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

We examined the effects of acute stress on the immune system and disease resistance of juvenile chinook salmon (Oncorhynchus tshawytscha) in laboratory and clinical trials. Immune function, as measured by the ability of lymphocytes from the anterior kidney to generate specific antibody-producing cells (APC) in vitro, was depressed 4 h after stress, when plasma cortisol levels were highest. At the same time, resistance to the fish pathogen, Vibrio anguillarum, was also depressed. Compared with controls, plasma cortisol and APC of stressed fish were unchanged after 24 h, and disease resistance was enhanced as evidenced by higher survival rate and longer mean time to death of mortalities. After 7 days, even though numbers of APC were depressed, plasma cortisol concentration and disease resistance did not differ from controls. This pattern was generally the same, independent of the type of stress applied: i.e. being held out of water in a dipnet for 30 s, manipulation during hatchery operations for 4 h, or transportation for 9 h. These and earlier findings suggest that similar endocrine-immune interactions operate in the mammalian and salmonid systems during acute stress.
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PMID:Stress alters immune function and disease resistance in chinook salmon (Oncorhynchus tshawytscha). 291 64

We investigated the effects of acute and chronic stress on the DNA synthesis of the gastroduodenal mucosa of the rat using two different methods of physical stress at various time intervals. Acute stress was produced in the rats being briefly plunged or swimming for two hours (water temperature 37 degrees C). "Sham - transported" rats were used as controls. The results indicate that in the stomach the DNA synthesis was substantially reduced during acute stress in both groups tested (when compared to controls). The DNA synthesis was also reduced in experimental rats after one and two weeks of stress (as compared to day one). By four and eight weeks, the rate of DNA synthesis in the gastric mucosa had significantly increased in the stressed animals. Controls demonstrated significantly lower DNA values following two to eight weeks of stress (as compared to day one). From the outset, the DNA replication values were 2.5 to 3 times higher in the duodenal mucosa than in the gastric mucosa. Following two weeks of stress, the duodenal mucosa of both test groups showed significantly lower DNA values than controls, but significantly higher values after four weeks of stress. By eight weeks, the duodenal mucosa in all rats had reached the same values as that of day one. This was considered a sign of "adaptation to stress" in the duodenal mucosa. The above results suggest that the fluctuations of DNA replication may be connected to compensatory mechanisms aimed at adjusting the gastroduodenal mucosa to protracted stress situations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:DNA synthesis in the gastroduodenal mucosa during acute and chronic stress in the rat. 297 30

The biodistribution of [3H]Ro 15-1788 in control and stress-loaded mice (forced swimming) was compared. In control mice, carrier-free [3H]Ro 15-1788 was selectively and highly distributed in Bz receptor rich brain regions, while radioactivity in the brain was very low following administration of carrier-added tracer, which suggested that in vivo non-specific binding of this tracer was very low. Significant changes in biodistribution of carrier-free [3H]Ro 15-1788 were observed in stress-loaded mice, which strongly indicated that in vivo binding availability of Bz receptor in the brain was rapidly and reversibly reduced by acute stress. The degree of these changes was very dependent upon the stressful conditions, such as swimming duration and water temperature, and a significant alteration in biodistribution of [3H]Ro 15-1788 was particularly observed in the cerebral cortex. Simplified Scatchard analysis of in vivo binding of this tracer was performed, and results suggested that these alterations were mainly caused by changes in the Kd value rather than the Bmax value.
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PMID:Alterations in biodistribution of [3H]Ro 15-1788 in mice by acute stress: possible changes in in vivo binding availability of brain benzodiazepine receptor. 300 45

In order to explore the peripheral microcirculation and to obtain an outline of autonomic innervation in SART (specific alternation of rhythm in temperature)-stressed (repeated cold-stressed) animals, which are regarded as model animals for clinical vagotonic-type dysautonomia, peripheral tissue blood flow was determined in mice, using the hydrogen clearance method. SART-stressed mice showed a decrease in gastric blood flow, no change in hepatic blood flow and an increase in dermal blood flow. In the mice exposed to the restraint and water immersion stress (RWIS), a type of acute stress, in contrast with SART stress which is a subacute type, remarkable decreases were observed in gastric, hepatic and dermal blood flows. Changes of both gastric and dermal blood flow in SART-stressed mice were dose-dependently prevented and maintained within normal limits by the treatment with Neurotropin, a sedative analgesic which is an extract isolated from vaccinia virus-inoculated and inflamed skin of rabbits. In RWIS-loaded mice, Neurotropin exhibited a great preventive effect on changes of blood flow in the stomach, a slight effect in the liver, and no effect in the cutis. When mice were loaded with SART stress after left-cervical vagotomy, SART stress failed to elicit any decrease in gastric blood flow. In SART-stressed mice treated with 6-hydroxydopamine, gastric and dermal blood flows tended to show a further decrease and increase, respectively, over and above the changes caused by SART stress. From these results, it is suggested that SART-stressed mice may have decreased gastric parasympathetic tone, a decrease in sympathetic tone and also other anomalies such as increased tension of the sympathetic cholinergic vasodilator nerves in the cutis.
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PMID:Changes of tissue blood flow in mice loaded with SART (repeated cold) stress or restraint and water immersion stress and the effect of administered neurotropin. 309 Mar 31

The effect of stress on drinking, water balance and endocrine profile was studied using ten castrated rams. Individual sheep were exposed to 30-h periods of total isolation (psychological stress) or physical separation from their social group (control). Plasma was analysed for haematocrit, osmolality, electrolyte levels and concentrations of cortisol and arginine vasopressin. Isolation stress significantly reduced water intake, increased haematocrit and plasma concentration of cortisol, but did not alter osmolality or vasopressin concentration. The physiological effects of this self-imposed water restriction contrast with those obtained by depriving the sheep of water for 24 h under conditions that were not stressful, i.e. by keeping them grouped together. These results suggest that cortisol may act to defend plasma volume in sheep exposed to acute stress. The results also indicate that vasopressin probably should not be considered to be a 'stress hormone' in the sheep.
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PMID:Endocrine and behavioural factors affecting water balance in sheep subjected to isolation stress. 381 41

Plasma levels of corticosterone and aldosterone were determined by radioimmunoassay in ducks consuming diets containing different concentrations of sodium and potassium. Compared with control diet birds, maintenance on a high-Na+ diet for 5 days caused a 2-fold increase in the basal plasma corticosterone concentration, while adaptation for 8 days to a low-Na+ diet resulted in a 2.6-fold increase in the basal plasma concentration of aldosterone. Both corticosterone and aldosterone basal plasma levels were greatly elevated in birds denied access to drinking water for 4 days. Adaptation to a high-Na+ diet or deprivation of water resulted in hyperosmolality and hypernatremia, while the high-K+, low-Na+/low-K+, and low-Na+ diets did not significantly alter the plasma sodium or potassium levels from the control levels. In addition, birds were stressed by semi-immobilization to determine the effects of acute stress-induced ACTH secretion on the adrenocortical response following changes in dietary sodium and potassium intake. In ducks adapted to low-Na+/low-K+, high-Na+, and low-Na+ diets, stress-induced adrenocorticotrophic hormone (ACTH) increased the aldosterone, but not the corticosterone, response to a level significantly greater than in the controls. These results demonstrate that in the duck secretion of corticosterone and aldosterone can be independently regulated. Furthermore, the endocrine changes that are induced by altered sodium and potassium intake are reflected in the adrenocortical responses to acute stress.
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PMID:Effects of chronic changes in dietary electrolytes and acute stress on plasma levels of corticosterone and aldosterone in the duck (Anas platyrhynchos). 398 30

The enhancement of tumor development following acute stress has been demonstrated in some animal studies. This study was designed to explore mechanisms that would account in part for the relationship between stress and tumor development at the level of DNA repair, using a rat model. Forty-four rats were given the carcinogen dimethylnitrosamine in their drinking water, and half were randomly assigned to a rotational stress condition. The levels of methyltransferase, a DNA repair enzyme induced in response to carcinogen damage, were significantly lower in spleens from the stressed animals. These data suggest that stress may impair DNA repair.
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PMID:Effects of stress on methyltransferase synthesis: an important DNA repair enzyme. 407 16

1. Rhesus monkey (Macaca mulatta) foetuses were delivered by Caesarean section 3-10 days before term. Aortic blood and cerebrospinal fluid (c.s.f.) samples were taken, the latter from the cortical subarachnoid space and the cisterna magna. The umbilical cord was clamped and foetal breathing prevented for 14-17 min. Blood and c.s.f. were sampled further during this total asphyxiation and for up to 24 hr thereafter.2. The [K(+)] in the cortical subarachnoid fluid started to rise within 2-3 min after the onset of asphyxia and increased up to 7 times the normal level. The [K(+)] of blood plasma and cisternal fluid also increased, but much more moderately. All these effects reversed rapidly upon resuscitation of the foetus.3. A pronounced rise in the cortical subarachnoid fluid [glucose] and a lesser effect on cisternal fluid [glucose] were noted in most cases by the end of, or immediately following, the period of asphyxia. The onset, magnitude and reversal of these effects on [glucose] were less predictable than the observed effects on [K(+)].4. There were no significant changes in the [Mg(2+)], [Ca(2+)] or [Na(+)] of any of these fluids. The calculated total osmolarity of the cortical subarachnoid fluid and, to a much lesser extent, of cisternal fluid and plasma, increased during asphyxia mainly as a result of increased [K(+)].5. The results are interpreted as indicative of a rapid release of K(+) from cortical cells during total asphyxia. The (immature) haematoencephalic K(+) transport system becomes saturated and thus K(+) accumulates in the extracellular fluid (e.c.f.) whence it diffuses into adjacent regions of the c.s.f. system.6. The intracellular fluid of apical dendrites must become even more hypertonic than the e.c.f., since these cellular processes are known to swell during asphyxia at the expense of the e.c.f. space. This apparent increase in intracellular osmolarity could be accounted for by the release of normally bound intracellular cations.7. On the basis of our results and review of the relevant literature, the following sequence of events is proposed: the cortex responds to acute physiological stress (asphyxia, overstimulation, chemical or physical irritation, etc.) by releasing intracellularly bound cations (K(+) and possibly Na(+)). The increased intracellular osmolarity results in the absorption of water from the e.c.f. space. Passage of water across the blood-brain barrier is restricted; thus the e.c.f. space of the cortex does not swell, but becomes hyperosmotic. Under these circumstances, swelling of the cortical cells is limited by the volume of e.c.f. available.8. It is proposed that the release of intracellularly bound cations is a result of their displacement from their binding sites by NH(4) (+) which is released to, and recovered from, these cation binding sites by a glutamate-glutamine interconversion.9. It is concluded that the apparent organized ;shutdown' of the cortical cells in response to acute stress may contribute to the relative insensitivity of this area of the brain to permanent histopathological damage.
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PMID:On the physiological response of the cerebral cortex to acute stress (reversible asphyxia). 462 4

Analgesia induced in rats by cold-water swim stress and measured by the tail-flick and hot-plate methods was significantly antagonized after IP pretreatment for 3 days with 8 mg/kg dexamethasone. The analgesia developed by the cold-water swim stressor was also attenuated by 1 mg/kg naloxone. These results suggest that the corticosteroids may have a role in modulating stress-induced analgesia and that the adrenal-pituitary axis modulates the endogenous opiate system. These conclusions are based on recent reports that indicate the release of the opiate-like peptide beta-endorphin and adrenocorticotropin (ACTH) from the pituitary are increased by acute stress and inhibited by administration of the synthetic glucocorticoid dexamethasone.
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PMID:Dexamethasone and stress-induced analgesia. 640 29

Experiments were conducted to delineate the acute stress response of commercial broilers to feed and water deprivation for 10 hr. The effect of method of nutrient deprivation, cooping versus removal of feed and water from broiler floor pens, was also considered. Bihourly plasma corticosterone measures were made during 10-hr withdrawal periods, and significant alterations in this adrenal steroid were considered indicative of stress. In all studies, feed and water deprivation produced significant elevations in plasma corticosterone concentrations. Cooped broilers exhibited a shorter onset and more exaggerated magnitude of adrenal responsiveness than floor penned broilers deprived of feed and water. There was also evidence that plasma corticosterone secretion in floor penned broilers was continual (linearly increasing) throughout the 10-hr withdrawal period. In contrast, maximal corticosterone responses followed by waning hormonal levels (an increasing quadratic function) were evident in cooped broilers. It was concluded that procedures involved in physically cooping birds, as well as the restraint cooping imposed, were acting additively to the stress associated solely with feed and water deprivation. Changes in plasma volume, as evidenced by percent packed cell volume changes during treatment periods, were not responsible for the corticosterone elevations observed. In a separate experiment, battery housed Japanese quail deprived of feed and water for 12 hr exhibited a temporal plasma corticosterone response very similar to that observed in floor penned broilers deprived of feed and water. Full-fed control quail exhibited only random temporal hormonal fluctuations during this time. It was likewise concluded that the practice of feed and water deprivation in quail constitutes a significant nonspecific stressor.
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PMID:Circulating corticosterone responses of feed and water deprived broilers and Japanese quail. 683 5


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