Stimuli for male mouse (Mus musculus) ultrasonic courtship vocalizations: Presence of female chemosignals and/or absence of male chemosignals.

In research on animal chemocommunication, biological odors are sometimes presented by being applied to a "neutral" animal (e.g., castrated or ovariectomized conspecific). This technique is typically utilized when the behavioral response to the odor requires the presence of a conspecific. In 5 experiments, DBA/2J and 2 F? hybrid strains of mice that might be expected to be neutral stimuli were examined for their abilities to elicit ultrasonic courtship vocalizations from male mice. Paradoxically, adult castrated males, adult males that were neonatally castrated, hypophysectomized males, prepubertal females, and hypophysectomized females all elicited more vocalizations than would have been predicted from previous research in which their urine alone was used as the stimulus. These and previous results are consistent with courtship vocalizations being promoted by chemosignals from females and/or by an absence of cues from males. Thus, a truly neutral conspecific for presenting female sex odors may not exist in mice. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactions of deer mice (Peromyscus maniculatus) and white-footed mice (Peromyscus leucopus) to homospecific and heterospecific urine odors.

Examined approach and withdrawal behaviors to homospecific and heterospecific urine odors in 2 experiments with 64 sexually naive mice from sympatric populations of Peromyscus maniculatus and Peromyscus leucopus. In Exp I, P. maniculatus females preferred homospecific male urine odor to air during both estrus and diestrus, and air to P. leucopus male urine odor under comparable conditions. P. leucopus females did not show similarly consistent behavior in the presence of these stimuli. In Exp. II, 32 P. leucopus Ss avoided male urine odors of both species, whereas 32 P. maniculatus Ss showed neither attraction nor avoidance to these odors. Results suggest urine might be used by P. maniculatus, but probably not by P. leucopus, for intra- and interspecific communication. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preferences of female house mice (Mus domesticus) in seminatural enclosures.

Preferences for male odors by female house mice (Mus domesticus) were examined with respect to age, dominance status, and spatial relationships. Mice were free living in 6 field enclosures. Estrous or nonestrous females were placed in an aquarium with soiled bedding from live traps as the odor source. Females were tested for preferences between (1) adult and juvenile male odors, (2) dominant and subordinate male odors, and (3) "near" and "far" male odors. In dominance odor tests, estrous females preferred odors from dominant males; nonestrous females exhibited no significant preferences. In adult juvenile and spatial odor tests, there were no significant differences between odor preferences of estrous and nonestrous females. However, most females preferred odors from adult and "near" males. Male dominance status appears to be the strongest influence on female odor preference in these seminatural enclosures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex differences in urinary odors produced by young laboratory rats (Rattus norvegicus).

Examined the responses of 75 primiparous Long-Evans rat dams and 20 nonmaternal Long-Evans females to male and female pup urine in 3 experiments. Investigatory sniffing of male and female pup urine deposits by maternal Ss was compared in a series of simultaneous choice tests given at 3-day intervals between Day 2 and Day 17 postpartum. Male urine was consistently preferred. Introduction of male but not female pup urine to the nest was found to significantly elevate maternal licking of anogenital regions of pups. Thus, urine from pups of various ages contains sex-identifying odors that differentially elicit spontaneous maternal interest. The odor of male urine may provide a sufficient stimulus to account for the greater anogenital licking that males of this species normally receive. Nonmaternal, naive, adult Ss behaved like maternal Ss, preferring male urine in the choice test, which indicates that the maternal condition of a dam is not necessary either for the olfactory discrimination or for the male odor preference. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexually dimorphic enhancement by estradiol of male urinary odor detection thresholds in mice.

We asked whether sex and adult estrogen exposure influence the detection thresholds for urinary odors used by mice to guide their social behaviors. Gonadectomized (GDX) male and female mice were trained on a two-choice food-motivated task to determine detection thresholds for male urinary odors. There was no significant sex difference in the detection of these odors by GDX subjects without hormone replacement. However, during treatment with estradiol benzoate (EB), GDX females, but not GDX males, showed an enhanced ability to detect these odors. To investigate a possible mechanism for this effect, the authors measured GDX females' odor-sampling behavior (sniffing) by monitoring intranasal pressure transients during performance of the urinary odor detection task with and without EB treatment. Under both hormone conditions, females decreased their sniffing frequency as the urinary odor concentration decreased, with this decrease being significantly greater while GDX females received EB. Thus, estradiol enhanced detection thresholds for male urine in a sex-specific manner, and this enhanced sensitivity in females was correlated with altered odor-sampling behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of vomeronasal organ removal from male mice on their preference for and neural Fos responses to female urinary odors.

Four experiments were conducted to determine whether vomeronasal organ (VNO) inputs in male mice mediate the rewarding properties of estrous female urinary odors. Sexually naive male mice with either an intact (VNOi) or lesioned (VNOx) VNO preferred to investigate female urine over water in Y-maze tests. Subsequently, VNOi males ran significantly more quickly and remained in nasal contact longer with estrous female urine than with male urine, whereas VNOx males investigated these odors equally. In home-cage habituation-dishabituation tests, VNOi males also investigated female urine significantly longer than did VNOx males, although both groups investigated female urine longer than other non-body odors. Finally, female urinary odors induced Fos in the nucleus accumbens core of VNOi males but not of VNOx males. Our results suggest that female urinary odors retain some incentive value in VNOx males. However, once direct nasal contact is made with female urine, VNO inputs further activate forebrain mechanisms that amplify the reward salience of this stimulus for the male mouse. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Odor preference and urine-marking scales in male and female rats: Effects of gonadectomy and sexual experience on responses to conspecific odors.

Investigation and urine-marking responses of 112 male and female Long-Evans rats toward conspecific urine odors were recorded in pair-wise comparison tests. Each of 16 S groups was given 15 preference tests, 1 for each of the possible pairs of 5 urine odors and a no-odor control (N). The urine sources were own group (G), intact male (M), castrated male (Mc), ovariectomized female (Fo), and estrous females (F). Results were scaled by using a technique based on L. L. Thurstone's (1927) law of comparative judgment. Intact males with sexual experience ordered their odor preferences N?     

Intermale fighting affected by home-cage odors of male and female mice.

Conducted 3 experiments to test the hypothesis that male mice can produce an aggression-inhibitory or facilitory odor under varying conditions of social stimulation. In Exp I, 25 male fighter mice fought 25 castrated opponents more vigorously in soiled home cages of either single or stable groups of male mice than they did in clean cages. Fighting was also stimulated in cages briefly occupied by other pairs of fighting mice. It is concluded that the release of aggression-promoting home-cage odors by male mice is not necessarily a consequence of social instability and that they are of urinary, rather than preputial, origin. In Exp II (with 21 fresh Ss) and Exp. III (with 30 Ss from Exp I), odors deposited by either single or groups of female mice greatly reduced fighting, indicating that their urinary aggression-inhibiting pheromone is effective after deposition upon the home environment. Testosterone propionate implants abolished the females' inhibitory pheromone and did so independently of their enlarged preputial glands. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male-produced ultrasonic vocalizations and mating patterns in female rats.

Investigated the influence of male-produced 50-kHz vocalizations on mating behavior and choice of partner in estrous female rats. In Exp I, 17 estrous female Long-Evans rats were given a mating-choice test; 2 tethered males, one of which was devocalized, were used as incentives. Darting was directed toward the vocalizing male more frequently than toward the muted test partner, but ultrasonic vocalizations had no influence on visit rate or the amount of time that the females spent with each male. When 2 intact or 2 muted males were used as stimulus objects, the females' solicitation behavior was more evenly distributed between the 2 males. In Exp II, 16 estrous females were given a mating-choice test between 2 muted males; tape-recorded 50-kHz vocalizations or tape hiss was transmitted from a speaker located behind one of the males. Females spent equal amounts of time with the tethered males in both the vocalization and tape-hiss conditions; however, females directed more darting toward the males that were tethered in front of the speaker transmitting the ultrasonic vocalizations than toward the other muted tethered males. Findings demonstrate that the principal function of the male-produced ultrasounds is to facilitate and orient the solicitation behavior of the estrous female during mating. The vocalizations have little demonstrable effect in attracting the female to the immediate physical proximity of the male. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory recognition of conspecifics by domestic Norway rats

In order to learn more about their ability to recognize one another via olfaction, domestic male rats were given a series of preference tests in which pairs of odors from male conspecifics were presented. Both immature and mature males prefer (p less than .05) the odor from immature strangers over that from immature cage mates but are indifferent to the ordors from mature strangers versus cage mates. Both immature and mature males prefer (p less than .05) the odor from mature novel cage mates over that from mature cage mates to which they are temporarily habituated but are indifferent to the odors from immature novel versus familial cage mates. Mature males prefer (p less than .08) the odor from a cage mate over the subject's own odor, and they prefer (p less than .01) their own odor over no odor. Under certain conditions, male rats can discriminate between the odors from (a) strangers versus cage mates, (b) two cage mates, and (c) their own body versus a cage mate.     

Male mouse (Mus musculus) attraction to airborne urinary odors of conspecifics and to food odors: Effects of food deprivation.

Five experiments demonstrated that 112 male mice were strongly attracted to the urinary odors of females, and that male urinary odors were considerably less attractive. The strong attraction to female urinary odors did not require that the males have postweaning experience with females. Males with continuous access to food and water were much more strongly attracted to female urinary odors than to the airborne food odors. Female urinary odors remained more attractive than food odors after 24-hr food deprivation, and only after 48-hr deprivation did the attractiveness of food odors approximate that of female urine. Although 48-hr food deprivation appeared to equalize the attractiveness of urinary and food odors, this regimen did so not by diminishing the attractiveness of female urine but rather by increasing the attractiveness of food odors. It is argued that the attraction that male mice exhibited to female urinary odors in this odor-testing apparatus reflected, at least in part, a biologically important precopulatory communication system. (29 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Histochemical localization of adenylate cyclase in cultured sympathetic neurons

The influence of female odors on agonistic behavior among grouped male prairie voles (Microtus ochrogaster) was studied. After the introduction of female odors, investigative behavioral interactions between the males increased in frequency. The source of the odor, the sexual experience of the males, and the ongoing behavior of the group influenced the intensity of the behavioral response. Sexually experienced males showed the greatest number of agonistic instances and attempted sexual interactions after the introduction of urine from estrous females. Agonistic interactions did not decrease upon the introduction of female odors, as has been reported for Mus musculus. It is concluded that these behavioral changes are not due to a response to a releaser pheromone, but are the result of confusion in communication between males.     

A natural food aversion in Norway rats.

During a single 1-hr feeding test, adult male Norway rats were offered intact carcasses of adult male rodents, sacrificed by CO? asphyxiation. In Exp I, 79 Ss fed more readily on conspecifics dead 24–220 hrs than on conspecifics dead 10 min or 6 hrs. In Exp II, 22 Ss fed readily on roof rats (Rattus rattus) whether they had been dead 10 min or 24 hrs. In Exp III, 15 Ss rendered anosmic by zinc sulfate treatment fed more readily on conspecifics dead for 10 min than did 17 controls. In Exp IV, 34 Ss consumed more flesh from house mice coated with roof rat urine than from mice coated with Norway rat urine. It is concluded that Norway rats exhibit a natural aversion to feed on the intact carcasses of freshly sacrificed adult conspecifics in the sense that they are more likely to feed on other species of rodent. The aversion diminishes with the dissipation of the chemoreceptive cue(s) identifying the carcass as a conspecific. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Escape deficits following inescapable shock: The role of contextual odor.

Three experiments, with 192 male albino rats, examined the role of contextual odor in mediating deficits in escape performance produced by pretreatment with inescapable shock. Impaired leverpress performance (Exp I) and shuttle-escape performance (Exp II) were observed when the pretreatment and test chambers were odorized by previously shocked conspecifics. These deficits were eliminated in both experiments when the test chambers were thoroughly cleaned. Exp III determined whether the same odor must be present during pretreatment and testing, or whether mere exposure to a fear pheromone is sufficient to impair test performance. Shuttle escape was impaired only when the same odor was present in the pretreatment and test chambers. Results indicate that an odor common to the pretreatment and test chambers mediates impaired escape performance and suggests that other types of deficits observed following inescapable shock may also be mediated by such contextual cues. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Discrimination among colony mates' anogenital odors by guinea pigs (Cavia porcellus).

Three experiments used an aversively motivated learning task to examine the ability of adult guinea pigs to discriminate among odors from nonspecific anogenital swabbings of colony mates. Exps I and II examined the ability of 8 male (M) and 8 female (F) Ss to discriminate among odors of colony mates controlled for age and sex. Both sexes were able to discriminate among individual Ss on the basis of odor. Since individual Ss could be discriminated, Exp III, examining detection of physiological estrus, tested the ability of 6 Ms and 6 Fs to discriminate preserved odor samples from the same F during conditions of estrus and nonestrus. Both Ms and Fs were able to discriminate between the conditions. Results are discussed with reference to the involvement of odor in the social behavior of guinea pigs. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens).

Examined, in 5 experiments, whether the olfactory differences apparent to mice are also accessible to humans, using a total of 63 human Ss. In Exp I, Ss were asked to distinguish between the whole-body odors of live mice differing genetically only at the major histocompatibility gene complex (H-2). In Exps II and III, the odor source was mouse fecal pellets, and in Exps IV and V, the odor source was mouse urine. Results reveal that humans can use olfaction to discriminate closely related strains of mice. The possibility that excreted metabolites with characteristic odors may have predated the evolution of an adaptive function for these odors in social communication is suggested. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of ultrasonic vocalizations emitted by intruders during aggressive encounters among rats (Rattus norvegicus).

Determined the ultrasonic vocalizations produced by intruders during aggressive interactions and investigated the role of these signals in agonistic behavior of rats. In Exp I, 7 experienced resident male Long-Evans rats were paired with both devocalized and intact vocalizing naive intruder males (n?=?14). Devocalization of the intruder males resulted in a drastic decrease in 50-kHz vocalizations and the elimination of all 22-kHz vocalizations. This almost total absence of ultrasonic vocalizations was not accompanied by any change in resident aggressive behavior or intruder defensive and submissive behavior. In Exp II, 16 naive intruders were tested with either deafened or intact resident males (n?=?8). Similarly, preventing residents from hearing intruder ultrasounds had no detectable effect on any aggressive behavior. These experiments are not consistent with the correlative evidence that intruder-produced 22-kHz vocalizations inhibit the aggressive behavior of the resident. Results show that most of the ultrasonic vocalizations emitted during aggressive encounters were probably produced by the intruder. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experiential determinants of postpartum aggression in mice.

Explored the experiential determinants and the social controls of postpartum aggression in inbred ICR mice. In Exp I, 7 lactating females were tested repeatedly from Day 2 to Day 22 postpartum against male mice; attacks by the females continued through Day 18. Two other groups of 7 females tested only once showed diminished attacks against males by Day 14 postpartum. In Exp II, 8 females were paired with a male for 1 wk prior to parturition; they showed reliably fewer attacks on Day 2 postpartum than a group of 9 females that were isolated prior to parturition. All of these results were obtained in a standard 3-min test. A 24-hr test on Day 4 of Exp II revealed that in both groups female attacks dropped to near zero after 30 min. After female attacks declined, males initiated social behavior which occasioned vocalizations by the females. Further, males attacked in 65% of the tests and destroyed the litters of the females in 53% of the tests. The behavior of the male exerted important influences on the structure of extended female–male interactions. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learned aversions to copulatory behaviors in male rats.

Used LiCl for an aversive effect on copulatory behavior in adult experienced and inexperienced male hooded rats (Exp I) and in inexperienced adult male Holtzman rats (Exp II). When males received an injection of LiCl immediately after an encounter with an estrous female, the vigor of subsequent copulatory responding was initially unaffected. After 5–20 such pairings, however, males displayed an aversion to copulatory behaviors; they ceased to copulate entirely. These aversions persisted when Ss were tested in a novel environment and extinguished after 4 nonreinforced trials. This multiple-trial adaptation of the conditioned taste aversion paradigm provides a new approach to the aversive control of sexual behavior. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)