PSX-B-23 Immune tolerance of dairy heifers in response to repeated bacterial endotoxin exposure

Lipopolysaccharide (LPS) endotoxin from the membrane of Gram-negative bacteria is often used to simulate bacterial infection in mammals. Repeated exposure to LPS over a short period of time, however, is reported to result in an attenuated acute-phase response. This “LPS tolerance” is an essential immune-homeostatic response that can protect against over-activation of the inflammatory response during chronic exposure to LPS. In the present study, Holstein calves (n=20) were initially intramuscularly challenged with either saline, or 100, 200 or 400 ng/kg of LPS and then all animals were re-challenged with 200 ng/kg of LPS 2-weeks later to assess potential LPS tolerance in ruminants. Serum was collected every 2 hrs for 6 hrs to profile changes in circulatory stress biomarkers. In comparison to the first challenge and saline control animals that received LPS for the first time, heifers re-challenged with LPS demonstrated significantly attenuated cortisol responses in the second LPS challenge (p < 0.05). Blood cell populations were also attenuated in animals receiving their second LPS challenge, in that re-challenged animals showed significantly less severe thrombocytopenic (p < 0.05), and leukopenic responses to their second LPS challenge as compared to their first (p < 0.05); this trend was also apparent when comparing newly LPS-challenged animals to the LPS re-challenged animals. MicroRNA expression profiles were determined to assess a potential epigenetic response to repeated LPS exposure, which may help identify therapeutic targets to protect against LPS-associated diseases including clinical mastitis and sepsis. The present study demonstrated that LPS tolerance occurs in dairy cattle, and understanding the roles of various miRNAs in the context of innate immune cell tolerance is essential for evaluating their impact on immune system homeostasis.

The Effects of Stocking Density and Distances on Electroencephalographic Changes and Cortisol as Welfare Indicators in Brahman Crossbred Cattle

The objective of the current study was to investigate the effects of stocking density and distances on electroencephalographic changes and cortisol as welfare indicators in Brahman crossbred cattle. Sixty Brahman crossbred heifers were subjected to road transport from a cattle feedlot farm located in Universiti Putra Malaysia (UPM), Serdang to a commercial ruminant abattoir in Shah Alam, Selangor. Animals were assigned to long (850 km) and short (450 km) distances and high (600 sqm), medium (400 sqm), and low (200 sqm) stocking densities. Results revealed that the intensity of cortisol responses and EEG parameters (such as alpha <0.001, beta < 0.001, delta < 0.001, theta < 0.001, MF < 0.001 and Ptot < 0.001) increased significantly. Long-distance transport also resulted in significantly more intense (<0.001) responses to nociception during slaughter than animals that had been transported over a shorter distance, as indicated by EEG and cortisol.

Physiological Stress in Rescued Wild Koalas (Phascolarctos cinereus) Being Held in a Rehabilitation Sanctuary: A Pilot Study

Koalas (Phascolarctos cinereus) are one of Australia’s most charismatic native small marsupial species. Unfortunately, populations of koalas are rapidly declining throughout Australia as they continue to face increasing pressure from a changing ecosystem. All wildlife species to some degree will use their hypothalamic–pituitary–adrenal (HPA) axis in response to stress. Depending on the duration of activation, the stress response can lead to either acute or chronic side effects and is modulated through the neuroendocrine stress system with the release of catecholamines and glucocorticoids (e.g., cortisol). It is well known that rehabilitation sanctuaries are inherently stressful for all animals, in particular for rescued wild koalas, as it is an unfamiliar environment where the animals cannot predict or control what will happen to them. In this pilot study, we set out to quantify faecal and fur cortisol metabolites in wild rescued koalas undergoing wildlife rehabilitation. Absolute levels of acute and chronic stress were indexed non-invasively, with faecal samples taken to evaluate acute stress, and fur samples taken to evaluate chronic stress. Sampling occurred sporadically over four months (the start of September 2018 to the end of December 2018), and was performed on three rescued koalas (Maree, Tai, and Solstice) being held at the rehabilitation centre. Results of this study show that between the three koalas, the highest recorded faecal cortisol result was 241 ng/g, and the lowest recorded faecal cortisol result was 4 ng/g, whereas the highest recorded fur cortisol result was 1.75 ng/g, and the lowest recorded fur cortisol result was 0.10 ng/g. Statistically, there was a significant difference between all three koalas and their faecal cortisol responses, as well as their fur cortisol responses. Statistically for Maree and Solstice, there was a significant difference in their faecal cortisol response between days when a stressor was recorded, and days when a stressor was not recorded. However, statistically for Tai, this was not the case, as there was no significant difference in his faecal cortisol response between days when a stressor was recorded, and days when a stressor was not recorded. In summary, the hypothesis that faecal glucocorticoids and fur glucocorticoids between koalas will differ based on individual responses to stressors was true as a whole, but individually, this hypothesis was true for Maree and Solstice, but untrue for Tai. The use of biological samples such as faeces and fur to obtain readings of glucocorticoids is a method of measuring absolute levels of physiological stress that is still evolving for koalas, and there is no current glucocorticoid baseline with which to compare the results of this study; although, measuring faecal and fur glucocorticoids is the first step in understanding how koalas undergoing wildlife rehabilitation respond to stressors.

Brain 5-HT1A Receptor PET Binding, Cortisol Responses to Stress, and the Familial Transmission of Suicidal Behavior

Background The serotonin 1A (5-HT1A) receptor has been implicated in depression and suicidal behavior. Lower resting cortisol levels are associated with higher 5-HT1A receptor binding, and both differentiate suicide attempters with depression. However, it is not clear whether 5-HT1A receptor binding and cortisol responses to stress are related to familial risk and resilience for suicidal behavior. Methods [ 11C]CUMI-101 PET imaging to quantify regional brain 5-HT1A receptor binding was conducted in individuals considered to be at high-risk for mood disorder or suicidal behavior on the basis of having a first or second degree relative(s) with an early onset mood disorder and history of suicidal behavior. These high-risk subjects were subdivided into: high-risk resilient having no mood disorder or suicidal behavior (HR-R, n=29); high-risk with mood disorder and no suicidal behavior history (HR-MOOD n=31); and high-risk with mood disorder and suicidal behavior (HR-SA/MOOD, n=25). Groups were compared to healthy volunteers without a family history of mood disorder or suicidal behavior (HV, n=34). Participants underwent the Trier Social Stress Task (TSST). All subjects were free from psychotropic medications at the time of the TSST and PET scanning. Results We observed no group differences in 5-HT1A receptor binding considering all regions simultaneously, nor did we observe heterogeneity of the effect of group across regions. These results were similar across outcome measures (BPND for all subjects and BPp in a subset of the sample), and definitions of regions of interest (ROIs; standard or serotonin system-specific ROIs). We also found no group differences on TSST outcomes. Within HR-SA/MOOD, lower BPp binding [β=-0.084, Standard Error or SE=0.038, p=0.048] and higher cortisol reactivity to stress [β=9.25, 95% CI (3.27,15.23), p=0.004] were associated with higher lethality attempts. There were no significant relationships between 5-HT1A binding and cortisol outcomes. Conclusions 5-HT1A receptor binding in ROIs was not linked to familial risk or resilience protecting against suicidal behavior or mood disorder although it may be related to lethality of suicide attempt. Future studies are needed to better understand the biological mechanisms implicated in familial risk for suicidal behavior and how HPA axis function influences such risk.

Associations between Personality Traits and Basal Cortisol Responses in Sailing Athletes

There is a paucity of literature regarding the psycho-physiological profiles of sailors on board. This study aimed at providing empirical evidence on the individual differences between bowmen and helmsmen taking into account a biopsychological perspective. To this purpose, sailors’ profiles were examined by focusing on the association between personality traits and basal cortisol. The sample was composed of 104 athletes (Mage = 21.32, SD = 0.098; F = 35%), who fulfilled a self-reported questionnaire including a socio-demographic section and the Big Five questionnaire. Cortisol samples were collected on the day before the competition, within 30 min after awakening. T-test analysis showed significant differences on cortisol levels: bowmen obtained higher levels on cortisol responses compared to helmsmen. No differences emerged on personality traits between athletes’ roles. Bivariate associations showed positive associations of cortisol responses with extraversion and conscientiousness in bowmen, whereas no significant associations of cortisol with personality traits were found in helmsmen. Regression analyses confirmed that sex and extraversion predicted higher level of cortisol responses. Results were discussed in terms of a bio-psychosocial theoretical approach and provided findings on the relationships between personality trait and the hypothalamus-pituitary adrenal (HPA) system in dinghy sailors. Suggestions for a more suitable selection of sailor roles were given to coaches in order to improve athletes’ performance.

Non-genetic maternal effects shape individual differences in cortisol phenotypes in wild chimpanzees

Glucocorticoids, such as cortisol, mediate homeostatic processes, allowing individuals to adjust to fluctuating environments. The regulation of circadian cortisol responses, a key homeostatic function, has been shown to be heritable. However, to understand better the role of parental care in shaping physiological functioning in long-lived mammals with protracted parental care, there is a need to disentangle genetic and non-genetic parental contributions to variation in glucocorticoid phenotypes. We used a dataset of 6,123 cortisol measures from urine samples from 170 wild chimpanzees spanning 18 years of data collection. We found consistent inter-individual differences in circadian cortisol phenotypes, with differences most apparent when considering average cortisol levels given the effect of time of day. Maternal effects explained around 10% (2-18%) variation in these average cortisol levels, while variation attributable to genetic factors was not distinguishable from zero. Our results indicate, relative to genetic effects, a qualitatively stronger influence of mothers, whether via epigenetic processes or via behavioral priming for coping with stressors, in shaping cortisol phenotypes in this species. This provides novel insight into the vital role of mothers in the developmental plasticity of long-lived mammals and, more generally, the selective pressures shaping physiological plasticity.