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PubMed2006

Conditioned partner preference in female rats for strain of male.

Female rats show conditioned place preference following paced copulation, and we have recently demonstrated that pairing almond odor with paced copulation induces a conditioned partner preference for almond-scented males. The present study examined whether cues of two different strains of male (albino and pigmented) induce a conditioned partner preference for the strain of male associated with paced copulation. Ovariectomized, hormone-primed Wistar (W) or Long-Evans (LE) female rats received 10 conditioning trials at 4-day intervals. In the Wistar-pacing group females copulated with W males in a chamber bisected by a 4-hole partition that only the female could pass through. Four days later, they copulated with LE males without the partition. The Long-Evans-pacing group received the opposite association. In the final preference test all females chose freely between two males tethered in opposite corners of an open field, one W and one LE. Regardless the strain of male, females displayed more solicitations toward the pacing-related male, and most of the females received their first ejaculation from that male. The preference was facilitated if the pacing-related male was of the same strain as the female. These results suggest that female rats have an unconditioned preference for males of the same strain, but this preference can be switched towards males of a different strain if that male is associated with the sexual reward induced by paced copulation.

Animals↗
PubMed2006

Post-castration retention of reproductive behavior and olfactory preferences in male Siberian hamsters: role of prior experience.

Reproductive behavior of virtually all adult male rodents is dependent on concurrent availability of gonadal steroids. The ejaculatory reflex is incompatible with long-term absence of testicular steroids and typically disappears within 3 weeks after castration. Male Siberian hamsters are an exception to this rule; mating culminating in the ejaculatory reflex occurs as many as 6 months after castration (persistent copulation). The emergence of persistent copulation many weeks after gonadectomy is here shown not to require repeated post-castration sexual experience. Preoperative sexual experience, on the other hand, significantly increases the percent of males that copulate after gonadectomy, but is not required for the emergence of this trait in 25% of males. Castration prior to puberty prevents persistent copulation in all individuals in adulthood. Persistent copulators, unlike males that cease mating activity after castration, prefer the odors of estrous over non-estrous females when tested 4 months after castration and 7 weeks after the last mating test. Neural circuits of persistent copulators retain the ability to mediate male sex behavior and preferences for female odors in the complete absence of gonadal steroids; they are influenced by preoperative sexual experience and organizational effects of gonadal hormones at the time of puberty.

Animals↗
PubMed2000

Fos induction in the Japanese quail brain after expression of appetitive and consummatory aspects of male sexual behavior.

We investigated the expression of Fos, the protein product of the immediate early gene c-fos in the brain of male Japanese quail after they engaged in either appetitive or consummatory sexual behavior (i. e., copulation). For 1 h, castrated males treated with testosterone were either allowed to copulate with a female or to exhibit a learned social proximity response indicative of appetitive sexual behavior. Control birds were either left in their home cage or placed in the experimental chamber but did not exhibit the appetitive sexual behavior because they had never learned it. Fos expression was studied with an immunocytochemical procedure in two sets of adjacent sections through the entire forebrain. These sections were immunolabelled with 2 different antibodies raised against a synthetic fragment corresponding to the 21 carboxy-terminal residues of the chicken Fos sequence. Contrary to the results of a previous study in which gonadally intact birds were used, Fos induction was observed neither in the medial preoptic nucleus nor in the nucleus intercollicularis in birds that had interacted for 1 h with a female. This may be related to a lower frequency of copulation in the testosterone-implanted birds than in intact birds, or to differences in the time the brains were collected after the birds engaged in sexual behavior between the two studies (60 min in this study, 120 min in the previous study). The performance of copulation and/or appetitive sexual behavior increased the number of Fos-immunoreactive cells in the ventral hyperstriatum, medial archistriatum, and nucleus striae terminalis. These increases were observed using both antibodies, although each antibody produced minor differences in the number of Fos-immunoreactive cells observed. Using one of the antibodies, but not the other, increases in Fos immunoreactivity were also observed in the nucleus accumbens and hyperstriatum after either copulation or appetitive sexual behavior. These differences illustrate how minor technical variations in the Fos immunocytochemical procedure influence the results obtained. These differences also show that Fos induction in a number of brain regions is observed after performance of consummatory (copulation) as well as appetitive (looking at the female) sexual behavior. This induction is, therefore, not related solely to the control of copulatory acts but, presumably, also to the processing in a variety of telencephalic association areas of stimuli originating from the female. The observation that increased Fos immunoreactivity is present in birds that had learned the response indicative of appetitive sexual behavior, and not in those that had not learned the behavior, further indicates that it is not simply the sight of the female that results in this Fos induction, but the analysis of the relevant stimuli in a sexually explicit context. Conditioned neural activity resulting from a learned association between the stimulus female and the performance of copulatory behavior may also explain some aspects of the brain activation observed in birds viewing, but not allowed to interact with, the female.

Analysis of Variance↗
PubMed1998

Inheritance of behavioural differences between two interfertile, sympatric species, Drosophila silvestris and D. heteroneura.

The Hawaiian fly species, Drosophila silvestris and D. heteroneura, are sympatric and interfertile but show strong behavioural isolation and major differences in male aggressive behaviour and the associated morphology. As a first step in elucidating the genetic control of the differences between these species, we examined the mating and aggressive behaviour of their reciprocal F1 hybrids. The latency to the first wing vibration and the latency to copulate did not differ significantly between the parental species. However, D. heteroneura females had a very low tendency to copulate with D. silvestris males, rarely mating during the observation period. The duration of copulation also differed significantly; same-species pairs of D. silvestris had copulations that lasted about 50% longer than those of same-species pairs of D. heteroneura. The hybrids were intermediate between the parental species for both the tendency to copulate with D. silvestris males and the duration of copulation, suggesting codominance or polygenic inheritance for those traits. The aggression traits that we scored were the leg posture and wing extension during early aggression, and the leg posture and head position during escalated aggression. The parental species showed clear differences for each of these traits. The F1 hybrids resembled one parent or the other, without showing intermediate values, suggesting single-gene dominance or threshold expression of many genes for those traits. None of the courtship or aggressive traits showed X-chromosomal effects, although the head shape of hybrids is influenced by genes on the X chromosome. It is difficult to reconcile the patterns of inheritance of aggressive behaviour and the lack of an X-chromosomal effect with the hypothesis that these traits are influenced by a coadapted gene complex.

Aggression↗
PubMed1989

Self-limiting reflex luteinizing hormone release and sexual behavior during extended periods of unrestricted copulatory activity in estrous domestic cats.

Estrous female cats (queens) were permitted 36-h periods of unrestricted mating activity; they then were injected with various doses of gonadotropin-releasing hormone (GnRH) at 36 h and allowed single copulations at 48 or 72 h of study. Serum luteinizing hormone (LH) levels were determined in samples collected prior to and 2 h after the initial copulation, before and 30 min after selected copulations during the next 10 h, and before and 30 min after copulations occurring at 20-24, 36, and 48-72 h, as well as 0, 15, and 30 min after the GnRH injections (0.3-3.0 micrograms/kg) at 36 h of study. Copulations occurred 14-20 times in 12 h and 20-36 times in 36 h. Copulation frequency (mean +/- SEM) decreased (p less than 0.05) from 5.5 +/- 0.6/2 h initially to 1.5 +/- 0.6/2 h during the subsequent 2-h period, and was 1.4 +/- 0.2/2 h at 12-36 h of study. Intromissions lasted 1-27 (8 +/- 0.3) s. Variation in durations of mounting by males (1.7 +/- 0.1 min; range, 0.3-10 min) or of the postcoital behavioral reactions displayed by the queens (2.5 +/- 0.1 min; range, 1-17 min) could not be related to animals or time of study. Peak serum LH levels (11-280 ng/ml; mean, 112 +/- 30 ng/ml) were observed at 2-4 h after the first mating. Mean LH steadily declined thereafter, reached basal values (less than or equal to 3 ng/ml) by 20-24 h, and remained low at 36 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1998

Evidence that a novel type of progestational phase control occurs in the corn mouse, a South American murid rodent.

Most Muridae display a short luteal phase that becomes functional as a consequence of the prolactin release induced by the stimulation of copulation and/or lactation. The corn mouse also shows a short luteal phase, and we wanted to know whether copulation and/or lactation would release prolactin and maintain progesterone secretion in this species. Females in postpartum estrus were either allowed to copulate with an intact male or not, and either to lactate their young or not. Afterward, plasma progesterone was elevated over the baseline level only in females that had copulated and were bearing growing embryos (whether or not they were lactating), while prolactin was elevated only in lactating females. In another experiment, endometrial scratching induced decidualization both in females that had copulated with a vasectomized male and in those that had not copulated; sham operations had no effect in either case. Progesterone levels were elevated in decidualized animals as compared with their sham-operated controls. Results indicate that the initiation of the progestational phase in the corn mouse is not dependent on prolactin release. A short luteal phase during which nidation may occur has not yet been described in any other mammal.

Animals↗
PubMed1992

Measures of libido and their relation to serving capacity in the ram.

The purpose of this study was to determine whether the ejaculation rate (serving capacity) of sexually experienced rams could be estimated by selected measures of sexual libido when rams were exposed to estrous ewes under conditions that prevented copulations. Twenty-four crossbred rams selected for either high or low rates of copulation were exposed to two restrained estrous ewes under three treatment conditions that 1) permitted the full range of precopulatory and copulatory behaviors, 2) permitted precopulatory behaviors and mounting but precluded copulation, or 3) permitted precopulatory behaviors but not mounting or copulation. Frequencies of precopulatory behaviors (bouts of leg-kicking and anogenital sniffing) in each of the three treatment conditions and mounting frequency in Treatment 2 occurred in proportion to the ram's characteristic ejaculation rate (P < .001), suggesting that the mating potential of rams can be estimated under conditions that preclude copulation. Frequencies of precopulatory behaviors and mounting were lower when the rams were allowed to copulate, due largely to periods of sexual inactivity after ejaculations.

Animals↗
PubMed1983

Aspects of copulatory behavior and peptide control of egg laying in Aplysia.

The atrial gland of the marine mollusc Aplysia is associated with the large hermaphroditic duct of the reproductive system and contains several peptides capable of inducing egg laying. The structure and function of these peptides are briefly reviewed. It has been hypothesized that during copulation the atrial gland of the female is stimulated by penile insertion to release its peptides, which in turn initiate events leading to egg deposition. To test this hypothesis we monitored reproductive activity over periods of weeks in individual, paired, and grouped A. brasiliana. It was found that copulation is not a necessary stimulus for egg laying, because individually housed Aplysia lay more eggs than when they are paired and allowed to copulate. Nor is copulation a sufficient stimulus, because the vast majority of copulations are not followed by egg laying. Simultaneous egg laying and female copulatory behavior were often observed with grouped and paired animals, but these events are probably not causally related. It is concluded that although the atrial gland contains at least three peptides that can induce egg laying, stimulation of this gland during copulation does not normally serve to initiate egg laying.

Amino Acid Sequence↗
PubMed1978

Effect of local anesthesia of the penis and dorsal penile neurectomy on the mating ability of bulls.

Eleven bulls were used to study the effect of the loss of nerve sensitivity in the free portion of the penis and glans penis on their ability to copulate. The loss of sensitivity was induced by topical anesthesia, infiltration anesthesia, and dorsal penile neurectomy. Topical anesthesia of the glans penis reduced the ability of the bulls to search for and to locate the vagina and to complete copulation; however, all bulls eventually copulated. Topical anesthesia of the free portion of the penis and glans penis blocked the ability of all bulls to copulate. Infiltration of the glans penis with lidocaine resulted in bulls failing to ejaculate, indicating the need for input from deep nerve receptors. Ten of the eleven bulls with unilateral neurectomy were able to copulate, but a longer time was required. In the one bull that failed to complete intromission and ejaculation, the sectioned nerve made up 75% of the nerve mass to the distal end of the penis, leaving only a small number of functional fibers. With this small number of fibers, there may have been insufficient sensory input to elicit the thrusting responses and to cause the animal to ejaculate. Bulls with bilateral neurectomy were unable to copulate.

Anesthesia, Local↗
PubMed2000

Sex identification and mating in the blue-ringed octopus, Hapalochlaena lunulata.

We studied the reproductive behaviour of the blue-ringed octopus, Hapalochlaena lunulata, in the laboratory by examining 15 male-male and nine male-female interactions. The initiation of physical contact was independent of sex, size or residency status, and there were no noticeable changes in behaviour such as sexual displays associated with courtship or aggression prior to contact. Males did not distinguish between females or other males and copulated (defined as the insertion of the hectocotylus into the mantle cavity of another octopus) readily with both. Spermatophores were released in all copulations with females but not with males. The duration of copulation was significantly longer in male-female interactions (median 160.5 min) than in male-male interactions (median 30 s). Although male-male copulations ended passively with the withdrawal of the hectocotylus by the initiating animal, male-female copulations were always terminated by the females following an intense struggle. These studies suggest the inability of male H. lunulata to determine the sexual identity of potential mates prior to the insertion of the hectocotylus and demonstrate the active role of the female during copulation. Copyright 2000 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1996

The hormonal induction of mating behavior in female gray short-tailed opossums (Monodelphis domestica).

The activating effects of estradiol alone and of estradiol plus progesterone on copulation and related behavior were examined in ovariectomized female gray short-tailed opossums. Following receipt of subcutaneous estradiol (E) or cholesterol (C) implants, E-females showed less screeching threat behavior toward intact males than C-females. Intact males showed more precopulatory behavior toward E- than toward C-females, and 20% of E-females and no C-females copulated with males. In a second experiment, females that had previously received subcutaneous E implants received injections of either corn oil alone (E + OIL) or 500 micrograms progesterone in corn oil (E + P) 4 hr before behavioral testing. Of E + P-females, 88% copulated with males, compared to 38% of E + OIL-females. All females that copulated in both experiments showed anogenital dragging just prior to copulation. Hormonal induction of estrous behavior and copulation has not been reported previously in a female marsupial.

Animals↗
PubMed1996

Seminal collection, seminal characteristics and pattern of ejaculation in llamas.

Semen was collected from 10/10 llamas during 26/30 (87%) collection attempts using an artificial vagina mounted inside a surrogate female. For the 26 semen collections, the duration of copulation (mount to dismount) with the artificial vagina was 31.7 +/- 12.0 min (mean +/- SD). Seminal pH was 8.1 +/- 1.1, and seminal volume per collection was 3.0 +/- 1.9 ml. Sperm concentration per collection was 1.0 +/- 0.8 x 10(6) sperm/ml, total number of spermatozoa was 2.9 +/- 3.1 x 10(6), total sperm motility was 23.7 +/- 20.0%, and the percentage of morphologically normal spermatozoa was 39.7 +/- 18.5%. Morphologically abnormal spermatozoa were categorized according to abnormal heads (20.1 +/- 19.9%), tail-less heads (8.7 +/- 8.9%), abnormal acrosomes (12.9 +/- 12.4%), abnormal midpieces (1.0 +/- 3.7%), cytoplasmic droplets (11.1 +/- 12.4%), and abnormal tails (6.6 +/- 12.0%). There were 0.3 +/- 0.3 million motile, morphologically normal spermatozoa per collection: less than 1000 during the first 5 min of copulation, 0.01 +/- 0.01 x 10(6) between 5 and 10 min of copulation, 0.04 +/- 0.08 x 10(6) between 10 and 15 min of copulation, 0.09 +/- 0.21 x 10(6) between 15 and 20 min of copulation, and 0.15 +/- 0.28 x 10(6) between 20 min and the end of copulation.

Journal Article↗
PubMed2000

A temporal analysis of sexual activity in a natural population of Drosophila willistoni.

We have analyzed the mating activity of F1 flies in mating chamber from five samples of wild Drosophila willistoni females. The files were collected from an area (in south Brazil) that has well-defined seasons and considerable variation in temperature and in the abundance of drosophilids. We estimated copulation frequency at first five minutes of observation, copulation frequency at ninety minutes of observation and copulation latency. We did not observe differences in the total copulation frequency throughout seasons, as opposed to copulation frequency in the beginning of the observation period and to copulation latency which varied significantly. The results show that mating activity in a natural population can vary along with the seasons and that this variation can be correlated to some environmental factor. Mating activity tended to be higher during high warm temperature periods, when the flies were abundant.

Animals↗
PubMed2000

Growth of the conceptus in alpacas.

OBJECTIVE: To determine growth of the alpaca conceptus during early gestation, using ultrasonography. ANIMALS: 40 pregnant alpacas (20 multiparous, 20 nulliparous). PROCEDURE: Transrectal ultrasonography with a 5-MHz probe was performed 3 times weekly from days 7 through 45 after copulation (day of copulation = day 0). Blood samples were collected for progesterone assay on days of ultrasonography. RESULTS: Forty embryonic vesicles and embryos were identified and measured. Embryonic vesicles were first detected on day 12 after copulation and appeared spherical. Cumulative percentage of embryonic vesicles detected was 50, 82.5, and 100% on days 12, 14, and 16, respectively. Embryos were first detected by day 22 and heartbeats by day 24. Similarly, cumulative percentage of embryos detected was 17.5, 82.5 and 100% for 22, 24, and 26 days after copulation, respectively. Embryonic vesicles occupied both uterine horns beginning on day 19. A positive correlation existed between length and width of embryonic vesicles. Size of embryonic vesicles and embryos and progesterone concentrations did not differ between multiparous and nulliparous females. Five sets of twins were detected from days 21 through 33 after copulation, but the conceptus identified in the right uterine horn became nondetectable between days 28 and 33. CONCLUSIONS AND CLINICAL RELEVANCE: Ultrasonography was useful in detecting the earliest appearance of alpaca embryonic vesicles and determining the changes in growth from days 12 through 45 after copulation. Embryos were first detected by day 22. Transrectal ultrasonography was not harmful to animals and did not provoke embryonic death in this study.

Animals↗
PubMed1991

Modification of male rat copulatory behavior by lateral midbrain stimulation.

Effects of electrical stimulation of the lateral midbrain tegmentum (LMT) on the copulatory behavior of male rats were examined in our investigation of the role of the LMT in this behavior. Sexually experienced male rats (n = 15) that had been implanted with chronic electrodes under sodium pentobarbital anesthesia were individually tested for copulation with a receptive female under a 30 s on, 30 s off pattern of stimulation. The ejaculation latency, and mount and intromission frequencies decreased significantly during the stimulation tests, indicative of facilitation of copulation. In contrast, a strong stimulus-bound inhibition of copulation was found in 12 males (80%). Six animals who showed accelerated copulation also depressed the lever for self-stimulation at an identical current during the copulation tests. These results suggest that the LMT functions in ejaculation, in the normal expression of intromission and in sexual reward, thereby regulating the copulatory behavior of male rats.

Animals↗
PubMed2006

Getting his act together: roles of glutamate, nitric oxide, and dopamine in the medial preoptic area.

Gonadal hormones have primarily slow, genomically mediated effects, but copulation requires rapid interactions with a partner. A major way in which hormones facilitate male sexual behavior is by increasing production of neurotransmitter receptors or of enzymes that regulate neurotransmitter synthesis or release. Dopamine is an important facilitative neurotransmitter, and the medial preoptic area (MPOA) is a critical integrative site for male sexual behavior. MPOA dopamine is released before and during mating and facilitates copulation, genital reflexes, and sexual motivation. Gonadal hormones regulate dopamine release in the MPOA of male rats in part by increasing nitric oxide synthase (NOS) in the MPOA; the resultant increase in production of nitric oxide (NO) increases both basal and female-stimulated dopamine release. Glutamate also increases dopamine release via increased production of NO. At least some of the glutamatergic inputs to the MPOA are from the medial amygdala (MeA) and bed nucleus of the stria terminalis (BNST), which mediate the female-stimulated increase in dopamine, which in turn enhances copulatory ability. Extracellular glutamate in the MPOA increases during copulation, especially during ejaculation, and increased glutamate facilitates copulation and genital reflexes. Previous sexual experience also facilitates copulation and confers resistance to impairment by various lesions, drugs, and stress. Experience enhances processing of sexual stimuli, and its effects require activation of glutamate NMDA receptors and NOS in the MPOA. Neuronal NOS is increased in the MPOA of experienced males. Therefore, glutamate, NO, and dopamine interact in the MPOA to facilitate mating and to enhance future sexual responsiveness.

Animals↗
PubMed1992

Copulatory stimuli in rats induce heat abbreviation through effects on genitalia but not through effects on central nervous mechanisms supporting the steroid hormone-induced sexual responsiveness.

Male copulatory stimuli in various animal species abbreviate the length of the period of their female conspecifics' heat. Such effect can be explained in some species as the result of copulation-induced alterations in ovarian hormone secretion (e.g. reflex ovulators). Other species require a different explanation: specifically, interactions in the hypothalamus between effects of steroid hormones and inhibitory neural afferents from the genital area have been hypothesized to play a role in some laboratory animals such as guinea pigs, hamsters and rats. However, the evidence in support of heat abbreviation through copulatory stimuli in rats is at best equivocal. There is obvious need for its unequivocal demonstration prior to any further analysis of the potential mechanism of action. The present study intended to find a model in support of the concept of 'centrally induced' heat abbreviation in rats. Virgin rats during 'natural heat' were examined with or without allowing them the opportunity to pace male copulatory activities. Ovariectomized, steroid hormone-treated rats were studied with minor or ample experience with sexual activities in prior tests and, also, with or without the opportunity to 'pace' male sexual acts. None of the experimental models revealed unequivocal support for detrimental effect of large numbers of intromittive copulations on 'central mechanisms' regulating heat duration. It rather seemed that frequent intromittive copulations and ejaculates affected the 'peripheral' genital tract (vulva, vagina, cervix) making further copulation of a highly aversive quality so that sexual encounters were avoided or prevented. This effect was noticed with great inter-individual variability. The conclusion is drawn that rats do not show the counterpart of heat abbreviation reportedly occurring rapidly and reliably in guinea pigs after a limited amount of vaginal/cervical stimulation through copulation or insertions of a glass-rod.

Animals↗
PubMed1994

Sexual behavior of chimpanzees (Pan troglodytes): male versus female regulation.

We investigated the sexual behavior of 13 chimpanzees (Pan troglodytes) in 2 types of pair test in order to clarify the interaction of social variables with female hormonal state. The frequency of copulation in tests in which the partners were freely accessible to each other was related to the male's dominance over the female; copulation was less frequent and was related to social compatibility in tests in which the female controlled access. Copulation was related to female hormonal state in both types of test. The results demonstrate (a) an association between female hormonal state and sexual activity of chimpanzees, (b) the influence of social relationships on sexual interactions, and (c) the importance of focusing on female sexual behavior before copulation, rather than copulation per se, in research on sexual arousability of female primates.

Animals↗