Coping styles in animals: current status in behavior and stress-physiology

Chronic defeat stress induces monoamine level dysregulation in the prefrontal cortex but not in the hippocampus of OF1 male mice

Chronic social stress can increase susceptibility to chronic diseases such as depression. One of the most used models to study the physiological mechanisms and behavioral outcomes of this type of stress is chronic defeat stress (CDS) in male mice. OF1 male mice were subjected to a stress period lasting 18 days. During that time, non-stressed animals were housed in groups. The cluster analysis of the behavioral profile displayed during the first social interaction divided subjects into two groups: active/aggressive (AA) and passive/reactive (PR). The day after the end of the stress period, the following behavioral analyses were performed: the sucrose preference test (SPT) on day 19, the open field test (OFT) on day 20, and the forced swim test (FST) on day 21. Immediately after completing the last test, animals were weighed, and blood samples were obtained. Then, they were sacrificed, and their prefrontal cortices and hippocampi were removed and stored to analyze monoamine levels. Stressed animals displayed anhedonia, and solely the PR mice continued to show higher levels of immobility in the OFT and FST. All stressed animals, regardless of the coping strategy, presented higher plasma corticosterone levels. In addition, stressed mice showed lower levels of tyrosine, dopamine, DOPAC, MHPG, kynurenine, kynurenic acid, and 5-HIAA levels but higher serotonin levels in the prefrontal cortex, not in the hippocampus. In conclusion, our results show that CSD induces differences in monoamine levels between brain areas, and these differences did not respond to the coping strategy adopted.

Effects of an herbal adaptogen feed-additive on feeding-related hypothalamic neuropeptides in chronic cyclic heat-stressed chickens

Heat stress (HS) is a global serious issue in the poultry industry with numerous adverse effects, including increased stress, depressed feed intake (FI), poor growth performance and higher mortality. Herbal adaptogens, plant extracts considered as stress response modifiers, are metabolic regulators that improve an organism's ability to adapt to and minimize damage from environmental stresses. Previously, we showed that herbal adaptogen supplementation increased FI and body weight (BW) of broiler (meat-type) chickens reared under HS conditions. Therefore, we hypothesized that these effects may be mediated through modulation of hypothalamic feeding-related neuropeptides. Male Cobb 500 chicks were reared in 12 environmental chambers with three diets: a corn-soybean-based diet (C) and two herbal adaptogen-supplemented diets at 500 g/1000 kg (NR-PHY-500) and 1 kg/1000 kg (NR-PHY-1000). Broilers in 9 chambers were exposed to chronic cyclic HS (35 °C for 8 h/day) from d29 to d42, while 3 chambers were maintained at 24 °C (thermoneutral, TN) for all 42 days. Hypothalamic samples were collected on d42 from each group, both before the onset of HS (Pre-HS) that day and after 3 h of HS (post-HS). Hypothalamic expressions of neuropeptide Y (NPY) receptors Y4 and Y7, Corticotropin-releasing hormone (CRH), orexin receptor 1 (ORXR1), melanocortin receptors (MC1R, MC4R, and MC5R), visfatin and neurosecretory protein GL (NPGL) genes were significantly upregulated by adaptogen supplementation. The hypothalamic expression of MC2R was affect by period, with a significant upregulation during post-HS phase. There was a significant period by treatment interaction for hypothalamic orexin and adiponectin expression. The hypothalamic expression of NPY, Y1, Y2, Y5, Y6, proopiomelanocortin (POMC), cocaine and amphetamine regulated transcript (CART), agouti-related peptide (AgRP), ORXR2, AdipR1/2, MC3R, and ghrelin was not affected by diet supplementation nor by HS exposure. In conclusion, these findings suggest that in-feed supplementation of adaptogen might improve FI and growth via modulation of hypothalamic feeding-related neuropeptides in heat-stressed broilers.

An Interactive Feeder to Induce and Assess Emotions from Vocalisations of Chickens

Understanding the emotional states of animals is a long-standing research endeavour that has clear applications in animal welfare. Vocalisations are emerging as a promising way to assess both positive and negative emotional states. However, the vocal expression of emotions in birds is a relatively unexplored research area. The goal of this study was to develop an interactive feeding system that would elicit positive and negative emotional states, and collect recordings of the vocal expression of these emotions without human interference. In this paper, the mechatronic design and development of the feeder is described. Design choices were motivated by the desire for the hens to voluntarily interact with the feeder and experience the different stimuli that were designed to induce (1) positive low-arousal, (2) positive high-arousal, (3) negative low-arousal, and (4) negative high-arousal states. The results showed that hens were motivated to engage with the feeder despite the risk of receiving negative stimuli and that this motivation was sustained for at least 1 week. The potential of using the interactive feeder to analyse chicken vocalisations related to emotional valence and arousal is being explored, offering a novel proof of concept in animal welfare research. Preliminary findings suggest that hens vocalised in response to all four stimulus types, with the number of vocalisations, but not the probability of vocalising, distinguishing between low- and high-arousal states. Thus, the proposed animal-computer interaction design has potential to be used as an enrichment device and for future experiments on vocal emotions in birds.

Long-term, medium-term and acute stress response of urban populations of Eurasian red squirrels affected by different levels of human disturbance

Animals in urban areas often encounter novel and potentially stressful conditions. It is important to understand how wildlife cope with anthropogenic disturbance. To investigate this specific adaptation we live-trapped squirrels in two study sites in Warsaw: a forest reserve and an urban park and we estimated stress responses at three levels: long-term and medium-term stress (the level of stress hormones, i.e. cortisol and cortisone concentrations, in hair and feces) and acute reaction to human-induced stress (measured during handling with the aid of the three indices: breath rate, struggle rate, and vocalization). According to GLMM models no difference in the stress hormones level was found between the two populations. The only differences in cortisol concentrations clearly depended on the season, i.e. being higher in autumn and winter comparying to other seasons. There was no influence of sex, or reproductive status on stress hormones. Forest squirrels had significantly higher breath rates, suggesting they were more stressed by handling. There was no difference in the struggle rate between study areas, this index was mostly affected by season (i.e. being highest in winter). First-trapped squirrels vocalized less than during the subsequent trappings. Assumingly, during the first, and more stressful trapping, squirrels used 'freezing' and/or little vocalization, while during next captures they used alarm calls to warn conspecifics. Overall, we showed that the two squirrel populations differed only in terms of their breath rate. This suggests that they did not differ in medium-term and long-term stress in general, but they can differ in acute response to handling. This also suggests that both populations were similarly affected by environmental factors. The lack of clear effects may also be due to population heterogeneity. Thus, in order to assess the effects of anthropogenic stressors a broader range of indicators and diverse analytical methods, including behavioral analyses, should be employed.

A hypothesis of teleological evolution, via endogenous acetylcholine, nitric oxide, and calmodulin pathways

The Extended Evolutionary Synthesis (EES) addresses the issues in evolutionary biology which cannot be explained by neo-Darwinian theory. The EES paradigm recognises teleology and agency in living systems, and identifies that organisms can directly affect their evolutionary trajectory in a goal-directed manner, yet the physiological pathways via which this occurs remain unidentified. Here, I propose a physiological pathway via which organisms can alter their genotype and phenotype by making behavioural decisions with respect their activity levels, partitioning of resources either toward growth, defence against disease, or their behavioural response to stressors. Specifically, I hypothesize that agential, teleological decisions mediated by acetylcholine result in induced nitric oxide (NO) activity, which regulates metabolism, blood flow, and immune response. Nitric oxide, however, is also a key epigenetic molecule, being involved in DNA acetylation, methylation, and de-methylation. Further, NO alters the histone complexes which scaffold nuclear DNA strands, and is thus a good candidate in identifying a system which allows an organisms to make teleological genetic changes. The proposed mechanisms of inheritance of these genetic changes is via the paternal line, whereby epigenetic changes in the somatic Sertoli cells in animals are transcribed by mRNA and included in the germline cells - the male gametes. The microsporangium in plants, and the sporophore cells in fungi, meanwhile, are proposed to form similar systems in response to sensory detection of stressors. Whilst the hypothesis is presented as a simplified model for future testing, it opens new avenues for study in evolutionary biology.

Multiple behavioral mechanisms shape development in a highly social cichlid fish

Early-life social experiences shape adult phenotype, yet the underlying behavioral mechanisms remain poorly understood. We manipulated early-life social experience in the highly social African cichlid fish Astatotilapia burtoni to investigate the effects on behavior and stress axis function in juveniles. Juveniles experienced different numbers of social partners in stable pairs (1 partner), stable groups (6 fish; 5 partners), and socialized pairs (a novel fish was exchanged every 5 days; 5 partners). Treatments also differed in group size (groups vs. pairs) and stability (stable vs. socialized). We then measured individual behavior and water-borne cortisol to identify effects of early-life experience. We found treatment differences in behavior across all assays: open field exploration, social cue investigation, dominant behavior, and subordinate behavior. Treatment did not affect cortisol. Principal components (PC) analysis revealed robust co-variation of behavior across contexts, including with cortisol, to form behavioral syndromes sensitive to early-life social experience. PC1 (25.1 %) differed by social partner number: juveniles with more partners (groups and socialized pairs) were more exploratory during the social cue investigation, spent less time in the territory, and were more interactive as dominants. PC5 (8.5 %) differed by stability: socialized pairs were more dominant, spent less time in and around the territory, were more socially investigative, and had lower cortisol than stable groups or pairs. Observations of the home tanks provided insights into the social experiences that may underlie these effects. These results contribute to our understanding of how early-life social experiences are accrued and exert strong, lasting effects on phenotype.

Multidimensional behavioral profiles associated with resilience and susceptibility after inescapable stress

Clinical depression is characterized by multiple concurrent symptoms, manifesting as a complex heterogeneous condition. Although some well-established classical behavioral assessments are widespread in rodent models, it remains uncertain whether rats also display stress-induced depression-related phenotypes in a multidimensional manner, i.e., simultaneous alterations in multiple behavioral tests. Here, we investigated multivariate patterns and profiles of depression-related behavioral traits in male Wistar rats subjected to inescapable footshocks (IS) or no-shocks (NS), followed by a comprehensive battery of behavioral tests and ethological characterization. We observed generalized stronger intra-test but weaker inter-test correlations. However, feature clustering of behavioral measures successfully delineated variables linked to resilience and susceptibility to stress. Accordingly, a noteworthy covariation pattern emerged, characterized by increased open field locomotion, reduced time in the elevated plus maze open arms, lower sucrose preference, and increased shuttle box escape failures that consistently differentiated IS from NS. Surprisingly there is little contribution from forced swim. In addition, individual clustering revealed a diversity of behavioral profiles, naturally separating NS and IS, including subpopulations entirely characterized by resilience or susceptibility. In conclusion, our study elucidates intricate relationships among classical depression-related behavioral measures, highlighting multidimensional individual variability. Our work emphasizes the importance of a multivariate framework for behavioral assessment in animal models to understand stress-related neuropsychiatric disorders.

Sex differences in responses to aggressive encounters among California mice

Despite how widespread female aggression is across the animal kingdom, there remains much unknown about its neuroendocrine mechanisms, especially in females that engage in aggression outside the peripartum period. Although the impact of aggressive experience on steroid hormone responses have been described, little is known about the impact of these experiences on female behavior or the subsequent neuropeptide responses to performing aggression. In this study, we compared behavioral responses in both male and female adult California mice based on if they had 0, 1, or 3 aggressive encounters using a resident intruder paradigm. We measured how arginine vasopressin and oxytocin cells in the paraventricular nucleus responded to aggression using c-fos immunohistochemistry. We saw that both sexes disengaged from intruders with repeated aggressive encounters, but that on the final day of testing females were more likely to freeze when they encountered intruders compared to no aggression controls - which was not significant in males. Finally, we saw that percent of arginine vasopressin and c-fos co-localizations in the posterior region of the paraventricular nucleus increased in males who fought compared to no aggression controls. No difference was observed in females. Overall, there is evidence that engaging in aggression induces stress responses in both sexes, and that females may be more sensitive to the effects of fighting.

Stress hyper-reactivity increases vulnerability to developing binge-type eating and associated anxiety-like behavior; comparison between Wistar-Kyoto and Sprague-Dawley rats

Introduction

Binge eating disorder (BED) is a widespread eating disorder that primarily affects women worldwide, and it is characterized by the presence of binge eating episodes and the absence of any compensatory behavior to prevent weight gain. BED presents elevated comorbidity with other psychiatric disorders, such as anxiety, and it has been suggested that stress sensibility could be a vulnerability factor for the development of BED and the associated anxiety comorbidity. In this study, we aim to investigate whether the Wistar-Kyoto rat strain (WKY), which has a stress hyper-reactive phenotype, could develop both binge-type eating and anxiety-like behaviors simultaneously. We also aim to compare its vulnerability to developing both behaviors with the Sprague Dawley rat strain (SD), a rat strain commonly used in binge-eating models.

Methods

WKY and SD rats were subjected to the model of intermittent access to palatable food (sucrose solution 30% or shortening) without calorie restriction or stress exposure. We evaluated and compared the development of binge-type eating behavior, anxiety-like behavior, and serum corticosterone variation as an index of the stress response in both rat strains.

Results

WKY rats presented a higher percentage of binge-type eaters and required less time to develop binge-type eating behavior than SD rats. The WKY eating pattern emulated a binge-eating episode regardless of the palatable food. Although the development of sucrose binge-type eating was similar between strains, WKY developed more easily the shortening binge-type eating than SD and was more susceptible to developing anxiety-like behavior. Additionally, sucrose binge eating seems to differentially affect both strains' hypothalamic-pituitary-adrenal (HPA) axis response to stress since it facilitated its response in SD and blunted it in WKY.

Discussion

Our results show that high-stress sensitive phenotype is a common vulnerability factor for the development of binge-type eating and anxiety-like behavior. Regardless of the macronutrient composition of the palatable food, WKY is susceptible to developing a binge-type eating behavior and is more susceptible than SD to developing anxiety-like behavior simultaneously. In conclusion, results showed that a hyper-reactive stress phenotype predisposes the development of binge-type eating behavior and anxiety-like behavior in the absence of calorie restriction and stress exposure.

Repeatability of measures of behavioral organization over two years in captive infant rhesus macaques, Macaca mulatta

Individual differences of infant temperament have been associated with future health outcomes that provide explanatory power beyond adult personality. Despite the importance of such a metric, our developmental understanding of personality-like traits is poor. Therefore, we examined whether young primates show consistency in personality traits throughout development. We replicated a Biobehavioral Assessment (BBA) at three time periods: 3-4 months, 1 year, and 2 years of age in 47 rhesus macaque (Macaca mulatta) subjects from large mixed-sex outdoor social housing units at the California National Primate Research Center. We report results for tests focused on responses and adaptation to the temporary separation and relocation, responses to a threatening stimulus, and ratings of overall temperament. We found consistently repeatable associations in measures of Emotionality; these associations were stronger in males, but also present in females, and broadly consistent between Years 1 and 2. We also explored whether behavioral responses to this experimental relocation might be influenced by their experience being relocated for other reasons (i.e., hospitalizations) as individuals' responses might be influenced by similar experiences to the BBA procedure. Only locomotion, during one of the assessments, was associated with past hospitalization events. Overall, repeatability in Emotionality-associated behaviors was evident across the 2 years, in both sexes. We did, however, find evidence of the emergence of sex differences via differentiated expression of behavioral responses during the BBA. We emphasize that there is likely contextual nuance in the use of these BBA factor-associated behaviors. Further research is required to determine whether and how shifts occur in underlying factor structure and the expression of associated behaviors.

Flexible feeding: Dairy cow personality affects changes in feeding behavior and milk production under feed competition conditions

The objective of this study was to determine the effect of individual cow personality traits on feeding behavior and production under low levels of feeding competition, and to determine whether personality traits influence how feeding behavior changes in response to greater feeding competition. Forty-two Holstein cows were assigned to 1 automated feed bin per cow (low competition condition) from 15 to 28 d in milk (DIM; period 1, P1), and 2 feed bins per 3 cows (higher competition condition) from 63 to 76 DIM (period 2, P2). A total mixed ration (TMR) was fed into the automated feed bins which recorded each feed bin visit time, duration, and intake. Cow personality traits were assessed at 21 DIM during P1 and at 70 DIM during P2 using a combined arena test, measuring behavioral responses to a novel environment, novel object, and novel human. Principal components analysis of behaviors observed during the P1 combined arena test revealed 1 factor (interpreted as active-explorative) from the novel environment test explaining 51% of the variance, and 3 factors (interpreted as fearfulness, active-explorative, and sociability toward conspecifics) from each of the novel object (76% cumulative variance) and human (75% cumulative variance) tests. The principal components analysis of behaviors observed during the P2 combined arena test revealed 2 factors jointly from the environment, object, and human tests (interpreted as fearfulness and active-explorative) that together explained 68% of the variance. Fearfulness and active-explorative trait scores were correlated across P1 and P2, indicating stability of personality over a challenging period and advancing DIM. In P2 when competition for feed was increased at greater stage of lactation, the more active-explorative cows appeared to make few alterations to their feeding behavior, yet still maintained their milk yield, compared with lower competition in P1. In contrast, cows who were more fearful increased their feed bin visits from P1 to P2, and less fearful cows increased their eating rate, without increased milk production, despite advanced lactation. Overall, the results indicate that cows of different personalities adopt different feeding strategies in response to a change in their environment, and may benefit from tailored management during challenging periods.

Individuals being high in their sensitivity to the environment: Are sensitive period changes in play?

All individuals on planet earth are sensitive to the environment, but some more than others. These individual differences in sensitivity to environments are seen across many animal species including humans, and can influence personalities as well as vulnerability and resilience to mental disorders. Yet, little is known about the underlying brain mechanisms. Key genes that contribute to individual differences in environmental sensitivity are the serotonin transporter, dopamine D4 receptor and brain-derived neurotrophic factor genes. By synthesizing neurodevelopmental findings of these genetic factors, and discussing them through the lens of mechanisms related to sensitive periods, which are phases of heightened neuronal plasticity during which a certain network is being finetuned by experiences, we propose that these genetic factors delay but extend postnatal sensitive periods. This may explain why sensitive individuals show behavioral features that are characteristic of a young brain state at the level of sensory information processing, such as reduced filtering or blockade of irrelevant information, resulting in a sensory processing system that 'keeps all options open'.

Infralimbic parvalbumin neural activity facilitates cued threat avoidance

The infralimbic cortex (IL) is essential for flexible behavioral responses to threatening environmental events. Reactive behaviors such as freezing or flight are adaptive in some contexts, but in others a strategic avoidance behavior may be more advantageous. IL has been implicated in avoidance, but the contribution of distinct IL neural subtypes with differing molecular identities and wiring patterns is poorly understood. Here, we study IL parvalbumin (PV) interneurons in mice as they engage in active avoidance behavior, a behavior in which mice must suppress freezing in order to move to safety. We find that activity in inhibitory PV neurons increases during movement to avoid the shock in this behavioral paradigm, and that PV activity during movement emerges after mice have experienced a single shock, prior to learning avoidance. PV neural activity does not change during movement toward cued rewards or during general locomotion in the open field, behavioral paradigms where freezing does not need to be suppressed to enable movement. Optogenetic suppression of PV neurons increases the duration of freezing and delays the onset of avoidance behavior, but does not affect movement toward rewards or general locomotion. These data provide evidence that IL PV neurons support strategic avoidance behavior by suppressing freezing.

Maintenance of Behavioral Variation under Predation Risk: Effects on Personality, Plasticity, and Predictability

AbstractClassic evolutionary theory predicts that predation will shift trait means and erode variance within prey species; however, several studies indicate higher behavioral trait variance and trait integration in high-predation populations. These results come predominately from field-sampled animals comparing low- and high-predation sites and thus cannot isolate the role of predation from other ecological factors, including density effects arising from higher predation. Here, we study the role of predation on behavioral trait (co)variation in experimental populations of guppies (Poecilia reticulata) living with and without a benthic ambush predator (Jaguar cichlid) to better evaluate the role of predation and where density was equalized among replicates twice per year. At 2.5 years after introduction of the predators (∼10 overlapping generations), 40 males were sampled from each of the six replicate populations and extensively assayed for activity rates, water column use, and latency to feed following disturbance. Individual variation was pronounced in both treatments, with substantial individual variation in means, temporal plasticity, and predictability (inverse residual variance). Predators had little effect on mean behavior, although there was some evidence for greater use of the upper water column in predator-exposed fish. There was greater variance among individuals in water column use in predator-exposed fish, and they habituated more quickly over time; individuals higher in the water column fed slower and had a reduced positive correlation with activity, although again this effect was time specific. Predators also affected the integration of personality and plasticity-among-individual variances in water column use increased, and those in activity decreased, through time-which was absent in controls. Our results contrast with the extensive guppy literature showing rapid evolution in trait means, demonstrating either increases or maintenance of behavioral variance under predation.

Towards an Integrated Concept of Personality in Human and Nonhuman Animals

Every individual has an idiosyncratic way of feeling, thinking and behaving, which is relatively stable across time and situations. Usually known as Personality, today this phenomenon is recognized in many species, including arthropods, fish, avian or mammals. From an evolutionary perspective, research has shown that personality differences are manifest in distinctive forms of dealing with selective pressures, with consequences for fitness. Despite these facts, the study of personality in animals other than humans is relatively new. Only two decades ago, consistent behavioral individual differences were considered 'noise' around an optimal strategy for behavioral ecologists. Also, psychologists were not interested in animal personality as a consequence of the fear of anthropomorphization and the erroneous belief that humans are unique in nature. Fortunately, this misconception seems already overcome but there are still conceptual issues preventing a unified concept of personality. Throughout this review, we first explore the etymological origins of personality and other terminological issues. We further revise the historical course of the study of personality in humans and other animals, from the perspectives of Psychology and Behavioral Ecology, on the basis of the most used approach, the trait theory. We present the study of nonhuman primates as a paradigmatic example in between both frameworks. Finally, we discuss about the necessity of a unified science of personality.

Energy allocation is revealed while behavioural performance persists after fire disturbance

Metabolic physiology and animal behaviour are often considered to be linked, positively or negatively, according to either the performance or allocation models. Performance seems to predominate over allocation in natural systems, but the constraining environmental context may reveal allocation limitations to energetically expensive behaviours. Habitat disturbance, such as the large-scale fire that burnt wetlands of Biebrza National Park (NE Poland), degrades natural ecosystems. It arguably reduces food and shelter availability, modifies predator-prey interactions, and poses a direct threat for animal survival, such as that of the wetland specialist root vole Microtus oeconomus. We hypothesized that fire disturbance induces physiology-behaviour co-expression, as a consequence of changed environmental context. We repeatedly measured maintenance and exercise metabolism, and behavioural responses to the open field, in a root voles from post-fire and unburnt locations. Highly repeatable maintenance metabolism and distance moved during behavioural tests correlated positively, but relatively labile exercise metabolism did not covary with behaviour. At the same time, voles from a post-fire habitat had higher maintenance metabolism and moved shorter distances than voles from unburnt areas. We conclude there is a prevalence of the performance mechanism, but simultaneous manifestation of context-dependent allocation constraints of the physiology-behaviour covariation after disturbance. The last occurs at the within-individual level, indicating the significance of behavioural plasticity in the context of environmental disturbance.

Use of infrared thermography to detect reactions to stressful events: does animal personality matter?

The study of the relationship between animal stress and personality for free-ranging animals is limited and provides contrasting results. The perception of stressors by an individual may vary due to its personality, and certain personality traits may help individuals to better cope with them. Using non-invasive infrared thermography (IRT), we investigated the link between physiological and behavioral components expressed during an acute stress event by free-ranging Fremont's squirrels (Tamiasciurus fremonti). We expected that, during the acute stress event of being approached by the researcher, individuals that showed a fast pace-of-life syndrome (bolder, more active, and less social/more aggressive) based on an arena test would exhibit stronger sympathetic-adrenal-medullary system reactivity showing a more intense stress-induced hyperthermia (high core body temperature and low peripheral temperature) than individuals with a slow pace of life (shy, less active, and more social). We successfully employed IRT technology to images of Fremont's squirrels with identification of the individuals' body parts (eye, nose, ear, hind foot). However, we found no support for our hypothesis. Squirrels' body surface temperatures told us more about a squirrel's external environment and less about the thermal state of the body in that environment following a stressful event. Further studies need to assess how to make IRT effective and efficient in the field and improve its performance in studying the relationships between physiology and personality in wildlife.

Structural consistency of exploratory behaviour of sub-adult and adult spiny mice (Acomys cahirinus) in seven different tests

The genus Acomys is of growing importance to many research fields. Previous research has shown that individuals differ when exploring new environments and that these behavioural strategies are consistent in time. In this study, we subjected 60 commensal Acomys cahirinus (37 males, 23 females) to a series of seven tests (free exploration, forced exploration under bright illumination, forced exploration under low illumination, hole board test, vertical activity test, elevated plus maze, and voluntary wheel running) to acquire independent behavioural traits and investigate whether and how personality develops in spiny mice. The full series of experiments was performed twice during ontogeny: once in the sub-adult stage (tested at 62-72 days of age) and once in the adult stage (102-112 days of age). We found that behaviour of the animals was repeatable both within (range of R values from 0.155 to 0.726) and across the two life-stages (0.238 to 0.563). While the structure of behaviour in adults was rather clear, it had not been fully crystalized in sub-adults, suggesting personality changes during maturation, even though some individual traits might be repeatable across ontogeny. Notably, the most consistent behavioural traits across the different tests were jumping and rearing, which are not commonly reported.

Effects of serta and sertb knockout on aggression in zebrafish (Danio rerio)

Zebrafish (Danio rerio) are unusual in having two paralogues of the serotonin re-uptake transporter (Sert), slc6a4a (serta) and slc6a4b (sertb), the transporter that serves in serotonin re-uptake from a synapse into the pre-synaptic cell or in serotonin uptake from the extracellular milieu into cells in the peripheral tissues. To address a knowledge gap concerning the specific roles of these paralogues, we used CRISPR/Cas9 technology to generate zebrafish knockout lines predicted to lack functional expression of Serta or Sertb. The consequences of loss-of-function of Serta or Sertb were assessed at the gene expression level, focusing on the serotonergic signalling pathway, and at the behaviour level, focusing on aggression. Whereas serta mRNA was expressed in all tissues examined, with high expression in the heart, gill and brain, only the brain displayed substantial sertb mRNA expression. In both serta-/- and sertb-/- fish, changes in transcript abundances of multiple components of the serotonin signalling pathway were detected, including proteins involved in serotonin synthesis (tph1a, tph1b, tph2, ddc), packaging (vmat2) and degradation (mao), and serotonin receptors (htr1aa, htr1ab). Using a mirror aggression test, serta-/- male but not female fish exhibited greater aggression than wildtype fish. However, both male and female sertb-/- fish displayed less aggression than their wildtype counterparts. These differences in behaviour between serta-/- and sertb-/- individuals hold promise for increasing our understanding of the neurophysiological basis of aggression in zebrafish.

[Effects of classical or heavy metal music in humans and animals: implications for intensive care medicine]

BACKGROUND

The importance of music in intensive care medicine is still controversial and the mechanisms of music are unclear. It is important whether different music styles (classical music [CM], Heavy Metal [HM] show measurable effects on blood pressure (BP) or heart rate (HR) in humans or not. It is also unclear whether behavioral patterns are influenced by music (CM, HM) in animals.

METHODS

We studied the influence of CM (Bach, Orchestral Suite No. 3, BWV 1068) and HM (Band Disturbed: Indestructible) compared to a control group (CO) without music exposure in 120 healthy subjects (60 study subjects, 60 control subjects) and 36 young pigs (18 Pietrains, 18 Wiesenauer Minipigs) according to an identical study protocol (21 minutes of music exposure (CM, HM) or 21 minutes of no music (C0).

RESULTS

We were able to clearly demonstrate in 36 pigs that CM led to significantly more activity behavior than HM or CO (p<0,01). HM caused significantly more stress behavior than CM or CO (p<0,01). In humans, there was a decrease in BPsyst, BPdiast or HR (beats per minute [bpm]) among CM: decrease BPsyst -7,5±9,1 mm Hg, BPdiast -4,9±7,5 mm Hg, HR -7,2±10,2 bpm. This was observed less frequently in HM: BPsyst -3,6±7,1 mm Hg, BPdiast -2,7±6,9 mm Hg, HR -5,9±9,0 bpm. The influence of BP and HR was significantly lower in CO compared to music: BPsyst -2,3±7,2 mm Hg, BPdiast -2,0±7,3 mm Hg, HR -5,8±12,3 bpm.

CONCLUSIONS

BP and HR in humans and behavioral patterns in animals are clearly influenced by music. CM leads more frequently to activity behavior in animals and to lower BP and HR in humans compared to HM or CO. In both animal breeds, stress behavior was observed more frequently in HM compared to CM or CO. Therefore, music may play a role in intensive care medicine.

Behavioral, physiological, and genetic drivers of coping in a non-human primate

Animals experience stressful situations, from predation to social conflicts, but mostly deal with them successfully. This adaptive mechanism, coping, reduces the adverse effects of stressors, and its failure may result in reduced fitness. Substantial inter-individual variation in coping is observed, yet little is known about how behavioral, physiological and genetic drivers regulate coping holistically and contribute to such variations. We assessed behavioral coping styles (n=30), emotional arousal (n=12), and personalities (n=32) of long-tailed macaques (Macaca fascicularis) and also investigated the association of coping with a valine/methionine polymorphism encoded by a critical human stress regulatory gene, catechol-O-methyltransferase (COMT) (n=26). Personality and the human equivalent COMT Val/Met polymorphism were associated with "nonaggression-based" and "aggression-based" coping styles. Compared to nonaggression-based, aggression-based copers maintained higher average facial temperatures, indicating potentially lower emotional arousal, as measured using infrared thermography. These findings demonstrate a complex interplay of various proximate mechanisms governing coping in a non-human primate.

Characterization and transcript expression analyses of four Atlantic salmon (Salmo salar) serpinh1 paralogues provide evidence of evolutionary divergence

Atlantic salmon (Salmo salar) are not only the world's most economically important farmed fish in terms of total value, but also a salmonid, which means that they are invaluable for studies of the evolutionary fate of genes following multiple whole-genome duplication (WGD) events. In this study, four paralogues of the molecular chaperone serpinh1 were characterized in Atlantic salmon, as while this gene is considered to be a sensitive biomarker of heat stress in salmonids, mammalian studies have also identified it as being essential for collagen structural assembly and integrity. The four salmon paralogues were cloned and sequenced so that in silico analyses at the nucleotide and deduced amino acid levels could be performed. In addition, qPCR was used to measure: paralogue- and sex-specific constitutive serpinh1 expression across 17 adult tissues; and their expression in the liver and head kidney of male Atlantic salmon as affected by stress phenotype (high vs. low responder), increased temperature, and injection with a multi-valent vaccine. Compared to the other three paralogues, serpinh1a-2 had a unique constitutive expression profile across the 17 tissues. Although stress phenotype had minimal impact on the transcript expression of the four paralogues, injection with a commercial vaccine containing several formalin inactivated bacterins increased the expression of most paralogues (by 1.1 to 4.5-fold) across both tissues. At 20 °C, the expression levels of serpinh1a-1 and serpinh1a-2 were generally lower (by -1.1- to -1.6-fold), and serpinh1b-1 and serpinh1b-2 were 10.2- to 19.0-fold greater, in comparison to salmon held at 12 °C. With recent studies suggesting a putative link between serpinh1 and upper thermal tolerance in salmonids, the current research is a valuable first step in elucidating the potential mechanisms involved. This research: supports the use of serpinh1b-1 and serpinh1b-2 as a biomarkers of heat stress in salmon; and provides evidence of neo- and/or subfunctionalization between the paralogues, and important insights into how multiple genome duplication events can potentially lead to evolutionary divergence.

Effects of temperament during handling and social rank on the blood biochemical parameters of common eland (Taurotragus oryx)

Large herbivores are subject to handling and social stress in captivity. These may affect blood biochemical values, which motivated this research. Twelve healthy common eland (Taurotragus oryx) were monitored for 12 months. The animals were handled monthly, and blood samples were collected. Samples from every second month were analysed for 14 blood biochemical parameters. Temperament throughout the handling, as the summation of various behavioural responses, was calculated as a proxy of the stress generated during handling. Social behaviour was recorded each month, and the agonistic interactions were used to calculate the social rank, which was considered a proxy of social stress. Generalised Linear Mixed Models were designed to test the effects of temperament and social rank on the blood biochemical parameters while keeping sex, age, body condition, and body weight as covariates. The results show that the temperament during handling influences blood levels of albumin, alkaline phosphate, blood urea nitrogen, glucose, total bilirubin, and total protein; however, social rank has little influence, affecting just albumin. The ranges observed in the values of these biochemical parameters were still within their reference intervals, implying the absence of pathology or physiological problems during the study. The results suggest that blood biochemical values of physically restrained common eland should be carefully interpreted, even in animals already habituated to routine handling. On the contrary, social rank has low effects on the blood biochemical parameters.

Hair cortisol concentration in finishing pigs on commercial farms: variability between pigs, batches, and farms

Hair cortisol is a stress indicator and could be used to assess the pigs' exposure to stressors in the weeks/months prior to non-invasive hair sampling. The main aim of this study was to describe the hair cortisol concentration (HCC) variability between individuals within a batch, between farms and between batches within a farm. The secondary aim was to determine how the number of sampled pigs influences the characterization of HCC within a batch. Twenty farrow-to-finish pig farms were recruited considering the diversity of their management practices and health status (data collected). Hair was sampled in two separate batches, 8 months apart. The necks of 24 finishing pigs were clipped per batch the week prior to slaughter. To describe the variability in HCC, an analysis of the variance model was run with three explanatory variables (batch, farm and their interaction). To identify farm clusters, a principal component analysis followed by a hierarchical clustering was carried out with four active variables (means and standard deviations of the two batches per farm) and 17 supplementary variables (management practices, herd health data). We determined how the number of sampled pigs influenced the characterization of HCC within a batch by selecting subsamples of the results. HCC ranged from 0.4 to 121.6 pg/mg, with a mean of 25.9 ± 16.2 pg/mg. The variability in HCC was mainly explained by differences between pigs (57%), then between farms (24%), between batches within the same farm (16%) and between batches (3%). Three clusters of farms were identified: low homogeneous concentrations (n = 3 farms), heterogeneous concentrations with either higher (n = 7) or lower (n = 10) HCC in batch 2 than in batch 1. The diversity of management practices and health statuses allowed to discuss hypotheses explaining the HCC variations observed. We highlighted the need to sample more than 24 pigs to characterize HCC in a pig batch. HCC differences between batches on six farms suggest sampling pigs in more than one batch to describe the HCC at the farm level. HCC variations described here confirm the need to study its links with exposure of pigs to stressors.

Temperament Behaviours in Individually Tested Sheep Are Not Related to Behaviours Expressed in the Presence of Conspecifics

Individual behavioural testing in sheep is common; however, outcomes may be misleading as they are a highly gregarious species that is usually managed in groups. We investigated whether behaviour expressed by 3-4-month-old Merino lambs (n = 220) in social isolation was related to their behaviour towards the same stimuli when three other conspecifics were present, and if measures of temperament (vocalisations and locomotory behaviours) were repeatable across both social situations. Expression of all behaviours were reduced when conspecifics were present, and vocalisations were rarely performed in social groups, suggesting that this behaviour is a response to social isolation. Similarities across the two social situations, in ranked order of how individual lambs expressed each behaviour, indicate that vigilance and attentional orienting towards a human were repeatable (p < 0.001), as was vigilance in a startle test (p < 0.05). However, no clear relationship between behaviours expressed across the two social situations was found. The results of this study suggest that testing sheep individually should be conducted with caution where the outcome is applied to animals managed in groups. Vigilance shows promise as a measure of an underlying trait that is stable across social contexts.

Characterization of social hierarchy formation and maintenance in same-sex, group-housed male and female C57BL/6 J mice

Social hierarchies are a prevalent feature of all animal groups, and an individual's rank within the group can significantly affect their overall health, typically at the greatest expense of the lowest-ranked individuals, or omegas. These subjects have been shown to exhibit various stress-related phenotypes, such as increased hypothalamic-pituitary axis activity and increased amygdalar corticotropin-releasing factor levels compared to higher-ranked subjects. However, these findings have been primarily characterized in males and in models requiring exhibition of severe aggression. The goals of the current study, therefore, were to characterize the formation and maintenance of social hierarchies using the tube test and palatable liquid competition in same-sex groups of male and female C57BL/6 J mice. We also aimed to examine the effects of tube test-determined social rank on plasma and hypothalamic oxytocin and vasopressin levels, peptides with established roles in social behaviors and the stress response. Lastly, we assessed the effects of environmental enrichment and length of testing on the measures outlined above. Overall, we demonstrated that males and females develop social hierarchies and that these hierarchies can be determined using the tube test. While we were unable to establish a consistent connection between peptide levels and social rank, we observed transient changes in these peptides reflecting complex interactions between social rank, sex, environment, and length of testing. We also found that many male and female omegas began to exhibit passive coping behavior after repeated tube test losses, demonstrating the potential of this assay to serve as a model of chronic, mild psychosocial stress.

Salivary corticosterone reflects plasmatic levels in a wild seabird

Wild animals have been increasingly exposed to a wide range of stressors, mainly due to the intensification of human activities and habitat modifications. Consequently, new tools in order to assess the physiological and health status of wild animals have been developed. In particular, glucocorticoids have received a special attention. Primarily metabolic hormones, they are also used to evaluate the stress level of organisms. While historically measured in blood samples, new less-invasive methods have been recently developed to measure glucocorticoids in matrices such as faeces, hairs/feathers, or saliva. To date, measurements in saliva are still in their infancy despite the numerous advantages of the matrix: non-invasive, reflects the biologically active portion of glucocorticoids, allows to measure both baseline and stress-induced levels. In addition, most studies using saliva have been performed on domestic and captive animals, and recent development in wild animals have focused on mammals. Here, we show, for the first time, that saliva could also be reliably used in free-ranging birds, as glucocorticoid levels in saliva strongly correlated with plasma levels. This promising result opens new avenues for a non-invasive sampling method to assess health status of wild birds in conservation biology and ecology.

Cat Inappropriate Elimination and its Interaction with Physical Disease

Inappropriate elimination or behavioral periuria/perichezia is likely the most reported feline behavioral problem worldwide. A change in behavior is often one of the early signs of physical disease and in addition can aggravate an existing behavioral response. An initial determination of causation is essential; is it medical or behavioral, or a combination of both? Stress activates both the sympathetic adrenomedullary system for short-term responses and the hypothalamic pituitary adrenal axis for long-term responses. Once medical problems have been treated or ruled out, attention should shift to minimizing and using various therapeutic options to help improve and/or resolve undesirable elimination problems.

Personality Affects Zebrafish Response to Sertraline

Sertraline is widely prescribed to treat anxiety and depression. Sertraline acts by blocking serotonin, norepinephrine, and dopamine transporters systems and has been detected in surface waters globally, where it may impact fish behavior. We classified zebrafish personality on three behavioral axes, boldness, anxiety, and sociability, assigning fish as either high or low in each category. The fish were exposed to nominal concentrations of 0, 5, 50, 500, or 5000 ng/L sertraline (measured concentrations: <10, 21.3, 370, and 2200 ng/L, respectively) to assess changes in boldness, anxiety, and sociability after 7 and 28 days. We also measured shoaling behavior and response to an alarm cue, and determined the gut microbiome of a subset of fish. After 7 days there was no overall effect of sertraline on boldness, but there was an interaction between initial personality and sex, with a stronger impact on females classified as low-boldness personality. Sertraline reduced sociability in all treatments compared with the control, but there was again an interaction between sertraline and initial personality. Fish that were classified as low-sociability responded more strongly to sertraline. After 7 days, fish exposed to a nominal concentration of 5000 ng/L (2200 ng/L measured) showed higher anxiety than controls, with the overall pattern of initial behavior retained. After 28 days, similar patterns were observed, but with higher variation. There was only a weak association between the gut microbiome and personality. Overall, the study highlights the importance of considering initial behavior, which can affect response to pollutants. Our results may also be applicable to human studies and provide a mechanism to explain why different individuals respond differently to the drug. Environ Toxicol Chem 2024;43:132-146. © 2023 SETAC.

A mouse model of the 3-hit effects of stress: Genotype controls the effects of life adversities in females

Helplessness is a dysfunctional coping response to stressors associated with different psychiatric conditions. The present study tested the hypothesis that early and adult adversities cumulate to produce helplessness depending on the genotype (3-hit hypothesis of psychopathology). To this aim, we evaluated whether Chronic Unpredictable Stress (CUS) differently affected coping and mesoaccumbens dopamine (DA) responses to stress challenge by adult mice of the C57BL/6J (B6) and DBA/2J (D2) inbred strains depending on early life experience (Repeated Cross Fostering, RCF). Three weeks of CUS increased the helplessness expressed in the Forced Swimming Test (FST) and the Tail Suspension Test by RCF-exposed female mice of the D2 strain. Moreover, female D2 mice with both RCF and CUS experiences showed inhibition of the stress-induced extracellular DA outflow in the Nucleus Accumbens, as measured by in vivo microdialysis, during and after FST. RCF-exposed B6 mice, instead, showed reduced helplessness and increased mesoaccumbens DA release. The present results support genotype-dependent additive effects of early experiences and adult adversities on behavioral and neural responses to stress by female mice. To our knowledge, this is the first report of a 3-hit effect in an animal model. Finally, the comparative analyses of behavioral and neural phenotypes expressed by B6 and D2 mice suggest some translationally relevant hypotheses of genetic risk factors for psychiatric disorders.

Prenatal exposure to bisphenol A and/or diethylhexyl phthalate alters stress responses in rat offspring in a sex- and dose-dependent manner

Background: Prenatal exposures to endocrine disrupting chemicals (EDCs) are correlated with adverse behavioral outcomes, but the effects of combinations of these chemicals are unclear. The aim of this study was to determine the dose-dependent effects of prenatal exposure to EDCs on male and female behavior. Methods: Pregnant Sprague-Dawley rats were orally dosed with vehicle, bisphenol A (BPA) (5 μg/kg body weight (BW)/day), low-dose (LD) diethylhexyl phthalate (DEHP) (5 μg/kg BW/day), high-dose (HD) DEHP (7.5 mg/kg BW/day), a combination of BPA and LD-DEHP (B + D (LD)), or a combination of BPA and HD-DEHP (B + D (HD)) on gestational days 6-21. Adult offspring were subjected to the Open Field Test (OFT), Elevated Plus Maze (EPM), and Shock Probe Defensive Burying test (SPDB) in adulthood. Body, adrenal gland, and pituitary gland weights were collected at sacrifice. Corticosterone (CORT) was measured in the serum. Results: Female EDC-exposed offspring showed anxiolytic effects in the OFT, while male offspring were unaffected. DEHP (HD) male offspring demonstrated a feminization of behavior in the EPM. Most EDC-exposed male offspring buried less in the SPDB, while their female counterparts showed reduced shock reactivity, indicating sex-specific maladaptive alterations in defensive behaviors. Additionally, DEHP (LD) males and females and B + D (LD) females displayed increased immobility in this test. DEHP (LD) alone and in combination with BPA led to lower adrenal gland weights, but only in male offspring. Finally, females treated with a mixture of B + D (HD) had elevated CORT levels. Conclusion: Prenatal exposure to BPA, DEHP, or a mixture of the two, affects behavior, CORT levels, and adrenal gland weights in a sex- and dose-dependent manner.

Clicker Training as an Applied Refinement Measure in Chickens

When using chickens in animal studies, the handling of these animals for sample collection or general examinations is considered stressful due to their prey nature. For the study presented here, plasma and salivary corticosterone as well as New Area Test behavior and fecal output were used to evaluate whether it is possible to influence this stress perception using a three-week clicker training program. The results indicate that clicker training seems to be a suitable refinement measure in the sense of cognitive enrichment for the husbandry of this species. However, since it was also shown that three-week training was not sufficient to sustainably reduce the stress perception with regard to prolonged stressor exposure, and since it was also evident that manipulations such as routine blood sampling are perceived as less stressful than assumed, further studies with prolonged training intervals and situations with higher stressor potential are warranted. Also, further parameters for training assessment must be considered. For the general use of training as a supportive measure in animal experiments, its proportionality must be considered, particularly considering the expected stress and adequate training time.

Environmentally relevant concentrations of triclocarban affect behaviour, learning, and brain gene expression in fish

Many chemicals spilled in aquatic ecosystems can interfere with cognitive abilities and brain functions that control fitness-related behaviour. Hence, their harmful potential may be substantially underestimated. Triclocarban (TCC), one of the most common aquatic contaminants, is known to disrupt hormonal activity, but the consequences of this action on behaviour and its underlying cognitive mechanisms are unclear. We tried to fill this knowledge gap by analysing behaviour, cognitive abilities, and brain gene expression in zebrafish larvae exposed to TCC sublethal concentrations. TCC exposure substantially decreased exploratory behaviour and response to stimulation, while it increased sociability. Additionally, TCC reduced the cognitive performance of zebrafish in a habituation learning task. In the brain of TCC-exposed zebrafish, we found upregulation of c-fos, a gene involved in neural activity, and downregulation of bdnf, a gene that influences behavioural and cognitive traits such as activity, learning, and memory. Overall, our experiments highlight consistent effects of non-lethal TCC concentrations on behaviour, cognitive abilities, and brain functioning in a teleost fish, suggesting critical fitness consequences of these compounds in aquatic ecosystems as well as the potential to affect human health.

Physiological response of roe deer (Capreolus capreolus) during stalking hunts depending on age

BACKGROUND

The European roe deer (Capreolus capreolus) is a species particularly reactive to all kinds of negative stimuli. Hunting activity is one of the most potent stressors that disturbs the welfare of wild animals. During stress, various endocrine responses are elicited to improve the physical performance of the affected individual. A commonly assessed hormone for overcoming stressful situations is cortisol (CORT). In this study, plasma CORT levels in roe deer were assessed during the season of the most intense stalking hunts in Poland (summer vs. late autumn), the sex of the harvested animals (males vs. females), and age of harvest animal. In addition, the health status of the roe doe was evaluated on the basis of selected indices of blood chemistry, which could be associated with circulating cortisol levels.

RESULTS

The mean cortisol levels were 58.066 ng/ml in the male group (summer) and 27.694 ng/ml in the female group (late autumn). Higher CORT levels were associated with a significantly lower of total cholesterol, lactate dehydrogenase, and uric acid (p < 0.05). Moreover, the mean concentration of uric acid was negatively correlated with the level of CORT in the male and female groups (p < 0.05). Together with the increase in mean CORT level, the HDL cholesterol of all the tested animals increased significantly (p < 0.05).

CONCLUSIONS

Higher CORT in males during the summer than in females during the late autumn were most likely due to the arousal with the mating season. The level of CORT increased with the animals' age. Uric acid and age are both predictors of roe deer's serum CORT level.

IoT and ML approach for ornamental fish behaviour analysis

Ornamental fish keeping is the second most preferred hobby in the world and it provides a great opportunity for entrepreneurship development and income generation. Controlling the environment in ornamental fish farm is a considerable challenge because it is affected by a variety of parameters like water temperature, dissolved oxygen, pH, and disease occurrences. One particular interesting ornamental fish species is goldfish (Carassius auratus). Machine learning (ML) and deep learning technique have significant potential in analysing voluminous data collected from fish farm. Through this technique, the fish farmers can get insight on feeding behaviour, fish growth patterns, predict diseases/stress, and environmental factors affecting fish health. The aim of the study is to analyze the behavioural changes in goldfish due to alterations in environmental parameters (water temperature and dissolved oxygen). Decision tree, Naïve Bayes classifier, K-nearest neighbour (KNN), and linear discriminant analysis (LDA) were used to analyse the behavioural change data. To compare the performance between all four classifiers, cross validation and confusion matrix used. The cross-validation error of LDA, Naïve Bayes classification, KNN and decision tree was 19.86, 28.08, 30.14 and 13.78 respectively. Decision tree was proved to be the most accurate and effective classifier. Different temperature and DO range were taken to predict fish behaviour. Some findings are, the behaviour of fish was rest between temperature 37.85 °C and 40.535 °C, erratic when temperature was greater than or equal to 40.535 °C, gasping when temperature was between 37.85 and 40.535 °C and when DO concentration was less than 6.58 mg/L. Blood parameter analysis has been done to validate the change in external behaviours with change in physiological parameters.

Are bold-shy personalities of European perch (Perca fluviatilis) linked to stress tolerance and immunity? A scope of harnessing fish behavior in aquaculture

The sensitivity to stress and its impact on immunity are supposedly related to a fish's personality. In the present study, European perch (Perca fluviatilis) were exposed to an open-field and a novel-object test to identify distinctive shy and bold individuals. This series of cognitive tests revealed clear differences between proactive individuals with pronounced exploration behavior (bold personality) and reactive individuals that took a freeze-hide position (shy personality). A cohort of shy and bold perch was then exposed to elevated stocking density. Frozen activity and lower explorative behavior were related to higher basal and stocking-induced cortisol levels compared to proactive individuals. Since cortisol is a well-known modulator of immune-gene expression, we used multiplex real-time PCR to profile the differential immune responses to the intraperitoneal injection of Aeromonas hydrophila in the head kidney and peritoneal cells of bold and shy perch individuals. These expression differences between stimulated bold and shy perch were generally modest, except for the genes encoding the complement component c3 and the matrix metallopeptidase mmp9. The strong differential expression of these two bactericidal and inflammatory genes in the context of the modestly regulated features suggests that a fish's personality is linked to a particular immune-defense strategy. In conclusion, our approach, based on behavioral video observations, phagocytosis and enzyme assays, immunogene-expression profiling, and quantification of stress-relevant metabolites, revealed indications for divergent coping styles in cohorts of bold or shy European perch. This divergence could be exploited in future selective breeding programs.

Impact of stress phenotype, elevated temperature, and bacterin exposure on male Atlantic salmon (Salmo salar) growth, stress, and immune biomarker gene expression

In this study, postsmolt male Atlantic salmon, previously identified as low responders (LRs) or high responders (HRs) based on poststress cortisol levels, had their head kidney and liver sampled at 12°C and 20°C before injection (time 0) and after injection (i.e., at 12- and 24-h postinjection, respectively) with either Forte Micro (a multivalent vaccine containing bacterin, to capture peak antibacterial responses) or an equal volume of PBS. Quantitative real-time PCR (qPCR) was then used to measure the expression of 15 biomarker genes in the head kidney and 12 genes in the liver at each temperature/sampling point. Target transcripts were chosen that were related to growth, stress, and innate antibacterial immune responses. Many temperature, phenotype, and injection effects were found for individual genes within these three broad categories, and multivariate statistical analyses (i.e., principal component analysis and permutational multivariate analysis of variance) were used to look for overall patterns in transcript expression. These analyses revealed that HR salmon at 20°C mounted a more robust response (P < 0.05) for the 10 head kidney immune-related transcripts when injected with Forte Micro than LR salmon. In contrast, the seven liver stress-related transcripts displayed a greater response (P = 0.057) in LR versus HR fish with Forte Micro at 12°C. Overall, although this research did find some differences between LR and HR fish, it does not provide strong (conclusive) evidence that the selection of a particular phenotype would have major implications for the health of salmon over the temperature range examined.NEW & NOTEWORTHY This is the first paper to describe the impact of both temperature and bacterial stimulation on head kidney and liver transcript expression in Atlantic salmon characterized as LRs versus HRs. Notably, we found that HR salmon at 20°C mounted a more robust innate antibacterial immune response than LR salmon. In addition, LR fish at 12°C may (P = 0.057) exhibit higher expression of stress-related transcripts in response to vaccine injection relative to HR fish.

Graduate Student Literature Review: Sociability, fearfulness, and coping style-Impacts on individual variation in the social behavior of dairy cattle

Dairy cattle typically live in groups, but individuals within these groups vary in their social behavior. An improved understanding of factors affecting the expression of social behavior may help refine management practices on farms to better accommodate the needs of all individuals within the herd. In this paper, we review (1) some examples of how social behavior is expressed in cattle, (2) commonly assessed personality traits in this species (i.e., sociability and fearfulness) as well as coping style, and (3) how these can affect the expression of social behavior of dairy cattle and in turn their welfare. We also identify understudied social behaviors that personality might influence (social learning, social stress, and social buffering of negative emotions), and that could inform how to improve the welfare of intensively housed dairy cattle.

Impacts of repeated social defeat on behavior and the brain in a cichlid fish

Social defeat is a powerful experience leading to drastic changes in physiology and behavior, many of which are negative. For example, repeated social defeat in vertebrates results in reduced reproductive success, sickness and behavioral abnormalities that threaten individual survival and species persistence. However, little is known about what neural mechanisms are involved in determining whether an individual is resilient or susceptible to repeated social defeat stress. It also remains unknown whether exclusive use of reactive behaviors after repeated social defeat is maintained over time and impacts future behaviors during subsequent contests. We used a resident-intruder experiment in the African cichlid fish Astatotilapia burtoni to investigate the behavior and neural correlates of these two opposing groups. Behavior was quantified by watching fish during defeat trials and used to distinguish resilient and susceptible individuals. Both resilient and susceptible fish started with searching and freezing behaviors, with searching decreasing and freezing increasing after repeated social defeat. After a 4 day break period, resilient fish used both searching and freezing behaviors during a social defeat encounter with a new resident, while susceptible fish almost exclusively used freezing behaviors. By quantifying neural activation using pS6 in socially relevant brain regions, we identified differential neural activation patterns associated with resilient and susceptible fish and found nuclei that co-varied and may represent functional networks. These data provide the first evidence of specific conserved brain networks underlying social stress resilience and susceptibility in fishes.

Non-invasive, real-time stress measurement: Vocalization compared with thermal imaging in kittens of the domestic cat in response to social separation

Finding tools to assess the stress response which can be easily applied, are non-invasive, reliable and measured in real time is still a relevant topic in many areas of biology. Vocal characteristics and temperature of certain body areas have been suggested to reflect HPA axis and ANS activation. We hypothesized that changes in vocalizations and peripheral body temperature will show the magnitude of the stress response, and that the change in these will covary. Our aim was to measure the change in vocal characteristics and eye and nasal temperature of kittens (n = 43 from nine litters of seven mixed-breed mothers) during a potentially stressful event and to test how these correlated. We found change in several vocal and thermal parameters during a short social separation. Our findings indicate that arousal due to ANS activation in kittens of the domestic cat resulted in an increasing number of vocalisations of longer duration and higher intensity, and in lower and a wider range in fundamental frequency. Calls also became less tonal with more jitter. Change in temperature was generally negative in the lacrimal caruncle as well as in the rhinarium, but with great variance across individuals. Change in eye temperature positively correlated with the intensity of the calls and the change in nose temperature positively correlated with the change in call length. The results suggest the continued difficulty in interpreting both physiological and behavioural data to assess an individual´s stress response.

Maze design: size and number of choices impact fish performance in cognitive assays

Although studies on fish cognition are increasing, consideration of how methodological details influence the ability to detect and measure performance is lagging. Here, in two separate experiments the authors compared latency to leave the start position, latency to make a decision, levels of participation and success rates (whether fish entered the rewarded chamber as first choice) across different physical designs. Experiments compared fish performance across (a) two sizes of T-mazes, large and standard, and a plus-maze, and (b) open choice arenas with either two or four doors. Fish in T-mazes with longer arms took longer to leave the start chamber and were less likely to participate in a trial than fish in T-mazes with shorter arms. The number of options, or complexity, in a maze significantly impacted success but did not necessarily impact behavioural measures, and did not impact the number of fish that reached a chamber. Fish in the plus-maze had similar latencies to leave the start box and time to reach any chamber as fish in the same-sized T-maze but exhibited lower overall success. Similarly, in an open choice arena, increasing the number of options - doors to potential reward chambers - resulted in lower probability of success. There was an influence of reward position in the choice arena, with rewarded chambers closest to the sides of the arena resulting in lower latencies to enter and higher probability of decision success. Together the results allow the authors to offer practical suggestions towards optimal maze design for studies of fish cognition.

Reaction to Novel Objects and Fecal Glucocorticoid Metabolite Levels in Two Species of Nocturnal Geckos

Many reptiles are maintained in captivity and heavily traded, although welfare measures for many species are not well established and are under-researched compared to other animals. In this study, we focused on two of these species: crested geckos (Correlophus ciliatus) and leopard geckos (Eublepharis macularius). To better interpret their behavior in captivity, the individual reaction to novel objects and the fecal glucocorticoid metabolite levels were measured in an attempt to identify the potential correlation between them. Also, we explored if some characteristic of the objects (e.g., color, shape, or smell) resulted in being more attractive to some species and/or individuals. Equivalent responses to different objects were not obtained for all the geckos, the behavioral response being highly individual and context-dependent, although modulated by the species. Individuals which manipulated earlier and interacted longer with novel objects showed lower basal fecal corticosterone metabolite (FCM) levels. Differences according to the species suggested that crested geckos have significantly greater and more variable FCM levels than leopard geckos. Our results can help to understand the reaction of geckos to novelty and have the potential to serve in their welfare assessment, although more studies are needed to proper establish welfare protocols.

Anxiety Modulation by Cannabinoids-The Role of Stress Responses and Coping

Endocannabinoids were implicated in a variety of pathological conditions including anxiety and are considered promising new targets for anxiolytic drug development. The optimism concerning the potentials of this system for anxiolysis is probably justified. However, the complexity of the mechanisms affected by endocannabinoids, and discrepant findings obtained with various experimental approaches makes the interpretation of research results difficult. Here, we review the anxiety-related effects of the three main interventions used to study the endocannabinoid system: pharmacological agents active at endocannabinoid-binding sites present on both the cell membrane and in the cytoplasm, genetic manipulations targeting cannabinoid receptors, and function-enhancers represented by inhibitors of endocannabinoid degradation and transport. Binding-site ligands provide inconsistent findings probably because they activate a multitude of mechanisms concomitantly. More robust findings were obtained with genetic manipulations and particularly with function enhancers, which heighten ongoing endocannabinoid activation rather than affecting all mechanisms indiscriminately. The enhancement of ongoing activity appears to ameliorate stress-induced anxiety without consistent effects on anxiety in general. Limited evidence suggests that this effect is achieved by promoting active coping styles in critical situations. These findings suggest that the functional enhancement of endocannabinoid signaling is a promising drug development target for stress-related anxiety disorders.

Fish personality: meta-theoretical issues, personality dimensions, and applications to neuroscience and psychopathology

While the field of personality neuroscience has extensively focused on humans and, in a few cases, primates and rodents, a wide range of research on fish personality has emerged in the last decades. This research is focused mainly on the ecological and evolutionary causes of individual differences and also aimed less extensively at proximal mechanisms (e.g., neurochemistry or genetics). We argue that, if consistent and intentional work is made to solve some of the meta-theoretical issues of personality research both on fish and mammals, fish personality research can lead to important advances in personality neuroscience as a whole. The five dimensions of personality in fish (shyness-boldness, exploration-avoidance, activity, aggressiveness, and sociability) need to be translated into models that explicitly recognize the impacts of personality in psychopathology, synergizing research on fish as model organisms in experimental psychopathology, personality neuroscience, and ecological-ethological approaches to the evolutionary underpinnings of personality to produce a powerful framework to understand individual differences.

Individual differences in behaviour are related to metabolism, stress response, testosterone, and immunity in the subterranean rodent Ctenomys talarum

The growth of personality research has led to the integration of consistent variation of individual behaviour in multidimensional approaches including physiological variables, which are required to continue building a more comprehensive theory about coping strategies. In this study, we used wild-caught males of Ctenomys talarum (tuco-tucos), a solitary subterranean rodent, to assess the relationships among personality traits and several physiological variables, namely stress response, testosterone, immunity, and energy metabolism. Subjects (n = 21) were used in experimental tests assessing behaviour, energy metabolism, testosterone levels, inflammatory cell-mediated and humoral immunity, and stress response to a simulated predator attack. The structural equation model explained a moderate portion of the variance of personality behaviours related to activity (52%), boldness (35%), and socioaversion (30%). More active and bold individuals showed higher oxygen consumption. While those subjects had lower baseline cortisol levels, there was no relationship between cortisol levels of the stress-induced response. Cell-mediated immune response was related to activity levels. Finally, testosterone only affected boldness. Despite some of these relationships diverge in direction to predicted ones, overall they support the existence of coping styles in male C. talarum; and are discussed in the light of current hypotheses and particular behavioural and ecological traits of tuco-tucos.

CATastrophic myths part 1: Common misconceptions about the social behavior of domestic cats and implications for their health, welfare, and management

Cats are among the most popular pets worldwide, but there are still major gaps in the public's general understanding of their social behaviors and related needs, including for socialization. In addition to these knowledge gaps, people often have negative or ambivalent attitudes about cats, which can directly impact their welfare outcomes. Insufficient attention to the behavioral ecology and development of cat sociality, along with failure to account for their highly variable individual preferences and tolerance for social behaviors can lead them to experience distress that undermines both their welfare and the human-animal bond. As Part 1 of a two-part series addressing common myths about cats, the purpose of this first paper is to review and debunk common misperceptions about the social needs and behaviors of cats, including misunderstandings about their social lives and abilities to bond with humans. We also identify where opportunities exist to improve socialization of cats and to advance research in related areas that might better support their behavior and welfare needs.

Individual differences in response to alcohol and nicotine in zebrafish: Gene expression and behavior

Alcohol and nicotine are psychoactive substances responsible for serious health consequences. Although the biological mechanisms of alcohol and nicotine have been studied extensively, individual differences in the response to these drugs have received little attention. Here we evaluated gene expression and behavior of bold and shy individuals after acute exposure to alcohol and nicotine. For this, zebrafish were classified as bold and shy individuals based on emergence tests, and then fish were exposed to 0.00, 0.10, and 0.50% alcohol or 0.00, 1.00, and 5.00 mg/L nicotine and their anxiety-like and locomotor behavior was observed. After behavioral assessment, brain mRNA expression (ache, bdnf, gaba1, gad1b, th1, and tph1) was evaluated. Locomotion patterns differed between profiles depending on alcohol and nicotine concentration. Anxiety increased in shy fish and decreased in bold fish after exposure to both drugs. Alcohol exposure induced an increase in tph1 mRNA expression in bold fish, while bdnf mRNA expression was increased in shy fish. Nicotine increased ache, bdnf, and tph1 mRNA levels in both profiles, but at higher levels in bold fish. Based on our research, we found that alcohol induces anxiogenic effects in both bold and shy zebrafish. Additionally, shy individuals exposed to a low concentration of nicotine exhibited stronger anxiety-like responses than their bold counterparts. These findings further support the validity of using zebrafish as a dependable tool for studying the effects of drugs and uncovering the underlying mechanisms associated with individual variations.

Age-related impairment in fear memory extinction is restored by ketamine in middle-aged mice

Posttraumatic stress disorder (PTSD), a disabling and chronic condition after exposure to an extreme traumatic event, affects approximately 8% of the population worldwide. However, the underlying mechanisms of PTSD are not clear. The ability to manage fear memories is critical for PTSD. Differences in stress responsiveness and coping strategies by age represent an important starting point for the understanding and prevention of PTSD. However, we do not know whether the ability to cope with fear memories is decreased in middle-aged mice. To investigate this, we compared fear memory extinction among different age groups of mice. We found that middle-aged mice exhibited impaired fear memory extinction, which was accompanied by sustained enhanced long-term potentiation (LTP) induction in the extinction process. Most interestingly, ketamine treatment restored the impaired fear memory extinction in middle-aged mice. Moreover, ketamine could ameliorate the increased LTP during the extinction process through a presynaptic mechanism. Altogether, our results indicated that middle-aged mice were unable to extinguish fear memories, which could be treated with ketamine via presynaptic-mediated synaptic plasticity in middle-aged mice, suggesting that ketamine administration may be a new strategy for the treatment of PTSD.

Predator-prey systems as models for integrative research in biology: the value of a non-consumptive effects framework

Predator-prey interactions are a cornerstone of many ecological and evolutionary processes that influence various levels of biological organization, from individuals to ecosystems. Predators play a crucial role in shaping ecosystems through the consumption of prey species and non-consumptive effects. Non-consumptive effects (NCEs) can induce changes in prey behavior, including altered foraging strategies, habitat selection, life history and anti-predator responses. These defensive strategies have physiological consequences for prey, affecting their growth, reproduction and immune function to name a few. Numerous experimental studies have incorporated NCEs in investigating predator-prey dynamics in the past decade. Interestingly, predator-prey systems can also be used as experimental models to answer physiology, cognition and adaptability questions. In this Commentary, I highlight research that uses NCEs in predator-prey systems to provide novel insights into cognition, adaptation, epigenetic inheritance and aging. I discuss the evolution of instinct, anxiety and other cognitive disorders, the shaping of brain connectomes, stress-induced aging and the development of behavioral coping styles. I outline how studies can integrate the investigation of NCEs with advanced behavioral, genomic and neurological tools to provide novel insights into physiological and cognitive health.

Effect of Hooding on Physiological Parameters During Manual Restraint in Rhode Island Red Hybrid Hens (Gallus gallus domesticus)

Manual handling of chickens is required for many veterinary, research, and breeding procedures. This study aimed to assess the changes in physiological parameters over time during manual restraint of chickens, as well as the effect of hooding on these parameters. Heart rate, heart rate variability, respiratory rate, and body temperature were measured every 3 minutes for 15 minutes during manual restraint in 13 adult laying hens (Gallus gallus domesticus). Heart rate variability was significantly higher in hooded hens than in nonhooded hens (P= 0.003) but was not significant over time. Hooded hens were also found to have significantly lower heart rate (P = 0.043) and respiratory rate (P = 0.042) compared to nonhooded hens. Heart rate and respiratory rate significantly decreased over time, independent of the use of the hood (P = 0.008; P = 0.01, respectively). Temperature was found to increase significantly (P = 0.001) over time for both groups. Overall, hooding increased heart rate variability, a factor associated with a lower stress level, and decreased heart rate and respiratory rate. In conclusion, these data suggest that the use of the hood reduces stress levels in birds during manual restraint. Therefore, the use of the hood is encouraged for short (less than 15 minutes) painless procedures, such as physical examination or radiographic acquisition.