Differences In Plasma Cortisol Concentrations Research Articles

Influence of weaning management on gastritis incidence in foals

This study evaluated the incidence of gastritis in foals subjected to different weaning management methods. Sixteen crossbreed foals [230 ± 35 kg], were enrolled in an experiment with a randomized block design. After weaning, foals were housed in either individual pens or a group pen. Gastritis in the foals was evaluated through gastroscopy. Data were submitted to analysis of variance by the non-parametric Friedman test at 0.05 significance level. Before weaning, gastritis was observed in 87.5% of the foals, and the scores for the number of gastric lesions were 2.10 and 1.56 for foals housed in group and individual pens, respectively. After weaning, the scores for the number of gastric lesions were 1.75 and 1.25 for foals housed in group and individual pens, respectively. For the intensity of gastric lesions, the average scores observed before weaning were 3.31 and 1.37 for foals housed in groups and individual pens, respectively. After weaning, the scores for the intensity of gastric lesions were 1.93 and 1.00 for foals housed in group and individual pens, respectively. The intensity of the gastric lesions decreased when comparing foals prior to weaning and after weaning, regardless of the management system (P < .05). The number of lesions was not significantly different but tended to decrease after weaning. Differences in plasma cortisol concentrations were observed between samples collected on the weaning date and after weaning (P < .05). No differences were detected in plasma gastrin concentration. In conclusion, gastritis in foals can be observed before weaning, which contributes to a decreased gastric lesion incidence.

Biomarker response and hypothalamus-pituitary-interrenal axis functioning in Arctic charr from Bjørnøya (74°30′ N), Norway, with high levels of organohalogenated compounds

The populations of Arctic charr (Salvelinus alpinus) residing in Lake Ellasjøen at Bjørnøya Island in the Norwegian Arctic (74° 30′N, 19° 00′E) possess substantially higher levels of organohalogenated compounds (strongly dominated by polychlorinated biphenyls, PCBs) than conspecifics residing in other, proximate lakes on the island. In the present study we sampled large (<400g), immature charr from Lake Ellasjøen (high PCB levels) and Lake Laksvatn (reference lake, low PCB levels) by hook and line for an immediate blood sampling, and blood and tissue sampling after a 1h confinement stressor. This was done in order to investigate possible effects of pollutants on an acute stress performance in a high-latitude fish species by comparing muscle PCB levels, hepatic cytochrome P4501A (CYP1A) biomarker activation and functioning of the hypothalamus-pituitary-interrenal (HPI) axis between these two populations of Arctic charr. As expected sum PCB muscle levels were 8-fold higher on a wet weigh basis, and 19-fold higher on a lipid weight basis, in charr from Ellasjøen than in charr from Laksvatn. This was accompanied by a 3.5-fold higher liver cyp1a mRNA abundance in the Ellasjøen charr compared to Laksvatn charr. Brain transcript levels encoding glucocorticoid receptor 1 and 2 (GR2) and corticotropin-releasing factor, and pituitary transcript levels encoding GR2 and proopiomelanocortin A1 and A2 were higher in Ellasjøen charr than in Laksvatn charr, while interrenal transcript levels encoding melanocortin 2 receptor and steroidogenic acute regulatory protein were lower. There were no differences in plasma cortisol concentration between the two charr populations immediately after capture and one hour after confinement. The strong biomarker response to OHCs and altered mRNA abundances of key genes related to HPI axis functioning in the Ellasjøen charr suggest endocrine disruptive effects of OHCs in this charr population. Possible ecological implications are not known, but it cannot be excluded that a slower growth rate in Ellasjøen charr compared to Laksvatn charr due to an increased metabolic demand associated with the activation of xenobiotic defense and detoxification systems may have contributed to the lower body mass of Ellasjøen charr compared to Laksvatn charr.

Start early! Does social instability during the pre- and early postnatal development prepare male wild cavies for social challenge later in life?

BackgroundThe social environment the mother experiences during pregnancy and lactation can powerfully influence the offspring’s behavioural profile. Our previous studies in wild cavies show that two different social environments during pregnancy and lactation bring about different behavioural strategies of male offspring later in life: An unstable social environment leads to a behavioural camouflage strategy, hypothesised to be beneficial at times of socially challenging situations. A stable social environment during early phases of life, however, leads to an early reproduction strategy, expected to be more successful at times of social stability. In the present study, we observed the behavioural strategies of the two types of males in direct comparison in a socially challenging situation: Two adolescent males were placed simultaneously in an unknown social group consisting of one adult male and two females in a semi-naturalistic environment. Cortisol as well as testosterone concentrations and activity levels were compared. Furthermore, paternities were analysed after the males reached sexual maturity. We hypothesised that sons showing a behavioural camouflage strategy are better adapted to cope with this socially challenging situation compared to those displaying an early reproduction strategy.ResultsAt the beginning of the experiment, no differences in plasma cortisol concentrations between the males were found, both showed a highly significant increase due to the challenging situation. From day 5 until the end of the experiment (duration = 40 days) sons showing an early reproduction strategy had significantly higher plasma cortisol concentrations compared with those showing a behavioural camouflage strategy. Plasma testosterone concentrations did not differ significantly. Activity levels decreased significantly over time independently of the male’s behavioural strategy. Both types of males did not sire offspring during the observation period.ConclusionHigher cortisol values from day 5 until the end of the experiment in sons showing an early reproduction strategy indicate higher levels of stress in these males compared to those displaying a camouflage strategy. We conclude that the modulation of the males behavioural strategy due to an unstable social environment during early development facilitates the endocrine adaptation to a comparable social situation later in life.

A psychophysiological comparison of on‐sight lead and top rope ascents in advanced rock climbers

Research suggests that lead climbing is both physiologically and psychologically more stressful than top rope climbing for intermediate performers. This observation may not be true for advanced climbers, who train regularly on lead routes and are accustomed to leader falls. The aim of this study was to compare the psychophysiological stresses of lead and top rope on-sight ascents in advanced rock climbers. Twenty-one climbers (18 men and three women) ascended routes near or at the best of their ability (22 Ewbank). Psychological stress was measured preclimb using the Revised Comparative State Anxiety Inventory (CSAI-2R). Plasma cortisol was sampled at six intervals. The volume of oxygen (VO2 ) and heart rate (Hr) were measured throughout the climbs. No significant differences were found in self-confidence, somatic, or cognitive anxiety between the conditions lead and top rope. No significant differences in plasma cortisol concentration were found between any time points. No significant relationships were found between cortisol and any CSAI-2R measures. No significant differences were found between conditions for VO2 or blood lactate concentration. During the lead climb, Hr was significantly elevated during the last part of the route. Findings suggest that advanced rock climbers do not find lead climbing to be more stressful than top rope climbing during an on-sight ascent.

Physiological and genetic correlates of boldness: Characterising the mechanisms of behavioural variation in rainbow trout, Oncorhynchus mykiss

Bold, risk-taking animals have previously been putatively linked with a proactive stress coping style whereas it is suggested shyer, risk-averse animals exhibit a reactive coping style. The aim of this study was to investigate whether differences in the expression of bold-type behaviour were evident within and between two lines of rainbow trout, Oncorhynchus mykiss, selectively bred for a low (LR) or high (HR) endocrine response to stress, and to link boldness and stress responsiveness with the expression of related candidate genes. Boldness was determined in individual fish over two trials by measuring the latency to approach a novel object. Differences in plasma cortisol concentrations and the expression of eight novel candidate genes previously identified as being linked with divergent behaviours or stress were determined. Bold and shy individuals, approaching the object within 180s or not approaching within 300s respectively, were evident within each line, and this was linked with activity levels in the HR line. Post-stress plasma cortisol concentrations were significantly greater in the HR line compared with the LR line, and six of the eight tested genes were upregulated in the brains of LR fish compared with HR fish. However, no direct relationship between boldness and either stress responsiveness or gene expression was found, although clear differences in stress physiology and, for the first time, gene expression could be identified between the lines. This lack of correlation between physiological and molecular responses and behavioural variation within both lines highlights the complexity of the behavioural–physiological complex.

Subgenual Prefrontal Cortex Activity Predicts Individual Differences in Hypothalamic-Pituitary-Adrenal Activity Across Different Contexts

Hypothalamic-pituitary-adrenal (HPA) system activation is adaptive in response to stress, and HPA dysregulation occurs in stress-related psychopathology. It is important to understand the mechanisms that modulate HPA output, yet few studies have addressed the neural circuitry associated with HPA regulation in primates and humans. Using high-resolution F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in rhesus monkeys, we assessed the relation between individual differences in brain activity and HPA function across multiple contexts that varied in stressfulness. Using a logical AND conjunctions analysis, we assessed cortisol and brain metabolic activity with FDG-PET in 35 adolescent rhesus monkeys exposed to two threat and two home-cage conditions. To test the robustness of our findings, we used similar methods in an archival data set. In this data set, brain metabolic activity and cortisol were assessed in 17 adolescent male rhesus monkeys that were exposed to three stress-related contexts. Results from the two studies revealed that subgenual prefrontal cortex (PFC) metabolism (Brodmann's area 25/24) consistently predicted individual differences in plasma cortisol concentrations regardless of the context in which brain activity and cortisol were assessed. These findings suggest that activation in subgenual PFC may be related to HPA output across a variety of contexts (including familiar settings and novel or threatening situations). Individuals prone to elevated subgenual PFC activity across multiple contexts may be individuals who consistently show heightened cortisol and may be at risk for stress-related HPA dysregulation.

Electroacupuncture analgesia in dogs: is there a difference between uni- and bi-lateral stimulation?

ObjectiveTo compare the analgesic effect of uni- and bi-lateral electroacupuncture (EA) in response to thermal and mechanical nociceptive stimuli and to investigate the cardiorespiratory, endocrine, and behavioral changes in dogs submitted to EA. Study designProspective, randomized cross-over experimental study. AnimalsEight adult, clinically healthy, cross-breed dogs, weighing 13 ± 4 kg. MethodsDogs underwent electrostimulation at false acupoints (T-false); bilateral EA at acupoints, stomach 36, gall bladder 34 and spleen 6 (T-EA/bil); unilateral EA at the same points (T-EA/uni) or were untreated (T-control). All animals received acepromazine (0.05 mg kg−1) IV; and heart rate, pulse oximetry, indirect arterial blood pressure, respiratory rate, Pe′CO2, rectal temperature, and plasma cortisol concentration were measured before, during, and after EA. Analgesia was tested using thoracic and abdominal cutaneous thermal and mechanical stimuli, and an interdigital thermal stimulus. Behavior was classified as calm or restless. Analysis of variance for repeated measures followed by Tukey's test was used for analysis of the data. ResultsThere were no cardiorespiratory differences among the treatments. The cutaneous pain threshold was higher after EA, compared with false points. The latency period was shorter and analgesia was more intense in T-EA/bil than T-EA/uni, when both were compared with T-false and T-control. Six out of eight animals treated with EA were calm during treatment, and 5/8 and 4/8 of the T-false and T-control animals, respectively, were restless. Latency to interdigital thermal stimulation increased in T-EA/bil compared with the others. There was no difference in plasma cortisol concentrations among the treatments. ConclusionsBilateral EA produced a shorter latency period, a greater intensity, and longer duration of analgesia than unilateral stimulation, without stimulating a stress response. Clinical relevanceBilateral EA produces a better analgesic effect than unilateral EA.

Cord blood cortisol level is lower in growth‐restricted newborns

To establish the difference in plasma cortisol concentrations between newborns with intrauterine growth-restricted (IUGR) and appropriate for gestational age (AGA) birthweights. We measured plasma cortisol concentrations in the umbilical venous cord blood of 68 IUGR newborns and 71 AGA birthweight newborns. All newborns were delivered in term, vaginally, in the morning, within 8 hours and had APGAR scores greater or equal to eight. There was no significant difference between compared groups according to maternal age, parity, gestational age and neonatal gender. Neonatal plasma cortisol levels were significantly lower in the IUGR (median: 312.3 mmol/L, min-max: 158.9-588.1 mmol/L) compared to the AGA group (median: 458.7 mmol/L, min-max: 314.5-718.5 mmol/L) (Mann-Whitney U-test; P<0000). The probability of having a cortisol plasma level greater than or equal to 458.7 mmol/L for IUGR newborns was only 1:12, and to have cortisol plasma level less than or equal to 312.3 mmol/L for AGA newborns was much lower (0:34). In the range of plasma cortisol level between 312.3 mmol/L and 458.7 mmol/L, no statistically significant difference in the plasma cortisol level between IUGR and AGA newborns was found. Neonatal plasma cortisol level is lower in the IUGR compared to the AGA group. Our results suggest that endocrine relationships seem to be lost in a specific group of the IUGR newborns. Although we usually tend to simplify the problem and declare only one cause, this time it is impossible. It is probable that the cause is hidden in small and insufficient placenta with deranged auto-regulation of placental 11beta-HSD-2 mechanism.

Diferencias interindividuales en las concentraciones de cortisol plasmático tras una hora de ejercicio mixto aeróbico-anaeróbico

Introduction and objectives The aim of the present study was to evaluate differences in plasma cortisol concentration in response to an intercalating aerobic-anaerobic exercise test in a group of physically active young people. Methods Fourteen healthy young male volunteers performed a 40-minute exercise test at 50% of individual peak oxygen uptake on a cycle ergometer, maintaining a pedal rate of 60 r.p.m., during which they aimed to intercalate 4 explosive anaerobic phases of 30 seconds with a workload of 0.04 kg per kg of body mass at 10, 20, 30 and 40 minutes. After this first phase, and without stopping the exercise and maintaining the corresponding workload of 50% of peak oxygen uptake, the volunteers ended the exercise by pedaling at the maximum number of revolutions possible for 20 minutes. Cardiopulmonary parameters were continuously monitored and blood samples were obtained at rest, every 10 minutes during the test, and at 15 minutes during the recovery period. Results Cardiopulmonary and metabolic responses were similar in all the participants during the test and the group tendency was to increase plasma cortisol levels significantly throughout the test (F = 5.16; p < 0.001). Plasma cortisol levels showed large interindividual differences (F = 6.74; p < 0.001). In 8 participants (57.1%), plasma cortisol levels increased during exercise and while in 6 (42.9%) minor changes with respect to resting values were observed. Conclusion Substantial differences in plasma cortisol levels were found in a homogeneous group of young male volunteers during a successive aerobic-anaerobic exercise test, which may have implications in adaptation to exercise.

Behavioural, health and cortisol responses of young calves to tail docking using a rubber ring or docking iron

The acute responses of thirty-six 7- to 17-d-old Holstein calves to tail docking using a rubber ring or a hot docking iron were examined. Plasma cortisol concentrations were measured on day 0 and day +1. Behaviour was examined on days –1, 0, +1, +2, and +5 after treatment. Milk intake, weight gain, body temperature and faeces scores were monitored. Rubber ring application caused an increase in tail grooming up to day +5 after treatment. Shorter standing and lying periods as well as higher frequencies of standing and lying on day 0 were seen in the rubber ring group. No significant differences in behaviour were observed between the control group and the docking iron group. No significant differences in plasma cortisol concentrations were found between any groups except for 60 min after treatment when the rubber ring group exhibited a significantly higher concentration than the control group. No differences in milk intake, weight gain, body temperature or faeces score were found. Tail docking with a rubber ring causes a more pronounced behavioural and physiological response than docking with a docking iron. However, long-term effects need to be investigated. Key words: Calves, tail docking, pain, behaviour, cortisol, stress

Cortisol and testosterone concentrations in wheelchair athletes during submaximal wheelchair ergometry

It is yet unknown how upper body exercise combined with high ambient temperatures affects plasma testosterone and cortisol concentrations and furthermore, how these hormones respond to exercise in people suffering spinal cord injuries. The purpose of this study was to characterize plasma testosterone and cortisol responses to upper body exercise in wheelchair athletes (WA) compared to able-bodied individuals (AB) at two ambient temperatures. Four WA [mean age 36 (SEM 13) years, mean body mass 66.9 (SEM 11.8) kg, injury level T7-T11], matched with five AB [mean age 33.4 (SEM 8.9) years, mean body mass 72.5 (SEM 13.1) kg] exercised (cross-over design) for 20 min on a wheelchair ergometer (0.03 kg resistance.kg-1 body mass) at 25 degrees C and 32 degrees C. Blood samples were obtained before (PRE), at min 10 (MID), and min 20 (END) of exercise. No differences were found between results obtained at 25 degrees C and 32 degrees C for any physiological variable studied and therefore these data were combined. Pre-exercise testosterone concentration was lower (P < 0.05) in WA [18.3 (SEM 0.9) nmol.l-1] compared to AB [21.9 (SEM 3.6) nmol.l-1], and increased PRE to END only in WA. Cortisol concentrations were similar between groups before and during exercise, despite higher rectal temperatures in WA compared to AB, at MID [37.21 (SEM 0.14) and 37.02 (SEM 0.08) degrees C, respectively] and END [37.36 (SEM 0.16) and 37.19 (SEM 0.10) degrees C, respectively]. Plasma norepinephrine responses were similar between groups. In conclusion, there were no differences in plasma cortisol concentrations, which may have been due to the low relative exercise intensities employed. The greater exercise response in WA for plasma testosterone should be confirmed on a larger population. It could have been the result of the lower plasma testosterone concentrations at rest in our group.

Diel and annual variation in plasma cortisol concentrations among wild and captive harbor seals (Phoca vitulina)

Annual and diel changes in plasma cortisol concentrations were investigated among wild and captive harbor seals (Phoca vitulina) of various sex and age classes. No significant effects of age, sex, or season were found in captive animals. However, significant inter-individual differences between two juvenile males were noted during both the breeding/molt (p = 0.041) and postbreeding/postmolt (p = 0.001) seasons. Seasonal and sex- and age-related differences were found among wild harbor seals. Across all sex and age categories, mean cortisol concentrations during the postbreeding and prebreeding seasons were significantly different from those measured during the breeding season (p = 0.014 and p = 0.038, respectively), but did not differ from each other. When each sex and age group was examined separately, seasonal effects were significant for mature females (p = 0.009) and mature males (p = 0.048). Differences in plasma cortisol concentration between captive and wild animals of the same sex during the same seasons were highly significant, particularly in mature animals (between p &lt; 0.0001 and p = 0.035). There was a diel pattern of plasma cortisol concentrations in samples collected from captive animals over a 24-h period. Mean concentrations differed between samples collected during the hours of light and dark, being highest at night (p = 0.009), peaking around 01:00, and dropping again at around 13:00. Annual and diel patterns of plasma cortisol concentrations occur in harbor seals, and seasonal differences may relate to important physiological and behavioral phases in the harbor seals' annual cycle.

Cortisol secretion in prepubertal children with major depressive disorder. Episode and recovery.

Plasma cortisol concentrations were measured every 20 minutes for 24 hours in a group of 45 rigorously assessed, drug-free, prepubertal children who met the unmodified Research Diagnostic Criteria for major depressive disorder (MDD), 20 children with nonaffective psychiatric disorders, and eight normal controls. All children were studied in a low-stress environment. There were no significant differences in plasma cortisol concentration among the three groups as measured by 24-hour mean, peak, nocturnal rise, or nadir values. Division of the MDD group into subgroups based on endogenicity, psychotic symptoms, and suicidality also failed to reveal significant differences for cortisol secretion. Hypersecretion of cortisol (defined as 2 SDs above the grand mean) was identified in only four children with depressive illness and one normal control. Following clinical recovery, 24 depressed children were restudied in a drug-free state and compared with themselves during the episode of illness and with both groups of controls. No significant differences in plasma cortisol concentrations were found. All four depressed hypersecretors were restudied after clinical recovery, and one showed persistence of hypersecretion. These results suggest that abnormalities of cortisol secretion occur infrequently in prepubertal children with major depression when they are studied in a nonstressful environment.

Arteriovenous studies on the uptake and metabolism of cortisol in human forearm.

1. Cortisol metabolism in human forearm tissues has been investigated by measurement of arteriovenous plasma differences. 2. There were no detectable differences in plasma cortisol concentration in fifty-four pairs of arterial and venous samples collected from twenty subjects at rest, nor in experiments in which 5 mg of cortisol was infused intravenously over a period of 30 min. 3. When [3H]cortisol was infused intra-arterially into the forearm for 10 min, radiochemical analysis of paired arterial and venous samples provided evidence for retention of cortisol in the local tissues and subsequent release into the venous effluent, and conversion of a small fraction of the infused cortisol into a substance chromatographically similar to cortisone. 4. It was demonstrated by the use of 125I-labelled albumin as a plasma marker that retention of the cortisol was due to penetration of the tissues by cortisol and not to a prolonged transit time in the vascular bed.