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

Both the peripheral sympatho-adrenomedullary and central catecholaminergic systems are activated by various psycho-social and physical stressors. Catecholamine stores in the hypothalamus, hippocampus, adrenal glands, and heart auricles of long-term socially isolated (21 days) and control 3-month-old male Wistar rats, as well as their response to immobilization of all 4 limbs and head fixed for 2 h and cold stress (4 degrees C, 2 h), were studied. A simultaneous single isotope radioenzymatic assay based on the conversion of catecholamines to the corresponding O-methylated derivatives by catechol-O-methyl-transferase in the presence of S-adenosyl-l-(3H-methyl)-methionine was used. The O-methylated derivatives were oxidized to 3H-vanilline and the radioactivity measured. Social isolation produced depletion of hypothalamic norepinephrine (about 18%) and hippocampal dopamine (about 20%) stores and no changes in peripheral tissues. Immobilization decreased catecholamine stores (approximately 39%) in central and peripheral tissues of control animals. However, in socially isolated rats, these reductions were observed only in the hippocampus and peripheral tissues. Cold did not affect hypothalamic catecholamine stores but reduced hippocampal dopamine (about 20%) as well as norepinephrine stores in peripheral tissues both in control and socially isolated rats, while epinephrine levels were unchanged. Thus, immobilization was more efficient in reducing catecholamine stores in control and chronically isolated rats compared to cold stress. The differences in rearing conditions appear to influence the response of adult animals to additional stress. In addition, the influence of previous exposure to a stressor on catecholaminergic activity in the brainstem depends on both the particular catecholaminergic area studied and the properties of additional acute stress. Therefore, the sensitivity of the catecholaminergic system to habituation appears to be tissue-specific.
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PMID:Effects of stress on catecholamine stores in central and peripheral tissues of long-term socially isolated rats. 1675 84

Homocysteine levels are affected by diet factors such as vitamin deficiencies, non-diet factors such as genetic disorders, and stress exposure. Hyperhomocysteinemia has been implicated in several disorders, including cardiovascular disease, depression, schizophrenia, Alzheimer's and Parkinson's disease. Since sex differences play a role both in stress responses and in susceptibility to various diseases, the objective of this study was to evaluate possible alterations in homocysteine metabolism including cysteine, folate, and vitamin B(6), and oxidative stress markers in female rats exposed to different types of acute stress. Female rats were randomly distributed into eight groups according to stress manipulation (restraint, swimming, cold and control) and estrous cycle (diestrus and estrus). In general no significant differences were seen between rats in estrus and diestrus. Restraint stress was the only type of stress that altered homocysteine concentrations (+33% relative to controls). An increase in levels of thiobarbituric acid reactive substances (TBARS) and a decrease in total glutathione (GSHt) concentration were also observed in animals subjected to restraint and swimming stress, suggesting the possibility of oxidative damage. Thus, both the homocysteine results and the oxidative stress data indicated that restraint stress was the most powerful stress manipulation in female rats, as previously observed in male rats. These findings indicate that hormonal and gonadal differences do not interfere with stress responses related to homocysteine metabolism and suggest that putative gender-related differences in homocysteine responses are probably not involved in the differential prevalence of some diseases in human males and females.
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PMID:Acute stressor-selective effects on homocysteine metabolism and oxidative stress parameters in female rats. 1705 2

Corticotrophin-releasing hormone (CRH) regulates acute stress-induced changes in neuroendocrine function and behaviour. However, little is known about CRH functions in animals that have prior experience with repeated stress. Repeatedly-stressed rats exhibit a habituated hypothalamic-pituitary-adrenal (HPA) response to a familiar, homotypic stressor but exhibit maintained or enhanced HPA responses to a novel, heterotypic stressor. We examined the effects of intracerebroventricular (i.c.v.) administration of two different nonselective CRH receptor antagonists, alpha-helical CRH(9-41) (ahCRH) or D-Phe CRH(12-41) (D-PheCRH), on HPA responses to acute restraint in rats previously exposed to repeated cold stress (i.e. facilitated responses). Antagonists were administered as single i.c.v. injections prior to restraint to provide a general index of CRH function in control versus repeatedly-stressed rats. CRH receptor blockade with either ahCRH or D-PheCRH produced different effects on HPA responses to novel restraint depending on whether the animal had been previously cold stressed or not. Interestingly, some agonist-type effects were observed but only in repeatedly-stressed rats. In summary, these results indicate that manipulations of the CRH receptor have different effects on HPA activity depending on the stress history of the animal.
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PMID:Intracerebroventricular administration of corticotrophin-releasing hormone receptor antagonists produces different effects on hypothalamic pituitary adrenal responses to novel restraint depending on the stress history of the animal. 1728 May 93

Sensitivity of target cells to glucocorticoids is regulated by the expression of intracellular glucocorticoid receptor (GR), which mediates the effects of glucocorticoids. The level of GR and of its nuclear transporter protein 70 (Hsp70) were followed in hippocampus and brain cortex of adult Wistar rat males exposed to acute (immobilization, cold) and chronic (social isolation, isolation, and 15 min daily swimming) stress or their combinations. Changes in plasma levels of adenocorticotropic hormone and corticosterone were also studied. A significant decrease in cytosol GR and Hsp70 was observed after acute stress. Opposite to that, chronic stress led to negligible changes in both cytosol GR and Hsp70 levels. Isolation, as chronic psychosocial stressor, caused reduced responsiveness to novel acute stressors, judged by the cytosol GR and Hsp70 levels. This was not observed if chronic isolation was combined with 15 min daily swimming prior to acute exposure to immobilization. The data suggest that repeated physical exercise may, at least in some cases, diminish detrimental effects of chronic social isolation on limbic-hypothalamic-pituitary-adrenocortical axis, as judged by the levels of GR and Hsp70 in the Wistar rat brain.
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PMID:The effect of repeated physical exercise on hippocampus and brain cortex in stressed rats. 1740 32

The effect of compound nutrients on serum concentrations of the cytokines, such as interleukin (IL)-2, tumor necrosis factor-alpha (TNF-alpha) and interleukin (IL)-6 in immobilization and cold water-immersion stressed rat were investigated. Oral (gavage) administration of compound nutrients was found to attenuate the acute and chronic immobilization and cold water-immersion stress-induced increase in serum IL-6 level and decrease in IL-2 level. Compound nutrients exerted different effects on TNF-alpha level in two different models studied, with reduced serum TNF-alpha level in acute stress, while no significant effect in chronic stress. These results suggested that compound nutrients might be proposed as a possible candidate in the research or therapeutic modulation of stress-related disorders.
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PMID:The effect of compound nutrients on stress-induced changes in serum IL-2, IL-6 and TNF-alpha levels in rats. 1743 9

The present study investigated the effects of acute stress exposure on learning performance in humans using analogs of two paradigms frequently used in animals. Healthy male participants were exposed to the cold pressor test (CPT) procedure, i.e., insertion of the dominant hand into ice water for 60 sec. Following the CPT or the control procedure, participants completed a trace eyeblink conditioning task followed by a virtual navigation Morris water task (VNMWT). Hypothalamic-pituitary-adrenocortical (HPA) axis and sympathetic autonomic system (SAS) activity were assessed by measuring salivary cortisol, heart rate, and skin conductance at selected timepoints. Results revealed positive effects of stress on performance in both tasks. The stress group showed significantly more conditioned blinks than the control group during acquisition of trace eyeblink conditioning. The stress group also performed significantly better in the VNMWT than the control group, with the former showing significantly fewer failures to locate the hidden platform in the allotted time and smaller heading errors than the latter. Regression analyses revealed positive relationships between HPA axis and SAS activity during stress and eyeblink conditioning performance. Our results directly extend findings from animal studies and suggest potential physiological mechanisms underlying stress and learning.
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PMID:Acute exposure to stress improves performance in trace eyeblink conditioning and spatial learning tasks in healthy men. 1752 23

The aim of the present study was to define the stress-induced pattern of cytosolic glucocorticoid receptor (GR) and Hsp70 protein in the liver of male Wistar rats exposed to different stress models: acute (2 h/day) immobilization or cold (4 degrees C); chronic (21 days) isolation, crowding, swimming or isolation plus swimming and combined (chronic plus acute stress). Changes in plasma levels of corticosterone were studied by radioimmunoassay (RIA). The results obtained by Western immunoblotting showed that both acute stressors led to a significant decrease in cytosolic GR and Hsp70 levels. Compared to acute stress effects, only a weak decrease in the levels of GR and Hsp70 was demonstrated in chronic stress models. Chronically stressed rats, which were subsequently exposed to novel acute stressors (immobilization or cold), showed a lower extent of GR down-regulation when compared to acute stress. The exception was swimming, which partially restores this down-regulation. The observed changes in the levels of these major stress-related cellular proteins in liver cytosol lead to the conclusion that chronic stressors compromise intracellular GR down-regulation in the liver.
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PMID:Liver glucocorticoid receptor and heat shock protein 70 levels in rats exposed to different stress models. 1755 76

The influence of peripheral nociceptin/orphanin FQ (N/OFQ) on cold restraint-induced gastric mucosal damage in the rat was investigated. Exposure to cold-restraint for 3 and 4h caused the formation of hemorrhagic lesions in the glandular portion of the stomach. N/OFQ dose-dependently decreased lesion formation, in the range 0.03-1 microg/kg/h i.p. Its effect was reversed by the selective NOP receptor antagonist [Nphe(1)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-101), 30 microg/kg/h ip. The selective NOP receptor agonist [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), 0.01-0.3 microg/kg/h i.p., similarly reduced lesion formation. Light and scanning electron microscopy confirmed the protective activity of N/OFQ. Cold-restraint stress causes a reduction in mucus content and in adhering mucus layer, partly counteracted by N/OFQ. These results suggest that N/OFQ counteracts acute stress-induced gastric mucosal damage by interacting with NOP receptor and by influencing mucous cell activity.
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PMID:Nociceptin/orphanin FQ prevents gastric damage induced by cold-restraint stress in the rat by acting in the periphery. 1765 65

Agmatine is an endogenous neuromodulator that, based on animal studies, has the potential for new drug development. As an endogenous aminoguanidine compound (1-amino-4-guanidinobutane), it is structurally unique compared with other monoamines. Agmatine was long thought to be synthesised only in lower life forms, until its biosynthetic pathway (decarboxylation of arginine) was described in the mammalian brain in 1994. Human arginine decarboxylase has been cloned and shown to have 48% identity to ornithine decarboxylase. In neurons of the brain and spinal cord, agmatine is packaged into synaptic vesicles and released upon neuronal depolarisation. Other evidence of a neuromodulation role for agmatine is the presence of a specific cellular uptake mechanism and a specific metabolic enzyme (agmatinase; which forms putrescine).Initially, agmatine was conceptualised as an endogenous clonidine-displacing substance of imidazoline receptors; however, it has now been established to have affinity for several transmembrane receptors, such as alpha(2)-adrenergic, imidazoline I(1) and glutamatergic NMDA receptors. In addition to activity at these receptors, agmatine irreversibly inhibits neuronal nitric oxide synthase and downregulates inducible nitric oxide synthase. Endogenous agmatine is induced in response to stress and/or inflammation. Stressful conditions that induce agmatine include hypoxic-ischaemia and cold-restraint stress of ulcerogenic proportion. Induction of agmatine in the brain seems to occur in astrocytes, although neurons also synthesise agmatine. The effects of injected agmatine in animals include anticonvulsant-, antineurotoxic- and antidepressant-like actions. Intraperitoneal or intracerebroventricular injections of agmatine rapidly elicit antidepressant-like behavioural changes in the rodent forced swim test and tail suspension test. Intraperitoneal injections of agmatine into rats and mice also elicit acute anxiolytic-like behavioural changes in the elevated plus-maze stress test. In an animal model of acute stress disorder, intraperitoneal agmatine injections diminish contextual fear learning. Furthermore, intraperitoneal injections of agmatine reduce alcohol and opioid dependence by diminishing behaviour in a rat conditioned place preference paradigm. Based on these findings, agmatine appears to be an endogenous neuromodulator of mental stress. The possible roles and/or beneficial effects of agmatine in stress-related disorders, such as depression, anxiety and post-traumatic stress disorder, merit further investigation.
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PMID:Agmatine : metabolic pathway and spectrum of activity in brain. 1792 94

Hematocrit has been implicated in the triggering of cardiovascular events and the development of cardiovascular disease. Studies have demonstrated the reliability of hematocrit at rest, however, data are lacking about hematocrit during repeated acute stress exposures. The current study assessed the reliability of hematocrit during rest and stress. Hematocrit was measured in two sessions during rest and in response to mental, cold and exercise stress in 84 healthy men and women. The stress tasks consistently elicited increases in hematocrit. Absolute levels of hematocrit were highly reliable between testing sessions. Changes in hematocrit with exercise stress were reliable whereas changes associated with mental and cold stress were not reliable between sessions. The findings indicate that hemoconcentration during brief mental and physical stress is more reliable for absolute levels than change scores. The reliability of stress-induced hemoconcentration may be improved by more provocative challenges and repeated sampling during stress.
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PMID:Reliability of hematocrit during rest and stress in healthy adults. 1795 May 18


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