Pre-natal administration of diazepam improves radial maze learning in mice

A number of studies have found that the peri-natal exposure of rodents to diazepam alters their adult behaviour. Adult male mice, treated with diazepam or appropriate controls during pregnancy, were examined in terms of their ability to learn a radial maze. Those animals receiving diazepam prior, but not after birth, learnt the maze significantly more rapidly. The results are discussed in terms of the possible involvement of the hippocampus in this influence of diazepam.     

Prevention by diazepam of adverse effects of maternal restraint stress on postnatal development and learning in the rat.

Rats on days 12--14 of pregnancy were treated with restraint stress alone (9h daily), restraint stress plus diazepam (1 mg/kg, twice daily), diazepam alone, or left as untreated controls. Postnatal development and behaviour was assessed on a wide-ranging battery of tests. Offspring of mothers subjected to restraint stress alone were significantly retarded on a number of developmental measures including growth, ear-opening, cliff avoidance response, auditory startle response and mid-air righting reflex. When adult these offspring also showed significantly impaired learning ability in a swimming maze. However, the rate of development and learning ability in the restraint plus diazepam or diazepam alone groups was comparable to or slightly advanced of that in untreated controls. It is concluded that concurrent administration of a low dose of the tranquiliser diazepam during restraint stress prevents the adverse postnatal effects of maternal restraint stress.     

Effects of Maternal LPS Exposure during Pregnancy on Metabolic Phenotypes in Female Offspring

It is increasingly recognized that intra-uterine growth restriction (IUGR) is associated with an increased risk of metabolic disorders in late life. Previous studies showed that mice exposed to LPS in late gestation induced fetal IUGR. The present study investigated the effects of maternal LPS exposure during pregnancy on metabolic phenotypes in female adult offspring. Pregnant mice were intraperitoneally injected with LPS (50 µg/kg) daily from gestational day (GD)15 to GD17. After lactation, female pups were fed with standard-chow diets (SD) or high-fat diets (HFD). Glucose tolerance test (GTT) and insulin tolerance test (ITT) were assessed 8 and 12 weeks after diet intervention. Hepatic triglyceride content was examined 12 weeks after diet intervention. As expected, maternal LPS exposure during pregnancy resulted in fetal IUGR. Although there was an increasing trend on fat mass in female offspring whose dams were exposed to LPS during pregnancy, maternal LPS exposure during pregnancy did not elevate the levels of fasting blood glucose and serum insulin and hepatic triglyceride content in female adult offspring. Moreover, maternal LPS exposure during pregnancy did not alter insulin sensitivity in adipose tissue and liver in female adult offspring. Further analysis showed that maternal LPS exposure during pregnancy did not exacerbate HFD-induced glucose tolerance and insulin resistance in female adult offspring. In addition, maternal LPS exposure during pregnancy did not aggravate HFD-induced elevation of hepatic triglyceride content in female adult offspring. In conclusion, LPS-induced IUGR does not alter metabolic phenotypes in adulthood.     

Behavioral thermoregulation in a sexually and developmentally dichromatic neotropical primate,the black-and-gold howling monkey (Alouatta caraya)

Behavioral thermoregulation in primates may provide a means for the conservation of heat during periods of low ambient temperature and/or food shortage as well as a way to dissipate heat under hot conditions. This article focuses on behavioral thermoregulation in a sexually dichromatic primate, the black-and-gold howling monkey (Alouatta caraya). Two models have been proposed to explain the evolution of sexual dichromatism in this species: thermoregulation and sexual selection. Five hypotheses associated with thermoregulatory behaviors are tested. These are as follows: (1) energy-conserving postures are used mainly under low ambient temperatures; (2) sunny resting places are selected during periods of low temperature; (3) exposure of the less-insulated ventral region to sunlight decreases with increasing temperature; (4) black-colored adult males use energy-conserving postures, sunny places, and exposure of the ventral region to sunlight less frequently than do blonde-colored adult females; and (5) smaller individuals use energy-conserving postures, sunny places, and exposure of the ventral region to sunlight in significantly greater frequency than do larger individuals. Over a 12-month period, behavioral data were collected on a free-ranging habituated group of 15–17 howlers of all age-sex classes. Ambient temperature was measured each hour. The results indicate that during resting, howlers showed a consistent use of heat-conserving postures, showed a preference for sunny places, and exposed their ventral region to sunlight under low ambient temperatures. A preference for shady places, heat-dissipating postures, and exposure of the back were observed under high ambient temperatures. Despite sex differences in adult color patterns and differences in size between age classes, no significant age or sex differences in thermoregulatory behaviors were detected. Failure to confirm a thermoregulation model implies that sexual selection may be responsible for sexual dichromatism in this species. Am J Phys Anthropol 106:533–546, 1998. © 1998 Wiley-Liss, Inc.     

Attempts to determine the status of electroshock-induced attack in male laboratory mice

An attempt was made using a combination of simple experimental manipulations and videotape recorder (VTR) analysis of bite targets employed to determine whether electroshock-induced attack on anosmic opponents in laboratory mice was an offensive or a defensive behaviour. VTR analysis suggested that ventral surface biting was more evident in this form of attack than in social conflict. Individually- and group-housed males showed similar levels of fighting on exposure to electroshock, but dominant males from pairs showed greater attack than their subordinate partners. Zinc sulphate-induced anosmia, 36 h of food deprivation, castration and lithium chloride treatment reduced electroshock-induced attack. Although significant changes were not obtained, there was some evidence that acute treatment with dexamethasone or ACTH augmented this behaviour. The direction of these changes is similar to that seen with social conflict, and it is suggested that electroshock-induced attack in the mouse (unlike the rat) is largely an aggressive offensive behaviour. The high incidence of ventral surface biting may be a consequence of the upright postures assumed on subjecting the animals to electroshock.     

Diazepam improves aspects of social behaviour and neuron activation in NMDA receptor‐deficient mice

NR1 knockdown (NR1KD) mice are genetically modified to express low levels of the NR1 subunit of N‐methyl‐d ‐aspartate (NMDA) receptors, and show deficits in affiliative social behaviour. In this study, we determined which brain regions were selectively activated in response to social stimulation and asked whether differences in neuronal activation could be observed in mice with reduced sociability. Furthermore, we aimed to determine whether brain activation patterns correlated with the amelioration of social deficits through pharmacological intervention. The cingulate cortex, lateral septal nuclei, hypothalamus, thalamus and amygdala showed an increase in c‐Fos immunoreactivity that was selective for exposure to social stimuli. NR1KD mice displayed a reduction in social behaviour and a reduction in c‐Fos immunoreactivity in the cingulate cortex and septal nuclei. Acute clozapine did not significantly alter sociability; however, diazepam treatment did increase sociability and neuronal activation in the lateral septal region. This study has identified the lateral septal region as a neural substrate of social behaviour and the GABA system as a potential therapeutic target for social dysfunction.     

Social recognition in male rats: age differences and modulation by MIF-I and Alaptide.

Social investigatory behaviour was used as a measure of olfactory recognition in two experiments to assess social memory in adult male rats. In Experiment 1, time spent in social investigation of juvenile males by 3-month-old adults was significantly higher than time spent by 7- and 11-month-old animals. Furthermore, a reexposure to the same juvenile male 30 min after the initial exposure elicited significantly less social investigation in adult males aged 7 and 11 months but not in those aged 3 months. If the reexposure occurs 2 h later, the same juvenile is thoroughly investigated by adult males irrespective of the age. The age-related differences in social recognition are discussed in terms of the internal readiness of adult males. While the social recognition was confirmed in older adult males, it is suggested that an ability to recognize the same juvenile may be masked in young animals by a high sexual arousal. Behavioural phenomenon of the social recognition was used in Experiment 2. An administration of hypothalamic MIF-I or its synthetic derivative Alaptide to adult males 7 or 11 months old immediately after their 1st exposure to a juvenile male resulted in decreasing the time spent in social investigation of the same juvenile during a reexposure performed 120 min later. Both drugs were ineffective if adult males were reexposed to a novel juvenile. The results suggest that both MIF-I and Alaptide improved an animal's capacity to store information received through olfactory cues.     

Development of Social Behaviour in Four Litters of Dogs (Canis familiaris)

The development of social behaviour in 4 litters of dogs was observed without interfering with the puppies from birth to 8 weeks of age. Direct and continuous observation was combined with video recording. Three of the litters were observed during one session of 2 h once a week, and the fourth litter during one session of 40 min twice a week. Social interactions were divided into 1) investigation of litter mates (licking, sniffing or investigating orally), 2) social play, 3) and interactions in which agonistic elements (dominance postures, threats, bites or submission) were displayed. The different forms of social interactions appeared for the first time when the puppies were between 14 and 21 days of age. Social investigation appeared first and was followed by play and agonistic interactions. From week 5, differences between the puppies in the tendency to initiate social play and agonistic interactions emerged. Generally, within the litters individual differences were consistent over weeks 6-8 (positive correlations between weeks), whereas the tendency in the puppies during these weeks were negatively correlated with those of week 3 (play) or weeks 3 and 4 (agonistic interactions), indicating a rebound effect for both play and agonistic behaviour. No significant correlations, however, were found for social investigation. More often than expected males played or engaged in agonistic with other males, whereas these behaviours occurred less often than expected between females. Both males and females, however, preferred male partners for agonistic interactions. No sex differences were found in the direction of social investigation. Agonistic behaviour was often responded to by play and play was often responded to by agonistic behaviour, and the results indicated that before 8 weeks of age differences in social behaviour between the puppies were already established.     

Social behaviour of captive bush dogs (Speothos venaticus)

The bush dog, Speothos venaticus , is a rare forest-dwelling South American canid. Social behaviour of a captive pack of three adult males and three adult females was observed over four years in a large enclosure. The dogs appeared to be compulsively sociable, sleeping in close physical contact, travelling together in single file, and feeding communally with minimal aggression. An alpha pair was dominant, but there was no clear hierarchy within the pack as a whole. There were, however, separate male and female hierarchies. The pack engaged in various communal behaviours, including greeting ceremonies in which individuals mutually submitted to one another. All dogs urine marked frequently, both sexes adopting postures to direct urine upwards and to soak their fur in odour. Only the alpha female bred successfully, and all other group members carried and guarded the young. These observations are discussed in the contexts of canid social behaviour and the breeding in captivity of this endangered species.     

Influence of Different Individual Traits on Vigilance Behaviour in European Rabbits

An animal's level of vigilance depends on various environmental factors such as predator presence or the proximity of conspecific competitors. In addition, several individual traits may influence vigilance. We investigated the effects of body condition, social rank and the state of pregnancy on individual vigilance (scanning) rates in individually marked European rabbits ( Oryctolagus cuniculus ) of a field enclosure population. We found lower rates in young rabbits than in adult females, but male and female juveniles did not differ. Vigilance of juveniles was positively correlated with their age-dependent body mass (used as a measure of body condition), i.e. young rabbits with lower body condition scanned less. We suggest that juveniles with low body condition were trading off vigilance against feeding to maximise their growth. In contrast, there was no significant correlation between body mass and vigilance in adult females. Adult females increased scanning rates during late pregnancy, which might constitute a behavioural compensation because of their lower capacity to escape predator attacks. In addition, adult females with low social ranks scanned more than high ranking individuals, likely because of their higher risk of attacks by conspecifics. In summary, our results highlight various individual characteristics that influence vigilance behaviour in European rabbits.     

Influence of Litter Gender Composition on Subsequent Maternal Behaviour and Maternal Aggression in Female House Mice

It has been suggested that the sex-dependent pattern of mother-pup interaction that occurs early in infancy can affect some aspects of the animal's behaviour repertoire in adulthood. The aim of this study was to investigate the effects of litter gender composition (LGC) on subsequent maternal behaviour and aggression in the female house mouse. Albino mouse litters were reduced at birth to six pups according to two conditions: FM (3 females and 3 males) and FF (all females). At weaning (day 21), all mice were rehoused in unisexual groups. At adulthood (70–90 days) the females were mated and litters culled at birth to 6 pups (3 females and 3 males). On days 2, 4, and 6 after delivery the females were tested for maternal behaviour (10 min) and retrieval of pups. On day 6, at the end of the recording of maternal behaviour, the females were also tested for maternal aggression towards a strange adult male conspecific (5-min exposure). In absence of differences in maternal behaviour scores, FM females showed shorter latencies for retrieval of the first pup on postnatal days 2 and 4. Maternal aggression was also significantly affected by the two conditions. FM females showed higher scores of both duration and frequency of aggressive grooming, defensive upright postures, fleeing and of the number of attacks. FF females spent more time self-grooming, crouching, and on nest. These results support the hypothesis that a series of factors, such as olfactory, tactile, and acoustic stimulation provided by the pups, the variation of maternal behaviour depending upon LGC, and the qualitative and/or quantitative variation in social interaction with the opposite sex in infancy, contribute to the broad interindividual plasticity to cope in different environmental situations.     

The Behaviour of Red Kangaroos (Megaleia rufa) on Hot Summer Days

To investigate the functional significance of the behaviour of large mammals in hot, arid conditions, field observations were made of the behaviour of red kangaroos. The behaviour of individual animals was recorded in detail during hot summer days and measurements of the prevailing temperature and radiation environment were made. Changes in the postures adopted by animals during the day are described in relation to environmental conditions; and the occurrence of certain postures and behaviours at periods of greatest heat stress is reported.     

Behavioural Thermoregulation in a Small Neotropical Primate

The maintenance of body temperature in endothermic animals imposes considerable metabolic costs that vary with air temperature fluctuations. To minimise these costs, endotherms can adopt certain behaviours to adjust the pattern of heat transfer between their bodies and the environment. In this study, we evaluated whether a small Neotropical primate, the black‐fronted titi monkey (Callicebus nigrifrons), living in a seasonal environment can use behavioural mechanisms to cope with fluctuations in the air temperature. We monitored the air temperature and the titi monkeys’ behaviour over 1 yr. When the animals were inactive, we recorded the microhabitat used, the huddling between individuals and the body postures adopted. The monkeys primarily responded to air temperature fluctuations through microhabitat selection: they spent more time in sunny places and used higher strata of forest under lower temperatures. Moreover, they used sunny microhabitats during the first hour of their active period after colder nights. The monkeys did not huddle or change body postures in response to air temperature fluctuations. Huddling behaviour seemed to be primarily influenced by social interactions, and body postures were more energy conserving, regardless of temperature. Titi monkeys, however, used more energy‐conserving postures and huddling behaviour under cloudy conditions than sunny conditions, suggesting that these behaviours may be important when they are unable to thermoregulate by microhabitat selection. We concluded that fluctuations in air temperature can promote significant changes in the behaviour of titi monkeys and can impose important restrictions on mammals’ activities, even in tropical regions.     

Effects of mother's dietary exposure to acesulfame-K in Pregnancy or lactation on the adult offspring's sweet preference

This study investigates whether mother's exposure to the artificial sweetener acesulfame-K (AK) during pregnancy or lactation affected her adult offspring's sweet preference. It was found that mother's dietary exposure to AK in pregnancy or lactation decreased the preference thresholds for AK and sucrose solutions in the adult offspring, whereas the preference pattern and the most preferred concentration for AK or sucrose solution were unchanged. Furthermore, the preference scores in the exposure groups were increased significantly when compared with the control group at a range of concentrations for AK or sucrose solution. The existence of AK and its dynamic changes within 24 h in amniotic fluid during pregnancy or in mother's milk during lactation after a single oral infusion of AK solution were revealed by the methods of reversed-phase high-performance liquid chromatography and mass spectrometry. Our data suggest that AK can be ingested by the prenatal or postnatal mice through their mother's amniotic fluid or breast milk, producing a long-dated function on the adult's sweet preference.     

Effect of social conditions during rearing on mating behaviour of gilts

The mating behaviour of 28 gilts was studied. The gilts were reared under two different social conditions known to affect both their puberty attainment and reproductive parameters during early pregnancy. The different social conditions were applied from an average age of 137 days onwards. Ten gilts were housed individually, having neither tactile nor visual contact with other pigs. The remaining gilts (n=18) were housed pairwise, having additional contact with gilts in adjacent pens and daily boar contact from 180 days of age onwards. At third oestrus, the gilts were artificially inseminated and subsequently introduced to one of three vasectomized boars for a period of 20 min. The gilts were slaughtered 10±1 days after insemination.

The mating behaviour varied considerably between individual gilts, partly because of differences in mating behaviour between the two groups of gilts. More (P<0.05) individually housed gilts showed a standing response latency upon introduction of the boar. During this latency period, the individually housed gilts initiated contact with the boar. Once the standing response was elicited, mating behaviour was similar in gilts of both social groups. One individually housed gilt did not show a standing response and consequently was not mated. The mating behaviour of the boars did not differ for the gilts of the two social conditions.

It was concluded that the social conditions of gilts during rearing affected their introductory sexual behaviour. The relationship with reproductive performance during early pregnancy is discussed.     

Influence of prior exposure to wood shavings on feather pecking, dustbathing and foraging in adult laying hens

It has been proposed that chicks acquire substrate preferences during an early 'sensitive' period. If a suitable substrate is absent during this period birds may develop alternative preferences for pecking at feathers. The aim of this study was to examine whether early substrate exposure has durable effects on the subsequent behaviour of adult hens. The effects of duration of substrate exposure, substrate change, age at exposure and time since exposure on adult bird behaviour were examined. From days 1 to 210, 144 laying strain birds were housed in pairs in pens with wire floors. The floors were replaced with solid floors covered in wood shavings at different ages and for different durations by allocation to 1 of 12 treatments. Adult birds that had never experienced shavings performed significantly more feather pecking than birds in any other treatment group. Thus, exposure to shavings, even for the minimum exposure duration of 10 days, was protective. However, current substrate was of great importance and adult birds housed on shavings performed significantly more ground pecking and less feather pecking than birds on wire, regardless of previous experience. From day 211 all hens were given shavings or straw, presented alternately for five 24h sessions over 10 consecutive days. Birds foraged on both substrates and their foraging behaviour was not influenced by previous experience. Dustbathing occurred primarily on shavings and was significantly influenced by the age at which birds had previously been exposed to shavings. Dustbathing on shavings was fairly constant throughout the 10-day test period in all groups, suggesting that relatively stable preferences had developed. A secondary 'sensitive period' for the formation of adult dustbathing substrate preference may have superseded the early 'imprinting' process. However, adult behaviour was generally flexible and strongly influenced by current substrate.     

A statistical analysis of the social behavior of the male stumptail macaque (Macaca arctoides)

The social behavior of male stumptail macaques was analyzed in terms of behavioral sequences recorded during paired encounters in a large test cage. Recurrent patterns of behavioral sequences were sought and used to hypothesize the structure of motivational systems of social behavior as has been done previously for other species. In addition to traditional statistical analyses to determine which dyadic behavioral sequences were nonrandom, there were several methodological innovations. Instead of analyzing behavior as a single channel of communications, we analyzed three independent channels and considered their inter-correlations: 1) acts and postures; 2) vocalizations; and 3) facial expressions. Also, we analyzed not only within-animal behavioral sequences but between-animal sequences as well. Results were derived from 40 tests, most of which included vigorous agonistic and sexual interactions and a behavioral repertoire similar to that of adult male stumptail macaques observed by previous investigators. There were 30 acts and postures, eight facial expressions, and seven vocalizations that occurred more than five times. Many acts and postures occurred in nonrandom sequences, 43 such sequences within-animal and 40 between-animal. From these sequences and their correlations with specific vocalizations and facial expressions, it was possible to differentiate six categories of social behavior that may correspond to six different motivational systems: offense, defense, submission, groom and contact, male sexual behavior, and display. Both the frequency of behaviors in each category and the nature of the behavioral sequences were affected by the relative dominance of the two animals.     

Social interactions associated with reproduction in the bushveld gerbil <Emphasis Type="Italic">Gerbilliscus leucogaster</Emphasis>

The study of social behaviour can give us important insights into the social and mating system of a species or population. We investigated male–female interactions in captive bushveld gerbils, Gerbilliscus leucogaster, to gain insight into the social behaviour and mating structure. We conducted two experiments. In experiment 1, we studied the interactions between two strangers for a week in a three-tank setup, which tested behavioural variation spatially and temporally. Although tolerance between strange males and females increased with time, it remained generally low throughout the experiment. Females appeared to be cautious of males initially, but they later became aggressive towards them. Males showed an increase in submissive behaviour over time. The ‘home’ cage did not appear to be defended by either sex. In experiment 2, we investigated the social interactions of male–female pairs during pregnancy and lactation. Aggression persisted throughout the study and amicable behaviour was low; females were much more aggressive than males. We did not detect changes in social behaviour with the progression of pregnancy and lactation. We suggest that pair bonding is unlikely and that promiscuity is the most probable mating system. Female aggression may be related to mate choice prior to mating and mate exclusion thereafter, while it may be a response to infanticide risk during pregnancy and lactation.     

An ethogram of the common marmoset (Calithrix jacchus jacchus): General behavioural repertoire

The behavioural repertoire of four captive breeding pairs of Callithrix jacchus jacchus is described. Social communication took the form of postures, facial expressions, vocalizations and piloerection displays. Detailed analyses were made of piloerection displays, adult play, copulatory, aggressive, and prey-catching behaviour. Aggressive behaviour was uncommon in adult mated pairs. Play between adults showed a degree of temporal organization. Vocalizations were the main methods of intragroup communication whilst piloerection displays were directed towards members of other groups and also to unfamiliar objects. The behavioural repertoire of C. jacchus jacchus is compared with that of other Primates.     

Individual and social behavior in a captive troop of mandrills (mandrillus sphinx)

Little is known about the behavior of mandrills in the wild, and few captive studies have been conducted. Individual and social behaviors of six captive mandrills were categorized and quantified. The captive troop consisted of one adult male, two adult females and three infants. Behavioral categories were constructed during 150 hr of preliminary observations. One hundred and sixty-seven hours of quantitative data were collected over an eight-month period. Although much of the mandrill's behavioral repertoire is similar toPapio, some facial expressions, body postures and various social behaviors were found to be unique.