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Background: Intra-abdominal adhesions are frequent side effects of surgery, associated with risks of serious complications such as abdominal pain, infertility, and small bowel obstruction. This study investigated a new autologous blood-based approach to adhesion prophylaxis. Materials and method: Two autologous blood-derived patches (whole-blood-derived, n = 20, and plasma-derived, n = 20) were evaluated as anti-adhesives. The patches were tested in a rat uterine horn damage model. We simulated an intraabdominal surgery by cauterizing and suturing the uterine horns and created an opposing damage by denuding a part of the abdominal wall. Each rat served as its own control with one treated uterine horn and one untreated. After 14 d of post-surgical recovery, the adhesions were assessed and graded macroscopically and microscopically. Statistical analyses were performed with Wilcoxon signed rank and Mann–Whitney U tests. Results: Both whole-blood and plasma-derived patches resulted in significantly less macroscopic adhesions than were found in untreated uterine horns (P = 0.001 and P = 0.002, respectively). Unpaired analysis found no significant differences between the whole-blood and plasma-derived patch outcomes in this study design. Histopathological evaluation of inflammation and fibrosis did not reveal significant differences between the patches and their matched controls. Conclusions: The autologous blood-derived patches reduced macroscopic adhesion formation significantly compared with no treatment. There were no adverse events and no histological differences between treatment and control, suggesting that the treatments were feasible and safe. In summary, this study confirms the potential of autologous anti-adhesives for the use in intraabdominal surgery.

We sought to investigate if varying levels of bedding had an effect on intra-cage ammonia levels in individually ventilated mouse cages (Euro Standard Types II and III). Employing a routine 2 week cage-changing interval, our goal is to keep ammonia levels under 50 ppm. In smaller cages used for breeding or for housing more than four mice, we measured problematic levels of intra-cage ammonia, and a considerable proportion of these cages had ammonia levels at more than 50 ppm toward the end of the cage-change cycle. These levels were not reduced significantly when the levels of absorbent wood chip bedding was either increased or decreased by 50%. The mice in both cage types II and III were housed at comparable stocking densities, yet ammonia levels in larger cages remained lower. This finding highlights the role of cage volume, as opposed to simply the floor space, in controlling air quality. With the current introduction of newer cage designs that employ an even smaller headspace, our study urges caution. With individually ventilated cages, problems with intra-cage ammonia may go undetected, and we may opt to utilize insufficient cage-changing intervals. Few modern cages have been designed to account for the amounts and types of enrichment that are used (and, in parts of the world, mandated) today, adding to the problems associated with decreasing cage volumes.

Exposing rats to repeated unpredictable stressors is a popular method for modelling depression. The sucrose preference test is used to assess the validity of this method, as it measures a rat’s preference for a sweet solution as an indicator of its ability to experience pleasure. Typically, if stressed rats show a lower preference compared to unstressed rats, it is concluded they are experiencing stress-induced anhedonia. While conducting a systematic review, we identified 18 studies that used thresholds to define anhedonia and to distinguish “susceptible” from “resilient” individuals. Based on their definitions, researchers either excluded “resilient” animals from further analyses or treated them as a separate cohort. We performed a descriptive analysis to understand the rationale behind these criteria, and found that the methods used for characterizing the stressed rats were largely unsupported. Many authors failed to justify their choices or relied exclusively on referencing previous studies. When tracing back the method to its origins, we converged on a pioneering article that, although employed as a universal evidence-based justification, cannot be regarded as such. What is more, through a simulation study, we provided evidence that removing or splitting data, based on an arbitrary threshold, introduces statistical bias by overestimating the effect of stress. Caution must be exercised when implementing a predefined cut-off for anhedonia. Researchers should be aware of potential biases introduced by their data treatment strategies and strive for transparent reporting of methodological decisions.

Traditionally, in biomedical animal research, laboratory rodents are individually examined in test apparatuses outside their home cages at selected time points. However, the outcome of such tests can be influenced by the novel environment, the time of day, separation from the social group, or the presence of an experimenter. Moreover, valuable information may be missed when the animals are only monitored in short periods. These issues can be overcome by longitudinal monitoring mice and rats in their home cages. To shed light on the development of home cage monitoring (HCM) and the current state of the art, a systematic review was carried out on 521 publications retrieved through PubMed and Web of Science. Both the absolute (∼ ×26) and relative (∼ ×7) number of HCM-related publications increased from 1974 to 2020. In both mice and rats, there was a clear bias towards males and individually housed animals, but during the past decade (2011–2020), an increasing number of studies used both sexes and group housing. More than 70 % of the studies did not involve a disease model, but the percentage of studies using disease models increased since the 2000s. In most studies, animals were kept for short (up to 4 weeks) length periods in the HCM systems; intermediate length periods (4–12 weeks) increased in frequency in the years between 2011 and 2020. Before the 2000s, HCM techniques were predominantly applied for less than 12 hours, while 24-hour measurements have been more frequently since the 2000s. The systematic review demonstrated that manual monitoring is decreasing but still relevant. Until (and including) the 1990s, most techniques were applied manually but have been progressively replaced by automation since the 2000s. Independent of the publication year, the main behavioral parameters measured were locomotor activity, feeding, and social behaviors; the main physiological parameters were heart rate and electrocardiography. External appearance-related parameters were rarely examined in the home cages. Due to technological progress and application of artificial intelligence, more refined and detailed behavioral parameters could be investigated in the home cage in recent times.Over the period covered in this study, techniques for HCM of mice and rats has improved considerably. This development is ongoing and further progress and validation of HCM systems will extend the applications to allow for continuous, longitudinal, non-invasive monitoring of an increasing range of parameters in group-housed small rodents in their home cages.

Background/Aim: The aim of this study was to investigate the effects of multimodal therapy comprising buprenorphine (BUP) and indomethacin (IND) on key translational parameters in the rat adjuvant induced arthritis (AIA) model. Furthermore, we investigated the difference between visual assessment scores and histology scores generated by blinded and non-blinded assessors and the robustness and generalizability of results by conducting a multi-laboratory study. Materials and Methods: The experiment was terminated on day 26 after 11 days (days 15-25) of voluntarily ingested buprenorphine and 7 days of gavage delivered indomethacin treatment (days 19-25). The treatment effects were assessed on the last day of the study, relying on body weight assessment, serum concentrations of α1- acid glycoprotein, and assessment of affected hind paws swelling, in-life and post mortem. Results: Across two laboratories, the combined analgesic treatments had minimal effects on the measured model parameters indicating that multimodal treatment did not affect the translatability of the model. We found an improvement in clinical scores (a negative change in scores) in nearly all medicated animals when scored informed, whereas it was essentially 50:50 for the blinded scorings and no difference between the blinded and informed histological scoring. Conclusion: The present results support the use of more effective analgesic treatment regimens and the good practice recommendations advocating blinding as a mandatory practice in conduct of preclinical in vivo efficacy studies. In spite of minor differences between results obtained at the two sites, there was good agreement between them indicating robustness of the AIA model.

Eliminating unnecessary pain is an important requirement of performing animal experimentation, including reducing and controlling pain of animals used in pain research. The goal of this study was to refine an adjuvant-induced monoarthritis model in rats by providing analgesia with a transdermal fentanyl solution (TFS). Male and female Sprague–Dawley rats, single- or pair-housed, were injected with 20 μL of complete Freund adjuvant (CFA) into the left ankle joint. CFA-injected rats treated with a single dose of transdermal fentanyl solution (0.33 or 1 mg/kg) were compared with an untreated CFA-injected group and sham groups that received either no treatment or TFS treatment (1 mg/kg) during 72 h. At the tested doses, TFS reduced mechanical hyperalgesia and improved the mobility, stance, rearing, and lameness scores at 6 h after CFA injection. Joint circumferences were not reduced by TFS treatment, and no significant differences were detected between the 2 doses of TFS, or between single- and pair-housed rats. Treatment with TFS did not appear to interfere with model development and characteristics. However, overall, the analgesic effect was transient, and several opioid-related side effects were observed.

BACKGROUND/AIM: This study aimed to investigate the analgesic effects of fluoxetine on Lewis rats of both sexes in the adjuvant-induced arthritis (AIA) rat model. In humans, chronic pain syndromes typical of rheumatoid arthritis (RA) co-exist with depression which is often treated with fluoxetine antidepressant known to have antinociceptive effects. MATERIALS AND METHODS: The experiment was terminated on day 26, after seven days of oral treatment (days 19-25) with fluoxetine and indomethacin. The effects of treatments were assessed on the final day of the study through measuring body weight, serum concentrations of a1-acid glycoprotein, visual arthritis assessment and post mortem histopathology assessment. RESULTS: Statistically significant difference was determined in the body weight of male subjects, with indomethacin-treated animals putting on significantly more weight than the vehicle and fluoxetine-treated counterparts. No differences were found between the different treatment groups in other study assessments. CONCLUSION: The present study did not provide support for analgesic effects of fluoxetine aimed at reducing the severity of the AIA model.

Objective:Oxidative stress has been suggested to increase after electroconvulsive therapy (ECT), a treatment which continues to be the most effective for severe depression. Oxidative stress could potentially be mechanistically involved in both the therapeutic effects and side effects of ECT.Methods:We measured sensitive markers of systemic and central nervous system (CNS) oxidative stress on DNA and RNA (urinary 8-oxodG/8-oxoGuo, cerebrospinal fluid 8-oxoGuo, and brain oxoguanine glycosylase mRNA expression) in male rats subjected to electroconvulsive stimulations (ECS), an animal model of ECT. Due to the previous observations that link hypothalamic–pituitary–adrenal (HPA)-axis activity and age to DNA/RNA damage from oxidation, groups of young and middle-aged male animals were included, and markers of HPA-axis activity were measured.Results:ECS induced weight loss, increased corticosterone (only in middle-aged animals), and decreased cerebral glucocorticoid receptor mRNA expression, while largely leaving the markers of systemic and CNS DNA/RNA damage from oxidation unaltered.Conclusion:These results suggest that ECS is not associated with any lasting effects on oxidative stress on nucleic acids neither in young nor middle-aged rats.

Hair glucocorticoids are increasingly popular biomarkers, used across numerous research fields as a measure of stress. Although they are suggested to be a proxy of the average HPA axis activity spanning a period of weeks or months into the past, this theory has never been tested.In the present study, adrenalectomized rats with no endogenous (adrenal) glucocorticoid production were used to study how circulating glucocorticoid levels would be reflected in the glucocorticoid levels found in hair samples. By dosing the animals daily with high levels of corticosterone for seven days, while sampling hairs before, during, and after treatments, a timeline for glucocorticoid uptake into hairs was constructed. This kinetic profile was compared to two hypothetical models, and the theory that hair glucocorticoids are a record of historical stress had to be rejected.Corticosterone concentrations in hairs were found to increase within three hours of the first injection, the highest concentrations were found on the seventh day of treatments, and the decrease in concentrations post-treatment suggests rapid elimination. We speculate that hair glucocorticoid levels can only be used to characterize a stress-response for a few days following a postulated stressor.An updated model, where glucocorticoids diffuse into, along, and out of hairs needs to be adopted to reconcile the experimentally obtained data. The inescapable consequence of this updated model is that hair glucocorticoids become a marker of – and can only be used to study – recent, or ongoing, stress, as opposed to historical events, weeks or months in the past.

Quantitating glucocorticoids (GCs) in hairs is a popular method for assessing chronic stress in studies of humans and animals alike. The cause-and-effect relationship between stress and elevated GC levels in hairs, sampled weeks later, is however hard to prove. This systematic review evaluated the evidence supporting hair glucocorticoids (hGCs) as a biomarker of stress. Only a relatively small number of controlled studies employing hGC analyses have been published, and the quality of the evidence is compromised by unchecked sources of bias. Subjects exposed to stress mostly demonstrate elevated levels of hGCs, and these concentrations correlate significantly with GC concentrations in serum, saliva and feces. This supports hGCs as a biomarker of stress, but the dataset provided no evidence that hGCs are a marker of stress outside of the immediate past. Only in cases where the stressor persisted at the time of hair sampling could a clear link between stress and hGCs be established.

Stress and depression are associated with an acceleration of brain and bodily aging; effects which have been attributed to chronic elevations of glucocorticoids. We tested the hypothesis that a three week administration of stress-associated levels of corticosterone (CORT, the principal rodent glucocorticoid) would increase systemic and CNS DNA and RNA damage from oxidation; a phenomenon known to be centrally involved in the aging process. We also hypothesized that older individuals would be more sensitive to this effect and that the chronic CORT administration would exacerbate age-related memory decline. Young and old male Sprague-Dawley rats were non-invasively administered CORT by voluntary ingestion of nut paste containing either CORT (25mg/kg) or vehicle for a total of 22 days. CORT increased the 24h urinary excretion of the hormone to the levels previously observed after experimental psychological stress and caused a downregulation of the glucocorticoid receptor in the CA1 area of the hippocampus. Contrary to our hypothesis, 24h excretion of 8-oxodG/8-oxoGuo (markers of DNA/RNA damage from oxidation) was reduced in CORT-treated young animals, whereas old animals showed no significant differences. In old animals, CORT caused a borderline significant reduction of RNA oxidation in CNS, which was paralleled by a normalization of performance in an object location memory test. To our knowledge, this is the first demonstration that chronic stress-associated levels of CORT can reduce nucleic acid damage from oxidation. These findings contradict the notion of elevated CORT as a mediator of the accelerated aging observed in stress and depression.

Background: Commercially available ELISA kits are popular among investigators that quantify faecal corticosterone or cortisol metabolites (FCM) for stress assessment in animals. However, in faeces, these assays mainly detect immunoreactive glucocorticoid metabolites. Since different assays contain antibodies of different origin, the detection level and cross-reactivity towards different metabolites and other steroids differ considerably between assays. Thus, the validity of one assay for FCM quantification in stress assessment is not necessarily the same for another assay. Materials and Methods: The present study was designed to investigate corticosterone (CORT) in serum and FCM levels in faeces of laboratory mice, as quantified in four different ELISA kits (DRG EIA-4164, Demeditec DEV9922, Enzo ADI-900-097 and Cayman EIA kit 500655). Assay kits were chosen based on the origin of the antibody, detection level and variation in cross-reactivity. Results: As expected, all four assay kits could detect higher serum CORT levels in mice treated with adrenocorticotropic hormone (ACTH), compared to untreated mice. Unexpectedly though, the measured concentration of serum CORT differed significantly between assays, in both groups of mice. In faecal samples, there was no consistent positive correlation between the levels detected in the four assays and the measured concentration of FCM also differed between assays. Conclusion: Whereas commercially available CORT ELISAs are frequently successfully used for FCM quantification, validation of the assays is necessary as all assays do not work well under all circumstances. In this study, the ELISAs could determine relative differences in serum CORT levels and FCM levels between samples; however, the fidelity of the measurements to the true concentrations was low.

Quantitating glucocorticoids (GCs) in hairs is a popular method for assessing chronic stress in studies of humans and animals alike. The cause-and-effect relationship between stress and elevated GC levels in hairs, sampled weeks later, is however hard to prove. This systematic review evaluated the evidence supporting hair glucocorticoids (hGCs) as a biomarker of stress.Only a relatively small number of controlled studies employing hGC analyses have been published, and the quality of the evidence is compromised by unchecked sources of bias. Subjects exposed to stress mostly demonstrate elevated levels of hGCs, and these concentrations correlate significantly with GC concentrations in serum, saliva and feces. This supports hGCs as a biomarker of stress, but the dataset provided no evidence that hGCs are a marker of historical stress. Only in cases where the stressor persisted at the time of hair sampling could a clear link between stress and hGCs be established.

The physiological stress response is frequently gauged in animals, non-invasively, through measuring glucocorticoids in excreta. A concern with this method is, however, the unknown effect of variations in diets on the measurements. With an energy dense diet, leading to reduced defecation, will low concentrations of glucocorticoids be artificially inflated? Can this effect be overcome by measuring the total output of glucocorticoids in excreta? In a controlled laboratory setting we explored the effect in mice. When standard mouse chow - high in dietary fiber - was replaced with a 17% more energy-dense diet, fecal mass was significantly reduced. As circulating levels of corticosterone and the total output of corticosterone metabolites over time remained unaffected, the result was an overestimation - more than a doubling - of the corticosterone metabolite excretion if expressed as concentrations. Similar results were obtained for testosterone metabolites. Although measuring the total output is not feasible in, for example, wildlife studies, the present findings highlight the perilousness of relying on concentrations of hormones in excreta with no associated information of the dietary intake as even moderate changes can exert a great influence.

Facial vein (cheek blood) and caudal vein (tail blood) phlebotomy are two commonly used techniques for obtaining blood samples from laboratory mice, while automated blood sampling through a permanent catheter is a relatively new technique in mice. The present study compared physiological parameters, glucocorticoid dynamics as well as the behavior of mice sampled repeatedly for 24 h by cheek blood, tail blood or automated blood sampling from the carotid artery. Mice subjected to cheek blood sampling lost significantly more body weight, had elevated levels of plasma corticosterone, excreted more fecal corticosterone metabolites, and expressed more anxious behavior than did the mice of the other groups. Plasma corticosterone levels of mice subjected to tail blood sampling were also elevated, although less significantly. Mice subjected to automated blood sampling were less affected with regard to the parameters measured, and expressed less anxious behavior. We conclude that repeated blood sampling by automated blood sampling and from the tail vein is less stressful than cheek blood sampling. The choice between automated blood sampling and tail blood sampling should be based on the study requirements, the resources of the laboratory and skills of the staff.

We compared delayed response task performance in young, middle-aged, and old cynomolgus monkeys using three memory tests that have been used with non-human primates. Eighteen cynomolgus monkeys--6 young (4-9 years), 6 middle-aged (10-19 years), and 6 old (above 20 years)--were tested. In general, the old monkeys scored significantly worse than did the animals in the two other age groups. Longer delays between stimulus presentation and response increased the performance differences between the old and younger monkeys. The old monkeys in particular showed signs of impaired visuo-spatial memory and deteriorated memory consolidation and executive functioning. These results add to the body of evidence supporting the utility of Macaca fascicularis in studies of cognition and as a potential translational model for age-associated memory impairment/dementia-related disorders.

Quantification of glucocorticoid metabolites in feces has been shown to be a powerful tool in evaluating well-being in vertebrates. Little is known however about the hypothalamic-pituitary-adrenal axis response to stressors, and consequent glucocorticoid excretion, in reptiles. In a longitudinal study, fecal corticosterone metabolite (FCM) levels in green iguanas (Iguana iguana) were quantified during periods of rest and exposure to hypothesized stressors. FCM quantification was combined with behavioral analysis to further contextualize the measured increases. It was shown that both daily 5-minute handling/restraint, as well as housing devoid of climbing opportunity, resulted in increased FCM excretion. Behavioral analysis suggested that the iguanas were chronically stressed by the lack of climbing opportunity, whereas handling may have induced only a transient stress response. The experimental design, using repeated periods of stressor-exposure, also revealed a facilitating effect, where the two stressors potentiated one another. Furthermore, the order of the two stressors was found to be important. The study provides insight into the functioning of the hormonal stress response in green iguanas, and to the refining of their housing and handling.

Buprenorphine is the most commonly used drug for peri-operative pain relief in laboratory rodents. The systemic concentrations of buprenorphine were measured in mice following administration intravenously (i.v.), subcutaneously (s.c.), orally by gavage and by voluntary ingestion, to determine the post-administration serum concentration of buprenorphine. Voluntarily ingested buprenorphine resulted in long-lasting high serum concentrations, as did oral gavage administration (24 h serum concentration: 110 ng h/mL for both routes of administration). In contrast, buprenorphine administered parenterally remained in the circulation for a substantially shorter time (24 h serum concentration for i.v. and s.c. were 40 ng h/mL and 30 ng h/mL, respectively). This marked difference was probably due to the higher dose used for oral administration, which is regarded necessary for sufficient analgesic effect, and to the slower absorption of the oral boli, as well as saturation of the hepatic buprenorphine metabolising pathways. Voluntary ingestion of buprenorphine was found to constitute a practical way to provide laboratory mice with efficient pain relief.

Quantification of corticosterone metabolites excreted in faeces and urine is increasingly being used for assessment of preceding corticosterone concentrations in the circulation. This is a promising approach to non-invasive stress assessment in laboratory rodents. It is however unknown whether the proportions of corticosterone metabolites excreted in faeces and urine may differ, depending on the concentration of corticosterone in blood. This uncertainty undermines the applicability of urinary and faecal corticosterone metabolite measurements as biomarkers for stress. Therefore, the terminal distribution and time course of corticosterone excretion, after intravenous injection of varying corticosterone concentrations, was investigated in female mice. Female BALB/c mice excreted 60% of all corticosterone in the urine with an approximate delay of 5 h from tail vein administration. The remaining 40% were excreted in faeces, with an approximate delay of 9 h from administration. The faecal/urinary excretion ratio, as well as time course of excretion, remained unaltered by administration of various doses of corticosterone covering the entire physiological range of serum corticosterone. Although currently untested for other strains of mice and species of animals, these findings add credence to the utility of faecal and urinary corticosterone as non-invasive biomarkers for physiological stress.

Consumer concerns about the welfare of laying hens are increasing, leading to increased interest in identifying reliable ways to assess welfare. The present study evaluated invasive and non-invasive welfare indicators in relation to a stressful challenge. The study included 126 Lohmann Selected Leghorn hens housed in furnished cages. Welfare indicators were measured between 61 and 70 wk of age in birds excluded from their nests for 5 consecutive d and control birds that had continuous access to nests. Baseline recordings were carried out in both groups prior to and post exclusion period. The assessed indicators were: corticosterone metabolites in droppings (FCM), corticosterone concentration in yolk, corticosterone concentration in plasma, irregularities of eggshells, heterophil to lymphocyte (H:L) ratio, tonic immobility duration, and feather cover. Behavioral observations showed that the birds had a clear preference for using the secluded nest sites, confirming that they were likely to perceive nest exclusion as an undesirable experience. Further, elevated levels of FCM in droppings, yolk corticosterone concentrations, H:L ratios and irregular eggshells were detected in both nest deprived and control birds during the exclusion. This suggests that these indicators were able to detect an increased stress response arising from nest deprivation, and it is hypothesized that the stress spread to birds in adjacent cages with access to nests. There was a positive and consistent correlation between FCM in droppings and eggshell irregularities, also supporting the use of eggshell irregularities as a potential non-invasive welfare indicator. However, the pattern of the stress response varied between indicators and correlations were generally few and inconsistent, highlighting the complexity of the relationship among welfare indicators.

BACKGROUND: Therapeutic antibodies are a developing field for treatment of an expanding number of inflammatory diseases, including Crohn's disease. Treatment with monoclonal antibodies is frequently hampered by development of anti-drug antibodies (ADAs) that may compromise the treatment.MATERIALS AND METHODS: We addressed this issue in a rabbit model of treatment with the anti-tumor-necrosis factor alpha (TNFα) antibody, infliximab (IFX). We developed an inhibition ELISA to selectively measure absolute concentrations of neutralizing antibodies and another ELISA for measuring the concentration of functional IFX in the circulation.RESULTS: We found that the concentration of functional IFX was inversely proportional to the concentration of neutralizing antibodies.CONCLUSION: Administration of IFX to rabbits showed diversity in immune responses/tolerance toward IFX, corresponding to responses observed in patients. The applied assay technology is easily adapted to human plasma samples and/or other therapeutic antibodies, including fully humanized antibodies, for which immunogenicity also is observed.

An adequate analgesic strategy is important to improve the postoperative recovery and welfare of laboratory rats and mice. It is desirable that the method for administering the drug is non-invasive and stress-free. We have previously validated a method for administering buprenorphine in a nut paste for voluntary ingestion. This method has many advantages over parenteral administration. To use the method in a successful way, however, it is important to prepare and administer the mix correctly. The present paper describes in detail how to implement the method, by means of habituation, presentation, adequate concentrations and amounts of buprenorphine/nut paste, and dosage of buprenorphine to rats and mice.

Background: The cynomolgus monkey (Macaca fascicularis) has shown promise as a spontaneous model of age-related dementias, such as Alzheimer's Disease. Methods: Using a series of memory tests, we have found evidence that performance on delayed response tasks was age-related, with poorer performance being demonstrated by old monkeys (> 20 years of age), compared to young (4-9 years of age) and middle-aged (10-16 years of age) individuals. Results: Performance on the memory tasks was correlated with levels of the core biomarkers indicative of Alzheimer's Disease in the circulation; in particular with amyloid-beta 1-42 (Aβ42). Structural magnetic resonance imaging (MRI) studies identified abnormalities, such as atrophy in the hippocampus and relevant cortical areas, in aged monkeys that were correlated with poor memory and low Aβ42 levels in the circulation. Conclusions: These data emphasize the potential importance of aged cynomolgus monkeys as spontaneous models for investigations of senile dementia as it affects humans. We are presently extending these studies to include investigations of whether the histopathological hallmarks of Alzheimer's disease (senile plaques of amyloid beta and nerve tangles) are present in the brains of those aged monkeys that exhibited memory performance deficits, low circulating Aβ42 and atrophy of relevant brain areas as determined by MRI.

Laboratory mice constitute an extensively used model to study the pathologic and functional outcomes of cerebral ischemic stroke. The middle cerebral artery occlusion (MCAO) model requires surgical intervention, which potentially can result in postsurgical pain and stress. In the present study, we investigated whether buprenorphine and meloxicam, at clinically relevant doses provided pain relief without altering infarct volume in male C57BL/6 mice. Common known side-effects of buprenorphine, including decreased food consumption, were noted after surgery in buprenorphine-treated mice, but these effects were brief and seen only during the treatment period. Fecal corticosterone metabolites did not differ significantly between the groups. In the present study, buprenorphine treatment did not alter infarction volume when compared with that of mice that did not receive analgesia. In contrast, meloxicam treatment significantly reduced infarct volume and may be a confounder if used as an analgesic during MCAO surgery. Furthermore, investigation of behavioral profiles by using an automated behavioral scoring system showed that rearing and sniffing behaviors decreased as infarct volume increased. This suggests that studies of exploratory behavior may aid in developing new markers of short-term stroke-related behavioral deficiencies in laboratory mice.

Background In an attempt to explore cynomolgus monkeys as an animal model for Alzheimer’s disease, the present study focused on the Alzheimer’s biomarkers beta amyloid 1–42 (Ab42) in serum, and total tau (t-tau) and phosphorylated tau (p-tau) levels in cerebrospinal fluid. Methods We measured biomarker levels in Young and Aged cynomolgus monkeys and correlated these with performance on three delayed response tasks. Results The Ab42 concentration of the Aged monkeys was significantly lower than in the Young subjects, while the t-tau and p-tau did not significantly differ between the groups. The Young subjects performed significantly better than the Aged individuals on the memory tests. Only Ab42 levels were significantly correlated with performance in the three delayed response tasks. Conclusions Circulating Ab42 levels were lower in Aged monkeys and were correlated with inferior performance on delayed response tasks in Aged animals; therefore, both measures may be useful in establishing cynomolgus monkeys as models for studies of AD.

The use of blood corticosterone and faecal corticosterone metabolites as biomarkers of post-surgical stress and pain in laboratory animals has increased during the last decade. However, many aspects of their reliability in laboratory mice remain uninvestigated. This study investigated serum corticosterone and adrenocorticotropic hormone (ACTH) in mice subjected to isoflurane anaesthesia and vasectomy, and mice subjected to isoflurane anaesthesia without surgery. Serum levels of corticosterone and ACTH after pre-treatment with dexamethasone were analysed to provide further information about the stress hormone profiles. Vasectomy resulted in an increase in corticosterone for at least four hours after surgery with a peak 30 min after the mice regained righting reflex. Mice subjected to isoflurane anaesthesia without surgery had the highest level of serum corticosterone 5 min after regained righting reflex and the level returned to baseline levels four hours after the procedure. In vasectomised mice, treated with dexamethasone, high levels of corticosterone remained 30 min after the procedure, whereas the anaesthetised mice, treated with dexamethasone, had significantly lower levels of corticosterone compared to anaesthetised mice not treated with dexamethasone. Thus, dexamethasone effectively inhibited the corticosterone response in the anaesthetised-only mice, but not in the mice subjected to surgery. In conclusion, both isoflurane anaesthesia and vasectomy during isoflurane anaesthesia resulted in an increase in serum glucocorticoids, but the negative feedback mechanism of newly operated mice, was altered. This may have consequences for the interpretation of glucocorticoids measurements as a biomarker of post-surgical stress in mice.

Recognition of pain and stress is a common challenge when working with laboratory mice. The aim of the current study was to identify noninvasive parameters to assess the severity and duration of possible pain and stress after vasectomy in BALB/c mice. Mice underwent isoflurane anesthesia with or without vasectomy. Body weight, food and water intake, and fecal corticosterone metabolites (FCM) were measured 3 d before and 3 d after the procedure. Behavior was recorded 1, 2, 4, and 8 h after the procedure. Food and water consumption and defecation were reduced postoperatively in the vasectomized group compared with mice given anesthesia only. FCM were elevated the first day after anesthesia in the control mice but not in the vasectomized group. Vasectomy resulted in behavioral changes that were not seen in the group that was anesthetized only. In conclusion, food and water consumption and pain-related behaviors, but not FCM, may be useful as noninvasive parameters to assess postoperative pain and stress in vasectomized mice.

The effect of perioperatively administered buprenorphine analgesia on rats subjected to surgically induced global ischaemia was assessed. Rats supplied with buprenorphine, mixed in nut paste for voluntary ingestion, displayed significant reductions in postoperative excretions of faecal corticosterone, in both magnitude and variance. This is indicative of lowered stress levels and less inter-animal metabolic variation. Although corticosterone has been reported to modulate the extent of cerebral damage, histology of coronal sections exhibited no differences in the extent of the ischaemia in buprenorphine-treated and untreated animals. A part from a slightly higher hyperthermia immediately after surgery and typical opiate-associated behaviour, the buprenorphine treatment had no apparent adverse effects on the experimental model. In contrast, the analgesic treatment improved the model by minimizing stress-associated confounding variables in the experimental animals.

Background Studies have reported that heparin may be unsuitable as an anticoagulant in human plasma samples when quantifying cytokines using multiplex bead array assays. For mouse samples, multiplex assays have been validated for serum and EDTA-plasma, but it remains to be elucidated whether heparin influences the quantification of cytokines, and if so – to what extent. Furthermore, laboratory mice are often anesthetized for blood sampling, which causes acute stress that may influence circulating cytokine concentrations and thus bias experimental results. The objectives of the present study were to identify whether specific cytokine concentrations varied between heparin-plasma, serum, and EDTA-plasma, and whether short isoflurane anesthesia would influence the concentrations of these cytokines in the circulation. Twenty-three acute phase and pro-inflammatory cytokines were quantified in matched serum, EDTA-plasma, and heparin-plasma samples from anesthetized and unanesthetized male NMRI mice using a multiplex assay. In addition, samples from unanesthetized mice were spiked with three levels of heparin. Results The concentrations of five out of 23 cytokines were significantly different between sample types, but only one cytokine (IL-17A) differed between heparin-plasma and serum. When further spiking the heparin-plasma with increasing concentrations of heparin, there was a significant effect on 11 cytokines, where the cytokine recovery could be correlated to the heparin concentration for ten of these cytokines. Anesthesia resulted in lower concentrations of G-CSF, but had no significant impact on the concentrations of the other 22 cytokines. Conclusion In mice, heparin seems like a suitable anticoagulant for obtaining plasma for multiplex assays for the cytokines IL-1α, IL-1β, IL-2, IL-6, IL-9, IL-12p40, IL-12p70, IL-13, G-CSF, GM-CSF, IFN-γ, KC, MCP-1, MIP-1α, MIP-1β, RANTES and TNFα, but an effect of heparin in high concentrations should be considered for the cytokines IL-9, IL-12p40, IL-12p70, KC, MCP-1, MIP-1β and RANTES. Short isoflurane anesthesia had significant impact on G-CSF, but none of the other cytokines.

This study investigated the effects of surgical placement of permanent arterial catheters on plasma corticosterone levels, fecal corticosterone excretion and body weight in male BALB/c/Sca mice. In addition, the effects of voluntarily ingested buprenorphine in doses of 0.5 and 1.0 mg/kg body weight on these parameters were studied. A catheter was placed in the carotid artery during isoflurane anesthesia. Immediately after surgery, the mice were connected to an AccuSampler® μ and blood samples for plasma corticosterone quantification were collected automatically during the first 24 h postoperatively. All fecal boli produced 24 h before and 24 h after surgery were collected for fecal corticosterone excretion measures and the pre- and post-operative body weights were registered. Plasma corticosterone levels were in the range of 150-300 ng/ml after the surgical procedure and the body weight was significantly lower 24 h after surgery compared to its pre-operative value. Contrary to what was expected, the total fecal corticosterone excretion was significantly reduced 24 h after surgery, as was the defecation. Buprenorphine treatment significantly lowered the plasma corticosterone levels, but had no effect on fecal corticosterone excretion or body weight change. It was concluded that surgical placement of an arterial catheter induces a significant stress response, as judged by its effect on plasma corticosterone and body weight. Voluntary ingestion of buprenorphine improved postoperative recovery by lowering plasma corticosterone concentrations. Neither fecal corticosterone excretion nor body weight change seems suitable for postoperative stress assessment in mice in the present experimental setup.

The present study investigated the postoperative plasma concentrations of corticosterone and buprenorphine in male Wistar and Sprague-Dawley rats, treated with buprenorphine administered either through subcutaneous (SC) injection or through voluntary ingestion (VI). The animals were treated with buprenorphine for pre-emptive analgesia prior to surgical placement of a jugular catheter, followed by automated blood sampling during 96 h. Buprenorphine was administered on a regular basis throughout the experiment, and blood was collected on selected time points. Body weight was measured before and 96 h after surgery. It was found that the two rat stocks responded in a similar manner to both buprenorphine treatments, with the exception of body weight change in Wistar rats, in which body weight was reduced after SC treatment. The plasma concentration of corticosterone was significantly higher in the SC-treated animals than in the VI-treated animals during the first 18 h of the study, while plasma buprenorphine concentration was at least as high and more even over time after VI treatment. The present study shows that buprenorphine administration through VI is suitable for both Wistar and Sprague-Dawley rats, with lower stress response and higher plasma concentrations of buprenorphine than after the traditional SC route of administration.

The analysis of glucocorticoids excreted in feces is becoming a widespread technique for determining animal wellbeing in a wide variety of settings. In the present study an extraction protocol and an ELISA assay for quantifying fecal corticosterone metabolites (FCM) in BALB/c and C57bl/6 mice were validated. Lower ratios of solvent (ethanol) to mass of fecal sample were found to be sufficient in extracting FCM compared to what has been reported previously. Feeding mice a high energy diet, high in fat content (60% of calories from fat), significantly lowered the FCM excretion, approximately halving the FCM output. This diet also reduced the fecal mass voided to approximately a third of that of the regular diet. The two reductions were not correlated. A difference in defecation pattern was seen between the two strains, with the BALB/c mice having a more pronounced diurnal rhythm compared to the C57bl/6 mice. Furthermore, throughout the experiment, the C57bl/6 mice excreted significantly higher levels of FCM compared to the BALB/c mice. The mice were also challenged with synthetic adrenocorticotropic hormone (ACTH) and dexamethasone (DEX). The effect of the challenges could readily be detected, but had a considerably lesser impact on data than did the difference in diet. The study demonstrates some problematic consequences of expressing FCM excretion as a measure of fecal dry mass. The study also serves to emphasize the caution that must be exercised when interpreting FCM excretion in conjunction with an uncontrolled or varied diet, or perturbations of gastro-intestinal functioning.