Social olfaction in male brown lemmings (Lemmus sibiricus?=?trimucronatus) and collared lemmings (Dicrostonyx groenlandicus): I. Discrimination of species, sex, and estrous condition.

Five experiments were conducted with 196 collared and 243 brown male lemmings. When tested in a Y-maze olfactometer, sexually experienced and naive Ss of both species preferred the odor of conspecific females to the odor of females of another species. Both experienced and naive males also preferred the odor of conspecific females to that of conspecific males. Only sexually experienced males showed a significant preference for estrous over nonestrous conspecific females. Sexually experienced males also discriminated between estrous and nonestrous heterospecific females of a familiar (lemming) and unfamiliar (meadow vole, Microtus pennsylvanicus) species. In conjunction with the results of earlier studies of the development of species-specific olfactory preferences, findings suggest that 2 olfactory cues mediate a male's attraction to receptive females: a species-specific odor that is learned during early development and a sexual attractant whose saliency is established as a result of adult experience with a receptive female. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Responses of male hamsters to odors of females in different reproductive states.

Six experiments investigated the responses of male hamsters to the odors of estrous, diestrous, pregnant, and lactating hamsters. Scent-marking by males in the soiled cages of females was less frequent when the females were estrous (Day 1 of the cycle) than when females were on Days 2, 3, or 4. Sexually experienced males preferred the odors of bedding material from the cages of estrous Ss over odors of bedding of diestrous Ss. Both of these effects were eliminated by surgically removing the vagina and thereby eliminating vaginal secretions. The quantity of vaginal secretions deposited in the vicinity of the nest may be responsible for the observed effects. In contrast, neither males with sexual experience nor males with both sexual and nonsexual experience with females demonstrated preferences for the odors of the estrous or diestrous Ss themselves. Males were, however, more attracted to the odors emanating directly from estrous Ss than to the odors of pregnant or lactating Ss. For hamsters the important sexual message may be not "estrous" vs "diestrous" but rather may be "will soon be estrous" (i.e., cycling) vs "not soon estrous" (i.e., pregnant, lactating, or acyclic). (36 ref) (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?     

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)     

Paternal influence on female behavior: The role of Peg3 in exploration, olfaction, and neuroendocrine regulation of maternal behavior of female mice.

Genomic imprinting represents a mechanism through which parent-of-origin effects on offspring development may be mediated. However, investigation of the influence of imprinted genes on behavior has been limited. Here the authors investigate the role of the maternally imprinted/paternally expressed gene, Peg3, in several aspects of behavior using both 129Sv- and B6-Peg3 mutant female mice. Virgin Peg3 females on both genetic backgrounds were less exploratory and had higher rates of defecation with strain-dependent effects on activity levels and olfactory discrimination. Reproductive success, pup retrieval, and postnatal maternal care of pups were reduced in these females whereas indices of maternal aggression were higher among B6 Peg3-KO females. Differences in maternal care were apparent in females caring for biological or cross-fostered offspring and deficits in pup retrieval apparent beyond the immediate postpartum period. Oxytocin receptor binding in the MPOA and LS was reduced in Peg3-KO females. Thus, the authors demonstrate that disruptions to Peg3 influences aspects of female behavior that are critical for mediating maternal effects on offspring development, such as postpartum licking/grooming, and that effects of Peg3 are dependent on the maternal genetic background. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Communication among hamsters by high-frequency acoustic signals: II. Determinants of calling by females and males.

A previous study by the authors (see record 1978-09410-001) showed that basal rates of high-frequency vocalization by estrous female hamsters exceeded those typical of nonestrous females. In the present 6 studies with random-bred (Lak:LVG) hamsters, even higher rates of calling by estrous females were provoked by male odors (male shavings or anesthetized males). This suggested that cues which normally indicate a male's proximity can increase the rate of high-frequency calls by an estrous female. These findings are consistent with a view of female "ultrasounds" as sexual advertisements which indicate the locations, sexual receptivity, and relative passivity of estrous females to nearby male conspecifies. Male hamsters also produced ultrasounds at rates that seemed to depend on the availability of potential males. Brief exposure to an awake female stimulated male calling; however, estrous females provoked higher call rates than did nonestrous females. Exposure to anesthetized females also increased the rate of male calling, which suggests that the stimulation of male calling by awake females depends in part on female odors. These results suggest that both male and female ultrasounds are parts of a communication system that facilitates reproduction by helping to coordinate social behavior with endocrine state. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analgesic responses of male mice exposed to the odors of parasitized females: Effects of male sexual experience and infection status.

The present study shows that parasites influence both the responses of males to infected females and the responses of male hosts to females. Male mice exposed for 30 min to the odors of females infected with the nematode parasite Heligmosomoides polygyrus displayed a naloxone-sensitive, opioid-mediated analgesia, whereas males exposed for 1 min showed a shorter duration and lower amplitude naloxone-insensitive "nonopioid" analgesia that involved serotoninergic (5-HT) and excitatory amino acid (N-methyl-D-aspartate [NMDA] receptor) systems. The male mice distinguished between the odors of infected and physically stressed females, displaying greater analgesia after exposure to the odors of infected than stressed females. The analgesic responses to the odors of infected females were also affected by the males' prior sexual experience; sexually experienced males exhibited significantly greater analgesia than sexually naive males. In contrast, male mice infected with H. polygyrus failed to show a nonopioid analgesia after exposure to the odors of infected females and displayed a markedly lower level of opioid analgesia than uninfected mice. These results show that male mice can discriminate between the odors of parasitized and nonparasitized females… (PsycINFO Database Record (c) 2010 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.     

Role of previous experience in the male rat's reaction to odors from group and alien conspecifics.

Observed male Long-Evans rats which had cohabited with ovariectomized females for 40 days for their reactions toward the odors from group vs. alien conspecifics. Under conditions where males were kept naive by not rendering their group females receptive, males preferred the odors from group males and females to those of aliens. Under conditions where males were permitted sexual experience, males failed to respond preferentially between group and alien males, and between both receptive and nonreceptive group and alien females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial amygdala involvement in discrimination of same-species and closely-related-species male stimuli in estrous female Mesocricetus hamsters.

Efficient discrimination between individuals of closely related species is important to maximize reproductive potential. Some studies using males as subjects have indicated that the medial amygdala (MeA) is involved in discrimination between odors of conspecific females and females from distantly related species. The authors investigated the involvement of the MeA in discrimination by females between odors of conspecific males and odors of males of a closely related species. The authors exposed estrous or diestrous female hamsters (Mesocricetus auratus) to saline, conspecific male odors, or heterospecific (M. brandti) male odors and quantified the expression of c-fos–related antigens in the anterior and posterior MeA. They found that estrous (but not diestrous) females investigated conspecific male odors longer than heterospecific male odors. Neural activity in both the anterior and the posterior MeA was higher in estrous than in diestrous females. In the anterior MeA, there were no significant differences in response to odors of conspecific and heterospecific males. In the posterior MeA, however, neural activity was higher when estrous females were exposed to conspecific odors than when they were exposed to heterospecific odors. No such difference was observed in diestrous females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The reproductive stage and experience of sexually receptive mothers alter their preference for pups or males.

Female rats show postpartum estrus, a unique stage in their reproductive cycle in which they are able to display maternal and sexual responses at the same time. To assess the relative value of pups or males for sexually receptive mothers with different hormonal profiles and reproductive experiences, we employed a 3-point star maze with 3 choice compartments containing: pups, a sexually active male, or no stimulus (neutral). Cycling maternal and nonmaternal females in late proestrus, independently of their previous reproductive experience, strongly preferred the male to the pups, although most postpartum estrous dams did not exhibit preference for the male. The majority of the postpartum primiparous females did not prefer the litter's chamber either, but a previous reproductive experience strongly determined their preference for the pups. These results suggest that the hormonal changes of the proestrus, in contrast to those of the postpartum estrus, promote a strong preference for the male that is not diminished by the maternal condition. Conversely, the endocrine changes of the postpartum facilitate the effect of previous reproductive experience in strengthening the incentive value of the pups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of frontal cortex in social odor discrimination and scent-marking in female golden hamsters (Mesocricetus auratus).

Orbital/agranular insular (ORB/AI) cortex has been implicated in traditional olfactory learning tasks and social behavior but its precise role in discriminating-learning social odors is not known. Female golden hamsters received aspiration lesions of ORB/AI or dorsomedial (DM) frontal cortex 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, and (c) scent-mark in response to male odors. Lesioned females readily discriminated between scents of individual males. Neither lesion altered female preferences for male odors. Females with DM lesions showed increased levels of scent marking to male odors, but those with ORB/AI cortex lesions did not differ from controls. Thus, ORB/AI cortex does not appear to be critical for discrimination of odors of individuals or sex or for scent-marking responses based on these discriminations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aggression in male mice lacking functional estrogen receptor α.

Estrogen receptor alpha knockout (ERαKO) male mice fail to display sexual behavior. The authors hypothesized that ERαKOs require higher testosterone (T) concentrations than wild-type (WT) males to exhibit copulatory behavior. Increasing T stimulated sexual behavior and preference for females in WT males but failed to do so in ERαKOs. However, T did induce female-directed aggression in ERαKOs. In aggression tests, WT residents selectively attacked T-treated male intruders. ERαKO residents attacked female, T-treated male, and estrogen-treated male intruders equally. Increased access to olfactory cues prior to direct contact reduced overall aggression in ERαKO versus WT males but did not cause ERαKOs to differentially attack male and female opponents. Results suggest that ERα is essential for normal social behavior, perhaps via processing of chemoinvestigatory cues, which are required to discriminate males from females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of vaginal secretion in hamster sexual behavior: Males' responses to normal and vaginectomized females and their odors.

Two experiments (with 60 adult male hamsters and 4 sexually naive male hamsters) examined the importance of vaginal secretion relative to other feminine odors for attraction of males and elicitation of copulatory behavior by comparing the behavior of males toward normal females with that toward vaginectomized Ss. Males were more attracted to intact females than to vaginectomized Ss when odors were the only cues available and also when auditory, visual, and odor cues were available but contact was prevented. There were no differences in the attractiveness of estrous and diestrous Ss whether intact or vaginectomized. When males and females were allowed to interact, there were no differences in any measures of male sexual behavior toward normal vs vaginectomized females, which indicates that the presence of vaginal secretion is not necessary for male sexual behavior. The significance for conceptions of pheromone action in mammals is discussed. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory conditioning of sexual behavior in the male rat (Rattus norvegicus).

The role of classical conditioning in the copulatory preferences of male Long-Evans rats (Rattus norvegicus) was examined by pairing a neutral olfactory stimulus (almond odor) with female reproductive status. During training trials, the males were given access to scented or unscented females that were either sexually receptive or unreceptive. Subsequently, copulatory preferences were tested in males given simultaneous access to 2 receptive females, 1 scented and 1 not. Males trained with scented-receptive females displayed an ejaculatory preference for the scented female. Males trained with scented-unreceptive females or with unscented-receptive females displayed an ejaculatory preference for the unscented female. Males displayed no preference when scent and reproductive status were paired randomly. These results demonstrate that classical conditioning produces an ejaculatory preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraspecific sexual preferences of female hamsters.

Studied the sexual preference behavior of 32 estrous females of 3 species of hamsters of the genus Mesocricetus by introducing individual females into an arena with a pair of males from 2 different species. When 1 male of the pair was a conspecific, females of all 3 species spent significantly more time investigating the conspecific male. When neither male was a conspecific, female Turkish hamsters (M. brandti) strongly preferred male Romanian hamsters (M. neutoni) to male Syrian hamsters (M. auratus), and female Romanian hamsters preferred male Turkish hamsters to male Syrian hamsters. Female Turkish hamsters displayed significantly more presentation behavior than did Romanian females, and Syrian females rarely presented. Female Turkish hamsters also displayed a stronger degree of preference behavior to a conspecific male than did females of either of the other species. The relatively stronger sexual preferences and greater amount of presentation displayed by Turkish hamsters may relate to the greater opportunity for sympatry with closely related forms and the polymorphic state of this species in the wild. The similarity of Turkish and Romanian hamsters on several characteristics may explain the preference of these species for each other when the alternative was a Syrian hamster. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-dependent variations in the sexual preference of male rats

Male rats were tested for their sexual preference behavior at either 37, 70, 90, or 150 days of age on three different occasions; while still sexually naive, after sexual experience with a receptive female, and while sexually aroused by having initiated copulation. These tests resulted in the following findings: a) 37-day-old sexually naive males showed a preference for other males and failed to show a preference for either sex after exposure to females; b) 70- and 90-day-old males showed a statistically significant preference for the female after acquiring sexual experience; c) 150-day-old animals showed a female-oriented preference only after being sexually aroused with two intromissions preceding the preference test, and d) none of the age groups tested showed a female-oriented preference without previous exposure to females. It was then concluded that a) female-oriented behavior requires sexual experience and b) the effects of experience varies with age.     

Odor modulation of ventral scent gland marking in the Mongolian gerbil.

In an experiment with 18 male and 18 female Mongolian gerbils, gerbil odors were allowed to accumulate in individual home cages for several months to provide stable olfactory stimuli that might modulate the number of ventral scent gland marks produced by the Ss. Male marking levels for most test conditions were 2–3 times larger than those in females, although, the relative patterns of responsiveness to particular odors were similar in both sexes. The number of scent marks in home cages was significantly smaller than the number obtained in clean cages. Marking levels in the home cages of other Ss were substantially higher than those seen in the test S's own cage and were maximal in the home cages of other males. Behaviorally receptive females marked at significantly higher levels in home, clean, and conspecific cages than did nonreceptive females. Conspecific urine odors, especially those from females, increased marking levels significantly over those obtained in home cages. In males, home cage marking was significantly enhanced by the presence of a female. Both sexes showed significant reductions in marking levels in another's cage if the resident was present. Results suggest that scent-marking like other olfactory guided behaviors and odor preferences, is context-specific. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of pre- and postpubertal social experience on sexual and social behavior in male and female brown lemmings (Lemmus sibiricus).

In 3 studies, male and female brown lemmings were either isolated at weaning (18 days) or then housed with siblings for another 10 days before being isolated. Before testing for sexual behavior at the age of 75–103 days, half of each group of males received a series of exposures to estrous females and half of each group of females was housed with a stud male. The results of mating tests indicate that whereas prior sexual experience facilitated subsequent copulatory behavior in both sexes, prepubertal interactions subsequently facilitated contact social and sexual behavior in males but did not increase the behavioral scores of females, who engaged in high levels of sexual behavior regardless of prepubertal experience. The effect of prior copulatory activity on male sexual performance could not be attributed to increasing age (i.e., maturational processes) because the behavior of males tested once but at different ages did not differ appreciably. Prepubertal social interaction appeared to predispose males to benefit from sexual experience later in life. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sex difference and testosterone modulation of pheromone-induced NeuronalFos in the Ferret's main olfactory bulb and hypothalamus

A carnivore, the ferret possesses a vomeronasal organ--accessory olfactory bulb (VNO-AOB) projection to the hypothalamus; however, little is known about its function. Pheromones in soiled bedding from estrous female ferrets or an artificial peppermint odor significantly augmented nuclear Fos protein immunoreactivity (Fos-IR), a marker of neural activation, in several main olfactory bulb (MOB) sites but not in the AOB of gonadectomized male and females. Testosterone propionate (TP) significantly augmented the MOB's neuronal Fos responses to estrous females' pheromones, but not to peppermint. Estrous odors, but not peppermint, also augmented neuronal Fos-IR in the medial preoptic area (mPOA) of female, but not male, subjects. Pheromones in soiled bedding from breeding male ferrets significantly augmented neuronal Fos-IR in the MOB and in the medial amygdala of gonadectomized, TP-treated male and female subjects. Again, male pheromones failed to influence neuronal Fos-IR in the AOB of either sex, and only females showed significant increases in neuronal Fos-IR in the lateral aspect of the ventromedial nucleus and mPOA. These results point to an essential role among higher mammals of the main olfactory epithelium-MOB projection to the hypothalamus in detecting and processing pheromones. Gonadectomized ferrets showed significant increases in sniffing behavior when placed on either female or male bedding. This occurred regardless of whether they had received TP or oil vehicle, suggesting that testosterone's facilitation of neuronal Fos responses to estrous females' odors in the MOB of both sexes cannot be attributed to increased scent gathering. Androgen receptor-IR was present in the MOB granule cell layer of male and female ferrets, raising the possibility that testosterone acts directly on these cells to augment their responsiveness to pheromones.