Penile responses of rats (Rattus norvegicus) in extended ex copula tests.

Conducted prolonged tests of male Long-Evans rats' penile responses outside the context of copulation (ex copula) to facilitate analysis of these penile components of copulatory behavior. Penile erections and flips were evoked for 1 hr following penile sheath retraction (SR), and Ss were retested for 30 min after a rest interval of 5 min to 4 hr. The number of penile responses declined sharply over the course of 1 hr. Following a 5-min rest, there was little likelihood of additional responses. Within 2 hrs, some measures of penile response potential approached their original high asymptotes: other measures were still depressed after the 4-hr rest. In control tests, the penile sheath was unretracted (SU) during the 1st 60 min, and hence few or no penile responses occurred. This condition caused no reduction in the number of erections and flips in the subsequent 30-min SR test; hence, the reduction in response to potential during and after SR tests was due to the responses displayed, not to the conditions of restraint. Ejaculation occurred frequently in the SU condition but rarely in SR tests. These results suggest that SR may normally inhibit ejaculation in ex copula tests and during copulation. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of morphiceptin in the medial preoptic area on male sexual behavior

Morphiceptin, a selective mu opioid agonist, injected into the medial preoptic area (MPOA), delayed the onset of copulation in male rats, but did not affect genital reflexes, sexual motivation or general motor activity. In a dose-dependent manner, morphiceptin (100 ng and 1000 ng) injected into the MPOA increased mount and intromission latencies. Similar injections of morphiceptin into the ventromedial hypothalamus had no effect on any parameter of copulation. The increase in copulatory latencies following the injection of the highest dose of morphiceptin was blocked by pretreatment with the opioid antagonist naloxone. In the X-maze task, morphiceptin had no effect on sexual motivation, as measured by the percentage of trials on which the male chose the female's chamber, but it increased the number of trials in which the subject did not select a chamber within 60 s and the latency to the female the first time he chose her chamber. Similar to the copulation task, the mount and intromission latencies were also increased in the X-maze, after the male reached the female. Morphiceptin in the MPOA had no effect on ex copula genital reflexes, tested in restrained supine males, or on motor activity, tested in a grid box. These results suggest that morphiceptin disrupts either the specific copulatory somatomotor pattern or a more general motivational component.     

Pacing of copulatory behavior in the male rat: Effects of receptive females and intermittent shocks.

Describes 2 experiments with 7 male hooded Long-Evans rats. In Exp I, Ss were tested with females continuously present and with the presence of the female after each sex act contingent upon a barpress. The sole effect of the barpress requirement was to increase the intervals between copulations before ejaculation. In Exp II, intermittent shocks were superimposed upon the conditions of Exp I. Shocks were followed with short latency by mounts in the ad-lib condition and by barpress and mounts in the operant condition. The pacing of copulatory acts before ejaculation is inferred to result from an interaction of stimuli from the female and feedback from the copulatory acts; after ejaculation, factors primarily endogenous to the male govern the timing of resumption of copulation. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of roof rats (Rattus rattus).

Investigated the copulatory behavior of a total of 71 male and 48 female roof rats (Rattus rattus) in 3 experiments. In Exp I, females were brought into behavioral estrus with exogenous hormones, and each pair was observed until 30 min elapsed without copulation. Roof rats appeared to be similar to laboratory rats (Rattus norvegicus) with regard to basic motor patterns of copulation, quantitative measures of copulation, behaviors accompanying copulation, and postejaculatory ultrasonic vocalizations. Only (a) patterns of tail rattling in females, (b) climbing and allogrooming in both sexes, and (c) an ability to ejaculate on a single insertion by males were observed in roof rats but not reported for laboratory rats. Exps II and III were designed to assess the role of various components of the copulatory pattern of male roof rats on the induction of pregnancy in normally cycling young females. A single ejaculation preceded by an abnormally high number of intromissions or 3 normal ejaculatory series maximized the incidence of pregnancy, whereas 1 normal ejaculatory series or 1 ejaculation preceded by an abnormally low number of intromissions did not. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determinants of mating success in the golden hamster (Mesocricetus auratus): I. Male capacity.

Studied the maximum copulatory capacity of 102 male golden hamsters to determine what effect a steady state of copulatory activity would have on the chronic fertility of the male, and to determine the rate of recovery from copulatory recovery. Rested Ss produced a mean of 13 ejaculations and then showed a modified copulatory pattern consisting of long intromissions (10–30 sec of intravaginal thrusting) during which no sperm transfer occurred. When a 2nd (fresh) female was introduced, 58% of the Ss produced at least 1 more ejaculation, and 17% of the Ss produced 1 further ejaculation when placed with a 3rd female. In similar 3-female tests conducted 24 hrs later, all Ss ejaculated (mean 4 ejaculations); this level of ejaculatory output was maintained over a subsequent 10-day period of daily testing. Four ejaculations ensured a nearly 100% pregnancy rate and maximum litter size in the 1st females. Second and 3rd females, however, received fewer ejaculations and subsequently showed reduced fertility. Two or 8 hrs of rest resulted in fewer than 50% of the Ss being capable of 1 further ejaculation. However, most of these single ejaculations were accompanied by long intromissions and resulted in successful pregnancies. Findings show that the male golden hamster has a higher ejaculatory output and more rapid recovery from sexual exhaustion than other small rodents that have been studied. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): II. A study of some factors regulating the fine structure of behavior.

In 7 experiments on factors regulating copulatory behavior in deer mice, changes in copulatory behavior across series within a test reflected changes in both male and female, with the male apparently predominant. Even when mating with females of a species with a very different copulatory pattern (cactus mice), male deer mice retained the species-typical pattern. Mating in a 2-male/1-female condition produced little alteration in copulatory behavior from that in the 1-male/1-female condition. Under some test conditions, levels of aggressive behavior in the 2-male/1-female condition was considerable. There was generally covariation among body weight, social dominance, and copulation, with heavier males being dominant and ejaculating more often than lighter males. When females were in hormone-induced estrus, mount and intromission latencies were longer and ejaculation frequencies were lower than with either cycling or postpartum estrus. Significant differences between cycling and postpartum estrus were detectable with a within-Ss design. Mate familiarity had little effect on parameters of copulatory behavior once initiated. Effects of both male and female were detected when mating partners were changed between tests and test–retest correlation coefficients were calculated. (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Contextual conditioning and the control of copulatory behavior by species-specific sign stimuli in male Japanese quail.

Three experiments were conducted to identify species-specific sign stimuli sufficient to elicit copulatory behavior in male Japanese quail and to determine how learning is involved in the control of behavior by these sign stimuli. In Exp 1, sexually experienced Ss were tested for copulatory behavior with a live female quail and with a model consisting of a female quail's head and neck mounted in front of a foam pad. Comparable levels of copulatory behavior were observed in the two tests, indicating that static visual cues provided by a female quail's head and neck are sufficient to elicit copulatory behavior in this species. Exp 2 showed that male birds that previously received numerous opportunities to copulate with a live female quail in the test situation were significantly more likely to copulate with the head?+?neck model than were sexually inexperienced Ss. Exp 3 showed that prior sexual experience with live quail facilitated responding to the head?+?neck model only if the sexual experience was provided in the same place where Ss were later tested with the model. This finding suggests that sexual experience facilitates control of copulatory behavior by species-specific sign stimuli through contextual conditioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electrical stimulation of dorsal and ventral striatum differentially alters the copulatory behavior of male rats.

Sexual behavior is a natural reward that activates striatal dopaminergic (DA) circuits, and dopamine exerts a facilitative influence on copulation. Electrical stimulation of the striatum has been shown to be rewarding, but its effect on male sexual behavior display has not been established. The objective of the present work was to assess the effects of low- and high-frequency electrical stimulation of the dorsal and ventral striatum on male rat sexual behavior expression. To this aim, copulatory activity of sexually experienced male rats was recorded during electrical stimulation of the nucleus accumbens (NAcc) or caudate-putamen (CP), at each stimulation frequency, before and after sexual exhaustion. Results showed that electrical stimulation of the NAcc at both frequencies increased the number of ejaculations that male rats were able to show in a 30-min period. By contrast, stimulation delivered to the CP inhibited sexual behavior by slowing its display. Each effect was more pronounced at low than at high stimulation frequencies. In the same rats, once sexually exhausted, electrical stimulation of these brain areas did not reverse the sexual behavior inhibition that characterizes the sexual exhaustion state. It is concluded that dorsal and ventral striatal DA brain regions exert opposite influences on copulatory behavior expression of sexually experienced male rats. Also, that the facilitative effect of NAcc electrical stimulation on sexual activity, with the stimulation parameters used, cannot surmount the sexual behavior inhibition resulting from copulation to satiation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual approach conditioning: Unconditioned stimulus factors.

Unconditioned stimulus (US) factors were investigated in a Pavlovian sexual conditioning paradigm with male Japanese quail (Coturnix coturnix japonica). Copulation with a female quail was more effective than exposure to a female without copulation, but the latter also produced conditioned responding (Exp 1). The greater effectiveness of copulatory opportunity as a US was probably not due to nonassociative effects of copulation (Exp 2). Visual cues of the female, as presented on a taxidermic model, were not effective unless the Ss had prior sexual experience that increased their response to the model (Exps 3a and 3b). Successful conditioning with noncopulatory female exposure is significant because it allows for sexual learning to occur in a broader range of circumstances than does conditioning with copulation and because it permits conducting multiple trials per day because males do not become satiated as rapidly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulation and intermale aggression in rats.

Exp I observed attack behavior of 9 reliably aggressive male Long-Evans rats against unfamiliar male intruders immediately following copulation to one or more ejaculations. Copulatory series to 5 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 2nd experiment determined the attack-eliciting capacity of foreign males placed in the home cage of an actively copulating S. As intromissions increased and the interval to ejaculation decreased, the probability of intermale aggression and interruption of copulation diminished. Findings suggest that a postejaculatory mechanism for behavioral inhibition exists in the male rat, preventing his interference with fertilization but without affecting his capacity to prevent other males from attempting to displace the fruits of his labors. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of deer mice (Peromyscus maniculatus): I. Normative data, subspecific differences, and effects of cross-fostering.

In Exp I, normative data were collected on copulatory behavior in 16 male–female pairs of Peromyscus maniculatus bairdi, each mated for 5 tests. P. m. bairdi display a pattern with no lock, no intravaginal thrusting, multiple intromissions prerequisite to ejaculation, and multiple ejaculations. They had a mean of 3.6 ejaculations, with the 1st ejaculation preceded by a mean of 6.4 intromissions spaced 72 sec apart. In Exp II, data from 17 male–female pairs of P. m. Blandus were compared with data from 2 samples of P. m. bairdi and a sample of P. m. gambeli from an earlier study. Although there were no qualitative differences among subspecies, significant quantitative differences were found for 11 of the 14 measures considered. In Exp III, data from 17 males cross-fostered to Mus musculus parents on the day of birth were compared with those of deer mice reared by their own parents. Cross-fostering produced no major qualitative alterations of copulatory behavior, with significant differences from normally reared males in 4 of 18 comparisons. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-dependent acquisition of copulatory behavior in the male rat: Role of female availability.

The effect of the environment in which sexual experience is acquired was examined on patterns of male rat copulatory behavior. Males trained in a pacing chamber with a 4-hole partition had significantly shorter ejaculation latencies compared with males trained in chambers with a 1-hole partition. Those differences persisted when males were switched into the other pacing condition, suggesting that the pattern of copulation in these males had become "fixed." In the second experiment, males were trained to associate an almond odor with copulation in either the 1-hole or 4-hole condition. Males ejaculated preferentially with females associated with the 4-hole pacing condition. Copulatory behavior in male rats is sensitive to female availability, and females associated with greater availability are preferred. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Life-span changes in the copulatory behavior of male rats (Rattus norvegicus).

Studied the copulatory behavior of 36 5-, 10-, 15-, and 20-mo old sexually naive male Long-Evans rats during 2-hr tests with receptive females. There was no apparent change in sexual arousal as measured by latency to initiate copulation across age, with Ss from all groups exhibiting comparable latencies to 1st mount and 1st mount with intromission. The numbers of ejaculations achieved were also similar across ages. Significant age differences were found for frequency of mounts, with 20-mo olds having the highest mean frequency. The persistent mounting by older Ss appeared to account for significant group differences in interintromission interval and ejaculation latency. It is suggested that motor deficits may impair the ability of older Ss to achieve intromission, increasing the number of mount bouts as well as the number of mounts for each bout, thus extending the length of each copulatory series. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lead toxicosis in a captive bottlenose dolphin (Tursiops truncatus) consequent to ingestion of air gun pellets

Male rats of the Wistar strain were selected as good copulators (displaying at least 1 ejaculation in each of three consecutive tests for male sexual behavior) and sexually sluggish animals (displaying no ejaculations in each of three consecutive tests). The administration of low doses (1 and 2.5 mg/kg, i.p.) of kainic acid in sexually sluggish rats induced an enhancement of some parameters of copulatory behavior. In particular, significant reductions in latency to the first mount and intromission and increases in frequency of mounts and intromissions were observed. In contrast, the drug failed to exert any effect in good copulators. At the dose of 5 mg/kg (i.p.) kainic acid exerted an inhibitory effect on sexual behavior parameters both in good copulators and in sluggish rats. A persistent increase in latency to the first mount, intromission and ejaculation, and reduction in frequency of mounts, intromissions and ejaculation both in good copulators and in sluggish rats were observed 20 days after kainic acid treatment at the higher dose. No persistent effect of kainic acid 1 and 2.5 mg/kg was observed 20 days after treatment. These results suggest that kainic acid may affect in a dose-dependent manner several copulatory parameters of male sexual behavior repertoire. The bimodal effects could be explained considering a possible interaction of kainic acid with different neurotransmissions or receptor subtypes.     

Testosterone acts as a prohormone to stimulate male copulatory behavior in male deer mice (Peromyscus maniculatus bairdi).

Determined the importance of reduced and aromatized metabolites of testosterone for male sexual behavior in 111 male castrated deer mice treated with 5-alpha reductase and aromatase inhibitors. In Exp I, testosterone propionate (TP) activation of male copulatory behavior was blocked by the administration of the 5-alpha-reductase inhibitor 4-androsten-3-17-beta-carboxylic acid (17BC). These treatments also prevented TP stimulation of seminal vesicles and ventral prostate gland weight. The inhibitory effects of 17BC were specific to testosterone, since 17BC did not prevent dihydrotestosterone propionate (DHTP) induction of male sexual behavior or seminal vesicles and ventral prostate gland weight increases. In Exp II, TP activation of male copulatory behavior was prevented by the administration of the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD). The ATD did not interfere with DHTP activation of male reproductive behavior. Also, TP and DHTP stimulation of accessory sex organ weight was not blocked by ATD. It is suggested that metabolism of testosterone to both 5-alpha-reduced androgens and estrogens is obligatory for testosterone to reliably stimulate male sexual behavior in castrated male deer mice. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The presence of genital mycoplasmas in women of reproductive age

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

An unusual pattern of copulatory behavior in a South American cricetid rodent: Akodon molinae..

We describe the copulatory behavior and the morphology of the male genital tract of a member of a tribe (Akodontini) for which no information on copulatory behavior has been available. Copulation in Akodon molinae is characterized by multiple intromissions with no intravaginal thrusting, a single ejaculation, and a brief lock with the deposit of a plug. This pattern is unusual because of the combination of locking with both multiple intromissions and plugs. The latter combination and similar standard measures of copulatory behavior, have been reported for Acomys cahirinus, a murid that frequently shows more than 1 ejaculation. Also, the standard measures of copulation in A. molinae resemble those of Calomys callosus, another South American cricetid, which shows intravaginal thrusting and infrequent locks. The functional significance and the anatomical correlates of locking and plug deposition in this species are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual-discrimination learning in male Japanese quail (Coturnix coturnix japonica).

We investigated how male Japanese quail (Coturnix coturnix japonica) learn through extensive social and sexual experience to discriminate between male and female conspecifics. Opportunity for heterosexual copulation was important for this learning, but even extensive copulatory opportunity was not sufficient to produce a sexual discrimination; subjects also required exposure to other males. Exposure to females after copulatory opportunity did not produce a sexual discrimination but facilitated its acquisition. Time or exposure to only the visual features of male birds (provided by taxidermic models) after copulatory opportunity did not result in differential responding to male and female conspecifics. Finally, presenting stimulus birds one at a time proved to be a more sensitive test of sexual-discrimination learning than presenting two stimulus birds at the same time. The results indicate that sexual-discrimination learning is similar to conventional associative learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recovery of masculine copulatory behavior from lesions of the medial preoptic area: Effects of age versus hormonal state.

Two experiments tested the hypothesis that one consequence of the hormonal activation of the onset of copulation in male rats is a reduction in the plasticity of the medial preoptic area (MPOA) with respect to its role in copulation. In Exp I, 31 male rats received 1 mg of testosterone propionate daily from 10 to 45 days of age, and 30 Ss received oil injections. Ss in each of these groups received either bilateral MPOA lesions (MPOAX) or a sham operation as juveniles (28–31 days of age). The proportions of MPOAX Ss copulating as adults did not differ for Ss previously injected with oil or testosterone. In Exp II, 33 male rats were castrated at 15 days of age. These castrated Ss as well as 34 gonadally intact males received bilateral MPOA lesions or a sham operation in adulthood. Following testosterone replacement, MPOAX Ss displayed copulatory impairments regardless of hormonal state during development. Taken together, the results of these experiments suggest that the plasticity (with respect to copulation) of the neural system encompassing the MPOA is a function of some aspect of chronological age unrelated to the rat's developmental hormonal condition prior to the time of the lesion. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acute renal failure following bone marrow transplantation

The medial preoptic nucleus (MPN) is an essential site for the regulation of male sexual behavior. Previous studies using c-fos as a marker for neural activation have shown that copulation increased c-fos expression in the MPN. Neural activation was also present in brain regions that are connected with the MPN and are involved in male sexual behavior, including the posteromedial bed nucleus of the stria terminalis (BNSTpm), posterodorsal preoptic nucleus (PD), posterodorsal medial amygdala (MEApd), and parvocellular subparafascicular thalamic nucleus (SPFp). The present study investigated whether the copulation-induced, activated neurons in these brain regions are involved in the bidirectional connections with the MPN. Therefore, mating-induced Fos expression was combined with application of anterograde (biotinylated dextran amine) or retrograde (cholera toxin B subunit) tracers in the MPN. The results demonstrated that neurons in the BNSTpm, PD, MEApd, and SPFp that project to the MPN were activated following copulation. However, in males that displayed sexual behavior but did not achieve ejaculation, few double-labeled neurons were evident, although both retrogradely labeled neurons and Fos-immunoreactive cells were present. In addition, retrograde neurons that expressed Fos were located in discrete subdivisions within the brain regions studied, where Fos is induced after ejaculation. Likewise, anterogradely labeled fibers originating from the MPN were not distributed homogeneously but were particularly dense in these discrete subdivisions. These results demonstrate that copulation-induced Fos-positive neurons in specific subdivisions of the BNSTpm, PD, MEApd, and SPFp have bidirectional connections with the MPN. Taken together with previous findings, this supports the existence of a discrete subcircuit within a larger neural network underlying male sexual behavior.