Ultrasonic vocalizing by adult female mice (Mus musculus).

Conducted 5 experiments, using 1,029 female and 805 male mice, to examine adult female mouse ultrasound emission. Results indicate female ultrasonic vocalizing to be (a) typically displayed among female mouse dyads and (b) comparable to the ultrasonic vocalizing levels obtained among male–female pairs. Genotypically based variations in the production of ultrasounds by females were also noted. Like males, socially naive females readily ultrasonically vocalized to anesthetized female conspecifics and rarely vocalized to anesthetized males. Unlike males, socially experienced females emitted few ultrasounds to either female urine or female-soiled cage shavings. Although social experience increased the ultrasound emission of males to female sex cues, the production of ultrasounds by females to these cues was decreased by social experience. Implications with regard to the existence of a behavioral/functional sexual dimorphism in adult mouse ultrasonic vocalizing are discussed. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kin recognition and choice of males by wild female house mice (Mus musculus).

Studied (a) whether wild house mouse females would, when given a choice between males, prefer to associate with siblings or nonsiblings and (b) whether, when they exhibited a preference, prior contact was necessary for sibling recognition. Adult females were injected with hormones to induce behavioral estrus and given a paired choice of adult males with which to associate. Males were littermate siblings (LS), reared with the female until weaning; nonlittermate siblings (NLS), full siblings the female had never met; or nonsiblings (NS), unrelated and unfamiliar males. Females preferred NS males to either LS or NLS males. This indicates that they recognized siblings, even unfamiliar ones, and preferred unrelated males to siblings as potential mating partners to optimize their fitness. The females associated more with LS than NLS males, but the preference appeared to be less than strong when an unrelated male was available. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal performance of inbred and hybrid laboratory mice (Mus musculus).

60 primiparous mice from 3 inbred strains (A/J, DBA/2J, C57BL/6J) and their reciprocal crosses were subjected to various tests of maternal behavior. During pregnancy, S was placed in a seminaturalistic environment, and her nest-building activity was assessed. Following parturition, S's retrieval behavior was measured under conditions that placed conflicting demands on her behavioral repertoire. Results indicate that there were both qualitative and quantitative differences between inbred and hybrid Ss. Prenatal nest-building activity showed heterosis on various measures of relevant environmental manipulations. The retrieval data suggest that inbred Ss were less able to integrate their behavior into a coherent pattern. The level of inbreeding of the pups had no significant effect on the aspects of maternal behavior measured. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of thirst and sodium appetite in mice (Mus musculus).

Intakes of water and NaCl solution were examined in mice following treatment with agents that stimulate or mimic components of the renin-angiotensin-aldosterone system. Injections of angiotensin II or isoproterenol produced little water intake compared with robust responses to either intracellular dehydration or extracellular dehydration induced by treatment with polyethylene glycol. In studies on appetite for NaCl solution, mice exhibited no spontaneous preference for NaCl solution over water and did not change this preference during treatment with deoxycorticosterone acetate, a sodium-deficient diet, or after adrenalectomy. Plasma concentrations of aldosterone were increased in intact mice fed a sodium-deficient diet but not eliminated by adrenalectomy. Acute treatment with furosemide in combination with a sodium-deficient diet stimulated an appetite for NaCl solution. Chronic oral administration of an angiotensin I converting enzyme inhibitor failed to induce a NaCl appetite. Findings show that mice are refractory to the induction of water or NaCl intake by stimuli of the renin-angiotensin-aldosterone system, highly effective in rats, suggesting that there may be major differences among rodents in hormonal determinants of behaviors related to hydromineral homeostasis. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Behavioral development and strain differences in perinatal mice (Mus musculus).

Examined the perinatal development of spontaneous body movements and reflexes in Slc:ICR, C3H/He, and BALB/c mice. Mice were observed from Day 18 (a day before normal parturition) to Day 21.5 of gestation. The developmental changes of spontaneous body movements and reflexes occurred quickly. Strain differences in behavioral development were detected in the duration of spontaneous body movements but not in the occurrence of reflexes. Hybrid mice were more active than their parental strains with regard to duration of spontaneous body movements. The rooting reflex and crossed extensor reflex in hybrid mice occurred more frequently on Day 18 than in their parental strains. These results indicate that the perinatal period is characterized by quick qualitative and quantitative changes in behavioral development and by the appearance of these genetic differences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observational learning of a left-right behavioral asymmetry in mice (Mus musculus).

B6D2F? hybrid mice that were allowed to observe a trained female mouse open a pendulum door to the right (or to the left) to enter a food compartment later solved this problem faster than pupils that had been placed behind a visual barrier. Male pupils that had observed a "left-handed" teacher performed sinistrally; males that had observed a "right-handed" model performed dextrally. Female pupils did not exhibit their demonstrator's laterality. Observational learning may provide a means to maintain certain lateralized behaviors. Such social learning may lead to the emergence of local traditions and to the cultural diffusion of behavioral asymmetries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal separation alters social odor preference development in infant mice (Mus musculus).

This study examined whether daily periods of maternal separation during the first two weeks of life would decrease attraction to familiar nest odors in CD-1 mice 10 and 14 days old. We also investigated whether placing a group of mice (Mus musculus) in nest shavings during the 180-min separation period would mitigate possible separation-induced deficits. The maternal separation procedure has been widely used as a rodent model for the effects of inconsistent or inadequate early caretaking on human development. From postnatal day (PND) 1 to 14, litters were separated from the dam, but not littermates for either 15 or 180 min, or were facility-reared controls. Control, facility-reared mice preferred home-cage nest to clean familiar shaving odors on PND 10, but not PND 14. In contrast, home-cage nest odors attracted maternally separated mice on both test days. Our results suggest that maternal separation maintains the olfactory tether to the nest in a period when the attraction normally begins to weaken. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of infanticide and onset of paternal care in male mice (Mus musculus).

In 7 experiments, using 331 male mice, unmated males tended to be infanticidal toward test pups. However, between mating and the birth of their litter, males stopped killing and became paternal toward test pups. Both the act of copulation and postmating cohabitation with the female influenced this onset of paternal care. The magnitude of the effect of copulation was markedly influenced by prior social experiences. However, just 1 day of cohabitation after mating had the effect of reducing infanticidal tendencies and increasing paternal responses. The timing of this effect coincided with changes in the agonistic interactions between the sexes and apparent changes in dominance/subordinancy relations. The overall effect was a complete inhibition of infanticide that allowed the onset of paternal care. Findings are discussed in relation to those of a previous study by the present author and M. C. Ostermeyer (see record 1985-00491-001), particularly with regard to the hypothesis that the reduction in infanticide may reflect subordination of males to females after mating. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sexual satiety diminishes the capacity of novel males to disrupt early pregnancy in inseminated female mice (Mus musculus).

Male mice (Mus musculus) are sexually aroused by previously inseminated females and can disrupt intrauterine ova implantation. In Experiment 1, females were mated with males of their own genetic strain (CF- 1) and then exposed for 5 days to novel males of the same or a different heterogeneous strain (HS). Half of these males had just mated with other females. HS males disrupted pregnancy more than did CF-1 males, with a nonsignificant trend toward greater influence of unmated males. In Experiment 2, HS males mated with 2 ovariectomized females that were made sexually receptive by injections of estrogen and progesterone, whereas other males lacked this exposure. Inseminated female CF-1 subjects were then housed near such males for 4 days. Unmated males disrupted pregnancy more often than did mated males. These data suggest that sexual satiety can diminish the capacity of novel males to disrupt pregnancy, by reducing sexual motivation, pheromonal emissions, or both. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Partial mediation of strange-male-induced pregnancy blocks by sexual activity in mice (Mus musculus).

Novel male house mice (Mus musculus) can disrupt early pregnancy in females. Previous research (e.g., A. E. Storey; see record 1986-16382-001) focused on pheromonal rather than behavioral mediation of this phenomenon. In Experiment 1, novel males were housed with females shortly after insemination. Litter production was negatively correlated with the males' sexual activity. Experiment 2 replicated this finding with a larger sample. In Experiment 3, females were exposed to castrated males. Testosterone-treated males completely blocked pregnancy, whereas untreated males did not. In Experiment 4, castrated testosterone-treated males were presented at intervals after insemination. Pregnancy was totally blocked at Days 3 and 4 and mostly blocked at Days 1 and 2 but was less affected at Days 5 and 6. In Experiment 5, females were exposed through a wire-mesh grid to castrated males. Pregnancies occurred in all conditions, even with testosterone-treated males. These data suggest a role for sexual activity in male-induced pregnancy blocks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus).

Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences and a spatial learning factor in two strains of mice (Mus musculus).

Current theoretical approaches to animal intelligence either in the form of adaptive specializations or general processes make no explicit predictions nor do they provide substantial evidence concerning individual differences in problem solving. Two strains of mice (Mus musculus) were run through a battery of water escape tasks consisting of 4 spatial learning tasks, a visual discrimination task, and an activity control. The 2 strains were the second filial generation (F2) from a cross between C57BL/6 and DBA/2Js inbred strains and a CD-1 outbred strain. Results indicated positive correlations across all learning tasks in both strains for latency and error measures. Factor analysis revealed a significant first factor for these measures in both strains. These results suggest that at least some spatial and visual tasks in mice under this motivational condition share common properties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of male social status on reproductive success and on behavior in mice (Mus musculus).

Differences in reproduction as well as in behavior in the presence of females were evaluated according to dominant and subordinate male rank in albino mice, in the temporary absence of each male's antagonist. Dominant males reproduced more successfully than subordinate males. Subordinate males were generally inactive, except for displacement activities, during the first 15 min they were exposed to female partners. These findings suggest that mechanisms other than male–male interference or mating order may be operating or influencing behavior and reproductive results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social dominance, reproduction, and release of the maturation-delaying chemosignal in the urine of female house mice (Mus musculus).

Conducted 5 experiments to investigate the effects of social status in groups of female mice on reproduction and on the release of urinary chemosignals that accelerate or delay the onset of sexual maturation. In Exps I and II, using 184 Ss, treatment of young females with urine from bottom-ranking, but not top-ranking, Ss in groups of 5 adult females resulted in delays in puberty comparable to those produced by treatment with urine pooled from females housed at moderate to high densities. In Exps III and IV, using 220 Ss, there was an interaction between the S's social rank and the stages of the estrous cycle with respect to the presence in the urine of chemosignals from grouping that delay puberty and estrus that accelerate puberty. Within groups of 5 Ss, top-ranking Ss were in estrus more frequently than bottom-ranking Ss. Individually caged Ss treated with urine from top-ranking females were in estrus more frequently than those treated with urine from bottom-ranking females. In Exp V, using 100 Ss, when grouped females were separated into individual cages and mated, more top-ranking Ss conceived and bore litters than bottom-ranking Ss. Bottom-ranking Ss produced more female pups than did top- and middle-ranking Ss. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of environmental complexity and space on social interactions of mice (Mus musculus and Peromyscus leucopus).

Examined the effects of environmental space and complexity on social behavior in albino laboratory and wild house mice (M. musculus) and wild white-footed mice (Peromyscus leucopus). Pairs of males or females of each type were introduced into circular arenas of 0.5-, 1-, or 2-m diameter containing 0, 8, or 16 internal barriers. Behavioral characteristics were assessed by multivariate cluster and principal components analyses. Differences between laboratory Ss and the 2 wild groups of Ss reflected the better sensory capabilities and greater reactivity of the wild Ss. M. musculus and P. leucopus were reactive at greater distances, they spent more time freezing and/or grooming, and their behavior was influenced by environmental complexity. The laboratory Ss exhibited reactions only at short distances. M. musculus were more aggressive than P. leucopus, and M. Musculus males were more aggressive than females. Although the amount of space available influenced all 3 types of Ss, effects differed. Laboratory Ss simply encountered each other less often in larger areas, whereas both groups of wild Ss actively used the space to avoid other individuals. Male M. musculus were more aggressive as space decreased; female M. musculus and P. leucopus showed no such change. Behaviors related to orienting toward other mice and moving away from them were more frequent in more open areas. Vision appeared to be the sensory modality used, although audition may have played a role. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of a natural food aversion in domestic rats (Rattus norvegicus) and house mice (Mus musculus).

During a 1-hr feeding test, 34 hungry male Long-Evans rats that had been reared individually from weaning with a Swiss Webster house mouse were less likely to feed on the intact carcass of a freshly sacrificed mouse than were 39 rats that had been reared individually with another rat. Likewise, 42 hungry mice that had been reared individually with a rat were less likely to feed on a dead rat than were 29 mice that had been reared individually with another mouse. Regardless of the social conditions during rearing, hungry mice were more likely to feed on a dead mouse than were hungry rats to feed on a dead rat. Findings suggest that the tendency by rats to reject conspecific flesh stems, at least in part, from prior experience with conspecifics and with their own bodies. The experiential factors mediating the tendency by mice to reject conspecific flesh remain unclear. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Urinary chemosignals from mice (Mus musculus): Acceleration and delay of puberty in related and unrelated young females.

Conducted 5 experiments (N?=?576) to determine the possible differential effects that urinary chemosignals from genetically related and unrelated donors have on puberty onset in female mice. The 1st 4 experiments (n?=?495), with a laboratory mouse strain, demonstrated no differential acceleration or delay of sexual maturation, with respect to a close genetic relation between donors and recipients, due to the chemosignals from estrous, diestrous, pregnant, or lactating females or grouped females. In the last experiment, wild stock Mus were used; all of the results were comparable to those found in laboratory stocks. There were no instances of differential acceleration or delay based on close genetic relatedness of donors and recipients. Results conform with a general hypothesis that the urinary chemosignals in mice communicate information about the adequacy of reproductive conditions to conspecifics. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions of contact, odor cues, and androgens in strange-male-induced early pregnancy disruptions in mice (Mus musculus).

Novel males can disrupt early pregnancy in female house mice (Mus musculus). In Experiment 1, exposure to novel males disrupted pregnancy, but exposure to male urine did not. In Experiment 2, urine from male or female mice or rats painted on females' noses did not influence pregnancy. In Experiment 3, the conjunction of urine painted on female's noses and vulval stimulation did not affect pregnancy more than water with similar stimulation. In Experiment 4, males housed above females were separated from them by a wire mesh grid; intact males disrupted pregnancy, but castrated ones did not. In Experiment 5, such housing of castrated males or ovariectomized females produced a strong disruption of pregnancy if the stimulus animal was given testosterone but not if it was given oil injections. In Experiment 6, transfers of odorous emissions failed to disrupt pregnancy. Contact and androgen activity are necessary for strange males to disrupt pregnancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Litter gender composition affects maternal behavior of the primiparous mouse dam (Mus musculus).

Thirty-nine litters of the outbred Swiss CD-1 mouse strain were reduced at birth to 6 pups, according to three conditions MM (all males), MF (3 males and 3 females), or FF (all females). The maternal behavior of their respective dams (frequency and duration of nursing, licking, nestbuilding, and other activities such as eating, drinking, sniffing, grooming, and undirected locomotor activity) were scored during a single 10-min session on Days 2, 3, 5, 7, 10, 14, and 18. Dams rearing MM litters showed higher scores of maternal care on Days 2 and 18 in the case of nursing, on Days 2, 7, and 10 in the case of nest-building, and on Day 18 in the case of licking. These results confirm previous rat data, which indicated that male and female pups are exposed early in infancy to a different pattern of maternal behavior. Concomitant measurements of pup development (body-weight gain and achievement of a number of physiological and neurobehavioral landmarks) indicated that these effects of litter gender composition are not mediated by gross changes in the maturational trends of the pups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the reduction of dodging in mice: A comparison of food wrenching and dodging in rats (Rattus norvegicus) and mice (Mus musculus).

Rats attempt to steal food from conspecifics by approaching them from the side to wrench the food from the victims' paws, but victims dodge laterally away to protect their food. Given the pervasive necessity of obtaining food, it might be expected that the behaviors of food wrenching and dodging would be common to many animals, but this idea has not been examined. In the present study, food wrenching and dodging were compared in Long-Evans and Sprague-Dawley rats (Rattus norvegicus) and out-crossed CDF1 and inbred C57b mice (Mus musculus). Mice stole food using a strategy very similar to that of rats, but they did not dodge in an open field test and dodged less in a home cage test and ran away or fought more than rats. There were no strain differences in rats, but C57b mice dodged less than CDF1 mice. Given that dodging is a component not only of food defensive behavior but also of play, sexual, and aggressive behavior, the species and strain difference may be a marker (or a key element) of changes in social behaviors that have occurred since the evolutionary separation of rats and mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)