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PubMedDate not supplied

Anatomical and physiological characteristics of perineal muscles in the female rabbit.

Little information is available on the participation of the perineal striated muscles in female reproductive processes. Here, we describe the gross anatomy and innervation of two striated perineal muscles in the female rabbit, the bulbospongiosus (BSM) and ischiocavernosus (ISM), and analyze their reflex electromyographic (EMG) activity in response to stimulation of the perigenital skin and vaginal tract. Twenty-four mature chinchilla-breed rabbit does were used: 12 to describe the anatomy and innervation of the muscles, 9 to determine reflex EMG activity of the muscles in response to stimulation of the perigenital skin and specific levels of the vaginal tract and 3 to analyze the effect of contraction of the muscles on intravaginal pressure. Both muscles were well developed, with their fibers originating at the ischiadic arch and inserting onto the ligamentum suspensorium clitoridis. Branches of the clitoral and perineal nerves innervated the BSM and ISM, respectively. Bilateral electrical stimulation of these nerves provoked retraction of the clitoral sheath and an increase in intravaginal pressure at the level of the perineal vagina. Whereas neither muscle responded to stimulation of the perigenital skin, both were reflexively activated during mechanical stimulation of the inner walls of the perineal vagina. Prolonged cervical stimulation inhibited this reflex. Thus, in reproductive processes such as copulation and/or parturition, the contraction of these muscles may be induced during stimulation of the perineal vagina.

Animals↗
PubMed2003

Characterization of 50-kHz ultrasonic vocalizations in male and female rats.

Male and female rats emit ultrasonic vocalizations in reproductive encounters. While estrous bedding has been used to elicit vocalizations of males, the number of responses is variable. We report a reliable method to assess vocalizations using exposure to a stimulus animal. The stimulus rat is placed behind a wire barrier for 5 min, then removed. Vocalizations are then recorded for 5 min. Experiment 1 validated this method and it was used for subsequent experiments. In Experiment 2, male rats were castrated and tested for the restoration of vocalizations. In one group, males were allowed to copulate freely; in the other, females had vaginal masks to prevent ejaculation, but not mounting. Vocalizations were restored only in males allowed to ejaculate. In Experiment 3, we measured vocalizations in sexually nai;ve and sexually experienced males following exposure to either castrated (CAS) males, testosterone (T)-treated males, ovariectomized (OVX) females, or OVX females receiving estrogen plus progesterone (E+P). Males vocalized most after exposure to E+P females, whether they were sexually experienced or naive. However, the rate of vocalizations was significantly higher after exposure to E+P females when the males were sexually experienced. In Experiment 4, we measured vocalizations in females following exposure to CAS males, T-treated males, OVX females, or E+P females. Females vocalized most after exposure to T-treated males. Our results show that (1) sexual experience facilitates vocalizations in male rats, (2) vocalizations are highest after exposure to hormonally receptive conspecifics, and (3) ultrasonic signaling is a sensitive index for assessing the hormonal disposition of conspecifics.

Animals↗
PubMed1997

Penile erection: a reflection of sexual arousal and arousability in male chimpanzees.

A study was conducted to determine if sexual motivation in male chimpanzees, defined by the two components, sexual arousal and arousability, could be quantified by measuring penile erection during laboratory pair-tests of sexual behavior. Sexual arousal, the momentary level of sexual excitation, was quantified by single measurements on a scale of penile erection. Sexual arousability, the propensity for arousal, was quantified by the rate of approach to full erection and by mean erection scores. Sexual arousability, as defined, was related to the frequency of male courtship displays, copulations, and ejaculations, which were highest at midcycle and positively correlated with a quantitative measure of female anogenital swelling. Sexual arousal was negatively correlated with continued exposure to the female and least variable during midcycle. These operational definitions of sexual motivation in the male chimpanzee facilitate comparative research in which analogous indexes of sexual motivation are required such as when extrapolating from animal to human.

Animals↗
PubMed1997

Computer programs to analyze brain electrical activity during copulatory pelvic thrusting in male rats.

Two microcomputer programs have been developed to simultaneously record and analyze the brain electrical activity: multiple unit activity (MUA) and electroencephalogram (EEG), and the accelerometric signals generated in relation to the pelvic thrusting that performs the male rat during the copulatory responses of mount, intromission, and ejaculation. CAPTUMUL is a program allowing the on line capture of the different signals and the further off line delimitation of the brain signals occurring in exact temporal relation with the accelerometric record of motor responses. The ANAMUA program allows the off line analysis of the neuronal firing rate in MUA records at different discrimination levels according to the amplitude of the neuronal spikes, and compare these data in various behavioral situations. The use of these programs provides a way of correlating in time the changes of brain electrical activity occurring in animals in free-movement with the brief motor events of copulation as well as with other behaviors (i.e., genital grooming, sniffing, running, walking). Advantages of this software include the recording of sequential events, a better and rapid handling of data and a reliable method to analyze the MUA with different discrimination levels according to the amplitude of the neuronal spikes.

Animals↗
PubMedDate not supplied

Female-soiled bedding induced fos immunoreactivity in the ventral part of the premammillary nucleus (PMv) of the male mouse.

Previous studies have indicated that the ventral part of the premammillary nucleus (PMv) of rodents is involved in the regulation of aggressive and male mating behavior, although the precise physiological function of the PMv is still unclear. To analyze the physiological role of the PMv in male mating behavior, the effects of exposure to bedding soiled by female mice on Fos immunoreactivity (Fos-ir), an early marker of neuronal activation, were studied in the PMv and some sex-related nuclei. We observed that exposure to female-soiled bedding induced Fos-ir expression in the PMv of the male mouse. Although Fos-ir positive cells were found in the posterodorsal part of the medial amygdaloid nucleus and in the posteromedial cortical amygdaloid nucleus, which are terminals of the neuronal projections from the main and accessory olfactory bulbs, the numbers of Fos-ir cells in those nuclei were not affected by exposure to female-soiled bedding. Moreover, Fos-ir was not detected in the ventromedial hypothalamic nucleus. It is well established that soiled bedding is useful as a source of chemosensory substances, which include "pheromones." Thus, our findings, in agreement with previous behavioral and anatomical data, suggest that the PMv plays a role in initiating male copulative behavior that is induced by a female mice pheromone(s).

Aggression↗
PubMed2003

Ultrastructural observations of spermatozoa and spermiogenesis in Wandella orana Gray, 1994 (Araneae: Filistatidae) with notes on their phylogenetic implications.

Spermatozoa and spermiogenesis of the prithine filistatid spider Wandella orana are described. The spider produces coenospermia, i.e. sperm aggregations that include several single sperm cells commonly surrounded by a secretion sheath. One sectioned coenospermium in W. orana contains at least five spermatozoa. During copulation many coenospermia are transferred into the female. Coenospermia are regarded as a peculiar transfer form of sperm which occurs in early derivative spiders such as Liphistiomorphae and Mygalomorphae. The only exception which was found in Araneomorphae until now was the filistatine spider Filistata insidiatrix. Our observation is the second case and supports the view that Filistatidae represent an early derivative taxon. Furthermore, the individual sperm cells show characteristics which also may be regarded as being plesiomorphic. There is a cone-shaped acrosomal vacuole, a very long acrosomal filament, a rather stout nucleus and a small implantation fossa. The axoneme shows the 9x2+3 pattern of microtubules which is synapomorphic in Megoperculata (Uropygi, Amblypygi and Araneae). The finding of coenospermia in two distant taxa of Filistatidae may have consequences for phylogenetic and systematic considerations.

Acrosome↗
PubMed2005

The genetic architecture of house fly mating behavior.

This chapter summarizes several experimental approaches used to identify the effects of dominance, epistasis, and genotype-by-environment interactions in the genetic architecture of the mating behavior of the common house fly (Musca domestica L.). Quantitative genetic investigations of mating behavior hold special intrigue for unraveling the complexities of fitness traits, with applications to theory on sexual selection and speciation. Besides being well suited to large-scale quantitative genetic protocols, the house fly has a remarkably complex courtship repertoire, affording special opportunities for studies on communication, social interactions, and learning. Increased additive genetic variances for the courtship repertoire of experimentally bottlenecked populations provided evidence for the presence of dominance and/or epistasis. Negative genetic variances in these populations suggested genotype-by-environment interactions, where the environment is the mating partner. Line cross assays of populations that had been subjected to selection for divergent courtship repertoire confirmed that both dominance and epistasis have significant effects. These crosses also showed more directly that the expression of the male's genotype is dependent upon the preferences of his mating partner. Repeatability studies also detailed how males alter their courtship performances with successive encounters within and across females, such that the males learn to improve their techniques in securing copulations. A review of 41 animal behavior studies found that a wide range of traits and taxa have dominance, epistasis, and genotype-y-environment interactions, although house fly courtship may remain a unique model where learning is an intersexually selected trait. Future development of more sophisticated molecular techniques for the M. domestica genome will help unravel the underlying biochemical and developmental pathways of these quantitative genetic interactions for a more complete understanding of the processes of inbreeding depression, outbreeding depression, and pleiotropy.

Animals↗
PubMed2002

Sexually conditioned incentives: attenuation of motivational impact during dopamine receptor antagonism.

The motivational impact of sexually conditioned incentives was examined in two experiments. In Experiment 1, male Long-Evans rats copulated to ejaculation in the presence of one of two scents (orange or almond extract) on five separate occasions. On alternating days, subjects spent an equal amount of time in social isolation with the opposing scent. Following the 10-day conditioning regimen, subjects ran more rapidly down an operant runway toward a goalbox containing the sex-paired scent (CS+) compared to trials on which the isolation-paired scent (CS-) or no scent was provided. In Experiment 2, comparably conditioned male rats were first given a baseline runway trial with an unscented goalbox. The following day, subjects were pretreated with one of four doses of haloperidol (0.0, 0.075, 0.15, or 0.30 mg/kg i.p.) 45 min prior to being tested in the runway for their motivation to approach either the CS+ or CS- scents. Control subjects given vehicle injections performed comparably to subjects from Experiment 1, taking significantly less time to approach the CS+ than an unscented goalbox. This decrease in run latency was not observed in subjects within the 0.075 and 0.15 mg/kg haloperidol groups. Subjects in the 0.30 mg/kg haloperidol groups took significantly more time to approach both the CS+ and CS- compared to their baseline run times. These data reveal that an olfactory cue associated with sexual reward becomes a conditioned incentive capable of eliciting approach behavior, and that dopamine receptor antagonism (at moderate but not high doses) selectively attenuates this cue-induced motivation.

Animals↗
PubMed2002

Chronic opiate exposure in the male rat adversely affects fertility.

We examined whether morphine administration to adult male rats adversely affected pregnancy outcome after mating with drug-naive females and at what point in the complex series of steps leading to viable offspring it exerted its actions. The results indicate that chronic paternal morphine exposure markedly influenced fertility measures in a number of important ways. There was a pronounced increase in pseudopregnancies in females mated with males treated chronically with morphine (40%) when compared to controls (<6%), indicating that vaginal penetration occurred, but successful impregnation failed; only 33% of matings between drug-naive females and morphine-treated males resulted in pregnancies, as compared to 74.5% in controls. In addition, there were fewer implantation sites in gravid females mated with morphine-treated males than in controls. Taken together, these observations suggest that morphine-exposed male rats were apparently able to copulate, but there was a failure in successful impregnation of the females. These findings suggest a primary defect in either the quality of male sexual behavior or a complete failure of the fertilization or conception processes in females mated with morphine-exposed males. This potentially important effect of paternal morphine administration on conception and/or preimplementation loss of embryos has not been previously noted and deserves more systematic study.

Analgesics, Opioid↗
PubMed1997

GABAergic drugs and socio-sexual behavior.

To elucidate the role of GABA in the control of sexual behavior, the effects of the GABA(A) agonist 4,5,6,7-tetrahydroisoxazolo[5,4c]-pyridin-3-ol (THIP), the GABA transaminase inhibitors sodium valproate and gamma-acetylen-GABA (GAG), and the GABA synthesis inhibitors isoniazide and deoxypyridoxine were evaluated in sexual behavior, exploration, and sociosexual interactions with a receptive female or a castrated male. Furthermore, to discriminate possible general inhibitory effects from those specific to sexual behavior, the doses of the drugs that produced a significant inhibition of copulation were tested in a free drinking procedure. THIP (16 mg/kg), sodium valproate (400 mg/kg), GAG (100 mg/kg), and deoxypyridoxine (400 mg/kg) produced a strong inhibition of sexual behavior. The percentage of animals displaying mounts and intromissions as well as the mean number of mounts and intromissions were significantly reduced. Sociosexual interactions with a receptive female or a castrated male and exploratory behaviors were also reduced. The most consistent effects observed were reductions in sniffing, self-grooming, and rearing. Drinking behavior was significantly reduced in doses that inhibited sexual behavior. These results further support the hypothesis that altered GABAergic neurotransmission produces reduced sensitivity to environmental stimuli and thereby inhibits sexual and drinking behavior in a nonspecific way.

Animals↗
PubMed2004

Indiscriminate polyandry and male parental effort.

Extrapair paternity involves cooperation between mated females and extrapair males. On the other hand, mated males exhibit a spectrum of anti-cuckolding strategies. Hence, extrapair attributes of diverse species and populations reported in the literature are particular solutions of evolutionary games involving gender-specific cuckolding/anti-cuckolding strategies. Here we use game theoretical methods to study the effect of male paternal effort conserving strategies in situations where females seek extrapair fertilizations (EPF) for reasons of genetic compatibility and/or in pursuit of genetic diversity for their offspring. In such cases, females cannot make a pre-copulatory selection of the optimal genetic partners, and therefore combine promiscuous copulation with the use of in copula and/or post-copulatory selection mechanisms to optimize the genetic endowment of their offspring-indiscriminate polyandry. Our results indicate that, when indiscriminate polygamy is constrained by the availability of extrapair male partners, there are three possible (parameter regime wise) evolutionary stable strategy solutions. (1). All females seek EPF, while all males restrict parental care. (2). All females seek EPF, while all males are unconditionally parental. (3). Females use a combination strategy where pursuit of EPF is mixed-on either a population, or an individual level-with genetic monogamy, while all males use a conditional paternal care strategy, which involves adjusting their parental efforts according to their certainty of paternity.

Animals↗
PubMed2001

Increasing imposex in populations of Bolinus brandaris (Gastropoda: Muricidae) in the northwestern Mediterranean.

The muricid gastropod Bolinus brandaris exhibited imposex, a phenomenon linked to the use of organotin biocides. Several stages of imposex development (1-5) could be distinguished and were documented with SEM-photographs for the first time in this species. Additional alterations of the genital tract in females (blocked vulva preventing copulation and deposition of egg capsules) and males (excrecences on the penis and vas deferens) were shown. Imposex intensity on the Catalan coast was very high. The frequency of imposex off Barcelona and Vilanova i la Geltrú was 100%, with all females showing stage 4. Imposex frequency off Sant Carles de la Ràpita was 99.7% and the VDS index scored 3.9. Despite regulations of TBT-containing antifouling paints in Spain since 1990, the present study revealed that frequency and intensity of imposex have increased on the Catalan coast, at least since 1997. However, at present, imposex does not apparently affect the population dynamics of B. brandaris in the studied area, since no serious consequences on female reproduction (only one case of female sterilization) were detected. Gonadal activity and oogenesis were not suppressed or supplanted by spermatogenesis. Sex ratios were not male-biased. Possible sources of organotin biocides are examined.

Animals↗
PubMed1990

Hormonal regulation of sociosexual behavior in female mammals.

The role of estrogen (E) and progesterone (P) in regulating the expression of agonistic, scent marking and proceptive displays is reviewed. In the intact sexually mature female, data indicate that agonistic, scent marking and proceptive patterns of behavior fluctuate significantly prior to and during the period of mating. The propensity to display a specific pattern of behavior is dependent upon the stimulus situation. Hence, agonistic behavior may be induced by the presence of a conspecific female whereas sexual behavior and proceptive responses will be elicited by a male. Administration of E to ovariectomized animals does not appear to produce significant effects on agonistic behavior and territorial scent-marking responses albeit in a few cases E appears to reduce agonistic tendencies toward male conspecifics. Exogenous E treatment, however, does appear to induce the occurrence of proceptive forms of scent-marking behavior as well as a variety of other proceptive responses which are further increased after P treatment. Importantly, the sequential administration of E and P facilitates both proceptive and copulatory responses in several rodent species. In addition, hormone implant studies indicate that sites in the brain which are sensitive to the hormonal facilitation of sexual receptivity concurrently facilitate proceptive behavior. On the basis of the current data, ovarian hormones appear to exert their strongest effects on producing behavioral displays which attract males prior to mating, facilitating sexual receptivity, and inducing concurrently proceptive responses which further enhance copulation and reproductive success.

Animals↗
PubMed1986

Effect of anosmia on reproduction in male and female wolves (Canis lupus).

Anosmia was produced in two female and three male wolves by transection of the olfactory peduncle and was confirmed by their inability to detect meat, urine, feces, anal-gland secretions, and fish emulsion. All operated animals continued to investigate the environment with their noses, to interact normally with other pack members, and to feed at levels which maintained presurgical body weights. No effect was found on reproductive physiology (females: estradiol or progesterone concentrations, ovulation, pregnancy or parturition; males: testosterone, testicular recrudescence or sperm numbers, motility or maturation). One anosmic female became dominant and although she urine-marked with a flexed leg, the rate was lower than typical for dominant females and perhaps contributed to her failure to pair-bond with the dominant male. One anosmic male raised-leg-urinated while competing for pack dominance and when kenneled away from other males. Precopulatory, copulatory, and maternal behavior were observed for one anosmic female and appeared normal. However, neither male that was sexually naive before surgery showed interest in proestrous or estrous females. The possibility that secondary degeneration of brain regions mediating sexual behavior was responsible for the failure of these males to respond was not supported. Not only was the lack of male sexual response the only serious deficit following transection, but the male which was sexually experienced prior to surgery did copulate successfully during his second postoperative breeding season despite continued anosmia. Chemosensory priming from female urine during the protracted proestrous phase, as well as urinary and vaginal odors during estrus, appear to be critical for induction of full sexual potency in sexually naive males. The importance of urine and vaginal secretions in the sexual response of experienced males is uncertain.

Animals↗
PubMed2002

Castration, dopamine and food choice: a cost/benefit test in male hamsters.

Testosterone is essential for copulation, and contributes to sexual motivation. In addition, castrated males are fatter and less active, suggesting that androgens may play a role in non-sexual behaviors, including food-related responses. To test this hypothesis, male hamsters were trained with a cost/benefit test, which compares operant responding for more-preferred food versus ad libitum consumption of lab chow. Males were tested before and after castration. The effect of the dopamine antagonist, haloperidol, on instrumental responses in intact and castrated males was also determined. Food-deprived hamsters responded vigorously for 45 mg Bio-Serv pellets in daily 30-min tests (665 presses, 6.0+/-0.9 g). When lab chow was available, males continued to respond for pellets (3.6+/-0.6 g) over chow ad libitum (1.2+/-0.3 g). Dopamine is central to this response because haloperidol (1.0 mg/kg i.p.) reversed food intake (pellets: 0.5+/-0.1 g; chow 2.0+/-0.5 g). Castration had no effect on operant responding for pellets alone (6.6+/-0.7 g). When chow was present, castrates consumed an even greater proportion of their total food intake as pellets [6.0+/-0.4 g pellets (92%), 1.6+/-0.5 g chow (8%), vs. 75 and 25%, respectively, for intact males]. This is contrary to our original hypothesis. In addition, castration did not change the effects of haloperidol on food intake: (0.4+/-0.1 g pellets; 1.6+/-0.5 g chow). These results support previous findings in rats that dopamine affects response allocation in a cost/benefit test. However, they do not support the hypothesis that testosterone modifies the allocation of food-related responses.

Animals↗
PubMed1998

The selectivity of sexual responses to song displays: effects of partial chemical lesion of the HVC in female canaries.

By stimulating female canaries with computer edited songs, we investigated the involvement of the caudal nucleus of the ventral hyperstriatum or high vocal center (HVC) in the selectivity of sexual responsiveness to different kinds of conspecific songs. Due to the fact that the types of conspecific song phrases act as relevant cues to give song its sexual potency, we compared courtship responses to two conspecific songs, highly sexually-stimulating and weakly sexually-stimulating song, before and after the partial ibotenate lesion of the HVC. Sexual responses to heterospecific song were also tested. Copulation solicitation displays were used as an index of female responses. The partial chemical lesions of the HVC whatever the HVC portion damaged affected female bird behavior; they responded more strongly to weakly sexually-stimulating song and to heterospecific song than before the lesions. However, the conspecific sexually attractive song continued to elicit the highest level of sexual displays. None of the control birds ever altered their pattern of responses to the three song types. The results suggest that the HVC is part of the neural network engaged in the control of sexual preferences to conspecific song displays.

Animals↗
PubMed2001

Gender effects on aggression, dominance rank, and affiliative behaviors in a flock of captive adult cockatiels (Nymphicus hollandicus).

Agonistic and affiliative behaviors and spatial positioning were studied in a small psittacine species, Nymphicus hollandicus. Subjects studied were flock-housed breeders including five hens and seven cocks. Fifteen-minute focal animal samples were collected for the entire flock in a randomly distributed order during mate selection and the onset of the breeding season. All agonistic behaviors were recorded, including the winner and loser of each interaction, along with allopreening and copulation behavior. Point samples were recorded every 60s to determine social spacing. Rates of aggression were significantly higher for male cockatiels than female cockatiels. Results based on dyadic agonistic interactions showed males to rank significantly higher in the social hierarchy than females. Associations within the flock were not random. Individual birds associated more with specific birds than would be predicted by chance. Analysis of spatial data revealed that there were both same-sex and opposite-sex preferred associations within the flock. Male cockatiels engaged in allopreening behavior with females significantly more than with other males. Observations of breeding and nesting behaviors revealed pairs, a triad, and extra-pair mating.

Journal Article↗
PubMed1999

Effects of centrally injected amylin on sexually behavior of male rats.

Amylin (AMY) is a peptide of pancreatic origin principally involved in the carbohydrate metabolism, but that may interfere with central and peripheral dopamine (DA) pathways. The peptide, injected intracerebroventricularly (ICV) at the dose of 2.5 microg/rat, induced a decrease of copulatory activity in good copulators (GCO) and sluggish (SLU) male rats. The dose of 0.1 microg/rat did not affect significantly the sexual behavior of GCO rats, whereas AMY 0.5 microg/rat increased only the latency and reduced the frequency of ejaculation. At the dose of 2.5 microg/rat AMY antagonized the activation of sexual behavior induced by the DA receptor agonist, apomorphine administered subcutaneously (SC) at the dose of 100 microg/kg. Moreover, this inhibitory effect was blocked by the calcitonin gene-related peptide and AMY receptor antagonist, CGRP (8-37) fragment (injected ICV at the dose of 1 microg/rat). These data suggest that AMY may exert inhibitory effects on male sexual behavior in rats, probably interfering with central DA neurotransmission and with CGRP receptors.

Amyloid↗