Elevated Plasma Cortisol Concentrations Research Articles

Negative feedback regulation in the hypothalamic-pituitary-interrenal axis of rainbow trout subjected to chronic social stress

The formation of dominance hierarchies in pairs of juvenile rainbow trout (Oncorhynchus mykiss) results in subordinate individuals exhibiting chronically elevated plasma cortisol concentrations. Cortisol levels reflect a balance between cortisol production, which is coordinated by the hypothalamic-pituitary-interrenal (HPI) axis in teleost fish, and negative feedback regulation and hormone clearance, which act to lower cortisol levels. However, the mechanisms contributing to the longer-term elevation of cortisol levels during chronic stress are not well established in fishes. The current study aimed to determine how subordinate fish maintain elevated cortisol levels, by testing the prediction that negative feedback and clearance mechanisms are impaired by chronic social stress. Plasma cortisol clearance was unchanged by social stress based on a cortisol challenge trial, hepatic abundance of the cortisol-inactivating enzyme 11-beta hydroxysteroid dehydrogenase type 2 (11βHSD2), and tissue fate of labelled cortisol. The capacity for negative feedback regulation in terms of transcript and protein abundances of corticosteroid receptors in the preoptic area (POA) and pituitary appeared stable. However, changes in 11βHSD2 and mineralocorticoid receptor (MR) expression suggest subtle regulatory changes in the pituitary that may alter negative feedback. The chronic cortisol elevation observed during social subordination likely is driven by HPI axis activation and compounded by dysregulated negative feedback.

Association between levels of serotonin, melatonin, cortisol and the clinical condition of patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic systemic connective tissue disease of autoimmune basis. It is characterized by inflammation of joints and systemic complications. The etiopathogenesis is still unknown. Predisposing factors for the disease include genetic, immunological and environmental. Chronic disease and the stress experienced by patients disrupt the body’s homeostatic state and weaken the human immune system. Reduced immunity and endocrine disruption may influence the development of autoimmune diseases and exacerbate their course. The aim of the study was to investigate whether there is a relationship between the blood levels of hormones such as cortisol, serotonin, melatonin and the clinical status of RA patients as determined by the DAS28 index and CRP protein. A total of 165 people participated in the study of these 84 subjects had RA and the rest were the control group. All participants completed a questionnaire and had their blood drawn to determine hormones. Patients with RA had higher plasma cortisol (324.6 ng/ml vs. 292.9 ng/ml) and serotonin concentrations (67.9 ng/ml vs. 22.1 ng/ml) and lower plasma melatonin (116.8 pg/ml vs. 330.2 pg/ml) compared to controls. Patients whose CRP concentration were above normal also had elevated plasma cortisol concentration. No significant association was observed in RA patients between plasma melatonin, serotonin and DAS28 values. However, it can be concluded that those with high disease activity had lower melatonin levels as compared to patients with low and moderate DAS28 values. Significant differences were found between RA patients not using steroids and plasma cortisol (p = 0.035). In RA patients, it was observed that as plasma cortisol concentration increased, the chance of having an elevated DAS28 score, indicating high disease activity, increased.

Group or individual housing does not reduce socio-sexual and reproductive responses in anestrous goats during the first contact with the photo-stimulated buck

Herein, we examined the effect of the type of housing (individual vs group housing) of anestrus female goats on plasma cortisol concentrations and socio-sexual behaviors during first contact with photo-stimulated male goats and determined the impact on sexual and reproductive responses after 15 d of contact with photo-stimulated males. Therefore, after weaning, 10 females each were individually and group-housed, respectively. Ten bucks were rendered sexually active by exposure to artificially long days (16 h of light and 8 h of darkness per day) for 2.5 mo. During the naturally increasing photoperiod, 15-mo-old females were exposed and maintained with males. On day 0, during the first contact with males, individually- and group-housed females exhibited similar plasma cortisol concentrations (22.6 vs 27.4 ng/mL, respectively). Likewise, socio-sexual behaviors did not differ between examined groups on day 0. Moreover, the interval from first contact with males to the first estrus, short and normal ovulatory cycles, ovulation, fertility, and prolificacy rates were similar between differently housed females. Furthermore, mounting attempts did not differ between males in contact with either female group. In conclusion, individually- and group-housed anestrus females displayed elevated and similar plasma cortisol concentrations during first contact with photo-stimulated males and similar socio-sexual behaviors and reproductive responses when exposed to photo-stimulated males.

Chronic social stress alters protein metabolism in juvenile rainbow trout, Oncorhynchus mykiss

When confined in pairs, juvenile rainbow trout (Oncorhynchus mykiss) form dominance hierarchies in which subordinate fish exhibit characteristic physiological changes including reduced growth rates and chronically elevated plasma cortisol concentrations. We hypothesized that alterations in protein metabolism contribute to the reduced growth rate of socially stressed trout, and predicted that subordinate trout would exhibit reduced rates of protein synthesis coupled with increases in protein degradation. Protein metabolism was assessed in dominant and subordinate fish after 4 days of social interaction, and in fish that were separated after 4 days of interaction for a 4 days recovery period, to determine whether effects on protein metabolism recovered when social stress was alleviated. Protein metabolism was assessed in liver and white muscle by measuring the fractional rate of protein synthesis and markers of protein degradation. In the white muscle of subordinate fish, protein synthesis was inhibited and activities of the ubiquitin-proteasome pathway (UPP) and the autophagy lysosomal system (ALS) were elevated. By contrast, the liver of subordinate fish exhibited increased rates of protein synthesis and activation of the ALS. When allowed to recover from chronic social stress for 4 days, differences in protein metabolism observed in white muscle of subordinate fish during the interaction period disappeared. In liver, protein synthesis returned to baseline levels during recovery from social stress, but markers of protein degradation did not. Collectively, these data support the hypothesis that inhibition of muscle protein synthesis coupled with increases in muscle protein breakdown contribute to the reduced growth rates of subordinate rainbow trout.

Stocking Density Induced Stress on Plasma Cortisol and Whole Blood Glucose Concentration in Nile Tilapia Fish (Oreochromis niloticus) of Lake Victoria, Kenya

Effects of high stocking densities (HSDs) were evaluated for Nile tilapia fish (Oreochromis niloticus) under culture to determine its influence on plasma cortisol and whole blood glucose concentration. Plasma cortisol levels (ng/ml) were assayed byEnzyme-LinkedImmunosorbentAssay (ELISA). Whole blood glucose levels were determined using a hand-held one touch ultraglucose meter (MD-300) and test strips. Plasma cortisol and whole blood glucose level determinations were replicated three times forO. niloticusreared under both low stocking densities (LSD) and HSD. One way Analysis of Variance (ANOVA) was performed on the data collected, and comparison of significant differences in means was carried out between LSD and HSD at 0.01%. Plasma cortisol levels revealed statistically (P≤0.01) significant values of HSD at 6.32 ± 1.06 ng/ml than in LSD at 4.62 ± 1.58 ng/ml for theO. niloticusgroups studied. Whole blood glucose analysis revealed a statistical (P<0.05) difference in the means in HSD and LSDO. niloticusgroups (F(df,1; 8) = 7.946 > Fcrit = 4.414;P=0.01). Mean plasma glucose concentration was statistically (P≤0.01) higher for HSD than LSDO. niloticusgroups at mean ± SD, 96.84 ± 5.28 and 76.82 ± 5.92, respectively. The findings of this study demonstrate that high stocking densities increase both cortisol and whole blood glucose concentration in tilapia fish, indicating a marked increase in stress levels. Elevated plasma cortisol and whole blood glucose concentration can be used as biomarkers for acute stress inO. niloticusproduced under aquaculture systems. The findings of this study can help inform policy on the management of stress caused by overstocking ofO. niloticusand other related Cichlids under industrial aquaculture production.

Effect of colony disruption and social isolation on naked mole-rat endocrine correlates

The social environment of animals can have profound implications on their behaviour and physiology. Naked mole-rats (Heterocephalus glaber) are highly social with complex dominance hierarchies that influence both stress- and reproduction-related hormones. Homeostasis may be affected by aggressive interactions, colony instability and social isolation. Furthermore, naked mole-rat colonies are characterised by a marked reproductive skew; a single female and few males are reproductively active while other colony members are reproductively suppressed. Thus, there are distinct differences in related hormone concentrations between reproductively active and non-active animals; however, this changes when non-reproductive individuals are removed from the colony. We investigated the effects of social isolation and colony disruption on plasma cortisol and progesterone concentrations in non-breeding naked mole-rats. During colony disruption, we found a significant increase in cortisol concentrations in females removed from the colony for social isolation (experimental) as well as in females that remained in the colony (control). Cortisol concentrations were reduced in both groups after experimental animals were paired up. No changes in cortisol concentrations were observed in control or experimental males after removal from the colony or pairing. This suggests that the females, but not the males, found colony disruption and social isolation stressful. Upon removal from the colony, both control and experimental females showed a small increase in progesterone, which returned to basal levels again in the control animals. Experimental females showed a dramatic spike in progesterone when they were paired with males, indicating reproductive activation. The sex difference in the stress responses may be due to the stronger reproductive suppression imposed on females, or the increased likelihood of dispersal for males. It is clear that the social environment reflects on the endocrine correlates of animals living in a colony, and that the colony structure may affect the sensitivity of the animals to changes in their environment.

Spatial distribution and activity patterns as welfare indicators in response to water quality changes in European sea bass, Dicentrarchus labrax

In aquaculture, fish are exposed to unavoidable stressors that can be detrimental for their health and welfare. However, welfare in farmed fish can be difficult to assess, and, so far, no standardized test has been universally accepted as a welfare indicator. This work contributes to the establishment of behavioural welfare indicators in a marine teleost in response to different water quality acute stressors. Groups of ten fish were exposed to high Total Ammonia Nitrogen concentration (High TAN, 18 mg.L-1), Hyperoxia (200 % O2 saturation), Hypoxia (20 % O2 saturation), or control water quality (100% O2 saturation and TAN < 2.5 mg.L-1) over 1 hour. Fish were then transferred in a novel environment for a group behaviour test under the same water quality conditions over 2 hours. Videos were recorded to assess thigmotaxis, activity and group cohesion. After this challenge, plasma cortisol concentration was measured in a subsample, while individual behavioural response was measured in the other fish using novel tank diving test. Prior to this study, the novel tank diving test was validated as a behavioural challenge indicative of anxiety state, by using nicotine as anxiolytic drug. Overall, all stress conditions induced a decrease in activity and thigmotaxis and changes in group cohesion while only fish exposed to Hypoxia and High TAN conditions displayed elevated plasma cortisol concentrations. In post-stress condition, activity was still affected but normal behaviour was recovered within the 25 minutes of the test duration. Our work suggests that the activity, thigmotaxis and group cohesion are good behavioural indicators of exposure to degraded water quality, and could be used as standardized measures to assess fish welfare.

Social stress increases plasma cortisol and reduces forebrain cell proliferation in subordinate male zebrafish (Danio rerio).

Many animals, including zebrafish (Danio rerio), form social hierarchies through competition for limited resources. Socially subordinate fish may experience chronic stress, leading to prolonged elevation of the glucocorticoid stress hormone cortisol. As elevated cortisol levels can impair neurogenesis, the present study tested the hypothesis that social stress suppresses cell proliferation in the telencephalon of subordinate zebrafish via a cortisol-mediated mechanism. Cell proliferation was assessed using incorporation of the thymidine analogue 5-bromo-2'-deoxyuridine (BrdU). After 48 and 96 h of social interaction, subordinate male zebrafish exhibited elevated plasma cortisol concentrations and significantly lower numbers of BrdU+ cells in the dorsal but not ventral regions of the telencephalon compared with dominant or group-housed control male fish. After a 2week recovery in a familiar group of conspecifics, the number of BrdU+ cells that co-labelled with a neuronal marker (NeuN) was modestly reduced in previously subordinate male fish, suggesting that the reduction of cell proliferation during social stress may result in fewer cells recruited into the neuronal population. In contrast to male social hierarchies, subordinate female zebrafish did not experience elevated plasma cortisol, and the number of BrdU+ cells in the dorsal telencephalic area was comparable among dominant, subordinate and group-housed control female fish. Treating male zebrafish with metyrapone, a cortisol synthesis inhibitor, blocked the cortisol response to social subordination and attenuated the suppression of brain cell proliferation in the dorsal telencephalic area of subordinate fish. Collectively, these data support a role for cortisol in regulating adult neurogenesis in the telencephalon of male zebrafish during social stress.

Adrenocortical Stress Response during the Course of Critical Illness.

Critically ill patients have elevated plasma cortisol concentrations, in proportion to illness severity. This was traditionally attributed exclusively to a central activation of the hypothalamus-pituitary axis. However, low rather than high plasma ACTH concentrations have been reported in critically ill patients, with loss of diurnal ACTH and cortisol rhythm. Low ACTH together with high cortisol is referred to as "ACTH-cortisol dissociation." Although cortisol production is somewhat increased with inflammation, a reduced cortisol breakdown explains to a larger extent the hypercortisolism during critical illness. Inflammation-driven decrease in cortisol binding proteins further increase the active free cortisol fraction. Several drugs administered to ICU patients suppress plasma cortisol in a dose-dependent manner. Sustained low circulating ACTH might contribute to adrenal atrophy and dysfunction in the prolonged phase of critical illness. In the acute phase of sepsis or septic shock, a condition referred to as "relative adrenal insufficiency" has been suggested to ensue from glucocorticoid resistance and insufficiently elevated circulating cortisol to overcome such resistance, with pathological changes possibly occurring at every level of the HPA axis. However, it remains highly controversial whether tissue-specific glucocorticoid resistance is adaptive or maladaptive, how to diagnose "relative" adrenal insufficiency, and how it should be treated. Large RCTs, investigating the effect of 200 mg/d hydrocortisone treatment for sepsis or septic shock have shown conflicting, mainly negative, results. Not taking into account the reduced cortisol breakdown, which increases the risk of overdosing hydrocortisone, might have played a role. Further research on diagnostic, therapeutic and dosing aspects is urgently warranted. Compr Physiol 8:283-298, 2018.

Effect of Ichthyophonus on blood plasma chemistry of spawning Chinook salmon and their resulting offspring in a Yukon River tributary.

Ichthyophonus is a protozoan parasite of Alaska Chinook salmon Oncorhynchus tshawytscha. In this study, we determined whether spawning Chinook salmon in the Yukon River drainage exhibited a measurable stress response (i.e. elevated plasma cortisol concentrations) and detectable changes in selected blood plasma chemistry parameters when infected with Ichthyophonus. The resulting alevin were also analyzed for any differences in blood plasma chemistry caused by parental infection with Ichthyophonus. In 2010, 2011, and 2012, spawning adult Chinook salmon were collected from the Salcha River, Alaska, USA, and the prevalence of Ichthyophonus in these fish was 7.8, 6.3, and 8.3%, respectively. Fish with no clinical signs of Ichthyophonus and Ichthyophonus-positive parents were cross-fertilized to investigate potential second-generation effects as a result of Ichthyophonus infection. We found no significant difference in cortisol concentrations in blood plasma between Ichthyophonus-positive and -negative adults or between alevin from Ichthyophonus-positive and -negative parents. There were no significant differences in blood plasma parameters (e.g. alanine aminotransferase, creatine kinase, glucose) of Ichthyophonus-negative and -positive adults, with the exception of aspartate aminotransferase, which was significantly higher in plasma of Ichthyophonus-negative adults. All clinical chemistry parameters for alevin resulting from both Ichthyophonus-negative and -positive parents were not significantly different. Based on this study, which has a limited sample size and low prevalence of Ichthyophonus, offspring of Chinook salmon appear to suffer no disadvantage as a result of Ichthyophonus infection in their parents on the Salcha River.

Changes in plasma steroids and cytokines levels in betel chewing patients in Taiwan

Betel nut is the second largest economic food product in Taiwan. In Southeast Asia, the habit of chewing betel nut seems to be highly correlated with oral submucous fibrosis and oral squamous cell carcinoma. Oral submucous fibrosis is characterized by abnormal accumulation of oral submucous collagen fibers and limitation of mouth opening. Although the mechanism responsible for tissue damage is still unknown, prolonged irritation caused by betel nut and tobacco is considered to be a major factor contributing to the pathogenesis of oral submucous fibrosis. The effect of betel nut chewing on immune system remains unknown. Present study aims to investigate the change of plasma hormones including cortisol, testosterone, and inflammatory cytokine concentrations in male chewing betel nut compared with normal subjects. Heparinized blood was obtained from control group (normal young+mid-aged individuals), betel nut-chewing, and oral cancer male subjects. The study was approved by the Ethics Committee of the Chang-Gung Memorial Hospital. Written informed consent was granted by the patients. Plasma cortisol and testosterone concentrations were detected by commercial enzyme-linked immunosorbent assay (ELISA). The inflammatory cytokines, including interleukin-1β (IL-1β), IL-15, tumor necrosis factor-α (TNF-α), were analyzed by ELISA with commercial monoclonal capture antibodies and polyclonal detection antibodies. The median concentrations of plasma IL-1β, IL-15, and TNF-α were 3.14pg/ml, 3.14pg/ml, and 6.85pg/ml, respectively, in patients with oral cancer, compared with median plasma IL-1β, IL-15, and TNF-α concentration of 2.64pg/ml, 5.86pg/ml, and 5.38pg/ml, respectively, in patients with betel nut-chewing habit. In contrast, the median concentrations of plasma IL-1β, IL-15, and TNF-α in mid-aged males (aged 30–50) were 7.00pg/ml, 10.64pg/ml, and 31.73pg/ml, respectively, compared with median plasma concentration of IL-1β, IL-15, and TNF-α of 4.48pg/ml, 33.36pg/ml, and 97.77pg/ml in young males (aged 20–22), respectively. Also, significantly elevated plasma cortisol concentration was noted in betel nut-chewing (median 727.2ng/ml) and oral cancer patients (561.9ng/ml) compared to the mid-aged (176.8ng/ml) and young males (173.4ng/ml), respectively. In addition, lower plasma testosterone concentrations were found in betel nut-chewing subjects compared with young males (2.6±3.3ng/ml vs 6.2±2.9ng/ml). To summarize, the inflammatory cytokines and steroid hormones may reflect the degree of inflammation in betel nut-chewing males and the oral cancer subjects. The above findings suggest that betel nut-chewing or oral cancer inhibits plasma cytokines and regulates steroid hormones concentrations compared to mid-aged or young normal subjects. It is also indicated that betel nut-chewing causes decreased inflammatory cytokines as the same levels as in oral cancer subjects.

Cortisol metabolism in critical illness: implications for clinical care.

Critical illness is uniformly characterized by elevated plasma cortisol concentrations, traditionally attributed exclusively to increased cortisol production driven by an activated hypothalamic pituitary adrenal axis. However, as plasma adrenocorticotropic hormone (ACTH) concentrations are often not elevated or even low during critical illness, alternative mechanisms must contribute. Recent investigations revealed that plasma clearance of cortisol is markedly reduced during critical illness, explained by suppressed expression and activity of the main cortisol metabolizing enzymes in liver and kidney. Furthermore, unlike previously inferred, cortisol production rate in critically ill patients was only moderately increased to less than double that of matched healthy subjects. In the face of low-plasma ACTH concentrations, these data suggest that other factors drive hypercortisolism during critical illness, which may suppress ACTH by feedback inhibition. These new insights add to the limitations of the current diagnostic tools to identify patients at risk of failing adrenal function during critical illness. They also urge to investigate the impact of lower hydrocortisone doses than those hitherto used. Recent novel insights reshape the current understanding of the hormonal stress response to critical illness and further underline the need for more studies to unravel the pathophysiology of adrenal (dys)functioning during critical illness.

Periodic hypokalemia associated with cyclic Cushing's syndrome.

A 69-year-old woman presented with periodic hypertension, edema, and hypokalemia that occurred within an interval of a few weeks. Her laboratory test values showed autonomously elevated plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations. The patient's Cushingoid features were not evident on first admission. Several weeks later, in spite of constant oral potassium supplementation, severe hypokalemia recurred with Cushingoid features and worsening symptoms of leg edema and pigmentation, which spontaneously disappeared within a few days. Her periodic symptoms occurred in parallel with fluctuations of plasma ACTH and cortisol concentrations. A series of endocrinological and pituitary imaging findings led to a tentative diagnosis of cyclic Cushing's syndrome caused by ectopic ACTH secretion. However, chest and abdominal computed tomography did not reveal any candidate lesion. The patient's periodic hypercortisolemia and symptoms were well controlled after treatment with metyrapone plus dexamethasone. This is a very rare case of periodic hypokalemia and hypertension caused by cyclic Cushing's syndrome.

Disentangling the Roles of Air Exposure, Gill Net Injury, and Facilitated Recovery on the Postcapture and Release Mortality and Behavior of Adult Migratory Sockeye Salmon (Oncorhynchus nerka) in Freshwater

We sought to improve the understanding of delayed mortality in migrating sockeye salmon (Oncorhynchus nerka) captured and released in freshwater fisheries. Using biotelemetry, blood physiology, and reflex assessments, we evaluated the relative roles of gill net injury and air exposure and investigated whether using a recovery box improved survival. Fish (n=238), captured by beach seine, were allocated to four treatment groups: captured only, air exposed, injured, and injured and air exposed. Only half of the fish in each group were provided with a 15-min facilitated recovery. After treatment, fish were radio-tagged and released to resume their migration. Blood status was assessed in 36 additional untagged fish sampled after the four treatments. Compared with fish sampled immediately on capture, all treatments resulted in elevated plasma lactate and cortisol concentrations. After air exposure, plasma osmolality was elevated and reflexes were significantly impaired relative to the control and injured treatments. Injured fish exhibited reduced short-term migration speed by 3.2 km/d and had a 14.5% reduced survival to subnatal watersheds compared to controls. The 15-min facilitated recovery improved reflex assessment relative to fish released immediately but did not affect survival. We suggest that in sockeye salmon migrating in cool water temperatures (∼13°-16°C), delayed mortality can result from injury and air exposure, perhaps through sublethal stress, and that injury created additive delayed mortality likely via secondary infections.

Photoperiod and stress regulation of corticosteroid receptor, brain-derived neurotrophic factor, and glucose transporter GLUT3 mRNA in the hippocampus of male Siberian hamsters (Phodopus sungorus)

In response to changing day lengths, small photoperiodic rodents have evolved a suite of adaptations to survive the energetic bottlenecks of winter. Among these adaptations are changes in metabolism, adiposity, and energy balance. Whereas hypothalamic and neuroendocrine regulation of these adaptations has been extensively studied, the impact of day length, and interaction of day length and stress, on the energy balance of neurons within the central nervous system remains unspecified. Thus, we exposed male Siberian hamsters (Phodopus sungorus) to either short or long day lengths for 14weeks to induce the full suite of adaptive responses, exposed them to 4h of restraint, and then measured relative mRNA expression in the hippocampus for low- and high-affinity glucocorticoid receptors (glucocorticoid receptor (GR), mineralocorticoid receptor (MR)), brain-derived neurotrophic factor (BDNF), and the neuron-specific glucose transporter GLUT3. Independent of photoperiod, restraint elevated plasma cortisol (CORT) concentrations and reduced expression of GR, MR, and BDNF. Neither restraint nor photoperiod significantly altered GLUT3 expression. Among all groups, plasma cortisol concentrations were negatively correlated with GR and MR expression. MR, BDNF, and GLUT3 levels were positively correlated with one another, even when controlling for photoperiod and CORT. Taken together, these results suggest that, as peripheral energy balance changes across day length in this photoperiodic species, the neurons of the hippocampus do not alter relative gene expression levels of three proteins involved in monitoring neuronal glucose regulation and morphology.

Vinclozolin affects the interrenal system of the rare minnow ( Gobiocypris rarus)

Vinclozolin, a widely used fungicide, has been characterized as a potent androgen antagonist. In this study, the effects of vinclozolin on the interrenal system of the rare minnow ( Gobiocypris rarus) were evaluated. The results revealed a decline of the renal somatic index (RSI) and the presence of histopathological effects, including shrinkage of the glomerulus and expansion of the Bowman's space in the kidneys, in rare minnows exposed to vinclozolin. Elevated plasma cortisol concentrations in females exposed to ≥2 μg/L vinclozolin and males exposed to ≥10 μg/L vinclozolin ( p < 0.05) suggested that endocrine stress was evoked by vinclozolin exposure. Significant decreases in mRNA levels of interrenal crf, pomc, gr, and nka in females and gr and nka in males were observed after exposure to ≥0.5 μg/L and 2 μg/L vinclozolin ( p < 0.05), respectively; however, no changes in expression of these genes were observed in the brain of males ( p ≥ 0.159) or females ( p ≥ 0.053) compared with the control. The results indicated that female rare minnows were more sensitive than males to vinclozolin exposure. In conclusion, vinclozolin exposure evoked endocrine stress on the hypothalamic–pituitary–interrenal axis in the rare minnow, and the interrenal tissue was more sensitive than the brain tissue to stress caused by vinclozolin exposure. These results provide additional data about the modes of toxicological action of vinclozolin.

Physiological Effects of Potassium Chloride, Formalin, and Handling Stress on Bonytail

AbstractWe characterized the sublethal physiological changes in bonytail Gila elegans subjected to consecutive 750‐mg/L potassium chloride (KCl) and 25‐mg/L formalin treatments for the removal of zebra mussel Dreissena polymorpha and quagga mussel D. bugensis veligers. Plasma cortisol, glucose, and osmolality were measured over 24 h and at 14 d posthandling after exposing bonytail to KCl and one net stressor (capture with a net), KCl plus formalin and two net stressors, and one or two net stressors without chemicals. Elevated plasma cortisol (322–440 ng/mL) and glucose (254–399 mg/dL) concentrations were observed in all treatments compared with the concentrations in control fish (plasma cortisol, 56 ng/mL; glucose, 43 mg/dL). While there were no detectable differences in plasma osmolality among the treatment and control fish, a difference was observed between fish that were handled once versus twice. Chemical effects of stress were not observed in any of the physiological responses when the KCl treatment was compared with the one‐net stressor treatment or when the KCl plus formalin treatment was compared with the two‐net stressor treatment. Cumulative responses, however, were observed between one net stressor and two net stressors for plasma glucose and osmolality but not for plasma cortisol. Plasma cortisol and glucose levels remained elevated at 24 h posthandling, indicating that bonytail had not completely recovered from the handling stressors and would benefit from a recovery period in protected refugia before being released.Received August 23, 2010; accepted January 20, 2011

Cardiovascular, endocrine and behavioural responses to suckling and permanent separation in goats

BackgroundSuckling can be a peaceful or vulnerable event for goats and kids, whereas, separation is suggested as stressful. The aim of this study was to investigate physiology and behaviour in these two different situations in dairy goats.MethodsFour studies were performed with seven goats kept with their first-born kid in individual boxes. The goats were videotaped and heart rate and arterial blood pressure were recorded every minute by telemetry from parturition until 24 hours after separation. One to two days after parturition, Study 1 was performed with analyses of heart rate and blood pressure around a suckling. In Study 2, performed 3-5 days after parturition, blood sampling was done before, during and after suckling. Study 3 was performed 4-6 days post partum, with blood sampling before and after a permanent goat and kid separation. In addition, vocalisations were recorded after separation. Blood samples were obtained from a jugular vein catheter and analysed for plasma cortisol, β-endorphin, oxytocin, and vasopressin concentrations. Study 4 was performed during the first (N1) and second nights (N2) after parturition and the nights after Study 2 (N3) and 3 (N4). Heart rate, blood pressure and time spent lying down were recorded.ResultsThe kids suckled 2 ± 0.2 times per hour and each suckling bout lasted 43 ± 15 s. In Study 1, heart rate and blood pressure did not change significantly during undisturbed suckling. In Study 2, plasma cortisol (P ≤ 0.05 during suckling and P ≤ 0.01 five minutes after suckling) and β-endorphin (P ≤ 0.05) concentrations increased during suckling, but oxytocin and vasopressin concentrations did not change. In Study 3, the goats and kids vocalised intensively during the first 20 minutes after separation, but the physiological variables were not affected. In Study 4, heart rate and arterial blood pressure declined gradually after parturition and were lowest during N4 (P ≤ 0.05) when the goats spent longer time lying down than during earlier nights (P ≤ 0.01 during N1 and N3 and P ≤ 0.05 during N2).ConclusionsSuckling elevated plasma cortisol and β-endorphin concentrations in the goats. The intensive vocalisation in the goats after separation, earlier suggested to indicate stress, was not accompanied by cardiovascular or endocrine responses.

Intrauterine growth restriction delays surfactant protein maturation in the sheep fetus

Pulmonary surfactant is synthesized by type II alveolar epithelial cells to regulate the surface tension at the air-liquid interface of the air-breathing lung. Developmental maturation of the surfactant system is controlled by many factors including oxygen, glucose, catecholamines, and cortisol. The intrauterine growth-restricted (IUGR) fetus is hypoxemic and hypoglycemic, with elevated plasma catecholamine and cortisol concentrations. The impact of IUGR on surfactant maturation is unclear. Here we investigate the expression of surfactant protein (SP) A, B, and C in lung tissue of fetal sheep at 133 and 141 days of gestation (term 150 +/- 3 days) from control and carunclectomized Merino ewes. Placentally restricted (PR) fetuses had a body weight <2 SD from the mean of control fetuses and a mean gestational Pa(O(2)) <17 mmHg. PR fetuses had reduced absolute, but not relative, lung weight, decreased plasma glucose concentration, and increased plasma cortisol concentration. Lung SP-A, -B, and -C protein and mRNA expression was reduced in PR compared with control fetuses at both ages. SP-B and -C but not SP-A mRNA expression and SP-A but not SP-B or -C protein expression increased with gestational age. Mean gestational Pa(O(2)) was positively correlated with SP-A, -B, and -C protein and SP-B and -C mRNA expression in the younger cohort. SP-A and -B gene expression was inversely related to plasma cortisol concentration. Placental restriction, leading to chronic hypoxemia and hypercortisolemia in the carunclectomy model, results in significant inhibition of surfactant maturation. These data suggest that IUGR fetuses are at significant risk of lung complications, especially if born prematurely.

Nitrate-induced elevations in circulating sex steroid concentrations in female Siberian sturgeon ( Acipenser baeri) in commercial aquaculture

Although nitrate is a ubiquitous component of aquatic environments, and has become a global pollutant in a variety of aquatic systems, it has only recently begun to receive attention for its ability to alter endocrine function. Aquaculture environments with limited water exchange often contain nitrate concentrations far in excess of natural environments, yet nitrate's impact on the reproductive health and endocrine function of commercially important species residing in these environments has not been investigated. Two experiments were conducted evaluating the effects of elevated nitrate on cultured Siberian sturgeon ( Acipenser baeri). The first experiment compared the effects of a 30 day exposure to 11.5 ± 0.36 and 57 ± 2.18 mg/L nitrate-N concentrations on plasma cortisol (F), glucose, 17β-estradiol (E 2), testosterone (T) and 11-ketotestosterone (11-KT) concentrations. The second experiment was similar to the first but evaluated concentrations of 1.5 ± 0.057 and 57 ± 1.52 mg/L nitrate-N. In both experiments, after 30 days of exposure to a given nitrate concentration, blood samples were obtained at time 0, and a portion of those fish were then placed under confinement stress for a period of 6 h to evaluate whether nitrate affects the associated stress response. The fish were bled at 1 h and 6 h during the confinement period. Results revealed that 57 mg/L nitrate-N exposure was associated with an increase in plasma T, 11-KT and E 2 concentrations at time 0, but did not alter the associated stress response defined by elevated plasma cortisol concentrations. An additional measure of the stress response, plasma glucose concentration, however, was altered by nitrate exposure during the 6 h period of confinement stress in Experiment 1, but was not in Experiment 2. These findings demonstrate that nitrate has the potential to disrupt endocrine function and possibly secondary stress responses in cultured Siberian sturgeon.