Indirect indicator of transport stress in hematological values in newly acquired cynomolgus monkeys

Rhododendron poisoning in alpacas (Vicugna pacos) in Northern Germany

Poisoning is often suspected to be the origin of disease in South American camelids (SACs) by owners, but only in a few cases this assumption can be confirmed. In small ruminants, rhododendron poisoning is a common emergency for livestock veterinarians. However, this condition has rarely been reported in SACs so far. This paper provides information regarding clinical findings, hematology, clinical chemistry, and treatment of four alpacas after presumed intake of rhododendron leaves including pathological findings of one of the animals. Rhododendron leaves contain grayanatoxins that lead to hyperpolarization of excitable cells. Clinical signs that were observed in the presented alpacas comprised: salivation, dehydration, decreased motility of compartment 1, uncoordinated regurgitation, and cardiac arrhythmia. Clinical chemistry revealed that rhododendron poisoning was associated with metabolic acidosis and azotaemia, hyponatremia and hyperkalemia. Most striking macroscopic and histopathological findings included gastric ulceration, and renal infarcts along with inflammatory changes. Leaves of Rhododendron spp. were identified in the forestomach content of this animal. Affected animals were treated symptomatically as there is no specific antidote in rhododendron poisoning. This included parenteral rehydration, treatment of metabolic acidosis (infusion of sodium bicarbonate solution), and oral administration of activated charcoal to bind potential toxins. In addition, antibiotic treatment might be necessary to prevent aspiration pneumonia in case of uncoordinated regurgitation. Of the four animals, the worst affected alpaca was euthanized, one had minimal signs and two responded to supportive care and recovered. In conclusion, rhododendron poisoning might be fatal for alpacas in individual cases and therefore rhododendron bushes should not be placed in the habitat of SACs.

Quality of hematology and clinical chemistry results in laboratory and zoo nonhuman primates: Effects of the preanalytical phase. A review

Most errors in clinical pathology originate in the preanalytical phase, which includes all steps from the preparation of animals and equipment to the collection of the specimen and its management until analyzed. Blood is the most common specimen collected in nonhuman primates. Other specimens collected include urine, saliva, feces, and hair. The primary concern is the variability of blood hematology and biochemistry results due to sampling conditions with the effects of capture, restraint, and/or anesthesia. Housing and diet have fewer effects, with the exception of food restriction to reduce obesity. There has been less investigation regarding the impact of sampling conditions of nonblood specimens.

Severe anaemia secondary to a perforated gastric ulcer in a male alpaca

BACKGROUND

Anaemia is a common condition in alpacas and attributable to a variety of causes. Severe anaemia with a packed cell volume (PCV) less than 10% is frequently diagnosed, usually due to blood loss resulting from haemonchosis. Many South American camelids (SACs) also suffer from gastric ulcers, which are often associated with anaemia in other species. However, in alpacas and llamas, gastric ulcers usually do not lead to anaemia due to blood loss according to the current literature. There are no detailed clinical and laboratory data on this condition in the scientific literature so far.

CASE PRESENTATION

We report on the case of a nine-year-old male alpaca that was presented to the clinic with suspected forestomach acidosis. The animal showed clinical signs of colic, hypothermia, tachypnea, tachycardia, pale mucous membranes, and died shortly after admission to the clinic. Laboratory diagnosis revealed a markedly decreased haematocrit (0.13 l/l), leucopaenia with band neutrophils, azotaemia, hypocalcaemia, hyperphosphataemia and vitamin D deficiency. Post-mortem examination revealed multiple ulcers in the first and third compartment with perforation of one ulcer in the first compartment, resulting in intraluminal blood loss and purulent peritonitis.

CONCLUSIONS

To the authors' knowledge, this is the first detailed description of clinical and laboratory data of severe anaemia due to a perforated gastric ulcer in a SAC. Although the current literature suggests that severe blood loss due to gastric ulcers does not occur in SACs, this condition should be considered as a possible differential diagnosis in anaemic animals. Clinical indicators can be colic and pale mucous membranes.

Effects of pair housing on behavior, cortisol, and clinical outcomes during quarantine-like procedures for rhesus macaques (Macaca mulatta)

BACKGROUND

Compatible pair housing of macaques in research settings increases species-typical behaviors and facilitates beneficial social buffering. It is not yet established whether these benefits are maintained after intrafacility transfer and domestic quarantine, which are two stressors that can lead to behavioral and clinical abnormalities.

METHODS

We evaluated 40 adolescent male rhesus macaques who were single- or pair-housed immediately following an intrafacility transfer. We measured behavior, fecal cortisol, body weight, and diarrhea occurrence. Body weight and diarrhea occurrence were also retrospectively analyzed in an additional 120 adolescent rhesus who underwent a similar transfer.

RESULTS AND CONCLUSIONS

Pair-housed macaques exhibited less of some undesirable behaviors (e.g., self-clasping) and experienced less diarrhea than single-housed subjects; however, no significant differences in cortisol levels or alopecia measures were found. The demonstrated beneficial effects of pair housing for rhesus macaques following intrafacility transfer and adjustment suggest pairing upon arrival at a new facility will bolster animal welfare.

Reference Intervals and Percentiles for Hematologic and Serum Biochemical Values in Captive Bred Rhesus (Macaca mulatta) and Cynomolgus Macaques (Macaca fascicularis)

Several physiological characteristics and housing conditions are known to affect hematologic and serum biochemical values in macaques. However, the studies that have been conducted either report values calculated based on a small number of animals, were designed specifically to document the effect of a particular condition on the normal range of hematologic and serum biochemical values, or used parametric assumptions to calculate hematologic and serum biochemical reference intervals. We conducted a retrospective longitudinal cohort study to estimate reference intervals for hematologic and serum biochemical values in clinically healthy macaques based on observed percentiles without parametric assumptions. Data were obtained as part of the Biomedical Primate Research Centre (Rijswijk, The Netherlands) health monitoring program between 2018 and 2021. In total, 4009 blood samples from 1475 macaques were analyzed with a maximum of one repeat per year per animal. Data were established by species, gender, age, weight-for-height indices, pregnancy, sedation protocol, and housing conditions. Most of the parameters profoundly affected just some hematologic and serum biochemical values. A significant glucose difference was observed between the ketamine and ketamine-medetomidine sedation protocols. The results emphasize the importance of establishing uniform experimental groups with validated animal husbandry and housing conditions to improve the reproducibility of the experiments.

Immunohematological features of free-living Alouatta belzebul (Linnaeus, 1766) red-handed howler monkeys in the Eastern Amazon

The red-handed howler monkey (Alouatta belzebul) is one of the 35 threatened Brazilian primate species found in two highly endangered Brazilian biomes. Their Amazonian native populations have been declining due to exponential deforestation associated with human activities, especially the construction of dams. The studied population (n = 27) was located in the Belo Monte dam Area of Influence. For the first time, we presented hematological parameters and the basic profile of T (CD3) and B (BSAP PAX5) cells by immunocytochemistry. The results supported the hypothesis that the immuno-hematological profile is influenced by sex, age, and season. Eosinophils were significantly higher in females (p = 0.03), monocytes statistically greater in juveniles (p = 0.04), and total plasma protein increased significantly (p > 0.001) during the dry season. Furthermore, adults showed a statistically higher average absolute number of B lymphocytes than young individuals (p = 0.03), in contrast to T lymphocytes. Even without knowing the full history of antigenic exposure, these results not only contribute to elucidating the boundaries between health and disease but may help lay the groundwork for future research into the effects of anthropogenic stress on immune activation.

Blood Analysis of Laboratory Macaca mulatta Used for Neuroscience Research: Investigation of Long-Term and Cumulative Effects of Implants, Fluid Control, and Laboratory Procedures

The nonhuman primate (NHP) constitutes an extraordinarily important model in neuroscience research for understanding the neuronal underpinnings of perceptual, motor, cognitive, and executive functions of the primate brain, and to study the physiological causes, effects, and potential treatments of brain disorders. Because of their cognitive capabilities, NHPs receive special attention in animal welfare regulations around the world, and their well-being is a benchmark for the evaluation, monitoring, and refinement of experimental procedures. As a consequence, many typical neuroscientific procedures are considered only mildly severe by animal welfare boards. There is, however, an ongoing debate about possible long-term and cumulative effects. Because of a lack of longitudinal data, it is unclear whether mildly severe procedures may cause more significant harm on the long-term, and to what extent they may impact animal well-being and healthiness over time. We here make use of a database of blood samples drawn over a period of 15 years from 39 rhesus monkeys (Macaca mulatta) to address the issue of long-term, cumulative effects of neuroscientific procedures. A careful analysis of indicative primate blood markers for chronic inflammation, hydration status, and stress levels, their comparison to baseline values from both the same animals and the literature, and evaluation of additional hematologic, physiological, and behavioral parameters did not provide support for the notion of long-term, cumulative effects on the monkeys’ healthiness and well-being. The results may serve the community as a reference for the severity assessment of neuroscientific experiments involving NHPs.

CHALLENGES TO ANIMAL WELFARE DURING TRANSPORTATION OF WILD MAMMALS: A REVIEW (1990-2020)

Wild mammal transport is an important component of conservation translocation as well as the economic wildlife trade. This article reviews the physiological responses to transport that have been measured in wild mammalian species, factors associated with these responses, and interventions that have been applied to mitigate these responses. By organizing the literature review along the "five domains model" of animal welfare, namely, the physical-functional domains (nutrition, environment, health, behavior) and the mental domain (mental state), it can be demonstrated that wild mammal transport is associated with challenges to ensuring positive animal welfare in all five domains. Transported wild mammals can experience dehydration, catabolism, fatigue, immunosuppression, behavioral changes, and stress. Factors influencing these physiological responses to transport have only been researched in a few studies encompassing species, journey length, ambient temperature, vehicle motion, stocking density, orientation, habituation, vehicle speed allowance, and road type. The administration of tranquilizers has been shown to mitigate negative physiological responses to transport. There is a need to further investigate species and situation-specific physiological responses to transport and factors associated with these responses in order to identify challenges to ensuring animal welfare and improving translocation success.

Effects of relocation on immunological and physiological measures in female squirrel monkeys (Saimiri boliviensis boliviensis)

In the present study, we have quantified the effects of transport, relocation and acclimate/adapt to their new surroundings on female squirrel monkey. These responses are measured in blood samples obtained from squirrel monkeys, at different time points relative to their relocation from their old home to their new home. A group of squirrel monkeys we transported, by truck, for approximately 10 hours. Peripheral blood mononuclear cells (PBMCs) were assayed in order to evaluate the phenotype of lymphocyte subsets by flow, mitogen-specific immune responses of PBMCs in vitro, and levels of cytokines at various time points including immediately before transport, immediately upon arrival, and after approximately 150 days of acclimation. We observed significant changes in T cells and subsets, NK and B cells (CD4⁺, CD8⁺, CD4⁺/CD8⁺, CD16⁺, and CD20⁺). Mitogen specific (e.g. PHA, PWM and LPS) proliferation responses, IFN-γ by ELISPOT assay, and cytokines (IL-2, IL-4 and VEGF) significant changes were observed. Changes seen in the serum chemistry measurements mostly complement those seen in the hematology data. The specific goal was to empirically assess the effects of relocation stress in squirrel monkeys in terms of changes in the numbers and functions of various leukocyte subsets in the blood and the amount of time required for acclimating to their new environment. Such data will help to determine when newly arrived animals become available for use in research studies.

Hypobaria-Induced Oxidative Stress Facilitates Homocysteine Transsulfuration and Promotes Glutathione Oxidation in Rats with Mild Traumatic Brain Injury

Background:

United States service members injured in combat theatre are often aeromedically evacuated within a few days to regional military hospitals. Animal and epidemiological research indicates that early exposure to flight hypobaria may worsen brain and other injuries. The mechanisms by which secondary exposure to hypobaria worsen trauma outcomes are not well elucidated. This study tested the hypothesis that hypobaria-induced oxidative stress and associated changes in homocysteine levels play a role in traumatic brain injury (TBI) pathological progression caused by hypobaria.

Methods:

Male Sprague Dawley rats were exposed to a 6 h hypobaria 24 h after mild TBI by the controlled cortical impact. Plasma and brain tissues were assessed for homocysteine levels, oxidative stress markers or glutathione metabolism, and behavioral deficits post-injury in the absence and presence of hypobaria exposure.

Results:

We found that hypobaria after TBI increased oxidative stress markers, altered homocysteine metabolism, and promoted glutathione oxidation. Increased glutathione metabolism was driven by differential upregulation of glutathione metabolizing genes. These changes correlated with increased anxiety-like behavior.

Conclusion:

These data provide evidence that hypobaria exposure after TBI increases oxidative stress and alters homocysteine elimination likely through enhanced glutathione metabolism. This pathway may represent a compensatory mechanism to attenuate free radical formation. Thus, hypobaria-induced enhancement of glutathione metabolism represents a potential therapeutic target for TBI management.

Faecal Glucocorticoid Metabolites and H/L Ratio are Related Markers of Stress in Semi-Captive Asian Timber Elephants

Simple Summary

Animals are kept in captivity for various reasons worldwide. Throughout its range countries, the Asian elephant is used for various purposes, with a significant proportion of the remaining population working as draft and transport animals in the timber industry. However, captivity can also lead to compromises in welfare that need to be quantified for successful intervention. A key way of assessing an animal’s well-being in wildlife and zoo biology is to measure its stress. Previous studies have found positive, negative, or no relationship between two commonly used measures of stress: stress hormones and the ratio of two types of white blood cells—heterophils to lymphocytes. Our study is one of the first to show a positive and consistent link between these two measures in semi-captive Asian elephants from Myanmar, irrespective of sex, age, or environmental context. Our results show that using the heterophil/lymphocyte ratio from blood smears on-site may offer a potentially cheaper and faster way to determine stress than measuring faecal glucocorticoid metabolite concentrations in the laboratory.

Abstract

Animals are kept in captivity for various reasons, but species with a slower pace of life may adapt to captive environments less easily, leading to welfare concerns and the need to assess stress reliably in order to develop effective interventions. Our aim was to assess welfare of semi-captive timber elephants from Myanmar by investigating the relationship between two physiological markers of stress commonly used as proxies for welfare, faecal glucocorticoid metabolite concentrations (FGM) and heterophil/lymphocyte ratios (H/L), and link these measures to changes in body condition (determined by body weight). We further assessed how robustly these two markers of stress performed in animals of different age or sex, or in different ecological contexts. We measured FGM concentrations and H/L ratios between 2016 and 2018 from 316 samples of 75 females and 49 males ranging in age from 4 to 68. We found a positive and consistent link between FGMs and H/L ratios in Asian elephants, irrespective of their sex, age, or ecological context. Our results will help to inform managers of (semi-) captive elephants about using heterophil/lymphocyte ratio data from blood smears on site as a potentially cheaper and faster alternative to determining stress than measuring faecal glucocorticoid metabolite concentrations in the laboratory.

Effects of Transportation and Relocation on Immunologic Measures in Cynomolgus Macaques (Macaca fascicularis)

NHP are a small, but critical, portion of the animals studied in research laboratories. Many NHP are imported or raised at one facility and subsequently moved to another facility for research purposes. To improve our understanding of the effects of transportation and relocation on the NHP immune system, to minimize potential confounds associated with relocation, and to maximize study validity, we examined the phenotype and function of PBMC in cynomolgus macaques (Macaca fascicularis) that were transported approximately 200 miles by road from one facility to another. We evaluated the phenotype of lymphocyte subsets through flow cytometry, mitogen-specific immune responses of PBMC in vitro, and plasma levels of circulating cytokines before transportation, at approximately 24 h after arrival (day 2), and after 30 d of acclimation. Analyses of blood samples revealed that the CD3+ and CD4+ T-cell counts increased significantly, whereas NK+, NKT, and CD14+ CD16+ nonclassical monocyte subsets were decreased significantly on day 2 after relocation compared with baseline. We also noted significantly increased immune cell function as indicated by mitogen-specific proliferative responses and by IFNγ levels on day 2 compared with baseline. After 30 d of acclimation, peripheral blood CD4+ T-cells and monocyte counts were higher than baseline, whereas B-cell numbers were lower. The mitogen-induced responses to LPS and IFNγ production after stimulation with pokeweed mitogen or phytohemagglutinin remained significantly different from baseline. In conclusion, the effects of transportation and relocation on immune parameters in cynomolgus monkeys are significant and do not fully return to baseline values even after 30 d of acclimation.

Effects of adaptation to handling on the circadian rhythmicity of blood solutes in Mongolian gerbils

The Mongolian gerbil has been widely used in many research fields and has been reported to be a diurnal laboratory animal. The circadian rhythmicity of these gerbils was investigated in the present study by measuring two hormones that show daily oscillations, cortisol and ACTH, in serum using ELISA kits. The levels of the two hormones were highest at 8:00 am and their rhythmic changes were similar to those in humans. In addition, the influence of stress of handling and blood collection on the physiological parameters of the gerbils was examined. After adaptation to handling for 1 week, some serum parameters in the animals changed. Handling and blood collection did not impact significantly on the following parameters: creatine kinase (CK), lactate dehydrogenase (LD), alanine aminotransferase (ALT), aspartate transaminase (AST), blood urea nitrogen (BUN), and albumin (ALB). However, blood glucose (GLU), total protein (TP) and globulin (GLB) significantly increased while creatinine (CRE) and albumin/globulin (A/G) significantly decreased after adaptation. This work further confirms that the Mongolian gerbil is a diurnal animal and also indicates that a suitable adaptation procedure is necessary for getting reliable results when performing experiments using these animals.

Hematological and serum biochemical parameters of rescued Sunda pangolins (Manis javanica) in Singapore

The Sunda pangolin (Manis javanica) population in Southeast Asia faces threats such as poaching and deforestation. Health assessments of rescued individuals including physical examination and blood work are crucial for clinicians to determine the health status of these animals. The establishments of reference intervals of hematology and serum biochemistry are important for identifying clinical abnormalities. The objectives of our study were to establish blood reference intervals for Sunda pangolins, to determine if there are age and sex related differences in hematology and serum biochemistry, and to compare our results with those of a previous study on confiscated Sunda pangolins in Thailand. Fifty-eight Sunda pangolins were rescued between January 2011 and December 2015. The hematology and serum biochemistry results of 51 clinically normal Sunda pangolins were selected for the establishment of the blood reference intervals. No sex related differences were noted in this study. Age-related differences were observed, in which adult Sunda pangolins had a significantly higher mean corpuscular volume than juveniles, and juvenile Sunda pangolins had significantly higher red blood cell counts and hemoglobin levels than those of the adults (P<0.05). Age-related differences were also noted in several serum biochemistry parameters: alkaline phosphatase (ALP) was significantly higher in juveniles, and total protein was significantly higher in adult Sunda pangolins. Compared to a previous study the white blood cell counts, neutrophil counts, and ALP were higher, and the lymphocyte counts were lower in the present study.

Tissue Physiology of Cynomolgus Monkeys: Cross-Species Comparison and Implications for Translational Pharmacology

We previously performed a comparative assessment of tissue-level vascular physiological parameters in mice and rats, two of the most commonly utilized species in translational drug development. The present work extends this effort to non-human primates by measuring tissue- and organ-level vascular volumes (V_v), interstitial volumes (V_i), and blood flow rates (Q) in cynomolgus monkeys. These measurements were accomplished by red blood cell labeling, extracellular marker infusion, and rubidium chloride bolus distribution, respectively, the same methods used in previous rodent measurements. In addition, whole-body blood volumes (BV) were determined across species. The results demonstrate that V_v, V_i, and Q, measured using our methods scale approximately by body weight across mouse, rat, and monkey in the tissues considered here, where allometric analysis allowed extrapolation to human parameters. Significant differences were observed between the values determined in this study and those reported in the literature, including V_v in muscle, brain, and skin and Q in muscle, adipose, heart, thymus, and spleen. The impact of these differences for selected tissues was evaluated via sensitivity analysis using a physiologically based pharmacokinetic model. The blood-brain barrier in monkeys was shown to be more impervious to an infused radioactive tracer, indium-111-pentetate, than in mice or rats. The body weight-normalized total BV measured in monkey agreed well with previously measured value in rats but was lower than that in mice. These findings have important implications for the common practice of scaling physiological parameters from rodents to primates in translational pharmacology.

Visual stimulation-induced mild stress enhances cognitive behavior in cynomolgus monkey

Cortisol is a well-known endogenous glucocorticoid that serves as a stress indicator. It is normally released under stressful condition to warn about imminent danger and thus is critical for survival of the species. However, it is unclear how cortisol relates to cognitive process under physiological condition in high-order primates such as non-human primates (NHP). Here, we report that a slight but significant increase in blood cortisol level by mild stress is positively correlated with the cognitive function in cynomolgus monkey. We stimulated 3 groups of monkeys by viewing consecutive series of pictures of monkeys, pictures of humans, or animation still pictures. We first found that the blood cortisol level was significantly higher during the stimulation session and returned to normal after stimulation session. Among the three types of pictures, the monkeys which were stimulated with monkey pictures showed the most significant increase in cortisol level during stimulation. Furthermore, the monkeys showed significantly enhanced manipulation, suggesting that cortisol affected cognitive processes. Overall, our study demonstrates that visual stimulation both increases blood cortisol and enhances manipulating behavior. Therefore, unlike the common notion that cortisol is a stress indicator, our data supports that a mild increase of cortisol enhances cognition in NHP.

Effects of transportation, relocation, and acclimation on phenotypes and functional characteristics of peripheral blood lymphocytes in rhesus monkeys (Macaca mulatta)

Nonhuman primates from domestic sources constitute a small, but critical, proportion of animals studied in research laboratories. Many of these nonhuman primates are raised at one facility and subsequently transported/relocated to another facility for research purposes. We examined the effects of transport, relocation, and acclimation on the phenotype and function of peripheral blood mononuclear cells (PBMCs) in a group of rhesus monkeys that were transported by road for approximately 21 hours from one facility to another. Using a panel of human antibodies and a set of standardized human immune assays, we evaluated the phenotype of lymphocyte subsets by flow, mitogen-specific immune responses of PBMCs in vitro, and levels of circulating cytokines and cortisol in plasma at various time points including immediately before transport, immediately upon arrival, and after approximately 30 days of acclimation. Analyses of blood samples revealed that CD3+ T-cell and CD20+ B-cell populations had decreased significantly immediately after relocation but had recovered within 30 days after arrival at the new facility. Similarly, circulating cortisol and cytokine levels in plasma were significantly higher immediately after relocation; and by the 30-day time point, these differences were no longer significant. However, immune assays of PBMCs indicated that mitogen-specific responses for proliferation, interferon γ (IFN-γ), and perforin were significantly higher after relocation and 30 days of acclimation. These findings have implications on the research participation of transported and relocated nonhuman primates in immunologic research studies, suggesting that 30 days is not sufficient to ensure return to baseline immune homeostasis. These data should be considered when planning research studies in order to minimize potential confounding factors associated with relocation and to maximize study validity.

When the ball is in the female's court: How the scramble-competition mating system of the North American red squirrel has shaped male physiology and testosterone dynamics

Male reproductive success in most mammals is determined by their success in direct inter-male competition through aggression and conflict, resulting in female-defense mating systems being predominant. This is linked to male testosterone levels and its dynamics. However, in certain environments, a scramble-competition mating system has evolved, where female reproductive behavior takes precedence and male testosterone dynamics are unlikely to be related to inter-male competition. We studied the North American red squirrel (Tamiasciurus hudsonicus), a species with a well-established scramble-competition system. Using an ACTH hormonal challenge protocol as a proxy for competitive interactions, we compared the testosterone dynamics in breeding males in late winter with that in nonbreeding males in late spring in the Yukon. To gain an integrated picture of their physiological state, we also assessed changes in their stress response, body mass, energy mobilization, and indices of immune function. Testosterone levels at the base bleed were high in breeding males (2.72ng/mL) and virtually absent in non-breeding males (0.04ng/mL). Breeding males were in better condition (heavier body mass, higher hematocrit, and higher erythrocytes), had higher indices of immune function (neutrophil:lymphocyte ratio), but a similar ability to mobilize energy (glucose) compared with non-breeding males. Though total cortisol was higher in non-breeding males, free cortisol was twice as high in breeding males as their corticosteroid binding globulin levels were half as high. In response to the ACTH challenge, testosterone levels in breeding males declined 49% over the first hour and increased 36% over the next hour; in non-breeding males levels showed no change. Free cortisol increased only modestly (26% in breeding males; 23% in non-breeding males). Glucose levels changed similarly in breeding and nonbreeding males, declining for the first 30min and then increasing for the next 60min. Thus, testosterone and components of the stress axis function in a profoundly different manner in male red squirrels than in males of mammals with female-defense mating systems. There are four probable interrelated reasons for these adaptations in male red squirrels: the marginal benefits of each mating, the constraints of mate searching away from their own resource-based territories, energy mobilization in a harsh environment, and a long life span.

Biologic Data of Cynomolgus Monkeys Maintained under Laboratory Conditions

The cynomolgus monkey (Macaca fascicularis) is a well-known non-human primate species commonly used in non-clinical research. It is important to know basal clinical pathology parameters in order to have a reference for evaluating any potential treatment-induced effects, maintaining health status among animals and, if needed, evaluating correct substantiative therapies. In this study, data from 238 untreated cynomolgus monkeys (119 males and 119 females of juvenile age, 2.5 to 3.5 years) kept under laboratory conditions were used to build up a reference database of clinical pathology parameters. Twenty-two hematology markers, 24 clinical chemistry markers and two blood coagulation parameters were analyzed. Gender-related differences were evaluated using statistical analyses. To assess the possible effects of stress induced by housing or handling involved in treatment procedures, 78 animals (35 males and 35 females out of 238 juvenile monkeys and four adult males and four adult females) were used to evaluate cortisol, corticosterone and behavioral assessment over time. Data were analyzed using a non-parametric statistical test and machine learning approaches. Reference clinical pathology data obtained from untreated animals may be extremely useful for investigators employing cynomolgus monkeys as a test system for non-clinical safety studies.

Effect of road transportation on the serum biochemical parameters of cynomolgus monkeys and beagle dogs

To determine the effect of long-distance (approximately 600 km) road transportation on the blood biochemistry of laboratory animals, we investigated the changes in serum biochemical parameters in healthy cynomolgus monkeys and beagle dogs transported by truck from Osaka to Tsukuba, Japan. The concentrations of serum cortisol, total bilirubin and aspartate aminotransferase in monkeys increased during transportation. Serum cortisol and total bilirubin levels in dogs also increased during transportation, but serum triglyceride decreased. Serum parameter values in truck-transported monkeys and dogs returned to baseline levels within two weeks following arrival. Taken together, these results suggest that a two-week acclimation period is the minimum duration required for adaptation following road transportation.

Responses of New World flying squirrels to the acute stress of capture and handling

Northern ( Glaucomys sabrinus ) and southern ( G. volans ) flying squirrels have glucocorticoid (GC; stress hormone) levels higher than most vertebrates but virtually no binding capacity for these GCs via the carrier protein, corticosteroid-binding globulin. Thus, their total GCs are essentially all free and biologically active. However, the GC estimates come from blood samples taken after squirrels had been in live traps, and thus in a stress-induced state. Obtaining baseline values for physiological variables is valuable for assessing the response of vertebrates to stressors in their environment. We compared baseline plasma total cortisol levels (within 3min of capture) to stress-induced levels (after 30min of trap restraint) in both flying squirrel species. We recorded baseline cortisol levels that were some of the highest ever reported for mammals, indicating their stress axes operate at a higher set point than most other species. As part of the stress response, we also measured 4 indices in addition to cortisol. Total cortisol and free fatty acids increased in both species, as predicted. In contrast with our predictions, blood glucose and neutrophil/lymphocyte ratio showed no overall change, and hematocrit decreased significantly. New World flying squirrels therefore appear to have a stress response that differs from many other mammals. The selective forces driving the physiology of these animals remain elusive, but this lineage may provide an interesting comparative system for the study of stress axis function and its evolution among vertebrates.

Evaluation of cynomolgus monkeys for the identification of endogenous biomarkers for hepatic transporter inhibition and as a translatable model to predict pharmacokinetic interactions with statins in humans

Inhibition of hepatic transporters such as organic anion transporting polypeptides (OATPs) 1B can cause drug-drug interactions (DDIs). Determining the impact of perpetrator drugs on the plasma exposure of endogenous substrates for OATP1B could be valuable to assess the risk for DDIs early in drug development. As OATP1B orthologs are well conserved between human and monkey, we assessed in cynomolgus monkeys the endogenous OATP1B substrates that are potentially suitable to assess DDI risk in humans. The effect of rifampin (RIF), a potent inhibitor for OATP1B, on plasma exposure of endogenous substrates of hepatic transporters was measured. From the 18 biomarkers tested, RIF (18 mg/kg, oral) caused significant elevation of plasma unconjugated and conjugated bilirubin, which may be attributed to inhibition of cOATP1B1 and cOATP1B3 based on in vitro to in vivo extrapolation analysis. To further evaluate whether cynomolgus monkeys are a suitable translational model to study OATP1B-mediated DDIs, we determined the inhibitory effect of RIF on in vitro transport and pharmacokinetics of rosuvastatin (RSV) and atorvastatin (ATV). RIF strongly inhibited the uptake of RSV and ATV by cOATP1B1 and cOATP1B3 in vitro. In agreement with clinical observations, RIF (18 mg/kg, oral) significantly decreased plasma clearance and increased the area under the plasma concentration curve (AUC) of intravenously administered RSV by 2.8- and 2.7-fold, and increased the AUC and maximum plasma concentration of orally administered RSV by 6- and 10.3-fold, respectively. In contrast to clinical findings, RIF did not significantly increase plasma exposure of either intravenous or orally administered ATV, indicating species differences in the rate-limiting elimination pathways.

Biomedical evaluation of Verreaux's sifaka (Propithecus verreauxi) from Kirindy Mitea National Park in Madagascar

Evaluation of the health, prevalence, and incidence of diseases in wild populations is a critical component of wildlife management. In addition, the establishment of reference physiologic parameters can Verreaux's sifaka (Propithecus verreauxi) from Kirindy Mitea National Park, Madagascar, during two field captures incontribute to the assessment of population risks. Complete medical evaluations were performed on 33 wild June 2010 and June 2011. Each animal received a complete physical examination: weight, body temperature, heart rate, and respiratory rate were recorded, and ectoparasites collected. Blood samples were collected for complete blood cell count, differential white blood cell count, hemoparasite examination, serum biochemical profile, fat-soluble vitamin analysis, trace mineral analysis, and toxoplasmosis and viral serology. Fecal samples were collected for bacterial culture and endoparasite examination. Significant differences exist between age classes for neutrophil and lymphocyte count, alkaline phosphatase, and creatinine values. Parasites detected were Callistoura sp., Bertiella lemuriformis, and Dipetalonema petteri. This publication reports the first complete biomedical evaluation of the P. verreauxi and provides a basis for hematologic and biochemical comparisons of P. verreauxi in the wild.

Interpreting Stress Responses during Routine Toxicity Studies

Stress often occurs during toxicity studies. The perception of sensory stimuli as stressful primarily results in catecholamine release and activation of the hypothalamic–pituitary–adrenal (HPA) axis to increase serum glucocorticoid concentrations. Downstream effects of these neuroendocrine signals may include decreased total body weights or body weight gain; food consumption and activity; altered organ weights (e.g., thymus, spleen, adrenal); lymphocyte depletion in thymus and spleen; altered circulating leukocyte counts (e.g., increased neutrophils with decreased lymphocytes and eosinophils); and altered reproductive functions. Typically, only some of these findings occur in a given study. Stress responses should be interpreted as secondary (indirect) rather than primary (direct) test article–related findings. Determining whether effects are the result of stress requires a weight-of-evidence approach. The evaluation and interpretation of routinely collected data (standard in-life, clinical pathology, and anatomic pathology endpoints) are appropriate and generally sufficient to assess whether or not changes are secondary to stress. The impact of possible stress-induced effects on data interpretation can partially be mitigated by toxicity study designs that use appropriate control groups (e.g., cohorts treated with vehicle and subjected to the same procedures as those dosed with test article), housing that minimizes isolation and offers environmental enrichment, and experimental procedures that minimize stress and sampling and analytical bias.

This article is a comprehensive overview of the biological aspects of the stress response, beginning with a Summary (Section 1) and an Introduction (Section 2) that describes the historical and conventional methods used to characterize acute and chronic stress responses. These sections are followed by reviews of the primary systems and parameters that regulate and/or are influenced by stress, with an emphasis on parameters evaluated in toxicity studies: In-life Procedures (Section 3), Nervous System (Section 4), Endocrine System (Section 5), Reproductive System (Section 6), Clinical Pathology (Section 7), and Immune System (Section 8). The paper concludes (Section 9) with a brief discussion on Minimizing Stress-Related Effects (9.1.), and a final section explaining why Parameters routinely measured are appropriate for assessing the role of stress in toxicology studies (9.2.).

Changes of N/L ratio and cortisol levels associated with experimental training in untrained rhesus macaques

BACKGROUND

Animal training prior to beginning an experiment is an essential procedure and a very important course because it may affect the results of hematologic and hormonal variables and the functions influenced by those factors. Because this training inevitably causes animal stress, we wondered how much time is needed for untrained monkeys to recover from stresses associated with experimental training.

METHODS

We measured the hematological and stress hormonal (e.g., cortisol) changes on weekly basis before and after experimental monkey chair training in newly acquired rhesus monkeys.

RESULTS

The neutrophil-to-lymphocyte (N/L) ratio significantly increased during the initial phase of the training and then gradually decreased after 3 weeks. Elevated serum cortisol levels in the initial phase also significantly decreased after 3 weeks of chair training.

CONCLUSIONS

We conclude that at least a 3-week period is needed in monkey chair training for recovery from training stress. These results suggest that many researchers using nonhuman primates should provide enough time (>3 weeks) for adaptation to the experimental environment prior to beginning a study.

Physiological and Welfare Consequences of Transport, Relocation, and Acclimatization of Chimpanzees (Pan troglodytes)

Manipulations of the environments of captive nonhuman primates often have welfare consequences to the animals, including behavioral effects, and for certain manipulations, physiological effects as well. The processes of transporting, relocating, and acclimatizing nonhuman primates across facilities represent manipulations that are likely to have welfare, behavioral, and physiological consequences to the relocated animals. Seventy-two chimpanzees were relocated from the Primate Foundation of Arizona (PFA) in Arizona to the Keeling Center (KCCMR) in Texas. Animals were transported for approximately 21 h in single cages in a USDA-approved, climate-controlled trailer. Chimpanzees were weighed, anesthetized, and blood samples were collected 1) immediately prior to departure from PFA, 2) immediately upon arrival at the KCCMR, and 3) at additional time point(s) between 3 and 12 weeks after arrival at the KCCMR. Chimpanzees were quarantined in familiar pairs or social groups for 60-90 days at the KCCMR. Blood samples were analyzed for hematological and clinical chemistry parameters and compared across time points. In addition, samples from a subset of animals were assayed for cell-mediated immune parameters. Comparisons of the data obtained just prior to transport, to the data obtained immediately upon arrival, revealed numerous statistically significant differences in hematological, clinical chemistry, and immunological parameters. Some of these were indicative of stress, and thus, changes in welfare state, although many remained within the published normal ranges for chimpanzees. Additional analyses showed that many of the clinical chemistry values collected 3 to 12 weeks after arrival at the KCCMR had returned to pre-transport values. In contrast, of the cell-mediated immune parameters that were affected by transport and relocation, few had returned to pre-transport levels 8 weeks after transport, and three of the four hematology variables analyzed had not returned to pre-transport levels 12 weeks after transport. Comparisons of body weights before and immediately after transport revealed that animals lost an average of 2.5 kg during the 21-h transport, a statistically significant reduction that some animals never regained. These results demonstrate that transport and relocation affect a variety of physiological parameters with potential welfare implications and that some of these effects last as long as 3 months. These findings have important implications for the welfare and use of recently transported nonhuman primates, especially chimpanzees, in biomedical research. In order to allow animals to adapt to their new surroundings and to prevent unwanted confounds from influencing experiments, sufficient time must be provided after transport for chimpanzees to acclimatize.

Social stress desensitizes lymphocytes to regulation by endogenous glucocorticoids: insights from in vivo cell trafficking dynamics in rhesus macaques

OBJECTIVE

To determine whether chronic social stress can desensitize leukocytes to normal physiologic regulation by endogenous glucocorticoids.

METHODS

We analyzed the longitudinal relationship between plasma cortisol levels and peripheral blood lymphocyte counts over 16 monthly assessments in 18 rhesus macaques randomized to recurrent social encounters with a stable set of conspecifics or continually varying social partners (unstable socialization).

RESULTS

Animals socialized under stable conditions showed the expected inverse relationship between plasma cortisol concentrations and circulating lymphocyte frequencies. That relationship was significantly attenuated in animals subject to unstable social conditions. Differences in leukocyte redistributional sensitivity to endogenous glucocorticoids emerged within the first week of differential socialization, persisted throughout the 60-week study period, and were correlated with other measures of glucocorticoid desensitization (blunted hypothalamic-pituitary-adrenal (HPA) axis response to acute stress and redistributional response to dexamethasone challenge). Effects of unstable social conditions on leukocyte sensitivity to cortisol regulation were not related to physical aggression.

CONCLUSION

Chronic social stress can impair normal physiologic regulation of leukocyte function by the HPA axis in ways that may contribute to the increased physical health risks associated with social adversity.

Impact of live trapping on stress profiles of Richardson's ground squirrel (Spermophilus richardsonii)

Researching the physiological ecology of natural populations requires an understanding of the impact of capture-induced stress because of its numerous effects on physiological processes. In many cases, initial blood samples to which comparisons are made are obtained well after capture and may differ markedly from free-ranging conditions. We examined the extent to which stress profiles of male Richardson's ground squirrels (Spermophilus richardsonii) were affected by short-term responses to live trapping. We compared stress profiles of true base animals (blood samples obtained <3 min of capture) with those of nominal base animals (blood samples obtained >1 h after capture). Total cortisol increased almost 40% whereas our measure of corticosteroid binding globulin (CBG) decreased by 21%, resulting in a two-fold increase in free cortisol levels in nominal base animals compared with true base animals. Capture caused androgen concentrations to fall to almost half of those of true base animals. Energy mobilization increased markedly (22% in glucose and 221% in free fatty acids). Although white blood cell counts did not change, the number of neutrophils was 48% higher in true base animals. There were no changes in hematocrit or lymphocyte counts. Although most of the changes were predictable, the changes in CBG and androgens were unexpected based on previous work on closely related Arctic ground squirrels (Spermophilus parryii). Our results emphasize the value of obtaining true base measurements whenever possible in order to assess the directions and degree of bias introduced by trapping.

Stress in cynomolgus monkeys (Macaca fascicularis) subjected to long-distance transport and simulated transport housing conditions

The stress associated with transportation of non-human primates used in scientific research is an important but almost unexplored part of laboratory animal husbandry. The procedures and routines concerning transport are not only important for the animals' physical health but also for their mental health as well. The transport stress in cynomolgus monkeys (Macaca fascicularis) was studied in two experiments. In Experiment 1, 25 adult female cynomolgus monkeys were divided into five groups of five animals each that received different diets during the transport phase of the experiment. All animals were transported in conventional single animal transport cages with no visual or tactile contact with conspecifics. The animals were transported by lorry for 24 h at ambient temperatures ranging between 20 degrees C and 35 degrees C. Urine produced before, during and after transport was collected and analysed for cortisol by enzyme-linked immunosorbent assay (ELISA). All monkeys exhibited a significant increase in cortisol excretion per time unit during the transport and on the first day following transport.Although anecdotal reports concerning diet during transport, including the provision of fruits and/or a tranquiliser, was thought likely to influence stress responses, these were not corrobated by the present study. In Experiment 2, behavioural data were collected from 18 cynomolgus macaques before and after transfer from group cages to either single or pair housing, and also before and after a simulated transport, in which the animals were housed in transport cages. The single housed monkeys were confined to single transport cages and the pair housed monkeys were kept in their pairs in double size cages. Both pair housed and singly housed monkeys showed clear behavioural signs of stress soon after their transfer out of their group cages.However, stress-associated behaviours were more prevalent in singly housed animals than in pair housed animals, and these behaviours persisted for a longer time after the simulated transport housing event than in the pair housed monkeys. Our data confirm that the transport of cynomolgus monkeys is stressful and suggest that it would be beneficial for the cynomolgus monkeys to be housed and transported in compatible pairs from the time they leave their group cages at the source country breeding facility until they arrive at their final laboratory destination in the country of use.

Considerations in the selection and conditioning of Old World monkeys for laboratory research: animals from domestic sources

Nonhuman primates from domestic sources constitute an important resource for the research community. The life history of the Old World monkey species that comprise the bulk of this resource is described, and issues that colony managers and researchers alike should consider regarding animal selection (e.g., species, age, sex, rearing history, temperament, genotype, viral status, geographic origin) are discussed. Preparation of domestically bred animals for research usually involves some combination of social separation, relocation, resocialization, alterations in physical space, photoperiod, and diet, as well as exposure to novel environments. The research literature that has focused on these issues is reviewed, and authors suggest that once animals have been assigned to their project housing situation, a period ranging up to 3 mo (depending on the magnitude of the change in housing) might be warranted before an experimental protocol should begin. Attention to issues of animal selection and conditioning by both researchers and colony managers can lead to the shared goal of high-quality research that utilizes the minimal number of animals.