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At least 19 recordsLinked to original sources

PubMed2003

Excitotoxic lesions of the tegmental pedunculopontine nucleus impair copulation in naive male rats and block the rewarding effects of copulation in experienced male rats.

The tegmental pedunculopontine nucleus (TPP) of the brainstem mediates food reward in food-sated animals and opiate reward in drug-naive animals. In the present study, we examine the effect of excitotoxic lesions of the TPP on sexual behaviour in naive and experienced male rats. Male, Long-Evans rats received either 0.25 micro L injections of NMDA (4.2 micro g/side) or vehicle (shams) into the TPP. In sexually naive males, complete bilateral TPP lesions decreased all measure of copulation (i.e. mounts, intromissions and ejaculations), prevented acquisition of conditioned sexual excitement, decreased approach preference for a receptive female over a non-receptive one, and decreased non-contact erections; unilateral or bilateral posterior-sparing TPP lesions did not affect any of these measures. Conversely, in sexually experienced males, lesions not only failed to disrupt copulation, but also increased conditioned sexual excitement, decreased post-ejaculatory interval and blocked the effect of prolonged copulation on conditioned sexual excitement. Following differential pairing of distinctive environments with and without copulation, sham males with sexual experience displayed a significant preference for the environment paired with copulation, whereas the lesion males with sexual experience displayed a significant aversion for the environment paired with copulation. These findings indicate that the TPP is critical for the acquisition of copulation in naive males and mediates the rewarding consequences of copulation in experienced males. Together these findings demonstrate that the TPP mediates sexual reward, but that sexual experience is not sufficient to produce a deprivation state.

Animals↗

PubMed1995

Effects of caffeine on mating frequency and pre-copulation and copulation durations in Drosophila prosaltans.

Parameters of sexual behaviour were studied in Drosophila prosaltans treated with 2,500 micrograms/ml of caffeine per 1 ml of banana culture medium. The mating frequency and copulation duration were greater in control than in treated flies, while the pre-copulation duration was greater in treated flies than in controls. Statistical analysis showed that for the pre-copulation duration the difference was significant.

Animals↗

PubMed2006

Comparative analysis of immunoreactive cells for androgen receptors and oestrogen receptor alpha in copulating and non-copulating male rats.

In some species, including gerbils, guinea pigs, mice, rams and rats, some apparently normal males fail to mate. These kinds of animals have been named 'noncopulating (NC)'. The cause of this behavioural deficit is unknown. The present study aimed to determine whether NC male rats have alterations in the amount of androgen (AR) and oestrogen receptor alpha (ERalpha) in a neuronal circuit important for the control of male sexual behaviour; the vomeronasal projection pathway. We evaluated the number of AR and ERalpha immunoreactive (AR-IR and ERalpha-IR) cells in the accessory olfactory bulb (AOB), the bed nucleus of the stria terminalis (BNST), the anterior-dorsal medial amygdala (MeAD), the posterior dorsal amygdala (MePD) and the medial preoptic area (MPOA). The results demonstrate that the number of AR-IR cells in NC males was significantly higher compared to copulating (C) males in the MePD, but no significant differences were found in any of the other structures analysed. ERalpha-IR cells were more abundant in NC than in C males in the MeAD and the MePD. However, in the MPOA the number of ERalpha-IR cells was significantly reduced in NC males. No significant differences were found in the AOB or in the BNST. A similar pattern of results was observed when regions within these structures that are activated by Fos expression, on mating or exposure to sexually relevant cues were analysed. The differences in the number of AR and ER in particular brain areas could be associated with alterations in sexual behaviour as well as partner and olfactory preference for receptive females seen in NC male rats.

Animals↗

PubMed1998

Copulatory behaviour and paternity in the American kestrel: the adaptive significance of frequent copulations.

The adaptive significance of repeated withinpair copulations is not well understood. We analysed the copulatory behaviour of 16 pairs of solitary-nesting American kestrels, Falco sparverius, in southern Quebec (Canada), and the achieved reproductive success (paternity) of 21 kestrel families determined by DNA fingerprinting, in terms of four hypotheses. (1) The paternity assurance hypothesis, which suggests that males copulate frequently to avoid being cuckolded, was rejected because there were few extrapair copulation attempts (<1% of all copulations observed), withinpair copulations were not timed during the fertile period and mate attendance did not increase as the fertile period approached. (2) The immediate material benefits hypothesis, which suggests that females trade copulations for food, was refuted because copulations most often occurred without food transfers, especially outside the fertile period. (3) The female mate guarding of males hypothesis, which suggests that females distract their mates from other mating opportunities by copulating frequently, was rejected because extrapair copulation attempts were infrequent, male and female solicitation frequencies were similar and females did not differ in the timing or frequency of solicitations. (4) The mate assessment hypothesis, which suggests that assessment of mate quality is mediated via copulation, most closely predicted the behaviour observed since withinpair copulations were frequent outside the fertile period and at pair formation, males and females solicited similar numbers of copulations and pairs did not differ significantly in solicitation or copulation frequency. In line with this hypothesis we found that only one brood was extrapair, probably the result of mate replacement.Copyright 1998 The Association for the Study of Animal Behaviour

Journal Article↗

PubMed1990

Endocrine responses in the llama to copulation.

Nine adult female llamas were used to determine the time course for secretion of luteinizing hormone (LH) and estradiol-17beta (E(2)) following a single copulation (average 18 min), and progesterone (P(4)) during the development of the subsequent luteal phase. Heparinized blood samples were obtained through an indwelling jugular cannula at 15-min intervals for up to 24 h following copulation and then once daily for up to 10 d. Luteinizing hormone, assayed by radioimmunoassay (RIA) using a monoclonal antibody 518B7 against the beta subunit of bovine LH, was determined at 15 min intervals for 24 h following copulation. Estradiol-17beta was determined by RIA at 4-h intervals following copulation, then daily, while P(4) values were determined daily by enzyme immunoassay. A significant increase in LH concentration was observed by 15 min after the onset of copulation, with the peak of the preovulatory surge of LH occurring at 2 h; values were basal by 7 h after copulation. Estradiol-17beta values, unchanged through 18 h after copulation, tended to decline at 22 h (24 h, P<0.10) and were significantly lower than 18 h values by 48 h (P<0.05) after copulation. The first significant P(4) increase occurred at 3 d after copulation, with values increasing through 10 d. The LH surge observed subsequent to copulation is consonant with the llama being an induced ovulator.

Journal Article↗

PubMed1995

Extracellular dopamine in the medial preoptic area: implications for sexual motivation and hormonal control of copulation.

Dopamine (DA) activity in the medial preoptic area (MPOA) contributes to the control of male rat sexual behavior. We tested (1) whether extracellular DA increases during precopulatory exposure to an estrous female and during copulation, (2) whether exposure to another male increases extracellular DA, (3) whether motor activity during copulation accounts for increased DA levels, and (4) whether concurrent or recent testosterone influences DA levels or copulation in castrates. Extracellular DA and its metabolites in male rats' MPOA were measured using microdialysis. DA level increased during precopulatory exposure to the female in all animals that subsequently copulated; this included all intact animals, all testosterone-treated castrates, and 9 of 14 1-week castrates treated with oil vehicle. DA levels did not increase in any animal that subsequently failed to copulate, including the remaining 1-week, and all 2-week, vehicle-treated castrates. When the barrier was removed and the animals were allowed to copulate, levels of DA and its metabolites continued to rise in intact males and in castrates that copulated. The DA response to the estrous female could not be attributed to nonsexual social stimuli, since exposure to another male was ineffective. The DA response to copulation could not be attributed primarily to motor activity, since animals running voluntarily in a running wheel did not show significantly increased DA. These and previous data suggest that DA released in the MPOA in response to an estrous female may contribute to sexual motivation and copulatory proficiency. Testosterone may promote copulation in part through permissive actions on dopamine release.

Animals↗

PubMed1996

Ejaculatory pattern of llamas during copulation.

The objective of this study was to use transrectal digital palpation of urethral pulses to define the ejaculatory pattern of llamas during copulation. Five male llamas were palpated during 5 to 6 copulations each with receptive female llamas (n = 28 copulations). The time from first exposure of a male to a female until mounting was 0.7 +/- 1.1 min (mean +/- SD), time to the first intromission was 1.7 +/- 1.4 min, and time from initial mount to final dismount (copulation duration) was 21.7 +/- 7.8 min. A total of 121.9 +/- 61.0 urethral pulses per copulation (5.6 +/- 1.7 pulses/min) was palpated. During the first 3.9 +/- 3.7 min of copulation, urethral pulses (11.0 +/- 10.1 urethral pulses at 3.5 +/- 2.5 pulses/min) occurred randomly and were not associated with whole-body strains. After the first 4 min of copulation, urethral pulses occurred in a pattern of clusters of frequent urethral pulses associated with whole-body strains, alternating with intercluster intervals of infrequent urethral pulses without whole-body strains. Individual clusters were characterized by 4.3 +/- 2.7 urethral pulses at 16.7 +/- 4.5 pulses/min during strains, and intercluster intervals were characterized by 1.7 +/- 2.3 urethral pulses at 2.2 +/- 1.8 pulses/min. Each cluster of urethral pulses during a strain was preceded by 2.3 +/- 1.8 repositions of the male's hindlegs and by 38.1 +/- 20.8 pelvic thrusts. There were 18.5 +/- 10.6 clusters of urethral pulses accompanied by strains per copulation at 0.9 +/- 0.3 clusters/min. The 18 to 19 clusters of urethral pulses appeared to be individual ejaculations. Therefore, we hypothesize that llamas ejaculated 18 to 19 times during their 22-min copulations.

Journal Article↗

PubMed2000

Brain control of mating behavior in the male cricket Gryllus bimaculatus DeGeer: brain neurons responsible for inhibition of copulation actions.

We localized brain neurons responsible for the inhibition of copulation actions in the male cricket, Gryllus bimaculatus. Males with one connective-cut between the brain and the terminal abdominal ganglion (TAG) were able to perform normal reproductive behaviors such as courtship, copulation and spermatophore protrusion. However, copulation response tests using a female dummy showed that they failed to exhibit a transient inhibitory state after application of noxious stimulation in the mating stage and to exhibit a tonic inhibitory state in the post-copulatory sexual refractory stage. A partial cut of a single connective (hemilateral connective-cut) combined with the copulation response test and an axonal backfilling demonstrated that approximately 40 brain neurons (per one connective), whose somata were located in the posterior region of the protocerebrum and mainly contralaterally to their descending axons running through the dorso-medial part of the connective, were candidates for the inhibition of copulation actions, at least in the mating stage. In addition, we report here for the first time, that copulation actions can be elicited shortly after copulation even in intact males. This unusual behavior was frequently observed in fledglings after the final molt. The results are discussed from the perspective of the operation of the brain inhibition system on the central pattern generator (CPG) for copulation.

Journal Article↗

PubMed2003

Effects of testosterone metabolites on copulation and medial preoptic dopamine release in castrated male rats.

The medial preoptic area (MPOA) is an important integrative site for male sexual behavior. Dopamine (DA) is released in the MPOA of male rats shortly before and during copulation. The recent presence of testosterone (T) may be necessary for this precopulatory increase in release. Previously, the postcastration loss of copulatory ability mirrored the loss of the DA response to an estrous female, and the restoration of copulation with exogenous T was concurrent with the reemergence of this DA response. The present study investigated the effectiveness of the two major metabolites of T in maintaining copulation and basal and female-stimulated DA levels. Adult male rats were castrated and received daily injections of estradiol benzoate (EB), dihydrotestosterone benzoate (DHTB), EB + DHTB, testosterone propionate (TP), or oil vehicle for 3 weeks. Microdialysis samples were collected from the MPOA during baseline conditions, exposure to an estrous female behind a barrier, and copulation testing. EB + DHTB- and TP-treated animals had normal basal DA levels and showed a precopulatory DA response, and most copulated normally. EB-treated castrates had high basal DA levels, but failed to show a female-stimulated increase; most intromitted, but none ejaculated. DHTB- and oil-treated groups had low basal levels of extracellular DA that did not increase during copulation testing; most failed to mount and none ejaculated. These results suggest that E maintains normal basal levels of extracellular DA in the MPOA, which are sufficient for suboptimal copulation, but that androgen is required for the female-stimulated increase in DA release and for facilitation of ejaculation.

Analysis of Variance↗

PubMed1999

Effects of a D1 antagonist and of sexual experience on copulation-induced Fos-like immunoreactivity in the medial preoptic nucleus.

The medial preoptic nucleus (MPN) of the medial preoptic area (MPOA) and the medial amygdala are two brain regions in which male rat sexual behavior increased Fos-like immunoreactivity (Fos-Li). Dopamine is released in the MPOA during male rat sexual behavior and facilitates copulation. Psychostimulants, which increase dopamine levels, induce Fos-Li in the striatum through D1 receptors. We examined whether copulation-induced Fos-Li in the MPN was also mediated through D1 receptors. In Experiment 1, sexually inexperienced male rats that received the D1 antagonist Schering 39166 prior to their first sexual experience had fewer Fos-Li cells in the MPN than did those that received vehicle. In Experiment 2, no significant effect of the D1 antagonist was observed on copulation-induced Fos-Li in male rats that had received repeated sexual experiences prior to the drug test day. Sexual experience increases copulatory efficiency; the mechanisms by which this improvement occurs are unclear. In Experiment 3, copulation by highly experienced male rats led to greater Fos-Li in the MPN than did copulation by sexually naive males. Although there were no differences between groups in amygdala Fos-Li in these studies, in several groups Fos-Li in the medial amygdala was positively correlated with the post-ejaculatory interval. These experiments indicate that (1) stimulation of D1 receptors may contribute to the transient copulation-induced increase in Fos-Li in the MPN, and (2) repeated sexual experiences enhanced copulation-induced Fos-Li in the MPN, which may represent a marker of altered responsiveness of neurons in the MPN to sexual or conditioned stimuli.

Amygdala↗

PubMed1992

Hemispheric specialization for the control of copulation in the young chick and effects of 5 alpha-dihydrotestosterone and 17 beta-oestradiol.

After intramuscular treatment with either oestradiol (1 mg/day for 4 days) or 5 alpha-dihydrotestosterone (0.5 mg/day for 7 days) the copulatory behaviour of young male chicks was tested monocularly using removable eye-patches. From day 11 to 14 copulation scores were significantly elevated in chicks treated with oestradiol or 5 alpha-dihydrotestosterone (5 alpha-DHT) and tested either binocularly or monocularly using the left eye. There was no elevation of copulation when the treated chicks were tested monocularly using the right eye. Thus, in the binocular condition neural circuits receiving input from the left eye, and therefore likely to be on the right side of the brain, are specialized for the activation of copulation. This result confirms previous findings using chicks treated with testosterone. On day 14 the eye-patches were changed to the other eye. For chicks treated with oestradiol, those now tested using the left eye showed significantly higher levels of copulation than those now using the right. In other words, there was very little interocular transfer from left eye to right eye. However, after transferring the eye patches, the chicks treated with 5 alpha-DHT had high copulation scores irrespective of the eye used. This suggests that there may be an interaction between prior copulatory experience and 5 alpha-DHT levels which leads to either interocular transfer of copulation behaviour or equal access of both eyes to the brain regions which control copulation.

Animals↗

PubMed1991

The effect of ovarian follicle size on pituitary and ovarian responses to copulation in domesticated South American camelids.

The relation of ovarian follicle size to pituitary and ovarian responses to copulation was studied in domesticated South American camelids (llamas and alpacas). Females from each species were divided into four groups according to follicle size: small (4-5 mm), growing (6-7 mm), mature (8-12 mm), and regressing (10-7 mm). The pituitary response to copulation was determined by analysis of LH and FSH concentrations in plasma. The ovarian response to copulation was determined by ultrasonography and by analysis of estrone sulfate (follicular status) and pregnanediol glucuronide (luteal status) concentrations in urine. Females with small follicles (4-5 mm) released less LH after copulation than did those with larger follicles, and ovulation was not induced. Females with growing and mature follicles (7-12 mm) released LH in response to copulation that was adequate to induce ovulation and to initiate normal luteal activity. While copulation-induced LH release in females with regressing follicles was similar to that released in animals with growing and mature follicles, regressing follicles were luteinized instead of being ovulated. The luteal structure formed as a result of luteinization of follicles had a short life span, i.e., 5.1 days. Copulation-induced LH release was significantly higher in llamas vs. alpacas in animals with mature or regressing follicles, but not in those with small or growing follicles. Urinary estrone sulfate and pregnanediol glucuronide concentrations correlated positively with the presence of follicles and corpora lutea, respectively.

Animals↗

PubMed1992

Pituitary response to repeated copulation and/or gonadotropin-releasing hormone administration in llamas and alpacas.

The response of the pituitary gland and ovary to repeated copulatory periods and/or gonadotropin-releasing hormone (GnRH, i.v. 1000 micrograms) administration was determined in llamas and alpacas. Eighty adult females (41 llamas and 39 alpacas with ovulatory follicles) were divided into three general groups for each species as follows: copulation (one or two copulations at either 6- or 24-h intervals) GnRH treatment (one or two treatments at either 6- or 24-h intervals), and combined treatment (copulation followed by GnRH treatment, or GnRH followed by copulation at either 6- or 24-h intervals). An additional control (nontreated) group was composed of 4 llamas and 4 alpacas. The first copulation or treatment with GnRH provoked LH release sufficient to cause ovulation in most of the females (alpacas, 89%; llamas, 92%); urinary pregnanediol glucuronide values, used to verify ovulation, were significantly elevated 48 h after copulation and/or GnRH treatment. A second stimulus, copulation or GnRH, provoked no LH response with concentrations similar to those in nontreated controls and in females not ovulating. Llamas and alpacas thus were refractory to a second copulatory or GnRH stimulus with regard to LH release for up to 24 h following an initial ovulatory release of LH.

Animals↗

PubMed1998

The function of Barbary macaque copulation calls.

In a wide variety of animal species, females produce vocalizations specific to mating contexts. It has been proposed that these copulation calls function to incite males to compete for access to the calling female. Two separate advantages of inciting male-male competition in this way have been put forward. The first suggests that as a result of calling, females are only mated by the highest ranking male in the vicinity (indirect mate choice hypothesis). The second proposes that copulation calling results in a female being mated by many males, thus promoting competition at the level of sperm (sperm competition hypothesis). In this paper, I give results from the first experimental study to test these hypotheses. Playback was used to examine the function of copulation calls of female Barbary macaques (Macaca sylvanus) in Gibraltar. Although rank did not affect lone males' likelihood of approaching copulation calls, when playbacks were given to pairs of males only the higher ranking individual approached. Moreover, females were mated significantly sooner after playback of their copulation call than after playback of a control stimulus. These results suggest that the copulation calls of female Barbary macaques play a key role in affecting patterns of male reproductive behaviour, not only providing an indirect mechanism of female choice, but also promoting sperm competition by reducing the interval between copulations. Potential fitness benefits of inciting male-male competition at these two levels are discussed.

Animals↗

PubMed2000

Why it is difficult to model sperm displacement in Drosophila melanogaster: the relation between sperm transfer and copulation duration.

We have investigated the effects of experimental manipulation of copulation duration on sperm displacement in Drosophila melanogaster. Both spermless and normal males were used as second (displacing) males in the experiments. Displacement induced in the absence of sperm, that is, by males that pass accessory gland fluid alone, was a relatively inefficient process and produced much lower levels of displacement than normal males. Therefore, the presence of second-male sperm is necessary (but unlikely sufficient) for the high levels of displacement commonly observed in D. melanogaster. Furthermore, when second matings were interrupted at various times after the initiation of copulation, the distribution of displacement was strongly bimodal. We conclude that sperm transfer is relatively rapid, beginning shortly after the initiation of copulation, and is essentially complete before the midpoint of copulation. Therefore, sperm transfer bears no simple relation to copulation duration. Because it would be difficult to manipulate the numbers of sperm transferred by manipulating copulation duration, methods used to study sperm displacement in other insect species are unlikely to be appropriate for D. melanogaster. We also investigated why males mate for more than twice the duration that appears to be necessary to complete sperm transfer. Experimental interruption of first matings indicated that the extra copulation time serves to delay female remating, rather than to increase that rate at which of offspring are sired before remating.

Animals↗

PubMed1989

D2/D1 ratio in the medial preoptic area affects copulation of male rats.

The D1/D2 dopamine agonist apomorphine, microinjected into the medial preoptic area (MPOA), facilitates male rat sexual behavior and the D1/D2 antagonist cis-flupenthixol in the MPOA impairs it. The present study investigated the roles of D1 and D2 receptors in the regulation of copulation by microinjecting drugs selective for these receptors into the MPOA. The D2 agonist LY-163502 delayed the onset and slowed the rate of copulation and also reduced the number of vaginal intromissions required to trigger ejaculation (reduced ejaculatory threshold). The D1 agonist SKF-82526 had no effect, either alone or together with LY-163502. The D1 antagonist SCH-23390 delayed the onset of copulation and decreased ejaculatory threshold, as had the D2 agonist. A low dose of the D2 agonist alone and together with the D1 antagonist delayed the onset of copulation and reduced ejaculatory threshold; the combination of drugs was more effective than LY-163502 alone. Only the combination of drugs slowed the rate of copulation and delayed the resumption of copulation after an ejaculation. Thus, increasing the D2/D1 ratio in the MPOA, by selective stimulation of D2 and/or antagonism of D1 receptors, delays the onset of copulation and reduces ejaculatory threshold, possibly by altering autonomic control of penile reflexes.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗

PubMed1997

Copulation and mate-guarding patterns in polygynous European starlings

We recorded the timing and frequency of copulation and mate-guarding behaviour during the fertile period in relation to day of first ovulation and time of day in the facultatively polygynous European starling, Sturnus vulgarisAll within-pair copulations were female-solicited. Females solicited them at a high rate during both the pre-ovulatory and ovulatory period, but there were differences in solicitation rates between monogamous, primary and secondary females. Extra-pair copulation attempts were all male-initiated and females rarely engaged in them. Attempts by males were most frequent during the ovulatory period, when the probability of extra-pair fertilization was highest. Males intensively guarded their mate during both the pre-ovulatory and ovulatory period. In contrast to most other passerines, female starlings lay their eggs not at dawn but usually between 0900 and 1100 hours, implying that they may be most fertile in the late morning. During the ovulatory period, extra-pair copulation attempts were more frequent in the late morning than in the early morning, suggesting that males try to take advantage of this putative 'insemination window'. Accordingly, there was some indication that mate guarding during the ovulatory period was more intense in the late than early morning. Females solicited within-pair copulations at a higher rate in the early morning than in the late morning, but copulation rate did not differ between early and late morning. The proportion of monogamous and polygynous males attempting extra-pair copulations did not differ significantly, but mate-guarding intensity differed significantly between female categories. Primary females were guarded less intensively than monogamous females suggesting that males trade mate guarding against mate attraction/courting additional females.

Journal Article↗

PubMed1997

Territorial intrusions and copulation behaviour in the great skua, Catharacta skua

Birds of many species intrude on to territories in order to obtain extra-pair copulations, and frequent within-pair copulations are thought to be a response to cuckoldry where mate guarding is not possible. Great skuas are colonial birds in which females are left alone in the breeding territory while males forage for the pair. Opportunities for cuckoldry are therefore numerous, and it could be predicted that sperm competition should be intense in this species. We tested several hypotheses that attempt to explain territorial intrusions by female great skuas. Few intrusions coincided with the main fertile period and extra-pair copulations were almost never solicited, and therefore the sperm competition hypothesis was rejected. Only 0.9% of the copulations observed (N=339) were extra-pair. Thus opportunity for cuckoldry is a very poor predictor of the intensity of sperm competition, in spite of the relevance given to this factor in the literature. Of three extra-pair copulations observed, two involved unpaired territorial males. This suggests that genetic benefits were not the aim of unfaithful females. All three were preceded by courtship feeding, while only 26% of within-pair copulations followed successful food begging. This statistically significant difference constitutes evidence for a trade of copulations for food in a monogamous bird. Evidence is presented supporting hypotheses that females intrude on to territories in order to induce males to give away some food, and to become familiarized with potential partners for future breeding seasons.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Journal Article↗