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PubMed1982

Role of striated penile muscles in penile reflexes, copulation, and induction of pregnancy in the rat.

In 4 experiments, various striated penile muscles of the rat were excised. Without the ischiocavernosus (IC) muscles no dorsiflexions ('flips') of the glans penis occurred during ex copula reflex tests, but erections were unaffected. In attempted copulation, males lacking the IC muscles rarely gained intromission, apparently because dorsiflexion of the glans penis is necessary for penetration of the vagina. Nonetheless some males lacking the IC muscles displayed the gross motor pattern of intromission and ejaculated, but rarely within the vagina. Males lacking the bulbocavernosus (BC) and levator ani (LA) muscles were incapable of developing intense erections ('cups') in ex copula tests, but they did have lesser erections, probably due to vascular action. Males with excised BC and LA muscles displayed normal copulatory behaviour, including intromission and intravaginal ejaculation, but only 1/15 females mated to these males became pregnant. The infertility of the males was attributed in part to their inability to form the penile cup, which caused them to withdraw a larger portion of the seminal plug from the vagina and, presumably, prevented the plug from being tightly lodged against the cervix. In male rats copulation apparently requires co-ordination of the penile vasculature with the contraction of separate groups of striated penile muscles, each having a distinct contribution to the integrated pattern of copulation and, ultimately, to the male's fertility.

Animals↗

PubMed1996

Relaxin in peripheral plasma of boars during development, copulation, after administration of hCG and after castration.

Seventy-two Yorkshire boars were used in five experiments to evaluate the temporal changes in relaxin concentrations in peripheral blood plasma during prepubertal development, copulation, after castration and after treatment with hCG. High concentrations of relaxin (484 +/- 27 pg ml-1) were detected at 11 weeks of age but there was no positive correlation with testicular development. Relaxin concentrations fluctuated in mature boars but the results do not suggest a diurnal rhythm, although there is the possibility of pulsatile secretion. A decrease (P < 0.05) in circulating relaxin was observed before and immediately after copulation. Castration of boars at 90, 115, 160 and 200 days of age did not significantly decrease relaxin concentrations within 48 h. Administration of hCG significantly depressed relaxin secretion at 90 days of age but not at 160 days of age. These studies suggest a non-gonadal source of boar relaxin that is not correlated with testicular growth or testosterone concentrations, is modulated by copulation and by hCG but only at specific stages of development.

Animals↗

PubMed1975

Plasma luteinizing hormone and testosterone in the adult male pig: 24 hour fluctuations and the effect of copulation.

Secretory patterns of LH and testosterone were characterized in the intact male miniature pig. All blood samples were taken from indwelling catheters. Hourly sampling was carried out over 24 h and during a morning period blood was collected for 2 h at 10 min intervals. No significant difference was detected in the plasma LH concentration on the basis of hourly sampling. Plasma testosterone was significantly (P less than 0-05) lower during the evening and night when compared with morning values. The second experiment was concerned with the pattern of plasma LH and testosterone concentrations before and after copulation. Blood sampling was performed at 10 min intervals. Plasma LH was significantly (P less than 0-001) raised for 30 min after copulation when compared with any 30 min period (0-120 min) before copulation. Plasma testosterone was not significantly altered for any 30 min period of the experiment (0-270 min). The data are interpreted as a possible mechanism for endocrine control of testicular function.

Animals↗

PubMed1984

The role of neurotransmitters in mediating copulation-induced ovulation in the rat.

Pentobarbitone-blocked pro-oestrous rats were subjected to either limited mating (maximum of 30 mounts), all-night cohabitation with males or stimulation of the vagina and cervix with a glass rod (2 or 5 min) to determine which type of stimulus was most effective in inducing ovulation. All-night cohabitation was the most successful procedure and resulted in 100% ovulation in those rats which mated. Treatment with either phenoxybenzamine, propranolol or pimozide did not interfere with this copulation-induced ovulation whereas methysergide treatment completely blocked copulation-induced ovulation. Administration of atropine resulted in a loss of mating behaviour and these animals therefore did not ovulate. Further experiments provided evidence that administration of atropine also blocked ovulation in response to vaginal stimulation with a glass rod. Pretreatment with methysergide or atropine had no effect upon the percentage of pentobarbitone-blocked, pro-oestrous rats ovulating in response to administration of LH releasing hormone (LHRH). However, those rats given atropine shed significantly fewer ova per rat following LHRH or LH infusion when compared with controls. These results suggest that the synaptic mechanisms responsible for mediating copulation-induced ovulation are different from those mediating steroid-induced ovulation, and that ovarian cholinergic receptors may play a role in ovulation.

Animals↗

PubMed1978

Investigation of copulative activity in male rats in chronic experiment.

Copulative activity of 28 male Wistar rats was investigated for one year at 6 to 8 day intervals. Metholds have been worked out for the selection of sexually active males. It was found that it is possible to investigate copulative activity permanently in a selected population of male rats. The sexual activity index number of intromissions/time of ejaculation can be applied to the 15-minute test. In order to evaluate individual differences observed during the experiments, the ratio positive experiments/all experiments has been used. During a one-year experimental period (791 experiments altogether) mean latency time was 56'', and that of the ejaculation 7'10''. The average number of intromissions was 7.89, and that of attempts 3.41. Ejaculation occurred 575 times. The average sexual activity index was 1.1. There was no seasonal fluctuation in copulative activity.

Animals↗

PubMed2003

Effects of testosterone in the VMN on copulation, partner preference, and vocalizations in male rats.

The present study tested whether testosterone propionate (TP) implanted in the ventromedial nucleus (VMN) of the hypothalamus could initiate performance, motivational, or sociosexual components of sexual behavior in castrated male rats. Twenty-seven intact male Long Evans rats were pretested for copulation, partner preference, and 50-kHz vocalization and were subsequently castrated. Approximately 3 weeks after castration, males were retested to confirm that these behaviors had declined, and groups were assigned. Groups 1 and 2 were implanted with bilateral stainless steel cannulae directed at the VMN that were either filled with TP (TVMN group) or remained empty (Blank group). A third group (TSC) was implanted subcutaneously with two 10-mm Silastic capsules filled with testosterone. Restoration of behavior was measured for 2 weeks after implants. We found that copulation and 50-kHz vocalization were not restored by TP in the VMN alone. However, partner preference returned to preoperative levels in both the TVMN and TSC groups, indicating that TP in the VMN was sufficient to restore sexual motivation. Following behavioral testing, prostate glands and seminal vesicles were weighed and confirmed that TP did not leak into the periphery in the TVMN group. Immunostaining for androgen receptors also verified that TP spread was confined to the immediate area surrounding the cannula tip. These results suggest that androgen activation at the VMN is sufficient to induce the motivational components of male sexual behavior, whereas activation of other brain sites is required for copulation and ultrasonic vocalization.

Animals↗

PubMed1994

Single- and multilocus DNA fingerprinting of communally breeding pukeko: do copulations or dominance ensure reproductive success?

In behavioral and ecological studies the "function" of dominance hierarchies is thought to be related to reproductive success. In particular, dominant males are regarded as likely to gain a reproductive advantage due to enhanced "access" to females. We compare the dominance status of adults with the frequency of copulations and the patterns of parentage in communally breeding pukeko or purple swamphen (Porphyrio porphyrio melanotus). This avian species has an unusual social system, often breeding in polygynandrous groups in which there is a strong dominance hierarchy. Typically, during the breeding season, there is considerable sexual activity, with heterosexual and homosexual copulations between adults being commonplace. Hae III-digested DNA from individuals belonging to breeding groups was hybridized to the minisatellite DNA probe YNH24, revealing putative single-locus profiles, while hybridization of the same DNA to the minisatellite probes pV47-2, 3'HVR, and per revealed typical multilocus profiles. The numbers of unattributable restriction fragments allowed the maternity and paternity of all individuals to be conclusively determined, despite high levels of band sharing among individuals within breeding groups. These close genetic similarities are a likely consequence of strong philopatry and inbreeding. We report instances of males which are high on the dominance hierarchy but have only a limited reproductive output in comparison with others and males which are subordinate but achieve a significant proportion of fertilizations. Generally these data reveal no consistent relationship between dominance, the frequency of copulations, and parentage among males. We conclude that pukeko highlight some difficulties with conventional explanations for the "function" of dominance.

Animals↗

PubMedDate not supplied

Behavior of triatomines (Hemiptera: Reduviidae) vectors of Chagas' disease. II. Influence of feeding, lighting and time of day on the number of matings, mating speed and duration of copulation of Panstrongylus megistus (Burm, 1835) under laboratory conditions.

To determine the influence of feeding, lighting and time of day on the copulating behavior of Panstrongylus megistus, 480 insect pairs were divided into four groups of 120 each and tested in the following respective situations: without food deprivation (F.D.), with five days of F.D., with ten days of F.D., and with 20 days of F.D. The tests were performed between 9:00 a.m. to 12:00 a.m. and 7:00 p.m. to 10:00 p.m., with light (700-1400 lux) and in the dark (1.4-2.8 lux) and behavior was recorded by the time sampling technique. Mating speed (MS) and duration of copulation (DC) were also calculated for each situation. The maximum frequency of copulation was observed after five days of F.D., at night, in the dark (n = 16), and the minimum was observed for recently-fed pairs, at night, with light (n = 4). Males approached females more often than females approached males. MS was lowest in pairs with twenty days of F.D., at night, with light (mean = 23.0 +/- 16.0 minutes), and highest in recently-fed pairs, during the day, with light (mean = 2.9 +/- 2.5 minutes). DC was shortest in recently-fed insects, during the day, in the dark (mean = 23.5 +/- 6.7 minutes), and longest in recently-fed animals, at night, in the dark (mean = 38.3 +/- 6.9 minutes).

Animals↗

PubMedDate not supplied

[A scale for the quantitative evaluation of male copulative function (the MCF scale)].

A scale of total quantitation of male copulative function (MCF) is offered to facilitate the diagnosis and monitoring of MCF abnormalities, control of MCF correction. The scale is based on normal values provided by statistical data on sexual activity of males and its age-related changes. The patient is asked to answer 13 questions of the questionnaire listed under the numbers I-XIII. Each question has 6 variants of answer having the score 0 to 5. The patient is to choose one variant and write down his choice. Such MCF scale is able to identify both sexual disorder and defects in components of the copulative cycle. The scale was applied 89 times to study sexual function of 68 males aged 24-77 years. The scale findings and those of a comprehensive clinical examination coincided. The scale was found useful in evaluation of male copulative function as a whole and by components, for analysis of the detected disorders, differentiation between psychogenic factor and primarily organic one, for ascertaining attitude of the patient to his sexual dysfunction.

Coitus↗

PubMed1998

Transmitter identification in neurons involved in male copulation behavior in Lymnaea stagnalis.

In this paper, we have mapped the cellular localization of various transmitters onto the central neurons which are involved in male copulation behavior in Lymnaea stagnalis, by combining retrograde tracing with immunocytochemistry and in situ hybridization. Evidence is provided that neurons which were backfilled from the penis nerve, the sole nerve to innervate the male copulatory organ, synthesize a multitude of neuropeptides (APGWamide, Lymnaea neuropeptide tyrosin [LNPY], conopressin, pedal peptide, SEEPLY, DEILSR, myomodulin, and Lymnaea inhibitory peptide [LIP]) as well as the classical neurotransmitter, serotonin. In the anterior lobe, the backfilled neurons mainly contain the tetrapeptide APGWamide and conopressin, and not LNPY or pedal peptide. The results suggest a central role in the regulation of copulation activity for the anterior lobe neurons that produce APGWamide and conopressin. Immunostainings of backfilled nervous systems revealed immunopositive axons originating from these neurons to form varicosities on the cell somata of neurons in the other clusters contributing to the innervation of the male sexual system. Neurons from the right parietal ganglion projecting into the penis nerve were electrophysiologically and morphologically identified by simultaneously recording from the cell body intracellularly and the penis nerve extracellularly and subsequently filling them with an anterograde tracer and subjecting them to immunocytochemistry. This method has provided links between morphology, physiology, and the transmitter contents of these neurons.

Animals↗

PubMed1999

Androgen threshold to activate copulation differs in male rats prenatally exposed to alcohol, stress, or both factors.

Few male rats prenatally exposed to a combination of alcohol and stress copulate spontaneously. This study determined adult sensitivity to testosterone (T) in males prenatally exposed to alcohol, to stress, or to both factors. Sexually naive males were tested with receptive females following castration and implantation of 20-, 30-, or 45-mm Silastic T-filled capsules. Serum T levels provided by these implants were measured. The behavior shown by males exposed only to prenatal alcohol did not differ from untreated control animals at any T dosage. Prenatal stress alone diminished the copulatory potential below control levels only when the intermediate T dosage was provided. Few males exposed to both alcohol and stress copulated under the lowest or the intermediate dose of adult T replacement, but most ejaculated normally when the largest capsule was implanted. The threshold to the sexual behavior-activating-properties of adult T exposure was moderately raised by prenatal stress but was severely affected when prenatal stress was combined with alcohol. We conclude that a diminished sensitivity to androgen in adulthood underlies some copulatory deficits resulting from treatments that alter fetal T levels. Such deficits may be concealed when behavior is evaluated in gonadally intact animals.

Androgens↗

PubMed1977

Transmission of Nosema kingi to offspring of Drosophila willistoni during copulation.

Transmission of the microsporidian Nosema kingi to offspring of Drosophila willistoni during copulation was investigated. Offspring from matings of infected females and non-infected males, infected males and non-infected females, and both infected females and males were parasitized with N. kingi. 28% of the offspring were infected when the parents mated immediately after exposure to the parasite. However, 43--93% of the offspring were infected with the microsporidian when copulation was delayed 2 weeks post-infection.

Animals↗

PubMed1986

Physiological changes during copulation in male and female stumptail macaques (Macaca arctoides).

Radiotelemetric recordings were made of uterine contractions in female stumptail macaques, and of heart and respiratory rate in stumptail monkeys of both sexes, before, during and after copulation. These data were fed into a multichannel recorder, along with a spoken record of behavioral changes. Males' heart and respiratory rates were raised during penile thrusting, reached a peak and then fell sharply after ejaculation. Uterine movements were similar during successive copulations. After uterine movements associated with penile thrusting prior to ejaculation a rise in contraction force occurred which lasted about 15 seconds. It is in this period, if ever, that a climax face was displayed by the female. The female's look-back and reach-back behaviors were not linked to either the pattern of uterine contractions or the occurrence of the climax face.

Animals↗

PubMed1987

Disruption of ejaculates by male copulation in deer mice (Peromyscus maniculatus).

Six experiments were conducted to analyze possible disruption of sperm transport occurring when one male deer mouse copulates soon after another male ejaculates. When a second male mated soon after the first, females had significantly fewer uterine sperm 1 hr later than when a delay of 7 or 15 min was imposed between males. However, it was impossible to detect any effect of such disruption on pregnancy initiation. Similarly, artificial stimulation soon after an ejaculation was ineffective in disrupting pregnancy initiation. No effect of a rapid resumption of copulation could be detected on litter composition in a sperm competition situation. Although it is clear, from these and other data, that the phenomenon of ejaculate disruption occurs in deer mice, technical difficulties may interfere with experimental analysis.

Animals↗

PubMed1988

GABAergic regulation of penile reflexes and copulation in rats.

In three experiments we investigated the role of the GABAergic system in regulating penile reflexes and copulation in rats. All males had the suspensory ligament of the penis removed 3 weeks before the experiments, thereby permitting the novel observation of penile body erections in addition to penile glans responses. In Experiments 1 and 2, rats were assigned to one of the following treatment groups: control (saline-injected); baclofen, a GABA-B receptor agonist (1 or 2 mg/kg); THIP, a GABA-A receptor agonist (5 mg/kg); or (+)bicuculline, a GABA-A receptor antagonist (0.25 mg/kg). Penile reflex tests began 20 min after SC injection. Baclofen treatment decreased the number of males responding with glans erections within the 30 min latency limit, and significantly reduced the number of glans erections displayed, in a dose-dependent manner. These results indicate that activation of GABA-B receptors inhibits penile reflexes outside the context of copulation (ex copula). Rats treated with baclofen also had a dose-dependent reduction in the ratio of clusters of glans erections to penile body erections, and a significant increase in the number of penile body erections observed prior to the first glans erection. These findings suggest that baclofen inhibited the mechanisms mediating penile glans responses more than those mediating penile body erections. Bicuculline was without effect in both experiments; THIP significantly increased erections in Experiment 2 but had no reliable effect in Experiment 1. Because baclofen inhibited penile responses in ex copula tests, Experiment 3 was designed to assess the effects of the same dosages of this agent on male copulatory behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

A novel environment disrupts copulation in sexually naive but not experienced male rats: reversal with naloxone.

Relative to sexually experienced male rats, sexually naive males typically display a pattern of copulatory behavior that is characterized by a larger proportion of rats that do not copulate: those that do copulate during their first exposure to a sexually receptive female have longer mount, intromission, and ejaculation latencies, and longer postejaculatory intervals. A male rat's first sexual experience often coincides with the first exposure to handling and to the novel testing apparatus. Because handling or exposure to novel environments is stressful and can induce the release of endogenous opioids, and because the opioid antagonist naloxone can facilitate the copulatory behavior of sexually naive male rats, we examined whether preexposure to handling alone, or to handling and a novel testing chamber, would diminish the magnitude of the relative disruption observed in sexually naive male rats. Handling alone did not increase the proportion of males that mounted or intromitted, whereas preexposure to the chamber increased these proportions significantly and decreased the mount and intromission latencies, and the number of mounts without intromission. Naloxone hydrochloride (10 mg/kg) facilitated the display of mounts and intromissions in rats that were preexposed to handling alone, but had no effect in rats that had been additionally preexposed to the testing chambers. In contrast, the copulatory behavior of rats with extensive sexual experience was not adversely affected in a novel testing chamber. Novelty disrupts the copulatory behavior of sexually naive males and may do so by increasing endogenous opioid activity. However, sexual experience appears to diminish or eliminate the disruptive effect of a novel environment.

Animals↗

PubMed1977

5-hydroxytryptamine depletion with para-chlorophenylalanine: effects on eating, drinking, irritability, muricide, and copulation.

Forty-four male rats were tested for eating, drinking, irritability, and copulation before and after intraperitonial para-chlorophenylalanine (PCPA) or control injections. Eleven of these rats were tested for muricide before and after PCPA injections (Group 1), while 18 others were tested only after PCPA injections (Groups 2). Group 1 rats received four 350 mg/kg PCPA injections spaced 6 days apart and showed hyperdipsia, weight loss, and a 24% increase in muricide. Group 2 rats received five daily 100 mg/kg PCPA injections repeated 11 days later and showed hyperdipsia and weight loss; in addition, 78% of them killed mice. Neither group showed significant changes in copulation. At the end of the experiment, t6 rats from Group 2 that were irritable and killed mice were injected intraperitonially with 5-hydroxytryptophan (80 mg/kg). Five of these rats lost their irritability and four stopped killing. The various behavioral changes were not corrleated significantly either with each other or with the degree of 5-hydroxytryptamine depletion. This tentatively suggests that PCPA may produce its effects on behavior by other means in addition to 5-hydroxytryptamine depletion.

Aggression↗

PubMed1980

Copulation-induced abbreviation of estrus in the female guinea pig: block by clonidine.

In the female guinea pig, copulation produces a rapid inhibition of subsequent sexual receptivity. Injection of the alpha adrenergic agonist clonidine before mating blocked the early inhibitory effects of coital stimulation, while the serotonergic antagonist methysergide, and the dopaminergic antagonist pimozide were without effect. The effects of clonidine were prevented by pretreatment with the alpha adrenergic antagonist yohimbine. These results suggest that an adrenergic system is involved in the copulation-induced inhibition of receptivity and provide further evidence that such a system has an important facilitative role in the control of female sexual behavior in the guinea pig.

Animals↗