Cortisol Parameters Research Articles

Temperature and humidity in the Brazilian tropical summer affecting the in vivo embryo production of Nelore breed in superovulation program

This study used Nelore embryo donors to evaluate the effects of summer temperatures and humidity in a tropical area on embryo recovery. Seventeen cows were randomly assigned to three groups (G1, G2 and G3) as well as 28 heifers into four groups (G4, G5, G6 and G7), and underwent a consecutive 4 d superovulation protocol (Day 0 to 3) and two artificial inseminations (AI; Day 4 and 5). Cortisol concentrations were determined on Day 0, 4 and 5. Temperature and humidity index (THI) was recorded from Days 0 to 7. Embryos were recovered on Day 11, and evaluated for quality and quantity. Heifers experienced higher thermal load than cows, however, there was no difference in the cortisol and reproductive parameters measured between both. The THI measured throughout the experiment oscillated between 65.8 and 85.2 (76.1 ± 3.9), which is a dangerous range for thermal comfort, especially above 78. Animals from G5 were subjected to high THI throughout the experimental protocol, approaching a dangerous condition (78.7 ± 0.9) on Day 4 (first AI). The THI for G2 cattle was also high, as in the other groups, but increased to over 80 two days after AI. Animals from group G5 had the lowest viable production being 2.4 ± 0.9 embryos (38% of viability), followed by cattle from group G2 (3.0 ± 0.9 viable, P<0.05). Thus, high thermal load in the summer expressed by high THI, on the day and post- insemination days (during embryo cleavage), compromises embryo numbers, viability and consequently reproductive performance of Nelore females.

RELATIONSHIPS BETWEEN LEAD EXPOSURE AND MATERNAL CORTISOL CONCENTRATIONS DURING PREGNANCY

Background and Aims: Gestational lead (Pb) exposure and stress may increase the risk of adverse maternal, neonatal, and childhood health outcomes. Some studies suggest that Pb may alter hypothalamic-pituitary-adrenal (HPA)-axis function. Correlates of psychological stress, like depression, may modify the effect of Pb exposure, increasing susceptibility to Pb-induced HPA-axis dysregulation. We examined the relationship between Pb exposure and HPA-axis function in a cohort of 850 pregnant women from Mexico City. Methods: Blood Pb concentrations were measured during the second trimester. Tibia and patella bone Pb concentrations were measured 1-month postpartum and represented cumulative Pb exposures. Second trimester salivary cortisol concentrations were measured in 10-timed saliva samples collected over 2-days and used to characterize diurnal HPA-axis function. Cortisol concentrations were parameterized as the area-under-the-curve, morning rise slope, and diurnal slope. Maternal depressive symptoms were examined as a modifier of Pb-coritsol relationships, measured with the Edinburgh Postnatal Depression Scale (EPDS), and dichotomized as (≥13/<13). Linear mixed-effect models were used to account for repeated measurements. Results: Median blood, tibia, and patella Pb concentrations were 3.3 □g/dL, 3.6□g/g and 3.1□g/g, respectively. After adjustment for confounders, parameter estimates between patella and blood Pb biomarkers and cortisol parameters were null in value. However, each 10 □g/g increase in tibia Pb concentrations was associated with a 20% increase (95% confidence interval [CI]:-7%, 55%) in morning rise slopes. This effect was greater among women with EPDS scores ≥13 (76%; 95% CI:13%, 175%, interaction p-value <0.05). Conclusions: These results suggest that tibia, but not blood or patella Pb concentrations might be associated with some aspects of HPA-axis function during pregnancy. We observed evidence that depressive symptoms modify the associations between tibia Pb concentrations and maternal cortisol rhythms. Future studies should validate these findings and determine the clinical significance of altered maternal cortisol profiles in pregnancy on child development.

Cortisol levels and metabolic parameters in middle- and advanced- age subjects: associations with age.

It has been reported that morning cortisol levels increase with age, although there is some controversy in the literature. The aim of this study was to examine associations of cortisol levels with advancing age in an elderly population and investigate possible interactions with metabolic and hormonal parameters. From 372 subjects initially evaluated, we studied 251 ambulatory subjects aged 51-90 yr, median 71 yr (169 women), all permanent residents of a small town in southern Greece. Anthropometric parameters, glucose, insulin, cortisol, and biochemical parameters were recorded. Fasting cortisol levels (08:00-09:00 h) varied between 150.9- 854 nmol/l (mean 362.4 nmol/l). A significant association was found between age and cortisol levels (Spearman's rho =0.170, p=0.01). There was a positive correlation between cortisol levels and creatinine (Spearman's rho =0.144, p=0.023), homocysteine (Spearman's rho =0.283, p<0.001) and a negative correlation with body mass index (Spearman's rho =-0.128, p=0.047). Multivariate analysis showed that when creatinine was taken into account, the association of cortisol with age and with homocysteine was no longer significant. When, however, diabetic subjects were included in the analysis, the adjusted for creatinine association of cortisol with age was significant (β=0.168, p<0.05). It is concluded that, in elderly ambulatory subjects, the reported associations between cortisol levels, age, and homocysteine may be affected by coexisting co-morbidities or possibly by a decline in renal function. In subsequent studies it is important that fasting glycemia is taken into account.

Alterations of postawakening cortisol parameters during a prolonged stress period: Results of a prospective controlled study

Though postawakening cortisol is considered to be altered under chronic stress prospective studies proving this assumption is missing, so far. Furthermore, there is some uncertainty which aspects of postawakening cortisol alterations are strongest related to stress. The present study thus analyzed the cortisol concentration at awakening itself (0 min), the cortisol awakening response (CAR; i.e. the increase within 30 min after awakening), the area under the curve of the first hour after awakening (AUC G60) and the mean of samples taken 0 min and 30 min after awakening (AUC G30) in 12 exam students, participating in a major exam and 12 matched control students not participating in any exam. Saliva samples were taken on two consecutive days at 0, 15, 30, 45, and 60 min after awakening, respectively, at four time points (T1–T4): on the verge of exams, when students anticipated and prepared the exam (T1), in the middle of exams (T2), and shortly after (T3). T4 (weeks after exams) represents a reference measure. Repeated measures analyses of covariance revealed a significantly higher AUC G30 ( p = 0.007) and AUC G60 ( p = 0.011) and higher cortisol concentrations at awakening ( p = 0.016) in exam students and a significant time by group interaction for concentration at awakening ( p = 0.031). No effects were found for the CAR. The results of this prospective controlled study support notions that chronic stress induces increases of overall postawakening cortisol. They further indicate that the CAR is not affected by chronic stress and that the awakening concentration responds later than the AUC G to conditions of chronic stress as analyzed here.

Cortisol Profiles in Sows Submitted to an Intermittent Suckling Regime Compared with that of Abruptly Weaned Sows

The aim of this study was to monitor changes in cortisol levels in sows around the time of separation from their piglets, in two different intermittent suckling regimes, compared with that in conventionally weaned sows. Sows were either weaned at 21 days of lactation (CONT) or subjected to an intermittent suckling regime (IS) from 14 days of lactation onwards. Sows in the IS regimes were separated from their piglets for 12 h every day, either from 08:00 to 20:00 hours (IS12) or from 08:00 to 14:00 hours and 20:00 to 02:00 hours (IS6). Separation caused a transient increase in cortisol levels on the first (CONT and IS12) and second (IS12) day of separation, compared with a gradual decline from early morning when the sows were still continuously suckling. In IS6 sows, in contrast, the transient rise in cortisol levels after separation at 08:00 hours was observed on the first 3 days and also on day 7 of the IS regime. Cortisol parameters were correlated with peri-ovulatory characteristics like onset of oestrus, onset of the LH surge and time of ovulation. Onset of the LH surge was delayed in IS6 sows. In conclusion, increase in cortisol levels as a consequence of separation of sows and piglets, is an acute, incidental phenomenon in IS12 and CONT sows, but shows a repeated acute elevation in IS6 sows, possibly placing IS6 sows at a higher risk of influencing peri-ovulatory processes and developing cystic follicles.

Cortisol patterns and brachial artery reactivity in a high stress environment

Chronic stress can result in frequent or persistent challenges of the hypothalamic-pituitary-adrenal (HPA) axis resulting in abnormal cortisol patterns and increased risk for cardiovascular disease (CVD). Police work is an environment replete with stress. The present article describes associations between cortisol, a biomarker of stress, and brachial artery flow mediated dilation (FMD) in police officers. A random sample stratified on gender ( n = 100, 33% women) was generated from officers in a mid-sized urban department. Four salivary cortisol parameters were derived: after awakening, following a standardized high protein meal challenge, during the entire day, and after a dexamethasone suppression test. Continuous scan B-Mode ultrasound was used to measure percent change in brachial artery FMD following occlusion and release. Elevated cortisol secretion after awakening was significantly associated with impaired FMD in women, reflected by an inverse trend. Adjustment for age, smoking, and alcohol consumption did not appreciably alter this trend. A similar result was not evident among male officers. Responses of other cortisol challenges to the HPA axis were not associated with FMD. In conclusion, increased cortisol secretion after awakening was independently associated with impaired FMD in female police officers only, indicating a possible link between HPA axis stress response and subclinical CVD. However, because associations were not found with other cortisol parameters and were not evident in male officers, replication of these findings with a prospective study design may be warranted.

Effect of feed type and feeding frequency on macrophage functions in tilapia ( Oreochromis niloticus L.)

In fresh water recirculation systems the type of feed and feeding frequency have a direct effect on water quality, growth, fish welfare and the response of the immune system. Four types of feed with different sources of plant protein (soybean concentrate, sunflower meal, corn gluten and pea) were provided at two feeding frequencies (two and eight times day −1) to observe effects on growth, cortisol levels and innate immunity (macrophage phagocytosis and respiratory burst) on tilapia in early stages of growth (2–10 g). Growth and cortisol parameters were quite similar among the groups of tilapia fed the different diets and frequencies at the end of the feeding period. Phagocytosis and respiratory burst were also very similar with the four feed types. However, macrophages from fish fed twice day −1 were much less efficient in clearing bacteria after 24 h than the groups fed eight times day −1. Our results suggest that an increased feeding frequency may confer a higher resistance to disease.

Salivary cortisol, serum lipids, and adiposity in patients with depressive and anxiety disorders

Depressive and anxiety disorders are associated with an increased risk of cardiovascular disease. Chronic stress induces hypothalamus-pituitary-adrenal (HPA)–axis perturbations, which might subsequently induce atherogenic lipoprotein profiles and adiposity. The aim of the present study was to investigate the relationship between basal saliva cortisol levels and serum lipids and adiposity in psychiatric patients. Eight salivary cortisol samples (awakening; 30, 45, and 60 minutes after awakening; 11:00 am, 3:00 pm, 7:00 pm, and 11:00 pm) on 2 consecutive days in medication-free outpatients with depressive and/or anxiety disorders (n = 72) and in healthy controls (n = 42) were used to derive 2 measures of HPA-axis function: basal cortisol concentrations (ie, area under the curve [AUC cortisol]) and circadian cortisol variability (variability cortisol). Index z scores were calculated for dyslipidemia (from serum triglycerides, inverse high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol) and adiposity (from body mass index and waist-to-hip ratio). Regression analyses were conducted to determine the contribution of AUC cortisol and variability cortisol in explaining the variance of, respectively, the lipid and adiposity index. Patients showed a higher mean AUC cortisol compared with healthy controls ( t = 2.7, P = .01). Both cortisol parameters were independently associated with dyslipidemia in patients after adjustment for age, alcohol use, and smoking habits ( β = .31, P = .02 and β = −.29, P = .02, respectively), but not in controls. Cortisol measures were not associated with adiposity in either group. We conclude that elevated basal cortisol concentrations and lower circadian cortisol variability were independently associated with a less favorable lipoprotein profile in patients with depressive and/or anxiety disorders. These data lend support to the hypothesis that the relationship between affective disorders and cardiovascular disease is partly mediated by HPA-axis perturbations.

Heritability of daytime cortisol levels and cortisol reactivity in children

SummaryIndividuals differ widely in cortisol output over the day and cortisol reactivity to challenge, both of which are relevant to disease risk. There is limited evidence concerning the heritability of these differences, so we evaluated the heritability of cortisol levels in the afternoon and cortisol reactivity using a twin design. The study involved 80 monozygotic (MZ) and 70 dizygotic (DZ) same-sex twin pairs aged 11.2 years on average. Salivary cortisol was measured in the afternoon at home before and after playing a computer game. Ratings of excitement and upset were also obtained, and objective task performance was assessed. Salivary cortisol levels averaged 4.08 (S.D. 2.3) nmol/l at pretask baseline, and declined on average over the session to 3.45 (1.9) nmol/l immediately after the tasks and 2.87 (1.6) nmol/l 10 min later. There were, however, marked individual differences, with cortisol reactivity (difference between pretask baseline and post-task 1) ranging from +4.53 to −6.23 nmol/l. Intra-class correlations for all the cortisol parameters were substantially greater for MZ (range 0.41–0.57) than for DZ (0.11–0.29) twin pairs. Quantitative genetic modelling confirmed significant heritability for pretask baseline cortisol (58%), the two post-task values (60 and 56%), and cortisol reactivity (44%). The study lacked power for assessing sex differences. Subjective reports of excitement were also somewhat heritable, but there was little covariation of cortisol and subjective responses, so genetic influences on covariation could not be tested. These findings indicate that individual differences in children’s cortisol levels recorded before tasks and cortisol reactivity to behavioural challenges are influenced by genetic factors.

HPA system regulation and adult attachment anxiety: Individual differences in reactive and awakening cortisol

Early life experiences can influence hypothalamus-pituitary-adrenal (HPA) axis regulation in adulthood, in both animals and humans. In humans, they have also been shown to influence adult attachment styles. However, the relationship between adult attachment styles and HPA axis regulation is largely unexplored. The present study investigated the relationship among varying levels of attachment anxiety and avoidance with both the cortisol response to acute stress (CRS) and the cortisol response to awakening (CRA) in 48 adult women. Attachment-unrelated stress was induced by a laboratory stress task. Saliva for free cortisol assessment was sampled before and after the stress task in the laboratory and at home on 2 consecutive days in the morning after awakening. We found that attachment anxiety but not attachment avoidance was associated with cortisol measures. Attachment anxiety was positively correlated with CRS and negatively with CRA. Finally, the two cortisol parameters were negatively associated with one another. The results are discussed with respect to (1) recent findings suggesting that the HPA system and hippocampus are programmed during critical development periods, establishing a certain trajectory of physiological responsiveness throughout life, and (2) a model that links development of the hippocampus with self development.

Hypothalamic–pituitary-end organ function in women with bipolar depression

Disturbance of each of the three hypothalamic-pituitary-end organ systems [hypothalamic-pituitary-thyroid (HPT), -adrenal (HPA), and -gonadal (HPG)] has been reported in depressive disorders. Little is known about potential reciprocal interaction among the three HP-end organ systems in patients with depressive disorders. The present pilot study examined selective HPA and HPG hormones in a detailed time series in women with bipolar disorder (depressed type) before and after treatment with levothyroxine (L-T4), and in matched control subjects. Six medically stable, euthyroid, premenopausal women with bipolar depression, and 5 age-matched controls underwent overnight blood sampling from 2100 to 0900 h for measurement of adrenocorticotropic hormone (ACTH), cortisol, luteinizing hormone (LH), and estradiol every 15 min. Bipolar patients underwent a second overnight blood sampling procedure following 7-weeks of open-label add-on treatment with L-T4. Results revealed lower baseline cortisol parameters in bipolar patients in comparison to control subjects, while ACTH, LH, and estradiol parameters were similar. Thyroid hormones (TSH, free and total T4) were not correlated with any of the HPA or HPG hormones. ACTH and cortisol levels were correlated in control subjects, but not in bipolar patients. After L-T4 treatment, thyroid hormones increased significantly and depression scores significantly declined. No significant changes in HPA or HPG hormones parameters were observed, although the small sample size may have limited results. Upon visual inspection, ACTH and cortisol appeared to decrease after L-T4 treatment, while estradiol appeared to increase. These pilot data suggest lower levels of cortisol in women with bipolar depression, unlike previously published studies that reported higher cortisol in patients with depression. The data also suggest reciprocal changes in the HPA and HPG axes upon pharmacological modulation of the HPT system, although whether this change was due to the L-T4 treatment or the improvement of depression is unknown. The results are preliminary, and require replication in larger samples.

A longitudinal study on cortisol and complaint reduction in burnout

Several studies have investigated the association between burnout and HPA-axis functioning, but the results are far from consistent. This does not preclude the possibility that within a group of burnout patients a recovery of symptoms in a longitudinal course corresponds to (changes in) cortisol parameters. The latter possibility is tested in the present study before and after treatment, and at follow-up. HPA-axis functioning and burnout complaints were assessed in burned-out participants at baseline (n=74), post-treatment (n=62) and at follow-up (n=53). Multilevel regression analysis was used to test the hypothesis. Burnout complaints were significantly reduced at 8.5 months post-treatment, but there was no further reduction in complaints at follow-up 6.3 months later. Cortisol after awakening, and after dexamethasone intake showed no changes from baseline to post-treatment and follow-up. There was a small decline in cortisol during the day over the longitudinal course. The cortisol level after awakening in the longitudinal course showed significant positive association with the initial exhaustion level, a negative association with the change in the burnout exhaustion score, and a positive association with the change in depression. Although these associations are statistically significant, they only explain a small fraction of the variance in cortisol after awakening between and within persons. This implies that changes at symptom level are hardly related to changes in cortisol functioning, therefore the clinical implications of this finding are limited.

Cortisol deviations in people with burnout before and after psychotherapy: A pilot study.

Burnout is characterized by exhaustion, cynicism, and feelings of reduced competence. These complaints may be reflected in disturbances in the main stress regulatory endocrine system: the hypothalamus pituitary adrenal (HPA) axis. In this study, the HPA-axis hormone cortisol was sampled after awakening and during the day in 22 participants with clinical burnout and in 21 healthy controls. The cortisol level after awakening was shown to be significantly lower in the burnout group as compared with the control group. Cortisol levels during the day did not differ. The same sampling procedure was repeated after 14 sessions of psychotherapeutic intervention. The intervention led to a significant reduction in complaints and to an increase of the initially lowered morning cortisol levels. No consistent correlations, however, between the changes in subjective complaints and the change in cortisol parameters were found.

Secretory dynamics of leptin in adolescent girls with anorexia nervosa and healthy adolescents

Leptin, an adipocytokine that suppresses appetite and may regulate neuroendocrine pathways, is low in undernourished states like anorexia nervosa (AN). Although leptin exhibits pulsatility, secretory characteristics have not been well described in adolescents and in AN, and the contribution of hypoleptinemia to increased growth hormone (GH) and cortisol in AN has not been explored. We hypothesized that hypoleptinemia in AN reflects decreased basal and pulsatile secretion and may predict increased GH and cortisol levels. Sampling for leptin, GH, cortisol, and ghrelin was performed every 30 min (from 2000 to 0800) in 23 AN and 21 controls 12-18 yr old, and data were analyzed using Cluster and deconvolution methods. Estradiol, thyroid hormones, and body composition were measured. AN girls had lower pulsatile and total leptin secretion than controls (P < 0.0001) subsequent to decreased burst mass (P < 0.0001) and basal secretion (P = 0.02). Nutritional markers predicted leptin characteristics. In a regression model including BMI, body fat, and ghrelin, leptin independently predicted GH burst interval and frequency. Valley leptin contributed to 56% of the variability in GH burst interval, and basal leptin and fasting ghrelin contributed to 42% of variability in burst frequency. Pulsatile leptin independently predicted urine free cortisol/creatinine (15% of variability). Valley leptin predicted cortisol half-life (22% of variability). Leptin predicted estradiol and thyroid hormone levels. In conclusion, hypoleptinemia in AN is subsequent to decreased basal and pulsatile secretion and nutritionally regulated. Leptin predicts GH and cortisol parameters and with ghrelin predicts GH burst frequency. Low leptin and high ghrelin may be dual stimuli for high GH concentrations in undernutrition.

Blood serum metabolites and meat quality in crossbred pigs experiencing different lairage time

Pigs of two crosses: A (♀ Duroc × ♂Swedish Landrace) × ♂Pietrain (n=24) and B (♀ Swedish Landrace × ♂Large White) × ♂Pietrain (n=26) were used to investigate the effects of different lairage time (2 and 24 hours) on levels of stress and meat quality traits. No direct effect of lairage time on cortisol, lactate, electrolytes and meat quality parameters was observed. However, after long lairage time, pigs showed lower level of glucose and higher CK, AST and ALT activity. Crossbred B pigs exposed to short lairage time, showed higher blood lactate, sodium, and potassium level, higher drip loss and lower pHi, whereas there were no significant differences between the crossbreeds in the long lairage group. The results indicate that long lairage time decreases blood glucose level and produces signs of muscle damage. In the short lairage period, the crossbreed B showed a higher response to pre-slaughter handling affecting the meat quality.

Lipid kinetics in obese patients undergoing laparoscopy. the impact of cortisol inhibition by etomidate

The aim of this study was to investigate the response of cortisol, insulin and lipid parameters [serum Lipoprotein Lipase activity, choleseryl-ester transfer protein, triglycerides, total Cholesterol, High Density Lipoprotein, Free Fatty Acids] during the perioperative period in obese patients undergoing laparoscopic cholecystectomy. Twenty obese patients were included and divided in two groups. In group A (n=10) patients were anaesthetized with propofol and group B (n=10) with etomidate. Blood samples were collected before induction in anaesthesia, just after the end of the operation and at one, two and three hours postoperatively. According to our results, in both groups serum LPL activity showed a significant decrease whereas serum Free Fatty Acids a potent increase over time. Likewise, both groups did not demonstrate significant changes over time in choleseryl-ester transfer protein activity, total cholesterol, triglycerides, High Density Lipoprotein or insulin concentrations in serum. Furthermore, cortisol release was significantly inhibited in the etomidate group while substantially enhanced in propofol group. Additionally, apart of triglycerides, no difference was found between the two groups in all the lipid parameters and insulin concentrations. In conclusion, serum Free Fatty Acids levels and Lipoprotein Lipase activity demonstrated significant alterations in obese patients underwent laparoscopic cholecystectomy and this result did not seem to be related with the anaesthetic agent used for induction in anaesthesia.

Lying behaviour and adrenocortical response as indicators of the thermal tolerance of pigs of different weights

AbstractThe aim of this study was to assess optimal temperature ranges for fattening pigs of different weights kept in pens with partially slatted floors. We examined the behavioural and adrenocortical responses of pigs of different weights (25–35 kg, 50–70 kg, and &gt;85 kg) to a wide range of ambient temperatures (2–29°C). On three days of each experimental period, we took saliva samples for the analysis of cortisol concentration, and recorded lying behaviour from 0800–0600h. Behavioural and cortisol parameters were analysed using linear mixed effects models. Optimal temperature ranges for the three weight-classes were calculated using logistic regression. Pigs chose different areas for resting depending on ambient temperature. With increasing temperature, pigs used the dung area more often and lay more often without contact with pen mates. Compared to lighter pigs, heavier pigs lay without contact with pen mates at lower temperatures. In general, lying without contact occurred at temperatures 5–7°C lower than lying in the dung area. Huddling increased with decreasing temperature, and, with increasing weight, pigs showed huddling at lower temperatures. There was a significant increase in cortisol levels at high ambient temperatures in pigs &gt;85 kg. In pens with partially slatted floors, the results indicate temperature ranges within the thermal tolerance of pigs to be 19–21°C for pigs weighing 25–35 kg (lying area of 0.46 m2/pig), 10–17°C for pigs between 50–70 kg and 5–17°C for pigs &gt;85 kg (both weights: lying area of 0.67 m2/pig).

Associations between neuroendocrine responses to the Insulin Tolerance Test and patient characteristics in chronic fatigue syndrome

Objective Subtle dysregulations of the hypothalamic–pituitary–adrenal (HPA) axis have been proposed as an underlying pathophysiological mechanism in chronic fatigue syndrome (CFS). This study attempted to assess the relationship between patient characteristics and HPA axis functioning using a neuroendocrine challenge test. Method A test battery designed to assess different dimensions of CFS was given to 18 CFS patients and 17 controls. To evaluate the integrity of the HPA axis, the Insulin Tolerance Test (ITT), a centrally acting neuroendocrine challenge test, was performed on patients and controls. ACTH, salivary free cortisol and total plasma cortisol levels were assessed as a measure of the HPA axis stress response. Correlations of patient characteristics were calculated with integrated responses for all endocrine parameters. Results CFS patients had a significantly reduced area under the ACTH response curve (AUC) in the ITT. The AUC was significantly associated with the duration of CFS symptoms ( r=−.592, P=.005) and the severity of fatigue symptomatology ( r=−.41, P=.045). In addition, duration of CFS was correlated with the severity of fatigue symptoms ( r=.38, P=.045). Similar associations were not observed for cortisol parameters. Conclusion It has been postulated that neuroendocrine dysregulations observed in CFS are of an acquired nature. The results of a strong association between the integrated ACTH response and the duration of CFS emphasizes the need to consider factors known to be risk factors for the chronicity of CFS symptoms, such as profound inactivity, deconditioning and sleep abnormalities, as possible candidates for secondary causes of neuroendocrine dysregulations in CFS.

Endocrine and Cardiovascular Responses to Corticotropin-Releasing Hormone in Patients with Posttraumatic Stress Disorder: A Role for Atrial Natriuretic Peptide?

Hypothalamic-pituitary-adrenocortical (HPA) axis data, such as low plasma cortisol concentrations in spite of increased corticotropin-releasing hormone (CRH) levels in patients with posttraumatic stress disorder (PTSD), are difficult to interpret. Atrial natriuretic peptide (ANP) may be an explanatory link in the neuroendocrine pathophysiology of the disorder, since it is a neuromodulator with antianxiety effects that inhibits HPA activity at multiple levels. Seventeen patients with chronic PTSD and 17 healthy control subjects were given 100 µg of human CRH at 3 p.m. ANP, adrenocorticotropic hormone (ACTH), and cortisol levels in plasma as well as blood pressure and heart rate were measured during basal conditions and after CRH stimulation. Basal ANP levels were significantly lower in PTSD patients in comparison with normal controls, but the response to CRH was undistinguishable. In contrast to our expectation, no significant differences in basal or CRH-stimulated ACTH or cortisol parameters could be observed. Systolic and diastolic blood pressures at baseline and after CRH were significantly elevated in PTSD patients. All group differences remained significant after controlling for basal blood pressure and/or body mass index. Our data do not support a role of ANP in abnormal HPA axis regulation in PTSD. However, the persistently low ANP plasma levels in PTSD patients despite elevated blood pressure may serve to facilitate anxiety behavior and have adverse long-term cardiovascular consequences. Further studies to assess ANP secretion in PTSD patients and to clarify its pathophysiological impact are needed.

Effects of combined Actinobacillus pleuropneumoniae challenge and change in environmental temperature on production, plasma insulin-like growth factor I (IGF-I), and cortisol parameters in growing pigs

There is limited information on the combined effects of stress factors on physiological and endocrinological parameters in growing pigs. This study measured the effects of pleuropneumonia and changes in environmental temperature singularly and in combination. Forty entire male pigs (liveweight 33 ± 5 kg) were allocated to 1 of 4 treatments: control (22�C room temperature), Actinobacillus pleuropneumoniae challenge (Day�1), temperature stress (15�C for 8 h on Days 0, 1, and 2, and 30�C for 24 h on Day 6), or combined A.�pleuropneumoniae challenge and temperature stress. Control pigs had an average daily gain of 1.15 ± 0.12 kg/day and an average daily feed intake of 2.29 ± 0.06 kg/day over 8 days. Challenge with A. pleuropneumoniae caused a reduction (P &lt; 0.001) in feed intake, weight gain, and plasma insulin-like growth factor I (IGF-I) concentration and an increase (P &lt; 0.001) in plasma cortisol concentration. There was no significant effect of the temperature stress on circulating cortisol and IGF-I concentrations or liveweight gain. Thus, the treatment effects did not appear to be additive and the effects of the A. pleuropneumoniae challenge were more profound than changes in ambient air temperature.