated positively with the incidence of these feelings and thoughts; for males, these correlations were negative. Females' attempts to continue regular coitus when they desired more investment than partners were willing to give produced feelings of distress, degradation, and exploitation despite acceptance of liberal sexual morality. Increasing numbers of partners did not mitigate these reactions in females and may exacerbate them. Multiple-partner females developed techniques for dealing with their emotional reactions to low-investment copulation: They frequently tested their partners for signs of ability and willingness to invest (e.g., dominance, prowess, jealousy, nurturance), and they limited or terminated sexual relations when they perceived partners' investment as inadequate. Results were consistent with the view that the emotional-motivational mechanisms that mediate sexual arousal and attraction are sexually dimorphic.

Adolescent↗
PubMed1993

Lack of effects of 5-HT3 antagonists on normal and morphine-attenuated sexual behaviours in female and male rats.

Although 5-HT1 and 5-HT2 receptor activity is known to influence copulation, the effects of 5-HT3 receptor-selective drugs on sexual activity have yet to be systematically studied. The following experiments investigated the effects of the 5-HT3-selective antagonists MDL 72222, ondansetron and ICS 205-930 on female sexual behaviour; male rats were studied using ondansetron and granisetron. These compounds influenced neither male nor female copulatory behaviours, suggesting that 5-HT3 receptors contribute little to the modulation of sexual activity. 5-HT3 receptor antagonists block certain opioid-induced behaviours and opioids selectively inhibit sexual behaviours; therefore, the ability of ondansetron and ICS 205-930 to modify morphine-attenuated copulatory activity was also tested. While morphine inhibited copulation, 5-HT3 antagonists failed to reverse the effects.

Animals↗
PubMed1990

Effects of ascorbic acid on the mouse embryo and on cyclophosphamide-induced cephalic DNA strand breaks in vivo.

Pregnant C3H mice were exposed to 3.34 and 6.68 g ascorbic acid/kg body weight on the 11th day post-copulation, and to co-administration of a teratogenic dose of cyclophosphamide (CP, 15 mg/kg body weight). The effects on embryonal cephalic DNA strand breaks were assessed 16 h after drug administration. In order to establish whether vitamin C was embryotoxic or altered CP-induced toxicity, mice were sacrificed on day 18 after copulation to record fetal weights, gross morphological abnormalities, and fetal mortality. Administration of 3.34 g ascorbate/kg was not associated with demonstrable toxic effects but with 6.68 g ascorbic acid/kg there was a 46% incidence of fetal mortality. In embryos exposed to CP, 15 mg/kg, there was a decrease in fetal weight (median fetal weight 678 mg compared with 967 mg in controls), all fetuses were morphologically abnormal and 59% of cephalic DNA was double stranded compared with 81% for controls (p less than 0.001). When vitamin C, 3.34 g/kg, was co-administered with CP the incidence of DNA strand breaks remained unchanged. However, all fetuses were morphologically normal and there was no reduction in fetal weight. These findings demonstrate that administration of 6.68 g vitamin C/kg is toxic to the mouse embryo, but a lower dose of 3.34 g/kg is not, and has a protective effect against the toxic manifestations of CP. This protection is not associated with prevention of cephalic DNA strand breaks.

Animals↗
PubMedDate not supplied

Behavioral analysis of Drosophila mutants displaying abnormal male courtship.

We describe six recessive autosomal male sterile mutations in Drosophila, generated by mobilization of single P-elements, exhibiting abnormal male courtship behavior. Detailed analysis of courtship behavior elicited by virgin wild type females indicated that five of the six mutants are affected in the early steps of courtship. The sixth mutant is blocked at the step of attempted copulation which occurs later in the courtship sequence. All of the mutants have normal olfactory responses and normal locomotor activity. No defect in the visual modality has been observed for the five mutants affected in the initiation of courtship. The mutant blocked at attempted copulation lacks the 'on' and 'off' transients, but this appears to be due to genetic background rather than the mutation itself. Abnormal spermatogenesis was observed in five of the mutants. Spermatogenic defects vary and include lesions in the proliferation of the germline, in meiosis, and in the differentiation and maturation of the spermatids into motile sperm.

Animals↗
PubMed2001

Body size and mating success in Drosophila willistoni are uncorrelated under laboratory conditions.

Mating activity and wing length were investigated in the F1; progeny of Drosophila willistoni females collected in the field to examine any possible relationship between body size and mating success. The flies were observed in a mating chamber under laboratory conditions. No significant differences in wing length were observed between copulating and noncopulating flies, and there was no significant correlation between wing length and copulation latency for both males and females. These results therefore suggest that the commonly accepted view that large body size is positively correlated with mating success in Drosophila does not always hold true. The results support the view that the extent of environmentally induced variation in body size may be an important factor in determining whether an association between body size and mating success is observed in Drosophila species.

Animals↗
PubMed2006

Defective transfer of seminal-fluid materials during matings of semi-fertile fruitless mutants in Drosophila.

In context of the semi-sterility exhibited by Drosophila males expressing certain mating-enabling fruitless (fru) mutant genotypes, we examined the transfer of seminal fluid using a transgene that encodes the Sex Peptide (SP) oligopeptide fused to Green Fluorescent Protein (GFP). We found that this fusion construct expresses SP-GFP in a valid manner within accessory glands of the male reproductive system in normal and fru-mutant males. Transfer of SP-GFP to live females was readily detectable during and after copulation. With respect to the pertinent combinations of fru mutations, we demonstrated that these abnormal genotypes cause males to transmit mating-related materials in two aberrant ways: one involving whether any seminal-fluid entities are transferred at all during a given mating; the other revealing an intriguing aspect of these fruitless effects, such that the mutations in question cause males to transfer female-affecting materials in a manner that varies among copulations. In this regard, certain mutant males that do not transfer SP nevertheless are able to transfer sperm: a fru-mated female possessing no GFP who was not fecund initially could produce progeny when seminal-fluid proteins were subsequently supplied by mating with a male that was spermless owing to the effects of a tudor mutation.

Analysis of Variance↗
PubMed1997

Investigation of different ontogenetic stages of Raillietiella sp. (Pentastomida:Cephalobaenida): accessory genital glands.

The ultrastructure of accessory genital glands in Raillietiella sp. is described and their function is discussed. In females we assume that they reactivate sperm, which are stored in the receptacula seminis after copulation. In males we think they are primer-pheromone glands, which inject secretions into the female during copulation and stimulate the development of the female genital system. This study presents a revised nomenclature, which allows for the comparison of former results.

Animals↗
PubMed2004

First experimental evidence for female mate choice in a nocturnal primate.

Female mate choice can be hypothesised in most nocturnal primates, since females show a higher investment in their offspring than males. The aim of this experimental study was to investigate if female grey mouse lemurs perform mate choice and whether age, relatedness (to the male), or male advertisement call activity systematically influence their decisions. A two-way mate choice design was developed in which females could choose between two males. Mate choice was deduced from the time spent in proximity to the males and from mating behaviour. During oestrus 12 of 17 females participated actively in the experiment and all of them showed either a significant spatial (n = 11) or behavioural (n = 1) preference for one male. In four cases copulations were observed. The influence of age on female mate choice was not statistically significant. In the cases with copulations, however, females mostly preferred the older male. This might indicate a preference for older age as an indicator of experience, fitness, and/or status. The influence of relatedness on female mate choice could not be definitely clarified. However, results imply a mechanism of kin recognition on the basis of familiarity. In the majority of choices, females preferred the male with higher trill call activity. Since trill call activity correlates with the relative dominance status of males, these results suggest an importance of the male dominance status for female mate choice in grey mouse lemurs. Altogether our findings indicate that females use a complex of different cues to choose their mates.

Age Factors↗
PubMed2006

Mating system of the European hornet Vespa crabro: male seeking strategies and evidence for the involvement of a sex pheromone.

We describe details of the mate finding strategy of drones of the European hornet, Vespa crabro, and present evidence for the involvement of sex pheromones. Tests were carried out with free flying drones in natural habitats. Males patrolled the nest site itself, as well as nearby nonresource-based sites, without showing territorial behavior. Patrolling was restricted to sunny spots in the vegetation, and thus, the locations changed throughout the day. Drones were attracted to both caged gynes and to dead workers treated with gyne extracts, indicating the presence of a female-produced sex attractant. Treated workers also elicited copulation attempts by the attracted drones. Extracts from gynes, workers, and drones contained exclusively cuticular lipids, and the profile from gynes was much more diverse than that of workers and drones. The most striking differences observed related to the alkenes, monomethyl- and dimethylalkanes. The results provide a lead for potential attracting and copulation-releasing semiochemicals in V. crabro.

Alkanes↗
PubMed1975

Characteristics of exaggerated sexual behavior induced by electrical stimulation of the medial preoptic area in male rats.

Twenty-two sexually experienced male rats were implanted with lateral preoptic (LPO) and medial preoptic (MPO) electrodes. Following surgery, the 22 MPO and 18 LPO electrodes were screened for the induction of stimulation-bound copulation in the presence of estrus females. Stimulation through 5 of the MPO electrodes induced highly exaggerated, stimulation-bound sexual behaviou. Ten MPO electrodes produced escape behavior, 2 electrodes aggression and one electrode induced sexual behavior intermingled with aggression. The tips of all the electrodes which effected exaggerated copulation were located within a small preoptic region, less than 1 mm lateral to the midline. LPO electrodes had either inhibitory effects on mating behavior or none at all. The increase in copulatory activity by MPO electrodes' stimulation was expressed in a great enhancement in the number of ejaculations, and marked decreases in the latency to ejaculation, the post-ejaculatory refractory period, and in the number of intromissions preceding an ejaculation. It is concluded that the electrical stimulation affected both the sexual arousal mechanism and the intromission-ejaculation mechanism involved in mating behavior.

Aggression↗
PubMed1982

Effects of ibotenic acid-induced neuronal degeneration in the medial preoptic area and the lateral hypothalamic area on sexual behavior in the male rat.

It is well known that electrolytic lesions in the medial preoptic area (MPOA) and the lateral hypothalamic area (LHA) seriously impair masculine sexual behavior in the rat. We here report that bilateral infusions of the neurotoxin, ibotenic acid (IBO), in the MPOA were as effective as electrolytic lesions in eliminating copulation whereas no behavioral effects were detected following similar infusions in the LHA. Histological examination of MPOA and LHA following IBO exposure revealed extensive degeneration of neuronal cell bodies with little evidence of non-specific damage. Also, immunohistochemical studies suggested that the serotonergic innervation of the MPOA remained largely intact in spite of IBO treatment; similarly, the damage inflicted by IBO in LHA on tyrosine hydroxylase-immunoreactive fibers in the medial forebrain bundle was insignificant. These data suggest that: (i) the functional integrity of MPOA nerve cell bodies is necessary for the expression of sexual behavior, and (ii) disruption of mating produced by electrolytic LHA lesions is due to disruption of medial forebrain bundle fiber systems. Behavioral observations of non-copulating males suggested that the MPOA injury did not interfere with all aspects of their sexual interaction with the estrous female; rather, they appeared specifically unable to perform the reflexive pelvic thrust pattern normally associated with mounting. We here report, however, that the ability to perform mounts with pelvic thrusts was temporarily restored in the vast majority of MPOA-injured males by the i.p. administration of the ergot derivative, lisuride. About 50% of these MPOA-damaged males even ejaculated, often after a low number of intromissions and short ejaculation latencies. On the other hand, injections of naloxone (an opiate receptor antagonist) failed to activate mounting in MPOA-lesioned or castrated rats. On the basis of these findings the possible ways in which steroid hormone-sensitive brain areas might interact with monoamine-containing pathways are discussed.U

Animals↗
PubMed1987

Olfactory bulb removal decreases androgen receptor binding in amygdala and hypothalamus and disrupts masculine sexual behavior.

In these experiments we examined the relationship between olfactory bulb removal, limbic system androgen receptor binding and male copulatory behavior. Sexually experienced male rats were castrated, and implanted with two 10 mm testosterone-filled silastic capsules. Animals then underwent either bilateral olfactory bulb removal (BOB) or sham surgery (Sham). Beginning 1-2 days postoperatively both BOB and Sham operates were given 4 tests for male copulation on alternate days. Less than 40% of BOB males ejaculated. In contrast, 80-100% of sham operates continued to ejaculate throughout the 4 postoperative tests. Cell nuclear androgen receptor binding was assessed in amygdala, hypothalamus, preoptic area and septum 1-2 and 8-9 days after either bulbectomy or sham surgery. We found that olfactory bulbectomy significantly reduces androgen receptor binding in amygdala and hypothalamus. The reduction in androgen receptor binding in amygdala occurs within 1-2 days following olfactory bulb removal and is correlated with the disruption of ejaculatory activity. These data suggest that the neuromodulation by olfactory bulb input to androgen-concentrating neurons in the amygdala and hypothalamus is necessary for effective copulation in male rats.

Amygdala↗