Urinary Scent Marks Research Articles

Regulation of Sexually Dimorphic Expression of Major Urinary Proteins.

Male house mice excrete large amounts of protein in their urinary scent marks, mainly composed of Major Urinary Proteins (MUPs), and these lipocalins function as pheromones and pheromone carriers. Here, we review studies on sexually dimorphic MUP expression in house mice, including the proximate mechanisms controlling MUP gene expression and their adaptive functions. Males excrete 2 to 8 times more urinary protein than females, though there is enormous variation in gene expression across loci in both sexes. MUP expression is dynamically regulated depending upon a variety of factors. Males regulate MUP expression according to social status, whereas females do not, and males regulate expression depending upon health and condition. Male-biased MUP expression is regulated by pituitary secretion of growth hormone (GH), which binds receptors in the liver, activating the JAK2-STAT5 signaling pathway, chromatin accessibility, and MUP gene transcription. Pulsatile male GH secretion is feminized by several factors, including caloric restriction, microbiota depletion, and aging, which helps explain condition-dependent MUP expression. If MUP production has sex-specific fitness optima, then this should generate sexual antagonism over allelic expression (intra-locus sexual conflict) selectively favoring sexually dimorphic expression. MUPs influence the sexual attractiveness of male urinary odor and increased urinary protein excretion is correlated with the reproductive success of males but not females. This finding could explain the selective maintenance of sexually dimorphic MUP expression. Producing MUPs entails energetic costs, but increased excretion may reduce the net energetic costs and predation risks from male scent marking as well as prolong the release of chemical signals. MUPs may also provide physiological benefits, including regulating metabolic rate and toxin removal, which may have sex-specific effects on survival. A phylogenetic analysis on the origins of male-biased MUP gene expression in Mus musculus suggests that this sexual dimorphism evolved by increasing male MUP expression rather than reducing female expression.

Contrasting central and systemic effects of arginine-vasopressin on urinary marking behavior as a social signal in male mice

Arginine-vasopressin (AVP) is a neurohypophyseal peptide that plays a critical role in the regulation of social behavior in mammals. Neuronal AVP regulates male-specific social signaling processes, such as exocrine urinary scent deposition and marking behavior in mice. In the periphery, AVP is transported to the portal bloodstream and acts as an antidiuretic hormone. These AVP dynamics imply that the central role of AVP in the stimulation of urinary marking is dissociated with the peripheral role of AVP in the retention of osmotic conditions. Using male BALB/c mice as subjects, peripheral injection of AVP decreased urinary marking and urination. In contrast, a central infusion of AVP facilitated urinary marking with no effect on urination, while an antagonist of the AVP 1a receptor inhibited marking. Centrally AVP-injected mice also exhibited typical behaviors, such as hiccough/sneeze-like reactions and flash scratching, particularly when confronted with a stimulus mouse through a wire mesh screen. Significant expression of these typical reactions in these mice resulted in the disruption of marking deposition. Further analysis of AVP synthesis illustrated that AVP levels increased in the midbrain but not in the circulation immediately after the test, particularly when confronted with a stimulus mouse. The central AVP regulates urinary marking and other typical behaviors in a dose- and situation-dependent manner. The sequential process implies that centrally synthesized AVP may be secreted into the circulation following immediate neuronal processes, and then peripheral AVP acts as an antidiuretic hormone on urinary marking behavior.

Pheromones that correlate with reproductive success in competitive conditions

The major urinary proteins (MUPs) of house mice (Mus musculus) bind and stabilize the release of pheromones and other volatile organic compounds (VOCs) from urinary scent marks, which mediate chemical communication. Social status influences MUP and VOC excretion, and the urinary scent of dominant males is attractive to females. Urinary pheromones influence the sexual behavior and physiology of conspecifics, and yet it is not known whether they also affect reproductive success. We monitored the excretion of urinary protein and VOCs of wild-derived house mice living in large seminatural enclosures to compare the sexes and to test how these compounds correlate with reproductive success. Among males, urinary protein concentration and VOC expression correlated with reproductive success and social status. Territorial dominance also correlated with reproductive success in both sexes; but among females, no urinary compounds were found to correlate with social status or reproductive success. We found several differences in the urinary protein and volatile pheromones of mice in standard cages versus seminatural enclosures, which raises caveats for conventional laboratory studies. These findings provide novel evidence for chemical signals that correlate with male reproductive success of house mice living in competitive conditions.

Meadow voles differentiate between scents of different sources

Abstract Scent marks are an important means of transmitting information between rodents, and they can be produced from several body sources. Previous studies have shown that scents from multiple sources can convey the same information; female meadow voles, for example, have three scent sources that communicate sex. However, possessing three separate sources that convey the same information is likely costly due to the metabolic energy required to produce these signals and the increased chance that eavesdropping individuals may intercept information present in these signals. In this study, we investigated if these scent sources could communicate other information, in addition to scent donor sex, by determining if male meadow voles could distinguish scent marks taken from different sources of a single female scent donor. This was accomplished with a habituation-test method, that allowed us to compare how male meadow voles differently investigate scent from a familiar and novel source of a female scent donor. Male meadow voles could distinguish between faeces and urine scent marks of a female, but could only distinguish mouth from urine and faeces scent marks when first familiarized with mouth scent marks. Our findings suggest that mouth, urine, and faeces scent marks of female meadow voles produce both redundant and distinct information. The overlap in information between scent marks produced from separate sources may be needed to provide social context, which allows receiving individuals to accurately weigh the tradeoffs associated with responding to an olfactory cue. While this overlap in information remains costly, this cost may be minimized by the different fade-out times of scent marks from distinct body sources, which may limit the amount of time information in a scent mark is available to a time period where this information is socially relevant.

The pheromone darcin drives a circuit for innate and reinforced behaviours.

Organisms have evolved diverse behavioural strategies that enhance the likelihood of encountering and assessing mates1. Many species use pheromones to communicate information about the location, sexual and social status of potential partners2. In mice, the major urinary protein darcin-which is present in the urine of males-provides a component of a scent mark that elicits approach by females and drives learning3,4. Here we show that darcin elicits a complex and variable behavioural repertoire that consists of attraction, ultrasonic vocalization and urinary scentmarking, and also serves as a reinforcer in learning paradigms. We identify a genetically determined circuit-extending from the accessory olfactory bulb to the posterior medial amygdala-that is necessary for all behavioural responses to darcin. Moreover, optical activation of darcin-responsive neurons in the medial amygdala induces both the innate and the conditioned behaviours elicited by the pheromone. These neurons define a topographically segregated population that expresses neuronal nitric oxide synthase. We suggest that this darcin-activated neural circuit integrates pheromonal information with internal state to elicit both variable innate behaviours and reinforced behaviours that may promote mate encounters and mate selection.

Evolutionary patterns of major urinary protein scent signals in house mice and relatives.

Scent marks are important mediators of territorial behaviour and sexual selection, especially among mammals. The evolution of compounds used in scent marks has the potential to inform our understanding of signal evolution in relation to social and sexual selection. A major challenge in studies of chemical communication is that the link between semiochemical compounds and genetic changes is often unclear. The major urinary proteins (MUPs) of house mice provide information on sex, status and individual identity. Importantly, MUPs are a direct protein product of genes, providing a clear link between genotype and phenotype. Here, we examine the evolution of urinary protein signals among house mice and relatives by examining the sequences and patterns of mRNA expression of Mup genes related to urinary scent marks. MUP patterns have evolved among mouse species both by gene duplication and variation in expression. Notably, protein scent signals that are male specific in well-studied inbred laboratory strains vary in sex-specificity among species. Our data reveal that individual identity signals in MUPs evolved prior to 0.35million years ago and have rapidly diversified through recombining a modest number of amino acid variants. Amino acid variants are much more common on the exterior of the protein where they could interact with vomeronasal receptors, suggesting that chemosensory perception may have played a major role in shaping MUP diversity. These data highlight diverse processes and pressures shaping scent signals, and suggest new avenues for using wild mice to probe the evolution of signals and signal processing.

Species differences in urine scent-marking and counter-marking in Peromyscus

Species comparisons indicate that scent-marking may differ as a function of mating system and co-housing with the opposite sex (“pairing”). We previously demonstrated that pairing may decrease male solicitation to unfamiliar females in the monogamous Peromyscus californicus but not in the non-monogamous P. leucopus. Whether urine scent-marking of females changes following pairing and whether scent-marking of paired males varies in response to scent-marks of their cagemate versus those of an unfamiliar female has not been examined. Therefore, we tested P. californicus and P. leucopus for within and between species differences in urine scent-marking of: 1) paired and non-paired females in an unscented arena, and 2) paired males in response to their female cagemate’s or an unfamiliar female’s scent-marks (counter-marking). Consistent with previous findings, P. californicus of both sexes deposited more urine scent-marks and covered greater surface area than P. leucopus. In both species, female scent-marking did not differ according to pairing status and male counter-marking did not differ in response to the scent-marks of their female cagemate versus an unfamiliar female. More females of both species and more P. leucopus, but not P. californicus, males scent-marked more around the perimeter than centrally. Potential explanations for these findings are discussed.

Spontaneous discrimination of urine odours in wild African lions, Panthera leo

Olfactory communication is the primary mode of communication for many mammals, yet research on this form of signalling is still largely descriptive in most species. Thus, despite the apparent importance of scent marking in the social lives of wild felids, experimental studies directly investigating the function of olfactory communication are lacking. We conducted scent presentation experiments to investigate whether wild African lions can discriminate another lion's social group and sex from a sample of its urine. Our results indicated that lion urine has the potential to signal depositor sex and social group, and that lions can use urine to discriminate males from females and residents from nonresidents. The response of lions to urine was also dependent on both the sex and age of the subject receiving the presentation. Female lions responded less frequently to urine from resident females than to either nonresident females or resident males. Males responded more strongly to urine from resident males than resident females, but did not appear to differentiate urine from nonresident and resident females. Observations of flehmen and further scent-marking responses from lions provide additional evidence that lion urine functions in scent marking. These results establish that urine scent-marks contain sufficient information for receivers to discriminate the sex and social affiliation of the signaller, and demonstrate the functional relevance of scent marking in African lions.

Reproductive endocrine patterns and volatile urinary compounds of Arctictis binturong: discovering why bearcats smell like popcorn

Members of the order Carnivora rely on urinary scent signaling, particularly for communicating about reproductive parameters. Here, we describe reproductive endocrine patterns in relation to urinary olfactory cues in a vulnerable and relatively unknown viverrid--the binturong (Arctictis binturong). Female binturongs are larger than and dominate males, and both sexes engage in glandular and urinary scent marking. Using a large (n = 33), captive population, we collected serum samples to measure circulating sex steroids via enzyme immunoassay and urine samples to assay volatile chemicals via gas chromatography-mass spectrometry. Male binturongs had expectedly greater androgen concentrations than did females but, more unusually, had equal estrogen concentrations, which may be linked to male deference. Males also expressed a significantly richer array of volatile chemical compounds than did females. A subset of these volatile chemicals resisted decay at ambient temperatures, potentially indicating their importance as long-lasting semiochemicals. Among these compounds was 2-acetyl-1-pyrroline (2-AP), which is typically produced at high temperatures by the Maillard reaction and is likely to be responsible for the binturong's characteristic popcorn aroma. 2-AP, the only compound expressed by all of the subjects, was found in greater abundance in males than females and was significantly and positively related to circulating androstenedione concentrations in both sexes. This unusual compound may have a more significant role in mammalian semiochemistry than previously appreciated. Based on these novel data, we suggest that hormonal action and potentially complex chemical reactions mediate communication of the binturong's signature scent and convey information about sex and reproductive state.

Mouse females devoid of exposure to males during fetal development exhibit increased maternal behavior

Many sex differences can be found in the expression of aggression and parental nurturing behaviors. It is important to determine if these are modulated by prenatal conditions. Here, using assisted reproduction technologies, we generated females that were (mixed-sex) or were not (same-sex) exposed to males during fetal development, raised them by cross fostering among fosters' own female only pups to control for effects of postnatal environment, and compared their reproductive abilities and behavior. There were no differences between females from the two prenatal conditions in estrus cycle length and length of time spent at individual estrus cycle stages. Both types of females had similar ovulation efficiency and bred equally well yielding comparable litter size and progeny sex ratio. Females from the two prenatal conditions were also indistinguishable in social behavior and exhibited normal social responses towards unfamiliar females in the three-chamber social approach and social proximity tests. When urine was collected from both types of females and used as a point source in a scent-marking paradigm, exposed males showed a similar distribution and extent of urinary scent marking in response to urine from each type of female but tended to engage in higher durations of sniffing the urine from same-sex females. When females were tested in a resident-intruder paradigm 3 days after giving birth, same-sex females exhibited enhancement of pup grooming and an overall decrease of non-pup activity prior to male intruder introduction, and after introduction were more defensive as evidenced by higher rates of burying, open-mouth threat/lunges, and attacks towards the male, and decreased latencies to display these defensive behaviors. Our results suggest that females devoid of male exposure during fetal development have reproductive abilities similar to those of females from mixed-sex pregnancies, and have normal social interactions with other females. However, they exhibit hyper-maternal behavior both in terms of the care and defense of pups in front of a male intruder, and potentially produce a pheromonal milieu that renders them more attractive to males during olfactory investigations.

A Novel ART Model System for Studying the Effects of Sex Differences on Mouse Behavior Reveals that Females Devoid of Exposure to Males During Fetal Development Exhibit Increased Maternal Defensiveness.

Many sex differences can be found in expression of aggression and parental nurturing behaviors. These differences are established during fetal development by the action of gonadal steroid hormones, especially the higher levels of androgens experienced by males, which are caused ultimately by the presence of the testis-determining gene Sry on the Y chromosome. Past studies indicated that intra-uterine position has consequences for behavior and reproduction in mice. Female fetuses developing between two male fetuses are 'masculinized' and differ from females developing between the female fetuses. Here, we tested for behavioral differences between females that were or were not exposed to males during fetal development using a novel model system: production of single sex pregnancies. Embryos generated by in vitro fertilization (IVF) were subjected to single blastomere biopsy at 4-cell stage and subsequently sexed via single cell PCR. Sexed embryos from the same IVF cohorts were transferred to surrogate females to generate single sex (female only, F) and mixed sex (female and male, FM) pregnancies. Female progeny from both types of pregnancies were subjected to three-chamber social approach, social proximity task, scent marking, and maternal aggression behavioral tests. We also measured estrus length and reproductive success of these females. Estrus length was similar in females from the two neonatal conditions (F: 7.21±0.52 vs. FM: 7.35±0.52; mean±SEM) and both types of females bred equally well yielding similar litter sizes (F: 6.8±0.7, n=14 vs. FM: 7.5±0.7, n=12), with a similar progeny sex ratio (F: 54% and FM: 48% females). Females from the two neonatal conditions were indistinguishable in social behavior and exhibited normal social responses in the three-chamber social approach and social proximity tests, towards unfamiliar females. When urine was collected from F and FM females and used as a point source in a scent-marking paradigm, exposed males showed a similar distribution and extent of urinary scent marking but tended to engage in higher durations of sniffing the urine from F females (P=0.02). To assess maternal aggression, F and FM females were mated, and three days after giving birth, were tested in a resident-intruder paradigm. F females exhibited enhancement of pup grooming (P=0.04) and an overall decrease of non-pup activity (P=0.01) prior to male intruder introduction. After introduction of the male intruder F females were more defensive evidenced by higher rates of burying, open-mouth threat/lunges, and attacks towards the male (P=0.006), and decreased latency to display these defensive behaviors (P=0.02). To summarize, our results suggest that females devoid of male exposure during fetal development have reproductive abilities similar to those of females from mixed sex pregnancies, and have normal social interactions with other females. However, they exhibit hyper-maternal behavior both in terms of the care and defense of pups in front of a male intruder, and potentially produce a pheromonal milieu that renders them more attractive to males during olfactory investigations. Further research will focus on investigation of the physiological systems that underlie increase in maternal defensiveness in those females. (platform)

Assessment of dominance hierarchy through urine scent marking and its chemical constituents in male blackbuck Antelope cervicapra, a critically endangered species

In ungulates the process of chemical communication by urinary scent marking has been directly related to reproductive dominance, territorial defense and proximity to resources. The differences in the frequency of urine marking and chemical composition of urine of males Antelope cervicapra before, during and after the dominance hierarchy period were assessed. The variations in the urine marking and its chemical profiles of dominant males (n=9), bachelors (n=5) and sub-adult males (n=5) were compared to find out how the dominance hierarchy influences the confined blackbuck herd under semi-natural captive conditions. The frequency of urine marking is significantly higher (p<0.001) in dominant males. Twenty-eight major constituents were identified in the urine of dominant males (before, during and after the dominance hierarchy period), bachelor and sub-adult males. Among these, three specific compounds namely, 3-hexanone (I), 6-methyl-5-hepten-2-one (II) and 4-methyl-3-heptanone (III) were seen only in dominant males urine during the dominance hierarchy period. Based on the behavioural observation and the unique chemical constituents in the urine, it is concluded that the dominant male scent odor suppresses aggression, scent marking, scent production and territorial patrolling activities of subordinate males, through which the dominant male establish their hierarchy and attains success in reproduction.

From the top down: flexible reading of a fragmented odor map

Animals that depend on smell for communication and survival extract multiple pieces of information from a single complex odor. Mice can collect information on sex, genotype, health and dietary status from urine scent marks, a stimulus made up of hundreds of molecules. This ability is all the more remarkable considering that natural odors are encountered against varying olfactory backgrounds; the olfactory system must therefore provide some mechanism for extracting the most relevant information. Here we discuss recent data indicating that the readout of olfactory input by mitral cells in the olfactory bulb can be modified by behavioral context. We speculate that the olfactory cortex plays a key role in tuning the readout of olfactory information from the olfactory bulb.

Female scent mobilizes leukocytes to airways in BALB/c male mice

The scent of receptive females as a signal to reproduction stimulates male mice to olfactory search of a potential breeding partner. This searching behavior is coupled with infection risk due to bacterial contamination of the fecal and urine scent marks. We hypothesized that sniffing of female soiled bedding induced the migration of immuno-competent cells into airways as a possible adaptation to breeding-related infection. Using bronchoalveolar lavage in a study on mice, we found the number of leukocytes to be significantly higher in male mice that were provided new portions of soiled bedding daily from female cages, in comparison with male mice that were kept in isolation from female scent. The number of leukocytes in blood was equal in both groups. However, monocytes were fewer in number in male mice exposed to female scent than in male mice isolated from female mice. Scent-induced migration of leukocytes was accompanied by typical behavioral (increased sniffing activity and aggressiveness) and morphological (increase preputial glands and seminal vesicles) responses to olfactory sexual stimulus.

Social features of scent-donor mice modulate scent marking of C57BL/6J recipient males

Territorial male mice can form familiarity-dependent amicable relationships, suggesting that they manage their territorial aggressiveness based on individual recognition, which may be mediated by olfactory signals. The present study demonstrated modulatory effect of odorant cues from mice of different social/housing groups on territorial scent marking by C57BL/6J males. Pair-housed males deposited few scent marks in a novel situation without mouse odors, while singly-housed males marked more in the same situation (Experiment 1). However, when confronted by a conspecific, singly-housed males made fewer marks to pair-housed than to singly-housed stimulus males, while pair-housed males showed few marks to either stimulus animal (Experiment 2). Reduction in scent marking in singly-housed males was also seen on exposure to urine scent alone from a pair-housed male, indicating that the inhibitory cue is mediated by urinary odor (Experiment 3). This inhibitory odor was effective even when singly-housed males were placed in a no-odor environment following exposure to soiled bedding used by pair-housed males (Experiment 4). When singly-housed males were exposed to scent from subordinate males, they showed less marking than when the stimulus scent was from dominants or singly-housed males (Experiment 5). Scent marking was not influenced by the total amount of urine scent marks deposited on the substrates (Experiment 6), suggesting that it is a particular component in urinary odor rather than the magnitude of the odor, that plays a significant role in recipient behavior. Together, these experiments indicate that conspecific male odor signals modulate territorial scent marking behavior in mice.

Female Scent Signals Enhances Male Resistance to Influenza

AbstractScent of receptive females as signal to reproduction stimulate male mice to olfactory search of a potential breeding partner^1, 2^. This searching behavior is coupled with infection risk due to bacterial contamination of the fecal and urine scent marks^4^. The theoretical consideration of host evolution under inevitable parasitic pressures, including helminthes, bacteria, virus etc., predicts adaptations that help protect against parasites associated with breeding^7^. In this study, we propose that acceptation of female signals by male mice leads to adaptive redistribution of immune defense directed to protection against respiratory infection risks. Our results reveal migration of macrophages and neutrophils to upper airways upon exposure to female odor stimulus resulting in increased resistance to influenza virus in male mice. Contrary to widely accepted immunosuppressive function of female sexual signals, our data provide the first demonstration of the adaptive immunological response to female odor stimulus through induction of nonspecific immune response in upper airways.

Neural correlates of scent marking behavior in C57BL/6J mice: detection and recognition of a social stimulus

Mice show urinary scent marking behavior as a form of social communication. Marking to a conspecific stimulus mouse or odor varies with stimulus familiarity, indicating discrimination of novel and familiar animals. This study investigated Fos immunoreactivity in inbred C57BL/6J (C57) males following scent marking behavior in response to detection of a social stimulus, or discrimination between a familiar and an unfamiliar conspecific. In Experiment 1 C57 mice were exposed for four daily trials to an empty chamber; on a test day they were exposed to the same chamber or to a male CD-1 mouse in that chamber. Increased scent marking to the CD-1 mouse was associated with increased Fos-immunoreactive cells in the basolateral amygdala, medial amygdala, and dorsal and ventral premammillary nuclei. In Experiment 2 C57 mice were habituated to a CD-1 male for 4 consecutive days and, on the 5th day, exposed to the same CD-1 male, or to a novel CD-1 male. Mice exposed to a novel CD-1 displayed a significant increase in scent marking compared to their last exposure to the familiar stimulus, indicating discrimination of the novelty of this social stimulus. Marking to the novel stimulus was associated with enhanced activation of several telencephalic, as well as hypothalamic and midbrain, structures in which activation had not been seen in the detection paradigm (Experiment 1). These included medial prefrontal and piriform cortices, and lateral septum; the paraventricular nuclei, ventromedial nuclei, and lateral area of the hypothalamus, and the ventrolateral column of the periaqueductal gray. These data suggest that a circumscribed group of structures largely concerned with olfaction is involved in detection of a conspecific olfactory stimulus, whereas discrimination of a novel vs. a familiar conspecific stimulus engages a wider range of forebrain structures encompassing higher-order processes and potentially providing an interface between cognitions and emotions.

Mice Recognize Recent Urine Scent Marks by the Molecular Composition

Male mice mark the territory with urine scent marks that are frequently renewed to maintain the territory ownership. We measured the response of male mice to small spots of urine deposed either 0, 5, 11, 22, 45, 90 min, or 24 h before testing and show that mice loose interest in sniffing scent marks as they become older and older. We asked what scent features tell a mouse how recent a scent mark is, and therefore, we studied the molecule-to-behavior relationship by correlating 6 behavioral variables--the number of sniffing acts, the latency to the first sniff, the number of urine marks, the latency to the first mark, the area of the marks, and the number of fecal pellets-to 2,4-dehydro-exo-brevicomin, linalool, 2-sec-butyl-4,5-dihydrothiazole, 2,4-dimethylphenol, 4-ethylphenol, and 6,10-dimethyl-5,9-undecadien-2-one released from urine spots over the time, identified, and quantified by gas chromatography and mass spectrometry. Canonical correlation between the molecular and the behavioral principal components was strong (R(1) = 0.96, P = 0.026). The principal component based on 2,4-dehydro-exo-brevicomin, linalool, and 2-sec-butyl-4,5-dihydrothiazole correlated negatively with countermarking and positively with the sniffing behavior, suggesting a semantic feature of fresh male mouse urine.

A new test paradigm for social recognition evidenced by urinary scent marking behavior in C57BL/6J mice

Olfaction is a major sensory element in intraspecies recognition and communication in mice. The present study investigated scent marking behaviors of males of the highly inbred C57BL/6J (C57) strain in order to evaluate the ability of these behaviors to provide clear and consistent measures of social familiarity and response to social signals. C57 males engage in scent marking when placed in a chamber with a wire mesh partition separating them from a conspecific. Male mice (C57 or outbred CD-1 mice) showed rapid habituation of scent marking (decreased marking over trials) with repeated exposure at 24-h intervals, to a stimulus animal of the C57 or CD-1 strains, or to an empty chamber. Subsequent exposure to a genetically different novel mouse (CD-1 after CD-1 exposure, or CD-1 after C57 exposure) or to a novel context (different shaped chamber) produced recovery of marking, while responses to a novel but genetically identical mouse (C57 after C57 exposure) or to the empty chamber did not. This finding demonstrated that male mice differentiate familiar and novel conspecifics as expressed by habituation and recovery of scent marking, but neither C57 or CD-1 mice can differentiate new vs. familiar C57 males; likely due to similarities in their odor patterns. The data also indicate that scent marking can differentiate novel from familiar contexts.

Scent marking behavior in male C57BL/6J mice: Sexual and developmental determination

The present study investigated urinary scent marking behavior in male C57BL/6J (C57) mice as olfactory social signaling. In Experiment 1, when compared scent marking toward adult males, C57 males showed substantial scent marking toward CD-1 males and even toward the odor alone of CD-1 males, but not toward C57 males. Experiment 2 explored scent marking in C57 males of different ages to males and females, and juveniles and adults of the same strain. C57 males deposited more marks than control conditions only toward an adult C57 female when tested at 100 days of age, but not at 60 days of age. Development of urine marking behavior was investigated in C57 males at the ages of 30, 60, 90, and 120 days in Experiment 3. When tested alone (control) or confronted with a C57 male, C57 males showed diminished scent marks throughout development. Compared to controls, marking toward a CD-1 male increased after the age of 60 days, while marks toward an adult female showed significant increases after the age of 90 days. This difference in scent marking depending on the sex of the stimulus animal is likely to be associated with development of sexual behavior, in which males need to set up territories against other males prior to advertising to females. Although highly inbred strains have similar odor components, C57 males are able to detect and deposit urine marks after puberty as social communication depending on age, sex, and genetic differences in the opponents.