A break from the pups: The effects of loft access on the welfare of lactating laboratory rats.
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ABSTRACT:
SUBMITTER: Ratuski AS
PROVIDER: S-EPMC8186774 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Lactating rats must continuously maintain a critical balance between caring for pups and aggressively responding to nest threats. We tested the neural response of lactating females to the presentation of their own pups and novel intruder males using blood oxygen level-dependent functional magnetic resonance imaging at 7 T. Dams were presented with a single sequence of a control stimulus, pups or a male intruder in one imaging session (n = 7-9). To further determine the selectivity of neural processing, dams were imaged for their response to a male intruder in both the absence and presence of their pups (n = 6). Several maternal cortical and limbic brain regions were significantly activated by intruder presentation but not by pups or a control stimulus. These included the nucleus accumbens, periaqueductal gray, anterior cingulate, anterior thalamus, basal nucleus of the amygdala, temporal cortex, prelimbic/orbital area and insula. The nucleus accumbens, periaqueductal gray, temporal cortex and mediodorsal thalamus still showed greater neural activity when compared with intruder presentation in the absence of pups. The present results suggest that the high emotional state generated by a threat to pups involves robust activation of classical limbic regions controlling emotional responses. This pattern of blood oxygen level-dependent activity may precede behavioral states upon which lactating rats initiate attacks against a potential threat to offspring.
| S-EPMC2758821 | biostudies-literature
Project description:BackgroundConjugated linoleic acid (CLA) is known to affect the lipid metabolism in growing and lactating animals. However, potential effects on the metabolism of fat-soluble vitamins in lactating animals and co-occurring effects on their offspring are unknown. We aimed to investigate the effects of dietary CLA on concentrations of tocopherol in various tissues of lactating rats and their offspring and expression of genes involved in tocopherol metabolism.MethodsTwenty-eight Wistar Han rats were allocated to 2 groups and fed either a control diet (control group) or a diet containing 0.9 % of cis-9, trans-11 and trans-10, cis-12 (1:1) CLA (CLA group) during pregnancy and lactation. Feed intake of dams and body weight of dams and their pups were recorded weekly. Tocopherol concentrations in various body tissues were determined at day 14 of lactation in dams and 1, 7 and 14 days after birth in pups. Expression of selected genes involved in metabolism of tocopherol was determined in dams and pups. The data were statistically analysed by analysis of variance.ResultsFeed intake and body weight development of nursing rats and their pups was similar in both groups. In livers of CLA-fed dams, tocopherol concentrations decreased by 24 % but expression of TTPA and CYP3A1, involved in tocopherol transport and metabolism, were not influenced. In the dams' adipose tissue, gene expression of receptors involved in tissue tocopherol uptake, LDLR and SCARB1, but not of LPL, increased by 30 to 50 % and tocopherol concentrations increased by 47 % in CLA-fed compared to control dams. Expression of LPL, LDLR and SCARB1 in mammary gland was not influenced by CLA-feeding. Tocopherol concentrations in the pup's livers and lungs were similar in both groups, but at 14 days of age, adipose tissue tocopherol concentrations, and LDLR and SCARB1 expression, were higher in the CLA-exposed pups.ConclusionsWe show that dietary CLA affects tissue concentrations of tocopherol in lactating rats and tocopherol metabolism in rats and pups, but hardly influences tissue tocopherol concentrations in their offspring. This indicates that supplementation of CLA in pregnant and lactating animals is uncritical considering the tocopherol status of new-borns.
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Project description:Background: There has been increased concern about the suitability of CO2 as a method for euthanasia of laboratory mice and rats, including the potential discomfort, pain or distress that animals may experience prior to loss of consciousness; time to loss of consciousness; best methods for use of CO2; and the availability of better alternatives. These discussions have been useful in providing new information, but have resulted in significant confusion regarding the acceptability of CO2 for rodent euthanasia. In some cases, researchers and veterinarians have become uncertain as to which techniques to recommend or use for euthanasia of laboratory mice and rats. Methods: The International Association of Colleges of Laboratory Animal Medicine (IACLAM) convened a taskforce to examine the evidence for adverse welfare indicators in laboratory rats and mice undergoing CO2 euthanasia using a SYRCLE-registered systematic review protocol. Of 3,772 papers identified through a database search (PubMed, Web of Science, CAB Direct, Agricola, and grey literature) from 1900 to 2017, 37 studies were identified for detailed review (some including more than one species or age group), including 15 in adult mice, 21 in adult rats, and 5 in neonates of both species. Experiments or reports were excluded if they only assessed parameters other than those directly affecting animal welfare during CO2 induction and/or euthanasia. Results: Study design and outcome measures were highly variable and there was an unclear to high risk of bias in many of the published studies. Changes in the outcome measures evaluated were inconsistent or poorly differentiated. It is likely that repeated exposures to carbon dioxide inhalation are aversive to adult rats and mice, based on avoidance behavior studies; however, this effect is largely indistinguishable from aversion induced by repeated exposures to other inhalant anesthetic gasses. Conclusion: There is insufficient evidence to permit an unbiased assessment of the effect of CO2 inhalation during euthanasia on welfare indicators in laboratory mice and rats. Additional well-designed, unbiased, and adequately powered studies are needed to accurately assess the welfare of laboratory mice and rats undergoing euthanasia via CO2 gas.
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Project description:Rodent grimace scales have been recently validated for pain assessment, allowing evaluation of facial expressions associated with pain. The standard scoring method is retrospective, limiting its application beyond pain research. This study aimed to assess if real-time application of the Rat Grimace Scale (RGS) could reliably and accurately assess pain in rats when compared to the standard method. Thirty-two male and female Sprague-Dawley rats were block randomized into three treatment groups: buprenorphine (0.03?mg/kg, subcutaneously), multimodal analgesia (buprenorphine [0.03?mg/kg] and meloxicam [2?mg/kg], subcutaneously), or saline, followed by intra-plantar carrageenan. Real-time observations (interval and point) were compared to the standard RGS method using concurrent video-recordings. Real-time interval observations reflected the results from the standard RGS method by successfully discriminating between analgesia and saline treatments. Real-time point observations showed poor discrimination between treatments. Real-time observations showed minimal bias (<0.1) and acceptable limits of agreement. These results indicate that applying the RGS in real-time through an interval scoring method is feasible and effective, allowing refinement of laboratory rat welfare through rapid identification of pain and early intervention.
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Project description:Minimum space allowances for laboratory rats are legislated based on weight and stocking rates, with the understanding that increased housing density encourages crowding stress. However, there is little evidence for these recommendations, especially when considering positive welfare outcomes. This study consisted of two experiments which investigated the effects of housing density (rats per cage), space allocation (surface area per rat) and social rank (dominance hierarchy) on the ability to perform simple behavioural tests. Male Sprague Dawley (SD) rats (n = 64) were allocated to either high-density (n = 8) or low-density (n = 8) cages. The second experiment investigated the effects of surface area. SD rats (n = 40) were housed in dyads in either the large (n = 10) or small (n = 10) cage. In both experiments, animals were tested on a judgment bias paradigm, with their responses to an ambiguous stimulus being ascribed as optimistic or pessimistic. Animals were also tested on open-field, novel-object recognition and social-interaction tests. Recordings were taken from 1700-2100h daily for rat observation and social rank establishment. Dominant animals responded with significantly more optimistic decisions compared to subordinates for both the housing density (p<0.001) and space allocation (p = 0.0015) experiment. Dominant animals responded with increased social affiliative behaviours in the social-interaction test, and spent more time in the centre of the open-field test for both experiments. No significance was detected between housing density or space allocation treatments. These findings suggest that social rank is a significantly greater modifier of affective state than either housing density or space allocation. This finding has not yet been reported and suggests that future drafts of housing guidelines should consider animal social status in addition to floor space requirements.
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Project description:We studied how space allowance affects measures of animal welfare in mice by systematically varying group size and cage type across three levels each in both males and females of two strains of mice (C57BL/6ByJ and BALB/cByJ; n = 216 cages, a total of 1152 mice). This allowed us to disentangle the effects of total floor area, group size, stocking density, and individual space allocation on a broad range of measures of welfare, including growth (food and water intake, body mass); stress physiology (glucocorticoid metabolites in faecal boli); emotionality (open field behaviour); brain function (recurrent perseveration in a two-choice guessing task); and home-cage behaviour (activity, stereotypic behaviour). While increasing group size was associated with a decrease in food and water intake in general, and more specifically with increased attrition due to escalated aggression in male BALB mice, no other consistent effects of any aspect of space allowance were found with respect to the measures studied here. Our results indicate that within the range of conditions commonly found in laboratory mouse housing, space allowance as such has little impact on measures of welfare, except for group size which may be a risk factor for escalating aggression in males of some strains.
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Project description:Early life stress compromises brain development and can contribute to the development of mental illnesses. A common animal model used to study different facets of psychiatric disorders is social isolation from early life on. In rats, this isolation can induce long-lasting alterations in molecular expression and in behavior. Since social isolation models severe psychiatric symptoms, it is to be expected that it affects the overall wellbeing of the animals. As also promoted by the 3Rs principle, though, it is pivotal to decrease the burden of laboratory animals by limiting the number of subjects (reduce, replace) and by improving the animals' wellbeing (refine). The aim of this study was therefore to test possible refinement strategies such as resocialization and mere adult social isolation. We examined whether the alternatives still triggered the necessary phenotype while minimizing the stress load on the animals. Interestingly, we did not find reduced wellbeing-associated burrowing performance in isolated rats. The hyperactive phenotype seen in socially isolated animals was observed for rats undergoing the adult-only isolation, but resocializing ameliorated the locomotor abnormality. Isolation strongly affected markers of neuroplasticity in the prefrontal cortex independent of timing: mRNA levels of Arc, Bdnf and the pool of Bdnf transcripts with the 3' long UTR were reduced in all groups. Bdnf splice variant IV expression was reduced in lifelong-isolated animals. Some of these deficits normalized after resocialization; likewise, exon VI Bdnf mRNA levels were reduced only in animals persistently isolated. Conversely, social deprivation did not affect the expression of Gad67 and Pvb, two GABAergic markers, whereas changes occurred in the expression of dopamine d1 and d2 receptors. As adult isolation was sufficient to trigger the hyperactive phenotype and impaired neuroplasticity in the prefrontal cortex, it could be a candidate for a refinement strategy for certain research questions. To fully grade the severity of post-weaning social isolation and the alternatives, adult isolation and resocialization, a more profound and multimodal assessment approach is necessary.
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Project description:Laboratory animal personnel may experience significant stress from working with animals in scientific research. Workplace stress can be assessed by evaluating professional quality of life, which is comprised of compassion fatigue (i.e., burnout and secondary traumatic stress) and compassion satisfaction. This research aimed to explore the associations between risk factors and professional quality of life in laboratory animal personnel. In a cross-sectional, convenience sample design, laboratory animal personnel were recruited from widespread online promotion. A total of 801 personnel in the United States or Canada completed an online survey regarding professional quality of life, social support, euthanasia, enrichment, stress/pain levels, and human-animal interactions. Participants worked in a wide range of settings (e.g., industry, academia), research types (e.g., basic, applied, regulatory), species (e.g., non-human primates, mice), and roles (e.g., animal caretaker, veterinarian). Data were analyzed using general linear models. Personnel who reported higher compassion fatigue also reported lower social support, higher animal stress/pain, higher desire to implement more enrichment, and less control over performing euthanasia (p's < 0.05). Higher burnout was associated with less diverse/frequent enrichment, using physical euthanasia methods, and longer working hours. Higher secondary traumatic stress was associated with more relationship-promoting human-animal interactions (e.g., naming animals) and working as a trainers (p's < 0.05). Higher compassion satisfaction was associated with higher social support, less animal stress/pain, and more human-animal interactions (p's < 0.05). Surprisingly, neither personnel's primary animal type (e.g., non-human primates, mice) nor frequency of euthanasia (e.g., daily, monthly) were associated with professional quality of life (p's > 0.05). Our findings show that the professional quality of life of laboratory animal personnel is associated with several factors. Personnel reporting poorer professional quality of life also reported less social support, higher animal stress/pain, less enrichment diversity/frequency and wished they could provide more enrichment, using physical euthanasia, and less control over performing euthanasia. Poorer professional quality of life was also seen in personnel working as trainers, at universities, and longer hours. This study contributes important empirical data that may provide guidance for developing interventions (e.g., improved social support, decreased animal stress, increased animal enrichment diversity/frequency, greater control over euthanasia) to improve laboratory animal personnel's professional quality of life.
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Project description:Boredom is an emotional state that occurs when an individual has nothing to do, is not interested in the surrounding, and feels dreary and in a monotony. While this condition is usually defined for humans, it may very well describe the lives of many laboratory animals housed in small, barren cages. To make the cages less monotonous, environmental enrichment is often proposed. Although housing in a stimulating environment is still used predominantly as a luxury good and for treatment in preclinical research, enrichment is increasingly recognized to improve animal welfare. To gain insight into how stimulating environments influence the welfare of laboratory rodents, we conducted a systematic review of studies that analyzed the effect of enriched environment on behavioral parameters of animal well–being. Remarkably, a considerable number of these parameters can be associated with symptoms of boredom. Our findings show that a stimulating living environment is essential for the development of natural behavior and animal welfare of laboratory rats and mice alike, regardless of age and sex. Conversely, confinement and under-stimulation has potentially detrimental effects on the mental and physical health of laboratory rodents. We show that boredom in experimental animals is measurable and does not have to be accepted as inevitable.
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Project description:Lactation represents a period of marked adaptation of the hypothalamo-pituitary-adrenal HPA axis. We characterized basal and stress-induced HPA activity during lactation and experimental weaning using dynamic blood sampling in rats. Pulsatile and diurnal corticosterone release occurred at all reproductive stages studied (virgin; day 10 of lactation; 3 and 14 days after experimental weaning on day 10 of lactation). However, in lactating rats the diurnal peak was significantly reduced, resulting in a flattened rhythm, and three days after weaning, basal HPA activity was markedly suppressed: the number of pulses and underlying basal levels of corticosterone were reduced and the diurnal rise phase delayed. Marked changes in the HPA response to 10 min noise stress also occurred at these times: being completely absent in lactating animals, but restored and highly prolonged in early weaned animals. Injection of methylprednisolone (2 mg, iv) was used to determine whether changes in fast glucocorticoid suppression correlated with these adaptive changes. Methylprednisolone induced a rapid suppression of corticosterone in virgin animals, but this effect was markedly attenuated in lactating and early weaned animals and was accompanied by significant changes in relative expression of hippocampal glucocorticoid and mineralocorticoid receptor mRNA. All effects were reversed or partially reversed 14 days after experimental weaning. Thus, the presence of the pups has an important influence on regulation of the HPA axis, and while postpartum adaptations are reversible, acute weaning evokes marked reorganisation of basal and stress-induced HPA activity.
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