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Query: UMLS:C0848237 (acute stress)
 4,619 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Sustained responsiveness of the hypothalamic-pituitary-adrenal (HPA) axis during chronic or repeated stress is associated with continuous activation of ascending noradrenergic neurons from the brainstem to the hypothalamic paraventricular nucleus (PVN). The fact that glucocorticoid receptor (GR) exists in the brainstem noradrenergic neurons including locus coeruleus (LC) suggests that glucocorticoids play a modulatory role in maintaining the activity of these neurons during chronic stress. To determine whether alterations in the sensitivity of noradrenergic neuronal activity to endogenous CORT occur during chronic or repeated stress, tyrosine hydroxylase (TH) and GR mRNA expressions in the LC were examined in acute (2 h) and repeated (2 h daily, 14 days) immobilization stress, using sham-operated rats and adrenalectomized rats with a moderate dose of CORT replacement (ADX+CORT group). In acute stress, TH mRNA in the LC increased in the ADX+CORT rats, but not in sham operated rats. In repeated stress, however, elevated endogenous CORT failed to inhibit TH mRNA responses in sham rats; LC TH mRNA in sham rats responded to the same extent as in ADX+CORT rats. A reduction of GR mRNA in the LC was observed in the acutely stressed and repeatedly stressed sham group, but not in the ADX+CORT groups. The decrease in LC GR mRNA levels in sham rats tended to be greater after repeated than after acute stress. LC GR mRNA levels decreased in response to systemic CORT treatment (200 mg pellet sc, for 14 days) and increased in response to adrenalectomy; neither CORT treatment nor adrenalectomy influenced TH mRNA levels in the LC. These results suggest that glucocorticoid responses to acute immobilization prevent LC TH mRNA levels from rising significantly, while glucocorticoids appear to decrease their capacity to restrain LC TH mRNA during repeated immobilization. Although the results clearly show glucocorticoid-dependent alterations in LC GR mRNA expression, the association between increased TH mRNA and decreased GR mRNA in the LC remains to be elucidated.
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PMID:Regulatory role of glucocorticoids and glucocorticoid receptor mRNA levels on tyrosine hydroxylase gene expression in the locus coeruleus during repeated immobilization stress. 1210 Oct 44

Gestational stress (GS) produces profound behavioural impairments in the offspring and may permanently programme hypothalamic-pituitary-adrenal (HPA) axis function. We investigated whether or not GS produced changes in the maternal behaviour of rat dams, and measured depression-like behaviour in the dam, which might contribute to effects in the progeny. We used the Porsolt test, which measures immobility in a forced-swim task, and models depression in rodents, while monitoring maternal care (arched-back nursing, licking/grooming, nesting/grouping pups). Pregnant rats underwent daily restraint stress (1 h/day, days 10-20 of gestation), or were left undisturbed (control). On post-parturition days 3 and 4, dams were placed into a swim tank, and time spent immobile was measured. GS significantly elevated immobility scores by approximately 25% above control values on the second test day. Maternal behaviours, in particular arched-back nursing and nesting/grouping pups, were reduced in GS dams over post-natal days 1-10. Adult offspring showed increased immobility in the Porsolt test, and also hypersecreted ACTH and CORT in response to an acute stress challenge. These data show that GS can alter maternal behaviour in mothers, and this might contribute to alterations in the offspring. GS may be an important factor in maternal post-natal depression, which may in turn detrimentally effect the offspring because depressed mothers do not sufficiently care for their offspring.
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PMID:Gestational stress induces post-partum depression-like behaviour and alters maternal care in rats. 1460 3

Physical and psychosocial stress challenge homeostasis, increasing glucocorticoid secretion (in rodents, corticosterone [CORT]) while decreasing testosterone (T) levels. The dynamics of stress-induced changes in T, CORT, and luteinizing hormone (LH) concentrations in mice have not been investigated previously. In particular, it remains to be established whether there is a rapid effect of CORT that is directly mediated by glucocorticoid receptors (GRs) in the testis. Therefore, serum and intratesticular T, serum CORT, and LH levels were measured during acute immobilization (IMO) stress, using the C57BL/6 strain of mice. The effects of testicular GR blockade were investigated by administration of the GR antagonist, RU486, via intratesticular (IT) or intraperitoneal (IP) injection. CORT levels increased in stressed males starting at 15 minutes, reaching a fivefold higher plateau by 1 hour compared with controls (P < .01). Conversely, starting from 30 minutes on, both serum and intratesticular T levels decreased in stressed males to 30% and 8% of control values, respectively, by 6 hours (P < .01). In contrast, LH was unchanged by IMO stress for up to 6 hours. Intratesticular treatment with RU486 partially prevented the IMO-induced decline in T levels. CORT treatment reduced intracellular cyclic adenosine monophosphate (cAMP) content in Leydig cells by 15 minutes and T production by 30 minutes in vitro. We conclude that 1) the rapid changes in T suggest a suppression of T biosynthesis by glucocorticoid through a nongenomic mechanism, lowering the production of cytoplasmic cAMP; 2) changes in gonadotropic stimulation of Leydig cells are unlikely to explain the suppression of T levels during acute stress; and 3) the results are consistent with a direct inhibitory action of CORT on Leydig cells.
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PMID:Rapid glucocorticoid mediation of suppressed testosterone biosynthesis in male mice subjected to immobilization stress. 1547 72

The pattern and intensity of glucocorticoid receptor (GR) and heat shock 70 protein (Hsp 70) changes in the hippocampus and brain cortex of adult Wistar rat males exposed to acute (immobilization, cold) and chronic (social isolation, crowding, daily swimming) stress or their combinations were followed by Western immunoblotting. Plasma ACTH and CORT were measured by chemiluminescent method and RIA. A significant decrease in cytosol GR and Hsp 70 was observed after acute stress, while chronic stresses led to negligible changes in both these proteins and caused a reduced responsiveness to a novel acute stress. This was valid irrespective of the type of chronic or acute stress combinations for both hippocampal and cortical GR and Hsp 70. The results support the hypothesis that chronic stress-induced deregulation of the LHPA axis may be caused, at least in part, by partial disruption of intracelullar negative feedback control in the higher centers of the brain.
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PMID:Brain glucocorticoid receptor and heat shock protein 70 levels in rats exposed to acute, chronic or combined stress. 1574 52

Chronic increases in stress hormones such as glucocorticoids are maladaptive, yet studies demonstrating a causal relationship among chronic stress, increases in glucocorticoid concentrations, and subsequent fitness costs in free-living animals are lacking. We experimentally induced chronic psychological stress in female European starlings (Sturnus vulgaris) by subjecting half of the females at our study site to a chronic stress protocol consisting of 4, 30 min stressors (loud radio, predator calls, a novel object, or predator decoys including a snake, rat, and owl) administered in random order daily for 8 days after clutch completion. Experimental females were captured at the end of the chronic stress protocol (9 days after the onset of the chronic stress protocol), and unstressed control females were captured at the same stage of the nesting cycle. Chronically stressed females had lower baseline corticosterone (CORT, the avian glucocorticoid) concentrations and lower reproductive success than unstressed females. Furthermore, surviving nestlings in experimentally stressed broods showed sensitization of the CORT response to acute stress, which is a physiological change that could persist to adulthood. Attenuation of baseline CORT concentrations in adult females is contrary to the general assumption that elevated CORT concentrations indicate stress, suggesting that more research is necessary before CORT concentrations can be used to accurately assess chronic stress in field studies.
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PMID:Chronic stress in free-living European starlings reduces corticosterone concentrations and reproductive success. 1728 Jun 63

The question of whether changes in glucocorticoid concentrations reflect consistent changes in physiology associated with transitions between different stages of reproduction, or whether they reflect responses to environmental conditions, is one the central issues in field endocrinology studies. We examined the temporal and spatial dynamics of corticosterone (CORT, baseline, and acute stress-induced) and corticosterone binding globulin (CBG) concentrations in blood of Black-legged Kittiwakes (Rissa tridactyla) breeding at four major colonies in the Bering Sea, Alaska, during 1999-2005. We found that total CORT, free CORT, and CBG capacity varied inconsistently among reproductive stages, colonies, and years. Total CORT levels were positively correlated with CBG capacity. Variation in free CORT was largely driven by variation in total CORT. Results suggest that the adrenocortical function and CBG in breeding kittiwakes do not vary as a consequence of stage-specific modulation associated with a particular reproductive stage as in some short-lived passerine birds. Rather, in accord with predictions for a long-lived species, the lack of consistent colony, year, and reproductive stage patterns in baseline and maximum CORT, and CBG indicates that environmental factors, probably local dynamics of food availability, drive variation in these factors.
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PMID:Spatial and temporal dynamics of corticosterone and corticosterone binding globulin are driven by environmental heterogeneity. 1816 97

Translocation and reintroduction have become major conservation actions in attempts to create self-sustaining wild populations of threatened species. However, avian translocations have a high failure rate and causes for failure are poorly understood. While 'stress' is often cited as an important factor in translocation failure, empirical evidence of physiological stress is lacking. Here we show that experimental translocation leads to changes in the physiological stress response in chukar partridge, Alectoris chukar. We found that capture alone significantly decreased the acute glucocorticoid (corticosterone, CORT) response, but adding exposure to captivity and transport further altered the stress response axis (the hypothalamic-pituitary-adrenal axis) as evident from a decreased sensitivity of the negative feedback system. Animals that were exposed to the entire translocation procedure, in addition to the reduced acute stress response and disrupted negative feedback, had significantly lower baseline CORT concentrations and significantly reduced body weight. These data indicate that translocation alters stress physiology and that chronic stress is potentially a major factor in translocation failure. Under current practices, the restoration of threatened species through translocation may unwittingly depend on the success of chronically stressed individuals. This conclusion emphasizes the need for understanding and alleviating translocation-induced chronic stress in order to use most effectively this important conservation tool.
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PMID:Stress and translocation: alterations in the stress physiology of translocated birds. 1932 94

Changes in plasma corticosteroid-binding globulin (CBG) capacity can alter free plasma concentration and tissue availability of glucocorticoids (GC) and hence alter the organismal response to stress. However, CBG change in response to stress has not been extensively studied. While it is clear that chronic stress can causes CBG decline and in some species acute stressors can reduce CBG during the 30-60 min of the stressor, more long-term changes in CBG following an acute stressor has received less attention. Here we investigated corticosterone (CORT: the primary GC in birds) and CBG levels 24h after an acute stressor in a unique study system: Japanese quail divergently selected for CORT reactivity to acute stress. Using this model, we examined the interaction of selected CORT reactivity with CBG response to determine if CBG shows a delayed decline in response to an acute stressor and if that decline varies by selected genetic background. We found lowered CBG capacity, elevated total CORT and free CORT 24h after acute stress in all three quail groups. These results demonstrate for the first time in an avian species that exposure to an acute stressor can affect CBG and CORT 24h later.
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PMID:How acute is the acute stress response? Baseline corticosterone and corticosteroid-binding globulin levels change 24h after an acute stressor in Japanese quail. 1968 48

Fear, an emotional response of animals to environmental stress/threats, plays an important role in initiating and driving adaptive response, by which the homeostasis in the body is maintained. Overwhelming/uncontrollable fear, however, represents a core symptom of anxiety disorders, and may disturb the homeostasis. Because to recall or imagine certain cue(s) of stress/threats is a compulsory inducer for the expression of anxiety, it is generally believed that the pathogenesis of anxiety is associated with higher attention (acquisition) selectively to stress or mal-enhanced fear memory, despite that the actual relationship between fear memory and anxiety is not yet really established. In this study, inducible forebrain-specific cholecystokinin receptor-2 transgenic (IF-CCKR-2 tg) mice, different stress paradigms, batteries of behavioral tests, and biochemical assays were used to evaluate how different CCKergic activities drive fear behavior and hormonal reaction in response to stresses with different intensities. We found that in IF-CCKR-2 tg mice, contextual fear was impaired following 1 trial of footshock, while overall fear behavior was enhanced following 36 trials of footshock, compared to their littermate controls. In contrast to a standard Yerkes-Dodson (inverted-U shaped) stress-fear relationship in control mice, a linearized stress-fear curve was observed in CCKR-2 tg mice following gradient stresses. Moreover, compared to 1 trial, 36 trials of footshock in these transgenic mice enhanced anxiety-like behavior in other behavioral tests, impaired spatial and recognition memories, and prolonged the activation of adrenocorticotropic hormone (ACTH) and glucocorticoids (CORT) following new acute stress. Taken together, these results indicate that stress may trigger two distinctive neurobehavioral systems, depending on both of the intensity of stress and the CCKergic tone in the brain. A "threshold theory" for this two-behavior system has been suggested.
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PMID:Bi-directional effect of cholecystokinin receptor-2 overexpression on stress-triggered fear memory and anxiety in the mouse. 2120 61

As anthropogenic stressors increase exponentially in the coming decades, native vertebrates will likely face increasing threats from these novel challenges. The success or failure of the primary physiological mediator of these stressors--the HPA axis--will likely involve numerous and chaotic outcomes. Among the most challenging of these new threats are invasive species. These have the capacity to simultaneously challenge the HPA axis and the immune system as they are often associated with, or the cause of, emerging infectious diseases, and energetic tradeoffs with the HPA response can have immunosuppressive effects. To determine the effects of invasive species on the vertebrate GC response to a novel stressor, and on immunity, we examined the effects of invasive fire ants on native lizards, comparing lizards from sites with long histories with fire ants to those outside the invasion zone. We demonstrated higher baseline and acute stress (captive restraint) CORT levels in lizards from within fire ant invaded areas; females are more strongly affected than males, suggesting context-specific effects of invasion. We found no effect of fire ant invasion on the immune parameters we measured (complement bacterial lysis and antibody hemagglutination) with the exception of ectoparasite infestation. Mites were far less prevalent on lizards within fire ant invaded sites, suggesting fire ants may actually benefit lizards in this regard. This study suggests that invasive species may impose physiological stress on native vertebrates, but that the consequences of this stress may be complicated and unpredictable.
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PMID:The impacts of invaders: basal and acute stress glucocorticoid profiles and immune function in native lizards threatened by invasive ants. 2222 59


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