Vaginal Marking Research Articles

Deep infiltrating endometriosis: Should rectal and vaginal opacification be systematically used in MR imaging?

ObjectivesTo evaluate the interest of rectal and vaginal filling in vaginal and recto-sigmoid endometriosis with MR imaging. To compare the results between a senior and a junior radiologist review. MethodsSixty-seven patients with clinically suspected deep infiltrating endometriosis were included in our MRI protocol consisting of repeated T2-weigthed sequences (axial and sagittal) before and after rectal and vaginal marking with ultrasonography gel. Vaginal and recto-sigmoid endometriosis lesions were analyzed before and after opacification. The inter-reader agreement between senior and junior scores was studied. ResultsConcerning vaginal and muscularis and beyond colonic involvement, no significant difference (P=0.32) was observed and the inter-reader agreement was excellent (K=0.96 and 0.97 respectively). Concerning serosa colonic lesions, a significant difference was observed (P=0.01) and the inter-reader agreement was poor (K=0). ConclusionsRectal and vaginal filling in endometriosis staging with MRI is not necessary no matter the reader experiment.

Endogenous oxytocin is necessary for preferential Fos expression to male odors in the bed nucleus of the stria terminalis in female Syrian hamsters

Successful reproduction in mammals depends on proceptive or solicitational behaviors that enhance the probability of encountering potential mates. In female Syrian hamsters, one such behavior is vaginal scent marking. Recent evidence suggests that the neuropeptide oxytocin (OT) may be critical for regulating this behavior. Blockade of OT receptors in the bed nucleus of the stria terminalis (BNST) or the medial preoptic area (MPOA) decreases vaginal marking responses to male odors; lesion data suggest that BNST, rather than MPOA, mediates this effect. However, how OT interacts with sexual odor processing to drive preferential solicitation is not known. To address this issue, intact female Syrian hamsters were exposed to male or female odors and their brains processed for immunohistochemistry for Fos, a marker of recent neuronal activation, and OT. Additional females were injected intracerebroventricularly (ICV) with an oxytocin receptor antagonist (OTA) or vehicle, and then tested for vaginal marking and Fos responses to sexual odors. Colocalization of OT and Fos in the paraventricular nucleus of the hypothalamus was unchanged following exposure to male odors, but decreased following exposure to female odors. Following injections of OTA, Fos expression to male odors was decreased in BNST, but not in MPOA or the medial amygdala (MA). Fos expression in BNST may be functionally relevant for vaginal marking, given that there was a positive correlation between Fos expression and vaginal marking for BNST, but not MPOA or MA. Together, these data suggest that OT facilitation of neuronal activity in BNST underlies the facilitative effects of OT on solicitational responses to male odors.

The medial preoptic area is necessary for sexual odor preference, but not sexual solicitation, in female Syrian hamsters

Precopulatory behaviors that are preferentially directed towards opposite-sex conspecifics are critical for successful reproduction, particularly in species wherein the sexes live in isolation, such as Syrian hamsters (Mesocricetus auratus). In females, these behaviors include sexual odor preference and vaginal scent marking. The neural regulation of precopulatory behaviors is thought to involve a network of forebrain areas that includes the medial amygdala (MA), the bed nucleus of the stria terminalis (BNST), and the medial preoptic area (MPOA). Although MA and BNST are necessary for sexual odor preference and preferential vaginal marking to male odors, respectively, the role of MPOA in odor-guided female precopulatory behaviors is not well understood. To address this issue, female Syrian hamsters with bilateral, excitotoxic lesions of MPOA (MPOA-X) or sham lesions (SHAM) were tested for sexual odor investigation, scent marking, and lordosis. MPOA-X females did not investigate male odors more than female odors in an odor preference test, indicating that MPOA may be necessary for normal sexual odor preference in female hamsters. This loss of preference cannot be attributed to a sensory deficit, since MPOA-X females successfully discriminated male odors from female odors during an odor discrimination test. Surprisingly, no deficits in vaginal scent marking were observed in MPOA-X females, although these females did exhibit decreased overall levels of flank marking compared to SHAM females. Finally, all MPOA-X females exhibited lordosis appropriately. These results suggest that MPOA plays a critical role in the neural regulation of certain aspects of odor-guided precopulatory behaviors in female Syrian hamsters.

X-ray kinematics analysis of vaginal scent marking in female Syrian hamsters (Mesocricetus auratus)

Vaginal marking is a stereotyped scent marking behavior in female Syrian hamsters used to attract male hamsters for mating. Although the modulation of vaginal marking by hormones and odors is well understood, the motor control of this proceptive reproductive behavior remains unknown. Therefore, we used X-ray videography to visualize individual bone movements during vaginal marking. Kinematic analyses revealed several consistent motor patterns of vaginal marking. Despite exhibiting a diversity of trial-to-trial non-marking behaviors (e.g. locomotor stepping), we found that lowering and raising the pelvis consistently corresponded with coordinated flexion and extension cycles of the hip, knee, and tail, suggesting that these movements are fundamental to vaginal marking behavior. Surprisingly, we observed only small changes in the angles of the pelvic and sacral regions, suggesting previous reports of pelvic rotation during vaginal marking may need to be reconsidered. From these kinematic data, we inferred that vaginal marking is primarily due to the actions of hip and knee extensor muscles of the trailing leg working against gravity to support the weight of the animal as it controls the descent of the pelvis to the ground. The cutaneous trunci muscle likely mediates the characteristic flexion of the tail. Interestingly, this tail movement occurred on the same time scale as the joint kinematics suggesting possible synergistic recruitment of these muscle groups. These data therefore provide new targets for future studies examining the peripheral control of female reproductive behaviors.

The bed nucleus of the stria terminalis is critical for sexual solicitation, but not for opposite-sex odor preference, in female Syrian hamsters

Successful reproduction in vertebrates depends critically upon a suite of precopulatory behaviors that occur prior to mating. In Syrian hamsters (Mesocricetus auratus), these behaviors include vaginal scent marking and preferential investigation of male odors. The neural regulation of vaginal marking and opposite-sex odor preference likely involves an interconnected set of steroid-sensitive nuclei that includes the medial amygdala (MA), the bed nucleus of the stria terminalis (BNST), and the medial preoptic area (MPOA). For example, lesions of MA eliminate opposite-sex odor preference and reduce overall levels of vaginal marking, whereas lesions of MPOA decrease vaginal marking in response to male odors. Although BNST is densely interconnected with both MA and MPOA, little is known about the role of BNST in female precopulatory behaviors. To address this question, females received either bilateral, excitotoxic lesions of BNST (BNST-X) or sham lesions (SHAM), and were tested for scent marking and for investigatory responses to male and female odors. Whereas SHAM females vaginal marked more to male odors than female odors on two days of the estrous cycle, BNST-X females marked at equivalent levels to both odors. This deficit is not due to alterations in social odor investigation, as both BNST-X and SHAM females investigated male odors more than female odors. Finally, BNST lesions did not generally disrupt the cyclic changes in reproductive behaviors that occur across the estrous cycle. Taken together, these results demonstrate that BNST is critical for the normal expression of solicitational behaviors by females in response to male odor stimuli.

Blocking oxytocin receptors inhibits vaginal marking to male odors in female Syrian hamsters

In Syrian hamsters ( Mesocricetus auratus), precopulatory behaviors such as vaginal scent marking are essential for attracting a suitable mate. Vaginal marking is dependent on forebrain areas implicated in the neural regulation of reproductive behaviors in rodents, including the medial preoptic/anterior hypothalamus (MPOA-AH). Within MPOA-AH, the neuropeptide oxytocin (OT) acts to facilitate copulation (lordosis), as well as ultrasonic vocalizations towards males. It is not known, however, if OT in this area also facilitates vaginal marking. In the present study, a specific oxytocin receptor antagonist (OTA) was injected into MPOA-AH of intact female Syrian hamsters to determine if oxytocin receptor-dependent signaling is critical for the normal expression of vaginal marking elicited by male, female, and clean odors. OTA injections significantly inhibited vaginal marking in response to male odors compared with vehicle injections. There was no effect of OTA on marking in response to either female or clean odors. When injected into the bed nucleus of the stria terminalis (BNST), a nearby region to MPOA-AH, OTA was equally effective in decreasing marking. Finally, the effects of OTA appear to be specific to vaginal marking, as OTA injections in MPOA-AH or BNST did not alter general locomotor activity, flank marking, or social odor investigation. Considered together, these results suggest that OT in MPOA-AH and/or BNST normally facilitates male odor-induced vaginal marking, providing further evidence that OT generally supports prosocial interactions among conspecifics.

Olfactory experience and the development of odor preference and vaginal marking in female Syrian hamsters

Rodent reproductive behavior relies heavily on odor processing, and evidence suggests that many odor-guided sexual behaviors are shaped by prior experience. We sought to determine if exposure to male odors during development is required for the adult expression of proceptive sexual behavior toward male odors in female Syrian hamsters. Exposure to male odors was restricted in naïve subjects by removing all male siblings from the litter at three to five days of age. Control litters were also culled, but included equal numbers of male and female pups. As adults, naïve females displayed investigatory preferences toward male odors in a Y-maze that were comparable to control females; this preference was observed whether contact with the odor stimuli was prevented of allowed. In contrast, naïve females vaginal scent-marked equally toward male and female volatile odors, suggesting an inability to target behavior toward sexually relevant odors. However, naïve females marked preferentially toward male odors when allowed to contact the odor stimuli. These results provide evidence for the experience-dependent development of vaginal marking behavior toward volatile components of sexual odors. Furthermore, they suggest that distinct mechanisms regulate the development of odor preferences and vaginal marking behavior in this species.

Food deprivation and leptin prioritize ingestive and sex behavior without affecting estrous cycles in Syrian hamsters

Energy consumption is critical for the energetically expensive processes related to reproduction, and thus, mechanisms that increase ingestive behavior are directly linked to reproductive success. Similarly, the mechanisms that inhibit hunger and ingestive behavior might be most adaptive when these mechanisms cause individuals to stop foraging, hoarding and eating in order to find and court potential mates. In the laboratory, ingestive behaviors are typically studied separately from reproductive behaviors even though it is likely that these behaviors evolved under conditions in which both food and mates were available. We examined the choice between paracopulatory and ingestive behaviors in a semi-natural environment in which both food and potential mates were available. Intact female Syrian hamsters showed a high preference for males on days 3 and 4 (day 4 being the day of ovulation and estrous behavior), and a 48-h period of food deprivation significantly decreased preference for sex and increased preference for eating and food hoarding on day 3 in 89% of the hamsters, although none became anestrous. The same period of food deprivation significantly decreased the level of vaginal marking without significant effects on plasma estradiol concentrations. Next, hamsters were either food deprived (FD) or fed ad libitum, and half of each group was treated with vehicle or the adipocyte hormone leptin. The percentage of females with a low preference for sex was significantly greater in the FD compared to the ad libitum-fed groups, and leptin treatment prevented this effect. Metabolic fuels, possibly acting through leptin and other hormones, might influence sensitivity to estradiol or enhance the downstream effects of estradiol, thereby increasing motivation for sex and decreasing the relative motivation to forage, hoard and eat food.

Time Course of VMN Lesion Effects on Lordosis and Proceptive Behavior in Female Hamsters

Previous studies suggest that ultrasound production by female hamsters is better able than other reproductive behaviors to recover from an initial drop caused by damage to the ventromedial hypothalamus (VMN). At the same time, few studies have examined the time course of such lesion effects. To remedy this, female hamsters were observed before and after control operations or VMN lesions. The behaviors considered were ultrasound production, lordosis, approach, and vaginal marking. Ultrasound production, lordosis, and approach were affected by lesions, permitting the description of the time course of each of these effects. Only ultrasound rates showed evidence of recovery, which culminated in rates significantly above those observed preoperatively in the same animals. This suggests that ultrasound production is unusual in its response to VMN damage and that the underlying mechanism could be of interest in studies of the processes that determine recovery from brain damage.

Effects of Vomeronasal Organ Removal on Individual Odor Discrimination, Sex-Odor Preference, and Scent Marking by Female Hamsters

Removal of the vomeronasal organ (VNX) did not eliminate the ability of female hamsters to discriminate between individual male’s flank gland or urine odors in a habituation/discrimination task nor did it impair preference for male odors over female odors from a distance. Vomeronasal organ removal did reduce overall levels of investigation of flank gland odor in the habituation/discrimination task. Although VNX females did not show severe impairments in the frequency of either flank or vaginal marking in response to odors, they did show an abnormal pattern of marking. VNX females, unlike shams, did not flank mark more to female odors than to male odors, nor did they vaginal mark more to male odors than to female odors. Thus, the vomeronasal organ in female hamsters appears to be important for differences in scent marking toward male and female odors, but is not essential for discrimination of individual odors or for preferences for male over female odors.

Lesions centered on the medial amygdala impair scent-marking and sex-odor recognition but spare discrimination of individual odors in female golden hamsters.

The medial amygdala (Me) has been implicated in various social behaviors that depend on chemosensory cues, but its precise role in discriminating and learning social odors is not known. Female golden hamsters (Mesocricetus auratus) received electrolytic lesions of the Me or sham surgery and were tested for their ability to (a) discriminate between odors of individual males in a habituation-discrimination task, (b) show preferences for male over female odors in a Y maze, and (c) scent-mark in response to male and female odors. All females discriminated between scents of individual males. In contrast, Me lesions eliminated female preferences for male odors in a Y maze. Females with Me lesions also showed a substantial reduction in vaginal marking and virtually no flank marking in response to odors. Thus, the Me in female hamsters is critical for differential investigation of opposite-sex odors and for scent-marking behavior but is not involved in discrimination between odors of individuals.

Kin recognition in golden hamsters: evidence for phenotype matching

We assessed scent marking by golden hamsters in response to flank gland odours from kin and nonkin to investigate mechanisms of kin recognition by odour cues. Hamsters engage in two types of scent-marking behaviour, flank marking, which is associated with competition and aggression, and vaginal marking, which females use for sexual solicitation. In experiment 1, flank marking by males and flank and vaginal marking by females was significantly less in response to flank odours from siblings than nonsiblings. These results indicate a lower level of agonistic motivation (flank marking) and sexual interest (vaginal marking) towards kin than nonkin. In experiment 2, the marking responses of males and females to flank odours from siblings, unfamiliar half-siblings and unfamiliar nonsiblings were graded based on the degree of relatedness. In experiment 3, males from cross-fostered litters marked significantly less in response to flank odours from brothers than nonbrothers, regardless of whether they were reared with the odour donors. These results demonstrate a phenotype matching mechanism for kin recognition based on differences between odours from kin and nonkin. Because the presence of foster-siblings or a foster-mother in the nest did not change hamsters' responses to flank odours from kin versus nonkin, one possible explanation for our results is that hamsters use their own odour as a referent in this process (‘self-referent phenotype matching’).

Causes of scent marking in female golden hamsters (Mesocricetus auratus): specific signals or classes of information?

Odor-elicited scent marking is common among mammals, but the proximate causes of marking are not well understood. Scent marking by female hamsters in response to 8 different male odors was investigated. Two odors (flank, mouth) increased flank marking and 2 (flank, rump) increased vaginal marking; in the latter case the effects of flank and rump odors were additive. Two odors (feces, urine) decreased flank marking but did not affect vaginal marking; other odors (foot, ear, ano-genital) had no influence on either scent-marking behavior. Results show that scent marking by females is influenced by a limited number of male odors, suggesting specific effects of particular odors. Classes of information (such as sexual identity) were not relevant causes of scent marking, as some odors containing such information were effective but others were not.

Vomeronasal and/or olfactory mediation of ultrasonic calling and scent marking by female golden hamsters

The role of the olfactory and vomeronasal systems in mediating odor-stimulated ultrasonic calling, flank marking, and vaginal marking by female hamsters was investigated by selective lesions of either system. Removal of the vomeronasal organ resulted in reduced frequencies of ultrasonic calling by estrous and nonestrous females in response to conspecific odors but it had no influence on either scent marking behavior during the same tests. When tested immediately after separation from a male, ultrasonic calling was not reduced by vomeronasal removal, indicating that such surgery does not cause deficits in calling ability and that the vomeronasal organ specifically mediates odor-stimulated calling. Zinc sulfate treatment of the olfactory mucosa led to reduction in the frequency of ultrasonic calling, flank marking, and vaginal marking in response to conspecific odors. Females' ability to discover buried food was also impaired by this treatment. Thus, the stimulation of both scent marking behaviors due to the perception of conspecific odors appears to be mediated primarily by the olfactory system, whereas stimulation of ultrasonic calling is mediated by both olfactory and vomeronasal systems.

A possible role for Syrian hamster, Mesocricetus auratus, vaginal secretion in inter-female competition

The ability of the vaginal secretions of hamsters to facilitate spacing among conspecific females was examined in three experiments. In the first study, vaginal substances were applied to one half of a testing arena. Naive females placed into this apparatus spent significantly more time on the clean side and tended to deposit vaginal secretions in this area more often. In the second experiment, vaginal odours were again applied to the testing arena. The donor of the secretion and a second female were then introduced into the arena and allowed to interact. The females whose odours had been applied in the arena were significantly more aggressive. The third study evaluated the effectiveness of vaginal odours to reverse a recently established dominance relationship between female pairs. In eight of 12 pairs, a reversal was observed if the previously subordinate hamster's odours were present in the testing enclosure during the second dominance determination. The results of these studies indicate that vaginal marks could serve to space females in the native habitat. These substances are capable of inducing avoidance of a scented area and influencing the outcome of dominance contests.

Mate Choice, Mate Guarding and Other Mating Tactics in Golden Hamsters Maintained Under Seminatural Conditions

Abstract Female hamsters freely interacting with a triad of males which had established a dominance hierarchy mated first and received more ejaculates from the dominant male in 11 of 15 replicates. Continuous observations of the animals on the day preceding receptivity and the day of receptivity suggest that differential mating success of the dominant males is the result of differential behavioral responses displayed prior to onset of receptivity. The females attacked all males, however, the dominant males persisted in following and licking the female at significantly higher frequencies than the subordinate males. The females responded differentially to the dominant males by vaginal marking in response to being licked and also on day 3 of the cycle by placing a higher number of vaginal marks in and around the dominant male's home area. In nine replicates the dominant male and female slept together on day 3. In two other cases the dominant male dug open the female's burrow early on day 4. Dominant males and females became active significantly earlier than subordinate males on day 4. Thus, dominant males enhanced their chances of mating both by being active earlier and by sleeping in proximity to the female. Males cannot prevent the promiscuous female from mating with another male. However, successful males continued to follow and mount the female during the period when she is likely to accept a second male. At this time they also display a high level of attack and chases against the subordinate males plus a high frequency of flank marking in the subordinate's home areas. These behaviors suggest a mate guarding function and are consistent with protection of the male's sperm investment.

Estrogen regulation of agonistic and proceptive responses in the golden hamster

The role of estrogen in modulation of agonistic (attack-chase) and proceptive (vaginal-marking) responses of the female hamster toward a male was examined in relation to time course of induction and duration of response. In addition, the sex-specific nature of the vaginal-marking response was examined. Cycling females showed a significantly higher frequency of attack-chase when endogenous estrogen levels were minimal in comparison to that at peak estrogen levels during the estrous cycle. Removal of estrogen (ovariectomy) resulted in a significant increase in attack-chase scores compared to high endogenous estrogen. Addition of exogenous estrogen (Silastic capsule) resulted in a significant decrease in attack-chase scores compared to ovariectomized animals. The inverse effect was found for vaginal marking with the lowest frequency of vaginal marking at low endogenous estrogen levels or following ovariectomy. During high endogenous estrogen levels or following treatment with exogenous estrogen vaginal-marking scores were maximal. Maximal induction of vaginal-marking responses and reduction of attack-chase were found between 6 and 48 hr of estrogen treatment. Both behaviors then returned to the prehormonal treatment level. Failure to detect effects beyond 48 hr was not due to repeated testing, as animals lacking hormone, or animals first tested at 96 hr of estrogen exposure, showed no effect of the treatment. Males gonadectomized as adults never showed vaginal marking, whereas males gonadectomized neonatally showed a low level of vaginal marking which was increased significantly following estrogen treatment. Thus both attack-chase and vaginal marking in the presence of a male are modulated by estrogen. Further, since vaginal marking is estrogen sensitive in the neonatally gonadectomized male, expression of vaginal marking is determined by the hormonal environment during the neonatal period. However, peripheral feedback may be important for frequency of occurrence.

Diencephalic organization of estradiol sensitive sites regulating sociosexual behavior in female golden hamsters: contralateral versus ipsilateral activation

Dual ipsilateral, contralateral and bilateral 28-gauge estradiol (E 2) filled cannulae were implanted in the medial preoptic area (MPO) and ventromedial hypothalamus (VMH) of ovariectomized female golden hamsters housed in large arenas with male partners. Twenty-four hours after implantation, vaginal scent-marking patterns were significantly and equally elevated in all groups. Forty-four hours after implantation, progesterone was administered and females were tested for sexual receptivity 4–5 h later. Bilateral E 2 implants in the VMH as well as dual ipsilateral and contralateral MPO-VMH implants were significantly more likely to facilitate sexual responsiveness than bilateral MPO implants. More importantly, ipsilateral MPO-VMH implants produced significantly longer lordosis duration scores than bilateral VMH and contralateral MPO-VMH implants. After mating, females with bilateral MPO implants attacked their mates more frequently than females with bilateral VMH and dual MPO-VMH implants. Taken together, results suggest that: (1) although MPO and VMH regions are equally sensitive to the vaginal marking promoting effects of E 2, these same regions require synergistic ipsilateral activation for the effective priming of sexual responsiveness; (2) the heightened duration of lordosis behavior after ipsilateral MPO-VMH E 2 implantation may reflect an anterior diencephalic estrogenic removal of an inhibitory process occurring primarily in the ipsilateral VMH region; and (3) the difference in postcopulatory attacks may reflect variable actions of progesterone on E 2-induced progestin receptors in the MPO and VMH.

Determinants of mating success in the golden hamster ( Mesocricetus auratus): Social dominance and mating tactics under seminatural conditions

We tested the hypothesis that high social status leads to high levels of copulatory behaviour and increased number of offspring in hamsters. When paired with albino female golden hamsters, males of three genotypic strains showed differences in the frequency and temporal patterning of some measures of copulatory behaviour but did not differ in general fertilization success. The results of two-male, one-female tests in which mating order and ejaculation frequencies were controlled indicated only relatively small differences in differential fertilizing capacity among these genotypes. Males of the genotypic strains displayed an equal probability of achieving alpha status in three-male, one-female competitive mating tests in which animals were habituated to semi-natural enclosures. Alpha males often slept in the female's nest box the night before she became receptive, were the first to mate on the following morning, achieved higher scores for all measures of sexual behaviour including ejaculation frequency and subsequently sired more young than did lower ranking males. However, the differential reproductive success of alpha males was not simply a function of higher ejaculation scores since they obtained more than twice as many young per ejaculation as subordinate males. Alpha males continued to copulate with long intromissions after exhausting their supply of ejaculates. Although females mated with several males, mating preferences were evidenced by their flank-gland and vaginal marking patterns on the day before receptivity and in their initial choice of mates during tethered male tests. The behaviour of alpha males is consistent with previous findings regarding the effects of mating order and prolonged copulation on sperm competition and suggests that sperm utilization patterns and mating tactics have coevolved.

Social and Sexual Behavior of the Rufous Elephant-Shrew (Elephantulus rufescens) in Captivity

Sexual behavior, behavioral changes associated with the estrous cycle, and the behavioral effects of changing mates are described for the monogamous Elephantulus rufescens . Sexual interactions were brief and facilitated by familiarity between the male and female. Several features of sexual behavior differed from the typical conservative mammalian pattern. Except for sexual behaviors, the only dramatic behavioral change associated with the brief estrous period was an increase in vaginal marking by females that probably distributed a secretion containing a chemical signal of receptivity. There was also a decrease at estrus in female agonistic behavior toward males. New mates were readily accepted but there was a general increase in social behavior between newly paired males and females. Social and sexual behavior in elephant-shrews appears to be adapted to reducing predation risks.