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At least 19 recordsLinked to original sources
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↗
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↗
PubMed1989

Failure of fertilization following abbreviated copulation in the ferret (Mustela putorius furo).

In the first experiment, copulations in 10 domestic ferrets were interrupted 5 minutes after penetration. Ten control females were bred without interruption to the same males. Both control and experimental animals were rebred in the same manner to the same males 24 hours later. Sperm were present in all postcoital washes. We allowed all females from the first experiment to proceed to their expected date of parturition. All females who had been interrupted during copulation failed to conceive, whereas all controls produced litters. In a second experiment, the same procedure was followed; however, in this experiment, ferret oviducts and uteri were flushed 10 days after copulation. Nine control females (one failed to ovulate) averaged 5.2 blastocysts (range 2-10; S.D. = 5.8) per animal. Of nine interrupted copulation ferrets (one failed to ovulate), only one animal produced a single blastocyst. The interrupted copulation group averaged 4.4 unfertilized eggs (range 2-10; S.D. = 5.0) per female. Although ferrets ovulated during short copulations, those eggs are not likely to be fertilized.

Animals↗
PubMed1989

Testosterone implanted in the preoptic area of male Japanese quail must be aromatized to activate copulation.

Intracranial implantation of minute pellets of gonadal steroids was combined with aromatase inhibitor treatment to determine if aromatization within the preoptic area (POA) is necessary for androgens to activate sexual behavior in the Japanese quail (Coturnix japonica). In this species, implantation of pellets of testosterone propionate (TP) or estradiol benzoate (EB) in the POA of castrated males restores male-typical copulatory behavior. In Experiment 1, adult male castrated quail were implanted intracranially with 200-micrograms pellets of equimolar mixtures of crystalline TP + cholesterol (CHOL), TP + 1,4,6-androstatriene-3,17-dione (ATD, an aromatase inhibitor), EB + ATD, or CHOL and behavior-tested with intact males and females. Copulation was stimulated by POA implants containing TP or EB (three of six CHOL + TP males and two of seven ATD + EB males copulated vs zero of four CHOL males), but copulation was not inhibited by combining ATD with TP (three of four ATD + TP males copulated). In Experiment 2, adult male castrated quail were injected systemically with ATD or oil for 6 days prior to and 14 days after intracranial implantation of 200-micrograms pellets containing the same amounts of TP or EB as in Experiment 1. The ATD injections completely blocked copulatory behavior in males with TP implants in the POA such that ATD/TP and Oil/TP mount frequencies differed significantly, but failed to block copulation in males with EB implants in the POA (proportions of males copulating were ATD/EB, 6/8; ATD/TP, 0/6; Oil/TP, 4/7). The cloacal foam gland, an androgen-sensitive secondary sex character, was unaffected by the dose of ATD used. We conclude that activation of copulatory behavior by TP implants in the POA is not due to nonspecific effects of high local testosterone concentrations but rather to aromatization. These results support the hypothesis that cells within the POA aromatize testosterone to estrogens, which directly stimulate the cellular processes leading to activation of male-typical copulatory behavior.

Androstatrienes↗
PubMed1977

Secretion in the rat coagulating gland (anterior prostate) after copulation.

The effect of copulation on the rat coagulating gland (anterior prostate) was studied. At 4 to 6 h after the beginning of copulation the coagulating glands of rats that had produced copulatory plugs were nearly empty of secretion. Ultrastructurally, the coagulating gland has large cisternae of rough endoplasmic reticulum (RER) and few condensing vacuoles or secretion granules. After copulation the number of secretion granules and the frequency of their expulsion into the lumen increased. Also in the lumen were "fragmentation" vesicles (50-100 nm diameter) that were bounded by a unit membrane and appeared to arise from microvilli. At 4, 6, and 7h after the beginning of copulation there was an increase in apical blebbing. Blebbing was found in both perfusion and immersion-fixed tissue. Also, after copulation there was an increase in "light cells" that were characterized by reduced RER cisternae, an electron lucent cytoplasm, and atrophic Golgi apparatus. The luminal ground substance, secretion granules, and some Golgi elements, contained polysaccharides as seen with the periodic acid-thiocarbohydrazide-silver proteinate method.

Animals↗
PubMed1991

Dopamine receptors in the ventral tegmental area affect motor, but not motivational or reflexive, components of copulation in male rats.

Microinjection of apomorphine into the ventral tegmental area (VTA) of male rats was previously shown to delay the onset of copulation and slow its rate, presumably by stimulating impulse-regulating autoreceptors on cell bodies of the A10 mesocorticolimbic dopamine tract. Such stimulation would be expected to slow the firing rate of these neurons and, thereby, to impair locomotion and/or motivational processes. The present experiments tested whether the delayed onset and slowed rate of copulation were related to deficits in motor performance, sexual motivation, and/or genital reflexes. In X-maze tests the speed of running to all 4 goal boxes was slowed; however, the percentage of trials on which the male chose the female's goal box was not decreased. Examination of videotaped copulation tests revealed that the male showed fewer complete copulatory behaviors (mounts, intromissions, and ejaculations), but more misdirected or incomplete copulatory attempts after apomorphine in the VTA. There were also fewer scores of active, as opposed to inactive, behaviors, and the onset and rate of copulation were slowed. The total number of female directed behaviors was not different in apomorphine tests, compared to vehicle. Finally, tests of ex copula genital reflexes revealed no significant effects of apomorphine in the VTA on erections, penile movements, or seminal emissions. These data suggest a role of the VTA in the motor aspects and/or sensorimotor integration of copulation. Sexual motivation and ex copula genital reflexes appeared to be unaffected by apomorphine in the VTA.

Animals↗
PubMed1992

Male rat copulation following 6-OHDA lesions of the medial preoptic area: resistance to repeated administration and rapid behavioral recovery.

Dopamine (DA) in the medial preoptic area (MPOA) has been shown to facilitate male rat sexual behavior. However, injections of the catecholamine (CA) neurotoxin 6-OHDA into the MPOA did not impair copulation in tests 3 days after injection. In the present study, three weekly (serial) injections produced no copulatory deficits compared to animals that received a single injection or to preinjection copulatory behavior scores. However, blocking CA synthesis, which did not impair control rats, produced deficits in both single and serial lesion animals, with significantly fewer serial than single lesion animals initiating copulation. Biochemical analysis of tissue punches showed no difference in MPOA concentrations of dopamine, norepinephrine, epinephrine, or the dopamine metabolite DOPAC between the two groups. Additional animals were tested at earlier intervals after 6-OHDA injections into the MPOA. Tests conducted 30 min after an MPOA injection of 6-OHDA revealed that all measures of copulation were impaired, relative to scores 24 h later. However, these scores were not significantly different from animals tested 30 min after a vehicle injection. A final group, tested 4 h after injection, showed impairment of all measures of copulation compared to vehicle injections and to tests 24 h later. Furthermore, in the tests 24 h later, 6-OHDA animals were not different from vehicle animals. Results from all experiments show that 6-OHDA injections into the MPOA impair copulation for at least 4 h, but that behavioral recovery is complete 24 h later. However, deficits can be reinstated by inhibiting DA synthesis, suggesting that increased synthesis in undamaged terminals contributed to behavioral recovery.

Animals↗
PubMed1992

Plasma testosterone concentration in adult male rats following acquisition of copulation-illness associations.

Prior research has identified stimuli and procedures that elicit increments in plasma testosterone in copulating male rats. In the present experiment, we demonstrate that associative inhibition of copulatory behaviors in male rats is not correlated with and cannot be attributed to a conditioned suppression of testosterone. Each male rat was paired with an inaccessible estrous female for 7 min and was then given an opportunity to copulate. Two groups received an injection of either lithium chloride (LiCl; 0.3 M, 20 ml/kg, IP) or saline (0.3 M, 20 ml/kg, IP) immediately after each of 11 pairings spaced at 3- to 4-day intervals. A third group received a noncontingent injection of LiCl 24 h after each pairing. After an initial screening for copulatory behaviors, a fourth group received only handling comparable to that received by the other three groups. Rats that received contingent LiCl gradually ceased to copulate; rats that received either noncontingent LiCl or saline remained vigorous copulators. Male rats were returned to their home cages on Trial 12 after 7-min exposure to an inaccessible female. Blood was collected by decapitation 38 min later. Testosterone levels, measured by radioimmunoassay, were significantly higher for saline than for handled control rats. Testosterone levels for handled control rats, however, were comparable to those of copulating and noncopulating rats that had received either noncontingent or contingent LiCl, respectively.

Animals↗
PubMedDate not supplied

Behavior of triatomines (Hemiptera: Reduviidae) vectors of Chagas' disease. I. Courtship and copulation of Panstrongylus megistus (Burm., 1835) in the laboratory.

A study of the courtship and copulation behavior of Panstrongylus megistus was carried out in the laboratory. Fifty-five newly-fed virgin couples were used. Experiments were performed during the day (9:00 to 12:00 a.m.) and at night (7:00 to 10:00 p.m.). Behavior was recorded by direct observation and was found to consist of the following sequence of behavioral patterns: the male approached the female and jumped on her or mounted her; he took on a dorsolateral position and immobilized the female dorsally and ventrally with his three pairs of legs; the male genital was placed below those of the female; the paramers of the male immobilized the female's genitals; copulation started. The couple joined by the iniciative of the male. The female could be receptive and accept copulation, or nonreceptive and reject the male. Copulation occurred more often on the occasion of the first attempt by the male. Duration of copulation was X = 29.3 +/- 9.3 min (CV = 83%). No behavioral differences were observed between couples tested during the day or at night.

Animals↗
PubMedDate not supplied

Red cell and total blood volumes during sexual excitement and copulation in the boar.

Measurements of hematocrit, total plasma protein and red cell volume were made during sexual excitement and copulation in boars. Red cell volume (RCV) was determined by isotope dilution technique using endogenous 51Cr-tagged red cells. Basing on these data changes in the total blood volume (TBV) and plasma volume (PV) were calculated by 2 indirect methods. RCV increased by 12% to 16% in the intial phase of ejaculation and remained increased during ejaculation and 40 minutes after copulation. TBV and PV decreased during copulation, greatest drop being found in the final phase of ejaculation. After ejaculation the TBV was increasing, first to the resting value before copulation (about 20 minutes after copulation), thereafter it became markedly higher than during the resting period. Depending on the method used for calculation significant differences were found in the quantity of TBV and PV drop during ejaculation.

Animals↗
PubMed1979

Copulation and intermale aggression in rats.

Attack behavior of reliably aggressive male Long-Evans rats against unfamiliar male intruders was observed immediately following copulation to one or more ejaculations. Compulatory series to five ejaculations did not differ from copulation to a single ejaculation or from a noncopulatory control in affecting aggressive behavior. Repetitive biting attacks occurred in all conditions, with comparable wounding. Evidently, the male postejaculatory state of insensitivity to sexual stimuli does not extend to stimuli eliciting intermale aggression. A second experiment determined the attack-eliciting capacity of foreign males placed in the home cage of an actively copulating male. As intromissions increased and the interval to ejaculation decreased, the probability of intermale aggression and interruption of copulation diminished. The results are discussed in reference to sexual and aggressive strategies of the copulating male.

Aggression↗
PubMed1975

Investigation of genetic factors influencing duration of copulation in "eastern" and "western" Drosophila athabasca.

Observations of mating behaviour were made on "eastern" and "western" Drosophila athabasca and on flies of mixed genetic background. Duration of copulation in mixed combinations of D. athabasca is determined by the male. In F1 males the source of X-chromosome, whether eastern or western, partly determined suration of copulation. However, durations of copulation of backcross males suggest autosomal influence, in that males derived from an eastern backcross demonstrate significantly shorter durations than males derived from a western backcross. In addition, durations of copulation from F2 combinations exhibit greater variance than the F1 and thereby represent evidence of F2 segregation.

Animals↗
PubMed1976

Copulation in noncopulators: effect of PCPA in male rats.

Twenty eight virgin male rats who failed to mount spontaneously on four successive mating tests were randomly assigned to two equal groups. One group received four daily injections of PCPA (100 mg/kg-IP), and the other, four vehicle injections. About 24 hr after the last injection all rats were subjected to a mating test. Eight rats of the PCPA group and only two of the vehicle, started to copulate. The difference is significant at the 0.05 level (two-tail). The 18 rats that did not start to copulate, failed to do so also on a repeated test a week later, and were then given four additional daily injections of PCPA. Sixteen of them started to copulate on the following mating test. Most of the rats copulated successfully on additional mating tests that took place three to eight weeks later, in the absence of further PCPA treatment.

Animals↗
PubMed1988

Extra-pair copulation and sperm competition in the zebra finch.

Most birds are monogamous, but recent studies have shown that extra-pair copulations (EPCs) occur frequently despite a range of paternity guards, including mate-guarding and frequent copulation. Although EPCs are known to result in extra-pair paternity, there are no previous quantitative estimates of the success of EPCs in fertilizing eggs. We present here estimates of the likelihood of success of extra-pair copulations in a monogamous passerine, the zebra finch Poephila guttata. We show that (1) EPCs occurring under semi-natural conditions in captivity result in extra-pair paternity, (2) sperm from the last male to mate has precedence over previous matings: a single EPC occurring last is disproportionately successful in fertilizing eggs, but EPCs followed by further pair copulations have a low probability of success. These results have important implications for sexual selection theory.

Animals↗
PubMed1991

The genetic properties of homosexual copulation behavior in Tribolium castaneum: diallel analysis.

The rate of homosexual copulation has been defined as the ratio between the number of homosexual mountings and the total number of mountings (homo and heterosexual) performed by a Tribolium castaneum male during a period of 30 min. In a laboratory population, the average rate when a number of males (m) and females (k x m) are tested together has been estimated in each of the six situations defined by m = 2 and 10 and k = 0.5, 1, and 2, k being the sex ratio among scored individuals. Good agreement was found between the observed rates of homosexual copulation and those expected assuming random contacts between pairs of individuals totally indiscriminate with respect to sex. The genetic properties of the trait have been investigated by means of a diallel analysis of six highly inbred lines derived from the same population and their F1 crosses. Significant general and specific combining ability effects were detected. When noninbred females were used for testing, the rate of homosexual copulation is expected to be higher for inbred than for noninbred males. This prediction, implying the existence of inbreeding depression for the trait, also was confirmed by the data.

Alleles↗
PubMed1982

Copulation increases offensive attack in male rats.

Twenty-four adult male rats with previous sexual experience were tested for aggression against intruders after one of four treatments (n = 6 per treatment): exposure to inaccessible estrous females; exposure to anestrous females; no female exposure, or copulation to ejaculation. Although both exposure to inaccessible estrous females and copulation significantly decreased latency to attack only copulation produced significant elevation of intensity and duration of attack. Results are discussed in reference to the role of aggression in maintaining priority of access to females, and as a means of assuring paternity of offspring by dominant males.

Aggression↗