The physiological and behavioral impact of sensory contact among unfamiliar adult mice in the laboratory

Housing mice in the laboratory in groups enables social interaction and is the way a laboratory should house mice. However, adult males show reciprocal aggression and are therefore frequently housed individually. Alternatively, a grid divider, which allows sensory contact by sight and smell but prevents fighting and injuries, can separate mice within 1 cage. This study examined the influence of this housing method on various physiological and behavioral parameters. Adult male mice housed for 10 days with sensory contact to an unfamiliar male displayed significant increases in heart rate (HR), body core temperature (BT), and motor activity (ACT). Furthermore, the mice suffered impaired nest-building behavior and significantly reduced body weight. Conversely, males housed in a similar manner with a female companion showed only a transient elevation of ACT, BT, and HR. Although no clear beneficial effect of housing males with sensory contact to females was evident, this study could not exclude it. On the other hand, housing of mature males in this way leads to sustained detrimental alterations of physiology and behavior, thus implying severe impairment of animal well-being.     

Impact of 'living apart together' on postoperative recovery of mice compared with social and individual housing

Social housing is the optimal way of housing female laboratory mice. However, individual housing may be required in experimental designs, for example after surgery. We therefore investigated whether housing two female mice in a cage, separated by a grid partition ('living apart together', LAT), counters the adverse effects of individual housing on postoperative recovery. Ten individually housed (IND) mice, nine socially housed (SOC) mice and nine mice, housed LAT, were surgically implanted with a telemetry transmitter. From one week prior to surgery until three weeks thereafter, several physiological and behavioural parameters were measured in the mice subjected to surgery. The telemetry transmitter measured heart rate (HR), body temperature and activity continuously. Body weight, food and water intake were scored regularly, as were wound healing, ease of handling, nest building and behaviour. Results indicated that SOC mice appear to be less affected by abdominal surgery than IND mice, as indicated by HR and behaviour. LAT, however, did not appear to be beneficiary to the mice. Increased HR levels and differences in behaviour as compared with both SOC and IND animals indicate that LAT may even be the most stressful of the three housing conditions. We therefore conclude that mice benefit most from social housing after surgery. If, however, social housing is not possible, individual housing appears to be a better option than separating mice by a grid partition.     

Influence of environmental enrichment and handling on the acute stress response in individually housed mice

In this study we investigated the effect of environmental enrichment and handling on the acute physiological stress response caused by short periods of restraint in individually housed female mice. Heart rate (HR) and body temperature (BT) were measured by radiotelemetry and compared with plasma corticosterone (pCORT) levels. Also, postmortem thymus weight and tyrosine hydroxylase (TH) activity were assessed. The acute stress response was seen in both HR and BT. Enrichment and handling were found to increase rather than decrease this stress response, but pCORT values, measured 90 min after restraint, suggested a lower stress response in the enriched groups. No effect was found with thymus weight or TH as parameters.     

Effects of wire-bottom caging on heart rate, activity and body temperature in telemetry-implanted rats

Some experimental procedures are associated with placement of animals in wire-bottom cages. The goal of this study was to evaluate stress-related physiological parameters (heart rate [HR], body temperature [BT], locomotor activity [LA], body weight [BW] and food consumption) in rats under two housing conditions, namely in wire-bottom cages and in bedding-bottom cages. Telemetry devices were surgically implanted in male Sprague-Dawley rats. HR, BT and LA were recorded at 5 min intervals. Analysis under each housing condition was performed from 16:00 to 08:00 h of the following day (4 h light, 12 h dark). During almost all of the light phase, the HR of rats housed in wire-bottom cages remained high (371 ± 35 bpm; mean ± SD; n = 6) and was significantly different from that of rats housed in bedding-bottom cages (340 ± 29 bpm; n = 6; P < 0.001; Student's t-test). In general, BT was similar under the two housing conditions. However, when rats were in wire-bottom cages, BT tended to fluctuate more widely during the dark phase. LA decreased when animals were housed in wire-bottom cages, in particular during the dark phase. Moreover, there was a significant difference with respect to the gain in BW: BW of rats housed in bedding-bottom cages increased 12 ± 2 g, whereas that of rats in wire-bottom cages decreased by 2 ± 3 g (P < 0.001). Our results demonstrate that housing rats in wire-bottom cages overnight leads to immediate alterations of HR, BW and LA, which might be related to a stress response.     

Determining the Value of Social Companionship to Captive Tufted Capuchin Monkeys (Cebus apella)

In general, guidelines on housing and care of animals in the laboratory state that rats and mice should not be housed in the same room. Mice may perceive rats as predators. Although one theory says this can cause stress, there is little scientific evidence to support this theory. In the wild, rats and mice usually do not share the same microhabitat, but this appears to be true for most small rodent species. Furthermore, reports of predatory behavior of rats toward mice mainly originate from experimental settings using rats with high inbred levels of aggression. This experiment measured heart rate (HR), body temperature (BT), activity (AC), and urinary corticosterone in female C57BL/6 mice before, during, and after introducing Wistar rats into their room. The study found no chronic effects of rat introduction on any parameters. The study concluded that housing rats and mice in the same room is at least less disturbing than cage cleaning, which caused a temporary increase of HR, BT, and AC. Current results do not support legislation based on compromised welfare.     

Impact of IVC housing on emotionality and fear learning in male C3HeB/FeJ and C57BL/6J mice

Housing conditions are known to influence laboratory animal behavior. However, it is not known whether housing mice in individually ventilated cages (IVCs) to maintain optimal hygienic conditions alters behavioral baselines established in conventional housing. This issue is important with regard to comparability and reproducibility of data. Therefore, we investigated the impact of IVC housing on emotionality and fear learning in male C3HeB/FeJ (C3H) and C57BL/6J (B6J) mice housed singly either in conventional type II cages with wire bar lids (Conventional), or in IVCs of the same size, but with smooth, untextured lids (IVC classic), thus acoustically attenuated from external stimuli and with limited climbing facilities compared to Conventional. To evaluate the role of climbing, additional mice were kept in IVCs with lids having wire bars ("grid") added to the inner surface (IVC grid). Spontaneous behavior, sensorimotor behavior, and fear learning were measured. IVC housing reduced activity and enhanced anxiety-related behavior in both strains, whereas grooming latency was reduced in B6J only. IVC housing increased Acoustic Startle Response in C3H but not in B6J mice. The "grid" did not compensate for these IVC housing effects. In contrast, B6J mice in IVC grid performed best in fear potentiated startle while B6J mice in IVC classic performed the worst, suggesting that climbing facilities combined with IVC housing facilitate FPS performance in singly-housed B6J males. Our data show that IVC housing can affect behavioral performance and can modulate behavioral parameters in a general and a strain-specific manner, thus having an impact on mouse functional genomics.     

Effect of differential housing in mice on natural killer cell activity, tumor growth, and plasma corticosterone.

Various forms of stress have been shown to alter natural killer (NK) cell activity and tumorigenesis; however, few studies have measured these two variables simultaneously. Isolation of mice was utilized as a model of stress by which to study NK cell activity and pulmonary metastatic response following a tumor challenge. Male C3H mice were group or individually housed for 3 weeks, after which CIRAS 3 fibrosarcoma tumor cells or the tumor vehicle was injected intravenously (tail vein), NK cell activity, pulmonary metastasis, and plasma corticosterone were measured 1, 7, and 21 days following tumor cell inoculation. Individually housed mice, irrespective of tumor or vehicle condition, had a higher NK response on Day 1 relative to group-housed animals (P less than 0.001). By Day 21, tumor condition, rather than housing, was the major significant factor affecting NK activity (P less than 0.001). Nevertheless, individually housed, tumor-injected mice still had higher NK activity compared with the other treatment groups on Day 21. No effect of housing condition was present for the incidence of pulmonary metastases or frequency of metastases in affected animals. Plasma corticosterone levels generally increased over the study period, with no housing or injection effects at Days 1 and 7. Individually housed, vehicle-injected mice had higher corticosterone levels at Day 21 (P less than 0.01). These data suggest that in response to housing condition, NK cell activity differs in tumor-bearing mice and vehicle controls. Furthermore, CIRAS 3 pulmonary tumor formation is not affected by differences in NK activity consequent to housing condition. Plasma corticosterone does not appear to be a major in vivo regulator of NK activity in this experimental tumor system. Finally, the interpretation of housing effects on NK activity and plasma corticosterone levels depends on the temporal window in which sampling occurs.     

Co-Housing Rodents with Different Coat Colours as a Simple,Non-Invasive Means of Individual Identification: Validating Mixed-Strain Housing for C57BL/6 and DBA/2 Mice

Standard practice typically requires the marking of laboratory mice so that they can be individually identified. However, many of the common methods compromise the welfare of the individuals being marked (as well as requiring time, effort, and/or resources on the part of researchers and technicians). Mixing strains of different colour within a cage would allow them to be readily visually identifiable, negating the need for more invasive marking techniques. Here we assess the impact that mixed strain housing has on the phenotypes of female C57BL/6 (black) and DBA/2 (brown) mice, and on the variability in the data obtained from them. Mice were housed in either mixed strain or single strain pairs for 19 weeks, and their phenotypes then assessed using 23 different behavioural, morphological, haematological and physiological measures widely used in research and/or important for assessing mouse welfare. No negative effects of mixed strain housing could be found on the phenotypes of either strain, including variables relevant to welfare. Differences and similarities between the two strains were almost all as expected from previously published studies, and none were affected by whether mice were housed in mixed- or single-strain pairs. Only one significant main effect of housing type was detected: mixed strain pairs had smaller red blood cell distribution widths, a measure suggesting better health (findings that now need replicating in case they were Type 1 errors resulting from our multiplicity of tests). Furthermore, mixed strain housing did not increase the variation in data obtained from the mice: the standard errors for all variables were essentially identical between the two housing conditions. Mixed strain housing also made animals very easy to distinguish while in the home cage. Female DBA/2 and C57BL/6 mice can thus be housed in mixed strain pairs for identification purposes, with no apparent negative effects on their welfare or the data they generate. This suggests that there is much value in exploring other combinations of strains.     

Social environment modulates photoperiodic immune and reproductive responses in adult male white-footed mice (Peromyscus leucopus)

Social cues may interact with photoperiod to regulate seasonal adaptations in photoperiod-responsive rodents. Specifically, photoperiod-induced adjustments (e.g., reproduction and immune function) may differ among individuals in heterosexual pairs, same-sex pairs, or isolation. Heterosexual cues may be more influential, based on their potential fitness value, than same-sex cues or no social cues. The present study examined the effects of pair (with a male or female) or individual housing on reproductive and immune responses in male white-footed mice (Peromyscus leucopus) maintained in long or short photoperiods. Female pairing did not affect reproductive responses in short-day males. In long days, however, the presence of a female increased both testosterone concentrations and testes mass compared with individually housed and male-paired mice, respectively. Short-day, individually housed males enhanced delayed-type hypersensitivity (DTH) responses compared with single-housed mice in long days, but all paired groups decreased DTH responses regardless of photoperiod. The lack of enhanced DTH response in male mice paired with females coincided with reduced circulating corticosterone concentrations in both photoperiod treatments. Together, these results suggest that social environment may have important modulatory effects on photoperiod-regulated immune responses in male white-footed mice.     

Long-term isolated housing causes anxiety in C57BL/6J female mice

Behaviour of female C57BL/6J strain mice was studied in the elevated plus-maze and Porsolt's tests after either long-lasting individual housing or keeping with daily shifting group-housed females (social instability). After 2-3 months, an increased level of anxiety in the individually housed females was revealed in the elevated plus-maze. However, in 3 months the least passive behaviour in the Porsolt's was in the individually housed females. No changes were found in behaviour of females individually housed at 3 weeks of age for 4 months. Also, females with preliminary social contacts with males and following individual housing for one month had not any abnormalities in the used behavioural tests. Social instability conditions did not significantly influence the females' plus-maze behaviour, but decreased the passive behaviour in the Porsolt's test.     

Reactions of calves to handling depend on housing condition and previous experience with humans

This study investigated the influence of stockperson's behaviour and housing conditions on calves' behavioural reactions to people, and behavioural and physiological reactions to handling and short transport. Sixty-four Finnish Ayrshire male calves were used; half of them were housed in individual pens, the other half were housed in group pens of two calves. In both housing conditions half of the calves received minimal contact from the stockperson, while the other half were stroked on their necks and shoulders for 90s a day, after milk meals. The effects of housing and contact with the stockperson on the responses of calves to people, either entering or approaching the pen, were studied. Furthermore, calves' behavioural and physiological (cortisol, heart rate) reactions to being loaded onto a truck, transported for 30min and unloaded were observed. When a person entered the home pen, calves housed by pairs took significantly more time to interact and interacted less frequently with the person than individually housed calves did (p<0.01). Calves that received additional contact interacted for longer time with the unfamiliar person than calves with minimal contact (p=0.02). When a person approached the front of the calves' pens, less withdrawal responses were shown by calves that had received additional contact (p<0.05) than those that had received minimal contact. When the calves were loaded onto the truck, it took more time and effort to load pair housed calves than individually housed calves (p<0.01) and less effort to load calves that had received additional contact (p<0.01) compared to those that had received minimal contact. During loading additional contact calves had lower heart rates (p<0.05) than those that had received minimal contact, while during transport pair housed calves had lower heart rates compared to individually housed ones (p<0.05). For all the observations performed, no interactions were found between housing conditions and human contact.It is concluded that, compared to calves housed individually, calves housed in pairs are less ready to approach humans and less easy to handle. Providing calves with regular positive contacts makes them less fearful of people and improves handling. Due to the greater difficulty in handling calves housed in groups, it is concluded that these animals need to have regular contact with humans.     

Comparative analysis and physiological impact of different tissue biopsy methodologies used for the genotyping of laboratory mice

Genotyping of genetically modified mice and control of authenticity of the genetic background of congenic or coisogenic strains by polymerase chain reaction (PCR) is a routine procedure that can be performed with different tissue biopsies causing variable grades of trauma. In this study, some invasive and non-invasive sampling methods were compared, with the main focus on the impact on animal physiology. We compared ear punch, tail biopsy, hair plugging, mouth and rectum swabs and the simple restraint of the animals, scoring for the impact on heart rate (HR), core body temperature (BT) and motor activity by telemetry, during biopsy and for the following 6 h. Furthermore, in order to correlate the physiological impact with the practicability and reliability of the genotyping results, we performed a PCR analysis of the biopsy samples obtained by using the same collection procedures analysed by telemetry. All sampling methods and restraint induced significant increase in HR and BT and a slight increase in motor activity for 1 h, independent of the invasiveness of the method used. Genotyping of all biopsies allowed the proper identification of transgenic animals, tail biopsies, ear punches and hair follicles giving clear signals, the last method being fast, but also susceptible to cross contaminations during sampling by large numbers of animals. Restraint and all biopsy methods provoked similar physiological changes, indicating that the handling of the animals is of major importance and that the sampling procedure does not strongly influence the physiological parameters.     

Effects of housing density on nasal pathology of breeding mice housed in individually ventilated cages

The 2011 edition of the Guide for the Care and Use of Laboratory Animals includes new recommendations for the amount of floor space that should be provided to breeding mice. When pairs or trios of continuously breeding mice are housed in shoebox cages, they may have less than this recommended amount of floor space. High housing densities may adversely affect animal health, for example, by compromising air quality inside the cage. Hence, some institutions are carefully reevaluating the microenvironments of breeding cages. The use of individually ventilated cages (IVCs) to house research mice allows for greater control over the quality of the cage microenvironment. The authors evaluated the microenvironments of shoebox cages in an IVC rack system housing breeding and non-breeding Swiss Webster mice. Ammonia concentrations were significantly higher in cages housing breeding trios with two litters. Histopathologic lesions attributable to inhaled irritants such as ammonia were found in mice housed in breeding pairs and trios. The authors conclude that the microenvironments of cages in an IVC rack system housing breeding pairs and trios may be detrimental to animal health.     

Cooperative social coordination and aggression in male laboratory rats: effects of housing and testosterone

A cooperative behavior, coordinated shuttling by pairs of laboratory rats in a rectangular chamber, can be influenced strongly by an interaction between housing and sex. Males and females learn readily when housed together socially, but individual housing ("isolation") causes severe deficits selectively in males. The aim of the present study was to examine the role of testosterone in the differential effects of housing on cooperation learning. Males of a Sprague-Dawley derived strain were housed socially or individually and treated daily in one of three ways (six groups, n = 6 per group): (1) castrated, injected with oil vehicle (without testosterone); (2) castrated, injected with 500 micrograms testosterone propionate (exogenous TP); and (3) sham operated, injected with oil (intact, endogenous testosterone). Socially housed pairs learned readily in all treatment groups, using strategies of coordination in which stereotyped contact or aggressive interactions were interpolated. Individual housing was associated with a deficit, but only in the TP-treated and intact groups in which some pairs either did not learn or performed poorly. The deficit was associated with violent fighting and extreme and stable differentiation into dominants and subordinates, the latter exhibiting prolonged freezing. Oil-treated castrates, when housed individually, were unimpaired and actually surpassed their socially housed counterparts on some measures. Their success was associated with an increase only in low-level aggression. The housing-hormone interaction in male rats suggests that testosterone influences the capacity to develop cooperative behavior by modulating both aggression and its consequences for the relationship between partners. The use of social interaction models, including cooperation, for the study of behavior-hormone interactions was also discussed.     

The use of radiotelemetry to assess the time needed to acclimatize guineapigs following several hours of ground transport

The objective of this study was to investigate the effect of ground transportation on guineapigs. Physiological parameters, i.e. heart rate (HR), body temperature (BT) and activity (ACT), were measured before and after transport, using previously implanted radiotelemetry transmitters. Body weight was measured before and after transport. After a postsurgical recovery period and data recording at the breeder's facility, the animals were transported for 2.25 h (Group 1) and for 7.5 h (Group 2) to a different animal facility. Data collection started immediately after arrival at the second animal facility. All parameters measured changed significantly after transport. These results suggest that a 10- to 12-day period is required for guineapigs to return to pre-transport levels of HR, BT and ACT.     

Association of cathepsin E deficiency with the increased territorial aggressive response of mice

Cathepsin E is an endolysosomal aspartic proteinase predominantly expressed in cells of the immune system, but physiological functions of this protein in the brain remains unclear. In this study, we investigate the behavioral effect of disrupting the gene encoding cathepsin E in mice. We found that the cathepsin E-deficient ( CatE −/−) mice were behaviorally normal when housed communally, but they became more aggressive compared with the wild-type littermates when housed individually in a single cage. The increased aggressive response of CatE−/− mice was reduced to the level comparable to that seen for CatE+/+ mice by pretreatment with an NK-1-specific antagonist. Consistent with this, the neurotransmitter substance P (SP) level in affective brain areas including amygdala, hypothalamus, and periaqueductal gray was significantly increased in CatE−/− mice compared with CatE+/+ mice, indicating that the increased aggressive behavior of CatE−/− mice by isolation housing followed by territorial challenge is mainly because of the enhanced SP/NK-1 receptor signaling system. Double immunofluorescence microscopy also revealed the co-localization of SP with synaptophysin but not with microtubule-associated protein-2. Our data thus indicate that cathepsin E is associated with the SP/NK-1 receptor signaling system and thereby regulates the aggressive response of the animals to stressors such as territorial challenge.     

Comparing the relative benefits of grooming-contact and full-contact pairing for laboratory-housed adult female Macaca fascicularis

Tactile social contact is the most effective form of environmental enrichment for promoting normal behavior in captive primates. For laboratory macaques housed indoors, pair housing is the most common method for socialization. Pairs can be housed either in full contact (FC), or in protected contact (PC). At Washington National Primate Research Center, PC is provided by grooming-contact (GC) cages whereby two partners are housed individually in adjacent cages with access to each other through widely spaced vertical bars. Grooming-contact has been used to accommodate research protocol restrictions and improve the likelihood of compatibility for various pairings, in part by enabling male-female pairs. This study compares the benefits between the two housing types by video recording 14 pairs of adult female Macaca fascicularis in four sequential housing phases following an ABBA design: baseline grooming-contact, full contact shortly after introduction, 1-month-later full contact, and after reversion to grooming-contact. Prior to this study, pairs had been housed compatibly in GC. Twelve of the 14 long-term pairs transitioned successfully to full contact and data presented exclude the two failed pairs. Allogrooming increased significantly when pairs first switched from GC to FC (P = 0.018), but the effect did not last through the on 1-month-later FC phase suggesting that the initial improvement in affiliative behavior was a transitory novelty response that did not persist. Self-grooming significantly decreased between the first GC and first FC phases (P = 0.016), likely due to redirected allogrooming. Non-contact affiliative behavior towards partner or other conspecifics in the room did not differ, nor did agonism towards partner or others in the room. Occurrence of abnormal, tension, manipulation, miscellaneous active, and inactive behaviors did not differ significantly across housing phases. Proximity measurements indicated that pairs were significantly out of arm's reach more often in protected contact than when in full contact (P ≤ 0.02). Proportion of time spent in physical contact significantly increased between the first GC and first FC phases (P = 0.002), but subsequently declined. For both FC phases, partners chose to spend about 50% of their time in the same cage. Few behavioral improvements were seen after pairs switched to full contact and no negative effects came of reversion to grooming contact. This study suggests that tactile contact provided through widely spaced bars (grooming-contact) is a viable alternative to full contact housing for adult female longtailed macaques. It provides a degree of social housing while allowing both partners choice and control, key concepts in contemporary animal welfare guidelines.     

Development of Dry Skin in the NOA Mouse Under Individual Housing Conditions: A Potentially Useful Animal Model for Evaluating Moisturizing Effects.

In a previous study, we reported the development of grossly observable dry skin in all of the Naruto Research Institute Otsuka Atrichia (NOA) mice that were housed individually. In the present study, dermal physiological function tests were conducted and the usefulness of this dry skin model for evaluating the efficacy of topical moisturizers was assessed. As a result, we have confirmed a marked reduction in the water content of the stratum corneum in these animals. Therefore, the development of dry skin in the NOA mouse strain under individual housing conditions may be expected to serve as a useful animal model for evaluating topical moisturizers. Specifically, the water content of the stratum corneum was restored in proportion to the oil content of the ointment base used to treat the animals, and the moisturizing effects of urea were confirmed in animals treated with urea-containing ointment. In addition, when the animals that had been housed individually were returned to group housing conditions, the water content of the stratum corneum was restored, with a corresponding improvement in dry skin. This finding suggests that socio-psychological factors are involved in the etiology of dry skin in individually housed NOA mice.     

The maternal social environment shapes offspring growth,physiology, and behavioural phenotype in guinea pigs

Background

Prenatal conditions influence offspring development in many species. In mammals, the effects of social density have traditionally been considered a detrimental form of maternal stress. Now their potential adaptive significance is receiving greater attention.Sex-specific effects of maternal social instability on offspring in guinea pigs (Cavia aperea f. porcellus) have been interpreted as adaptations to high social densities, while the effects of low social density are unknown. Hence, we compared morphological, behavioural and physiological development between offspring born to mothers housed either individually or in groups during the second half of pregnancy.

Results

Females housed individually and females housed in groups gave birth to litters of similar size and sex-ratios, and there were no differences in birth weight. Sons of individually-housed mothers grew faster than their sisters, whereas daughters ofgroup-housed females grew faster than their brothers, primarily due to an effect on growth of daughters. There were few effects on offspring behaviour. Baseline cortisol levels in saliva of pups on day 1 and day 7 were not affected, but we saw a blunted cortisol response to social separation on day 7 in sons of individually-housed females and daughters of group-housed females. The effects were consistent across two replicate experiments.

Conclusions

The observed effects only partially support the adaptive hypothesis. Increased growth of daughters may be adaptive under high densities due to increasedfemale competition, but it is unclear why growth of sons is not increased under low social densities when males face less competition from older, dominant males. The differences in growth may be causally linked to sex-specific effects on cortisol response, although individual cortisol response and growth were not correlated, and various other mechanisms are possible. The observed sex-specific effects on early development are intriguing, yet the potential adaptive benefits and physiological mechanisms require further study.

     

Effects of social isolation on growth,stress response,and immunity of zebrafish

Stressful housing conditions like social isolation have been shown to profoundly affect the physiology and health of various organisms which is rarely addressed in fish species. In the present study, we used a shoaling species, zebrafish, to investigate the stress reactivity of grouped and individually housed fish. We also hypothesized if isolation is a stressful condition may disrupt growth performance and innate immune response of individuals. To this end, fish were housed individually (social isolated treatment) or in groups of five fish (control treatment) for 60 days. Growth indices of fish were not affected by social isolation. Sixty-day social isolation did insignificant effect on baseline cortisol levels of specimens; however, individually housed zebrafish showed lower plasma cortisol to chasing stress than the control grouped fish. On the contrary, exposure to predator caused higher cortisol levels in social isolated fish. Serum lysozyme activity of isolated individuals was significantly lower than control fish, but activity of serum complement remained unchanged. Our results represent evidences that zebrafish experienced social isolation showed broad changes in physiological and immunological functions which may affect the quality of life.