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At least 703 records · Page 39Linked to original sources
PubMed1999

Yohimbine interacts with the dopaminergic system to reverse sexual satiation: further evidence for a role of sexual motivation in sexual exhaustion.

The possible interaction of yohimbine with the dopaminergic system in the mediation of sexual behaviour expression in sexually exhausted male rats was investigated. The behavioural effects of the simultaneous injection of yohimbine (500 microg/kg) plus apomorphine (50 microg/kg) and those of the combined treatment of haloperidol (125 microg), a nonspecific dopamine receptor antagonist, with an effective dose of yohimbine (2000 microg/kg) on sexually satiated rats were evaluated. Data show that yohimbine and apomorphine, per se, dose-dependently reverse sexual exhaustion by increasing the percentage of sexually satiated rats copulating and resuming copulation after ejaculation. Injection of haloperidol simultaneous to an effective dose of yohimbine, blocked the ability of the latter to reverse sexual satiation. The combined treatment with subthreshold doses of apomorphine and yohimbine synergised to reverse the sexual inhibition characteristic of sexual exhaustion. Data suggest that the dopaminergic system might be the final pathway for the yohimbine-induced sexual behaviour expression in satiated rats. The possible role of sexual motivation in the sexual exhaustion phenomenon is discussed.

Adrenergic alpha-Antagonists↗
PubMed2003

Female rats develop conditioned place preferences for sex at their preferred interval.

Female rats engage in approach and avoidance behaviors directed toward the male to "pace" the rate of copulation. These pacing behaviors result in a pattern of vaginocervical stimulation that triggers a neuroendocrine reflex that is important for pregnancy to result from insemination. Each female rat has a preferred pacing interval, and females develop conditioned place preferences for paced sex versus nonpaced sex. Research from this laboratory has reported that extracellular dopamine concentrations in striatum and nucleus accumbens are greater in female rats that are engaging in paced sex compared with those engaging in nonpaced sex. Furthermore, females who have males removed at their preferred intervals during a copulatory bout show extracellular dopamine concentrations comparable to females engaging in paced sex. It is unclear, however, whether they would also develop a conditioned place preference for sex under such conditions. This experiment was designed to address this question. Female rats had six exposures each to a chamber in which they engaged in nonpaced sex and a chamber in which they engaged in paced or preferred pacing interval sex. Following conditioning trials, females were tested for a conditioned place preference. The findings indicate that female rats develop conditioned place preferences for paced sex and for sex in which the male is removed at her preferred interval. This suggests that sexual behavior is reinforcing to female rats when their preferred interval is achieved, whether or not they are actively controlling the rate of copulation.

Animals↗
PubMed2003

Ultrastructure and function of long and short sperm in Cicadidae (Hemiptera).

The cicada, Graptopsaltria nigrofuscata, produces two distinct sizes of sperm, as determined by either nuclear volume of early spermatids or nuclear length of mature sperm. Between both sperm, there is no difference in location of the acrosome and flagellum during spermiogenesis. The acrosome is covered by an anteacrosomal bleb, which is inserted in a common mass, spermatodesm, derived from cyst cells. Both kinds of sperm linked to the spermatodesm form sperm bundles, respectively. During copulation, the sperm bundles are transported from the vesicula seminalis of the male to the bursa copulatrix of the female. Morphometric analyses of the nuclear length revealed that the two kinds of sperm reach the bursa copulatrix in the same condition as that found in the vesicula seminalis. Once transferred inside the latter, the sperm bundles disintegrated to individual sperm within a few hours, and the tail components, such as the axoneme and mitochondrial derivatives, become separated from each other over time. The tail completely splits from the sperm nucleus 24 h after copulation. Fertile sperm accumulate in the spermatheca, the final storage organ, where only long sperm survived for any length of time. Fertilized eggs examined by vital staining contain only sperm with long nuclei.

Acrosome↗
PubMed2001

The development of olfactory conditioned ejaculatory preferences in the male rat. II. Parametric manipulation of conditioning session number and duration.

We have previously demonstrated that repeated pairing of a neutral odor with copulation produces a subsequent conditioned ejaculatory preference (CEP) for females bearing that odor. The present study examines the course of CEP development. In Experiment 1, Long-Evans male rats were allowed access to almond-scented, sexually receptive females for either one, five, or nine conditioning sessions that were 30 min in duration. Males given five or nine sessions displayed significant CEPs. In Experiment 2, male rats were given a single conditioning session with multiple almond-scented females until either a duration (60, 120, 180, or 240 min) or copulatory criterion (two, four, or six ejaculatory series) was satisfied. Males that received 120-, 180-, or 240-min sessions or four ejaculations displayed significant CEPs; males that received two or six ejaculations displayed a trend for CEPs. Analysis of effect size estimates revealed that the strongest CEPs were produced by 120 min of copulation or four ejaculations. In Experiment 3, males receiving nine conditioning sessions each 30 min in duration displayed a more enduring CEP than did males receiving a single conditioning session 240 min in duration. These data suggest that early sexual experiences have particularly powerful influences on subsequent sexual preferences and that the development of sexual preferences are influenced by interactions between CS-UCS pairings and motivational variables.

Animals↗
PubMed1997

Sexually arousing events and relapse to heroin-seeking in sexually experienced male rats.

We have shown previously, using a reinstatement procedure, that both priming injections of heroin and exposure to footshock stress reinstate heroin-taking behavior following prolonged drug-free periods. In the present study, we examined the effect of another highly arousing event, exposure to a sexually active female, on reinstatement of heroin-seeking. Male rats were first given sexual experience, being allowed to copulate on 4 occasions with sexually active females and were then trained to self-administer heroin (100 micrograms/kg per infusion, IV) for 4 3-h sessions/day for 5-6 days and 1 6-h session/day for an additional 6 days. Extinction sessions were then given for 4 days, 6-h/day, during which saline was substituted for heroin. On tests for reinstatement, males were presented with: 1. The wire-mesh side of an empty cage (baseline condition), 2. the sight, odor, and smell of a sexually inactive female, 3. the sight, odor, and smell of a female in heat, 4. a female in heat, and allowed to copulate, 5. intermittent footshock (15 min, 0.5 mA, 0.5 s on, mean off period of 40 s), or 6. a priming injection of heroin (0.25 mg/kg, SC). Reinstatement of heroin-taking behavior was observed after exposure to the priming injection of heroin and to footshock stress. Reinstatement of heroin-taking behavior was not induced by exposure to the females in any of the conditions. Thus, motivational arousal, as such, does not appear to be a sufficient stimulus for relapse to heroin-taking.

Animals↗
PubMed1998

Influence of male-related stimuli on female postejaculatory refractory period in rats.

Female rats "pace" their sexual contacts with the male when tested in situations where they can escape from the male during copulation. The type and quality of vaginocervical stimulation that the females receive during copulation influences their pacing behavior. This study investigated the effect of several male-related stimuli on the female's postejaculatory refractory period (PER). Females were tested in a two-compartment test chamber from which they could escape the male through one of four openings along the bottom of the barrier separating the two compartments. Experiment 1 examined the influence of the seminal plug, the penile cup, and prostate secretions on the female's PER. Results showed that neither the seminal plug, the penile cup, nor prostate secretions contributed to the female's PER. Experiment 2 investigated the relation of pre-ejaculatory intromission frequency, ejaculation duration, and the number of pelvic thrusts during ejaculation to the female's PER. Results indicated that pre-ejaculatory intromission frequency and ejaculation duration but not the number of pelvic thrusts during ejaculation were significantly correlated with the female's PER. In addition, pre-ejaculatory intromission frequency was significantly correlated with ejaculation duration. Partial correlation analysis suggested that pre-ejaculatory intromission frequency affected ejaculation duration which, in turn, influenced the female's PER. This finding was further supported by the evidence that ejaculation duration and the female's PER were significantly shorter in tests in which the male ejaculated on the first or second intromission.

Animals↗
PubMed1997

8-OH-DPAT and male rat sexual behavior: partial blockade by noradrenergic lesion and sexual exhaustion.

As previously shown, the 5-HT1A agonist 8-OH-DPAT is a potent facilitator of male rat copulatory behavior in both sexually experienced and sexually exhausted male rats. The basis of this facilitation is still not clear. Therefore, the purpose of the present study was to determine whether 8-OH-DPAT-induced sexual-behavior facilitation could be counteracted by lesioning the NA system with the noradrenergic neurotoxin DSP4. In NA-lesioned, sexually experienced, non-exhausted rats, the facilitatory effects of 8-OH-DPAT on the number of mounts and the postejaculatory interval were reduced, the effect on the intromission latency disappeared, while the percentage of copulating rats was not significantly altered. In sexually exhausted rats bearing a lesion of the NA system, the facilitatory effects of 8-OH-DPAT on the percentage of copulating rats was blocked. Data are discussed on the basis of the interactions between the noradrenergic and serotonergic systems in the mediation of the facilitatory effect of 8-OH-DPAT in sexually exhausted and non-exhausted rats.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1987

Pharmacological analysis of male rat sexual behavior.

Pharmacological influences on male rat sexual behavior are reviewed in an attempt to identify neurotransmitters and their respective receptor types that regulate various factors comprising the behavioral pattern. Evidence is presented that: (1) serotonergic influence is generally inhibitory to sexual behavior, although two receptor subtypes may lower ejaculation threshold; (2) dopaminergic agonists facilitate several aspects of copulatory behavior and ex copula genital responses; (3) noradrenergic activity appears to increase sexual arousal; (4) cholinergic agonists facilitate ejaculation, or in some cases, delay or prevent initiation of copulation; (5) GABA agonists inhibit sexual responses both in and ex copula; (6) opiate agonists appear to inhibit copulation and penile reflexes, although antagonists have mixed effects; (7) ACTH and MSH peptides promote copulatory behavior and genital responses; (8) oxytocin facilitates ex copula penile responses, but may contribute to postejaculatory refractoriness; and (9) long-term exposure to prolactin inhibits sexual behavior and penile responses. Although some progress has been made in identifying neurotransmitter-receptor effects on behavioral components, copulatory behavior is complex and no drug has been found to affect only a single component. Furthermore, drug specificity is only relative.

Animals↗
PubMed1986

Mating-induced inhibition of receptivity in the female golden hamster. I. Short-term and long-term effects.

Female golden hamsters (Mesocricetus auratus) which have actively terminated mating with one male will respond in succession to two or more novel males. However, mating with the first male results in a reduction in receptivity shown toward a second male, with the size of the decrease being proportional to the amount of copulatory stimuli provided by the first male. Furthermore, the decreased receptivity shown toward the second male results in his achieving fewer ejaculations. These effects are more pronounced when the second mating occurs 5 min or 8 h after the first mating than when it occurs 1 or 4 h later, suggesting both short-term and long-term inhibitory effects. Copulation with a single male also effects a 40% shortening of behavioral receptivity. In a promiscuous species such as the hamster, prolonged copulation by the male may enhance the short-term inhibition of female receptivity, thereby reducing the risk of subsequent sperm displacement. The long-term effect occurs too late to affect sperm competition and may, instead, function to reduce the risk of predation as a result of unnecessary further mating.

Animals↗
PubMed1986

The effects of yeast on sexual behavior in Drosophila melanogaster.

The presence of yeast in the diet of virgin Drosophila melanogaster females increases the probability that the females will copulate, although it does not increase their attractiveness. Females raised on yeast move more slowly while being courted by males and elicit a greater number of attempted copulations per minute.

Animals↗
PubMed2002

Prehatching visual experience and lateralization in the visual Wulst of the chick.

We revealed functional lateralization of the chick visual system by placing injections of monosodium glutamate (0.5 microl, 100 mM) into the left or right Wulst regions of the hemispheres, and examined the effects of light experience before hatching on this lateralization. Following exposure of the left or right eye to light for 24 h beginning on day 18 of incubation, the chick's ability to categorize grain as distinct from pebbles was impaired by glutamate treatment of the Wulst contralateral to the exposed eye. Attack and copulation scores were also elevated. Following incubation of the eggs in darkness or with both eyes exposed to light, treatment of neither the left or right Wulst affected performance on the pebble-grain task: showing that either the left and right Wulst can assume control of this function. Treatment of either the left or right Wulst of these chicks elevates attack and copulation. However, examination of the distribution of attack scores revealed a bimodality in the attack scores of the chicks treated with glutamate in the right Wulst and not those treated in the left Wulst. In summary, light stimulation of one eye during a critical period of embryonic development causes the visual Wulst contralateral to the light exposed eye to develop dominance over its equivalent region in the other hemisphere. Without this lateralized stimulation of light both the left and right Wulst regions are largely but not exactly equivalent.

Aggression↗
PubMed1989

Reduction in anxiety after ejaculation in the rat.

The anxiety levels, tested in the conditioned defensive burying behaviour paradigm, were analyzed after various phases of copulatory behaviour. No differences in anxiety were found between the group of animals without sexual activity and the group of animals tested after five intromissions of the first ejaculatory series. A decrease in anxiety, reflected as a reduction in the burying behaviour, was found in the group of animals tested during the first and the second postejaculatory intervals or after two intromissions from the second series of copulation. The possible involvement of the GABAergic system mediating the reduction in anxiety during these phases of copulation is discussed.

Animals↗
PubMedDate not supplied

Dopamine and senescence in Drosophila melanogaster.

Five-day-old Drosophila melanogaster males, when exposed to 2-h-old males, will perform courtship rituals; the intensity and duration of this behavior rapidly diminishes with time. The ability of the older males to habituate to the attractive signals given off by the younger males is a dopaminergic-modulated experience-dependent modification of behavior that is abolished with increasing age. Dopamine-depleted females show increased resistance to copulation; 20-day-old females demonstrated an increase in copulation avoidance compared with younger (5-15-day-old) females. These changes in dopaminergic-modulated behaviors observed during aging parallel declines in whole body levels of dopamine. Immunocytochemical analysis of adult brains using an antibody raised against Drosophila tyrosine hydroxylase to visualize catecholaminergic cell bodies revealed increased degeneration of the cell bodies with aging. These results suggest that the deficits seen in dopaminergic-modulated behaviors may arise as a consequence of degenerative changes within the aging brain.

Aging↗
PubMed1999

Erectile function in male rats after lesions in the lateral paragigantocellular nucleus.

In previous research on rats, lesions of the lateral paragigantocellular nucleus (LPGi) in the medulla have facilitated the display of reflexive erection and ejaculation. The present research sought to replicate and extend these findings by determining whether LPGi lesions would also promote erection during copulation and during exposure of the male to inaccessible females, i.e. non-contact erections (NCEs). As expected, males with LPGi lesions (n = 10) had a greater incidence of reflexive erection than males with sham lesions (n = 8), and during copulation LPGi-damaged males required fewer intromissions before ejaculation. However, the lesions did not change the copulatory intromission ratio, a partial measure of erectile function, nor did they change the incidence, latency, or number of NCEs displayed. More direct measures of erection will be necessary to determine whether the inhibitory role of LPGi on sexual reflexes is absent in some erectile contexts, or whether its role in some contexts is too small to be evident in behavioral measures.

Animals↗
PubMed2001

The main olfactory system mediates pheromone-induced fos expression in the extended amygdala and preoptic area of the male Syrian hamster.

Copulation in male hamsters is stimulated by exposure to vaginal secretions of conspecifics. These pheromones also stimulate fos expression in neural areas that regulate copulation including: the medial nucleus of the amygdala, the bed nucleus of the stria terminalis, and the preoptic area. The pheromones in vaginal secretions are detected by both the main and accessory olfactory systems. However, the accessory system plays the greater role in the regulation of mating behavior and has direct connections with the medial nucleus of the amygdala and bed nucleus of the stria terminalis. The goal of the present study was to determine which system mediates the effect of pheromones on the stimulation of more central areas by deafferenting these systems in experienced male hamsters before exposure to vaginal secretions. Destruction of the receptors in the main olfactory system with zinc sulfate eliminated the increase in fos immunoreactivity in the amygdala, bed nucleus of the stria terminalis and preoptic area following exposure to sexually stimulating pheromones. Deafferentation of the accessory olfactory system by removing the vomeronasal organ had no effect on pheromone-induced fos expression in these areas. We conclude that neurons expressing fos following exposure to vaginal secretions are stimulated via the main olfactory system and are not associated with the expression of copulatory behavior.

Amygdala↗
PubMed2003

Masculine sexual activity affects slow wave sleep in Golden hamsters.

The sleep pattern is modified by events occurring during wakefulness. In rats, it has been shown that male sexual behavior has a direct influence on sleeping patterns, increasing slow wave sleep (SWS) duration. On the other hand, the sexual behavior pattern of the male Golden hamster differs from the copulatory pattern of male rats. Male hamsters copulate faster and they do not display the motor inhibition observed in rats after each ejaculation. Moreover, close to exhaustion, hamsters display a behavioral pattern known as Long Intromission, which has been linked to an sexual inhibitory process. The present study was performed to determine the effects of male sexual activity on the sleep pattern in hamsters. Subjects were allowed to copulate for 30 and 60 min. In addition, the effect of locomotor activity was also assessed. The results show that male sexual behavior induced a significant increase of SWS II, with a reduction of wakefulness. No effect was observed on REM sleep. Locomotor activity produced only a slight effect on sleep. The results are discussed in terms of the similarities between the effects observed after sexual behavior on sleep in rats and hamsters, despite the substantial differences in the behavioral pattern.

Animals↗
PubMed1997

Fertility of the male alpaca: effect of daily consecutive breeding.

The fertility of the male alpaca under different frequencies of daily consecutive matings was evaluated. Fifteen adult male Huacaya alpacas were divided randomly into three groups of five each to breed lactating female alpacas. The schedule of daily matings was two, four and six consecutive breeding per group and for nine consecutive days. Ovulation was determined by progesterone at seven days after breeding. Pregnancy was determined by ultrasonography at 15 and 30 days after breeding. Two hundred and eighty females were bred with some males not fulfilling their schedule of breeding. There were differences (P < 0.05) in the fertility rate of males breeding two and four times daily (76%) in contrast to 59% for males breeding six times. There were also differences (P < 0.05) in the fertility of individual males. Length of copulation was affected (P < 0.05) by schedule of matings, day of breeding and male. Ovulation was independent of length of copulation. Overall, it seems the fertility of the male alpaca is affected significantly when consecutive matings are over four times a day and for nine consecutive days.

Animals↗
PubMedDate not supplied

Effects of prenatal exposure to 5-bromo-2'-deoxyuridine on reproductive function in male mouse offspring.

The effect of the halogenated pyrimidine analog 5-bromo-2'-deoxyuridine (BrdU), on reproductive functions of male mouse offspring treated prenatally was studied. BrdU was administered intraperitoneally to pregnant ICR mice at 100 mg/kg/d on days 8 through 13 of gestation, and at 100 or 200 mg/kg/d on days 14 through 18 of gestation. Dams were allowed to deliver naturally. Male offspring were aged for 10 weeks and then cohabited with untreated female mice for assessment of reproductive performance. Histopathologic examination of the testes and pituitary, sperm analysis, and determination of plasma testosterone concentrations of offspring at 12 weeks of age were performed. In the subsequent study, pregnant ICR mice were treated with 200 mg BrdU/kg on day 10, 13, or 15 of gestation. The embryos or fetuses were obtained from mothers from 6 to 48 h after treatment, and pyknotic cells in the ventricular zone of the telencephalon were counted. There was a significant decrease in body weight gain of offspring in all of the BrdU-treated groups. A marked decrease in copulation rate was noted in the male offspring of dams treated on days 8 through 13 of gestation, whereas no significant decreases in copulation and fertility rates were found in the male offspring of dams treated on days 14 through 18 of gestation. Neither histopathologic examination of testes nor sperm analyses revealed adverse effects of this compound, whereas cysts in the pars distalis of the pituitary were observed in the male offspring treated on days 8 through 13 of gestation. Dilatation of the lateral ventricles was also observed in male offspring at 12 weeks of age in the group treated on days 8 through 13 of gestation. The incidence of pyknotic cells in the ventricular zone of embryos was markedly increased 24 h after treatment on day 10 of gestation. These results indicate that the impaired fertility of the male offspring of dams treated with BrdU on days 8 through 13 of gestation may be due to the effects of BrdU exposure on central nervous system function that result in loss of libido rather than to the direct effects of this compound on the male reproductive organs.

Animals↗