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

In an ongoing study of endocrine function in wild olive baboons living freely in Kenya, sustained social stress was associated with suppressed testosterone (T) concentrations in males. In the present report, the acute stressor of rapid capture and immobilization caused profound and rapid suppression of T concentrations in these individuals. Elevation of cortisol concentrations preceded, and was at least partially responsible for, the declining T concentrations, as dexamethasone (DEX) administration produced a similar suppression. DEX inhibited T secretion, but did not alter its clearance. The testes appeared to be the principal site of this inhibition; DEX did not alter LHRH-induced pituitary secretion of LH, somewhat attenuated LH bioactivity, but caused a complete suppression of LH-induced testicular secretion of T. Considerable individual variation occurred in sensitivity to stress-induced suppression of T concentrations. Some individuals had transient elevations of T concentrations during the poststress hour, although concentrations ultimately declined significantly. These males were also least sensitive to DEX inhibition of LH-induced T secretion. These studies demonstrate acute stress-induced suppression of gonadal function in a population of primates living in their natural habitat. Furthermore, they implicate glucocorticoid actions mostly at the testes as possible underlying endocrine mechanisms for such regulation.
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PMID:Stress-induced suppression of testicular function in the wild baboon: role of glucocorticoids. 298 42

Adult male and female rats were housed for 2 weeks in a Visible Burrow System resulting in the development of strong dominant-subordinate relationships among the male rats. Neuroendocrine measures indicated that the subordinate rats, and to a lesser extent dominant rats, experienced chronic HPA axis hyperstimulation during the 2 week experience. This paper focuses on the consequences of this chronic social stress on cytosolic type II corticosteroid receptor binding in the spleen. In the first study, rats were adrenalectomized 18 h prior to sacrifice in order to measure total cellular receptor protein levels in each animal. In spite of the severity of the social stress, there was no decrease in splenic type II corticosteroid receptor binding levels in these short-term adrenalectomized animals. In the second study, rats were left adrenal-intact. Corticosteroid receptor levels in these adrenal-intact animals reflect the level of receptors (available receptors) that were unoccupied by endogenous hormone at the time of sacrifice. Both subordinate and dominant rats had fewer available splenic type II receptors than control rats, suggesting that a greater proportion of receptors in subordinate and dominant rats were occupied and activated by endogenous hormone at the time of sacrifice than in control rats. The differences in available receptor levels were not a function of total plasma corticosterone levels at the time of sacrifice (mean corticosterone levels were the same for control and subordinate rats). Instead, the differences in available receptor levels may have been a function of plasma corticosteroid binding globulin (CBG) levels which regulate free corticosterone levels. There was a large reduction in plasma CBG levels of subordinate (-70%) and dominant (-40%) rats relative to control rats, and there was a significant correlation between plasma CBG level and available type II receptors in the spleen. These results suggest that a decrease in CBG levels as a result of chronic social stress led to greater access of free corticosterone hormone to type II receptors in the spleen than is typically present in rats under basal or acute stress conditions. This result illustrates one mechanism by which chronic stress may have a greater impact than acute stress on splenic immune function.
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PMID:Chronic social stress produces reductions in available splenic type II corticosteroid receptor binding and plasma corticosteroid binding globulin levels. 877 7

In the cooperatively breeding Florida scrub-jay, nonbreeders are subordinate to the breeders with which they share a territory. Corticosterone is secreted in response to a wide range of stressors, including social stress, and suppresses reproductive and territorial behaviors in several taxa; thus, elevated baseline levels of corticosterone might be a causal mechanism of reproductive suppression. To test the hypothesis that nonbreeder Florida scrub-jays are reproductively suppressed through the actions of corticosterone, we compared corticosterone levels of nonbreeders and breeders and found no differences. However, baseline corticosterone levels only provide information about a bird's current hormonal status. Virtually all species exhibit a rapid rise in glucocorticoids in response to an acute stressor. If the adrenocortical response of nonbreeders is greater than that of breeders, this might be a mechanism whereby nonbreeders remain reproductively quiescent. We compared the responses of breeders and nonbreeders to the acute stress of being captured and held for 1 h. Both exhibited significant but equivalent increases in corticosterone titers. Because in some species heavier or fatter individuals have reduced glucocorticoid responses to stressors, we examined whether body mass was correlated with corticosterone titers. Both baseline and maximum corticosterone levels covaried with body mass, and the effect of body mass on corticosterone levels explained the increase due to capture and handling. Our data do not support the hypothesis that Florida scrub-jay nonbreeders are reproductively suppressed through the actions of corticosterone.
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PMID:Corticosterone, reproductive status, and body mass in a cooperative breeder, the Florida scrub-jay (Aphelocoma coerulescens). 923 78

The study compares the impact of acute and chronic social confrontation on aspects of blood cellular immunity in Long-Evans intruder rats. An adult male was introduced for either 2 h or 48 h into a male-female resident group, which resulted in fights for dominance. Thirty-eight of the 42 intruders became losers. For immunologic measurements, blood samples were taken from the intruders before confrontation (baseline) and 2 h or 48 h after the beginning of confrontation. Two h of confrontation resulted in increased granulocyte (+65%) and decreased lymphocyte numbers (-60%), as well as in differential reductions in CD4, CD8, and B cell numbers. CD4/CD8 and T/B ratios were elevated. T cell responsiveness to ConA was markedly suppressed in proliferation assays using either whole blood (-90%) or PBMC (-50%). The direction of changes in leukocyte and lymphocyte subsets after 48 h resembled in many aspects the 2 h changes, although with lower magnitude. In contrast to acute stress, a lowered T/B cells ratio and unaffected CD4/CD8 ratio was determined after 48 h. Proliferative response of T cells was lowered by about 25% in the whole blood assay; but unaffected in the PBMC assay. Significant correlations were found between the amount of submissive behavior displayed by the losers and several immunologic measures after 2 h of confrontation. The data suggest that acute and chronic stressful conditions may not necessarily result in similar effects on immune functioning. This should be considered when evaluating the biologic and evolutionary consequences of social stress-induced immune alterations.
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PMID:Effects of acute and chronic social stress on blood cellular immunity in rats. 981 88

Using a nonhuman primate model, we examined the mechanisms by which acute social stress inhibits the ability of NK cells to form conjugates with, and lyse target cells. We examined the expression and role of the primary NK cell adhesion molecules, CD2 and LFA-1, in mediating conjugation to target cells. Acute stress induced a decrease in NK cell expression of CD2 (17+/-3%); and to a lesser degree induced a decrease in expression of LFA-1 (CD11a: 8+/-3%; CD18: 7+/-3%). Antibody blocking studies indicated that anti-LFA-1 significantly inhibited NK cell conjugate formation and cytotoxicity in both control (approximately 40% and approximately 50%, respectively) and stressed (approximately 20% and approximately 45%, respectively) conditions. However, anti-CD2 blocked conjugation and cytotoxicity in the control condition by approximately 50%, but had no capacity to further affect the inhibition of conjugation or cytotoxicity of NK cells induced by acute stress. These data indicate that there are differential effects of acute stress on the expression and function of LFA-1 and CD2, and that the stress-induced inhibition of NK cell adhesion and cytotoxicity is dependent upon modulation of adhesion and/or signalling through CD2.
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PMID:Acute stress impairs NK cell adhesion and cytotoxicity through CD2, but not LFA-1. 1050 80

In order to investigate the potential influence of stress as a component of the repeat breeding syndrome, the adrenocortical capacity for steroid production was evaluated in ovariectomised dairy heifers. In repeat breeder heifers (RBH), marginally elevated plasma progesterone levels during oestrus, so-called suprabasal progesterone levels, have earlier been measured and are believed to impair fertility. The aim was to distinguish if this progesterone could be of extra-gonadal or in this case, adrenal origin. Baseline levels of plasma cortisol and progesterone were determined as well as the corresponding response after induced acute stress in the form of an adrenocorticotropin (ACTH)-challenge. Comparisons were made between strictly selected RBH, n=5 and virgin heifers (VH), n=5 of the Swedish Red and White breed. The heifers were used as their own pre-challenge controls in a 2-day trial. On the control day, saline was injected i.v. and on the treatment day, a synthetic analogue of ACTH (60 microg Synachten(R)). Via a jugular vein catheter, blood samples were collected every 30 min for 6 h each day of the experiment. Analyses for plasma progesterone and cortisol were made. RBH had a significantly higher (P<0.01) pretreatment baseline cortisol level (10.1+/-2.3 nmol l(-1)) than VH (2.6+/-0.2 nmol l(-1)). Moreover, the cortisol response after stimuli was stronger in RBH than VH, especially concerning total hormone production (P<0. 001), but there was also a tendency towards higher peak values (P=0. 06) and longer duration of significantly increased hormone concentrations (P=0.08). Progesterone concentrations, however, did not differ between the groups. Both baseline levels (P=0.25) and posttreatment production (P=0.45) were of the same magnitude in RBH and VH. In conclusion, the study could not confirm that suprabasal progesterone concentrations during oestrus in RBH derive from the adrenal glands. Still, apparent differences were found in adrenocortical activity when ovariectomised heifers, VH and RBH, were subjected to an ACTH-challenge. It is suggested that a sustained adrenal stimulation associated with environmental or social stress could be one factor in the repeat breeding syndrome.
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PMID:Effect of ACTH-challenge on progesterone and cortisol levels in ovariectomised repeat breeder heifers. 1096 41

Epidemiological as well as experimental studies in elderly subjects have suggested that postmenopausal women are more susceptible to the memory impairing effects of elevated cortisol levels than elderly men. Little is known however about gender differences in the susceptibility to acute stress in young subjects. In the present study a total of 58 healthy young subjects learned a word list, with recall being tested after a brief distraction task. Twenty-two subjects had to learn the list after exposure to a psychosocial stressor (Trier Social Stress Test: TSST), while the remaining subjects served as controls. Free cortisol was determined via saliva samples taken before and 10 minutes after stress. Subjects exposed to the stressor, did not show impaired memory performance per se when compared to the control group. However the cortisol increase in response to the stressor was negatively correlated (r=-0.43, P<0.05) with the memory performance within the stressed group (i.e., subjects showing a larger cortisol response recalling less words than subjects showing only a small cortisol increase). Additional analysis revealed, that this correlation was solely caused by the strong association observed in men (r=-0.82, P<0.05), while no association was observed in women (r=-0.05, P=ns). Our data suggests, that gender modulates the association between cortisol and memory after stress. Whether these differences reflect activational effects of sex steroids or developmentally-programmed sex differences awaits to be determined.
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PMID:The relationship between stress induced cortisol levels and memory differs between men and women. 1150 Feb 52

It has been hypothesized that in avian social groups subordinate individuals should maintain more energy reserves than dominants, as an insurance against increased perceived risk of starvation. Subordinates might also have elevated baseline corticosterone levels because corticosterone is known to facilitate fattening in birds. Recent experiments showed that moderately elevated corticosterone levels resulting from unpredictable food supply are correlated with enhanced cache retrieval efficiency and more accurate performance on a spatial memory task. Given the correlation between corticosterone and memory, a further prediction is that subordinates might be more efficient at cache retrieval and show more accurate performance on spatial memory tasks. We tested these predictions in dominant-subordinate pairs of mountain chickadees (Poecile gambeli). Each pair was housed in the same cage but caching behavior was tested individually in an adjacent aviary to avoid the confounding effects of small spaces in which birds could unnaturally and directly influence each other's behavior. In sharp contrast to our hypothesis, we found that subordinate chickadees cached less food, showed less efficient cache retrieval, and performed significantly worse on the spatial memory task than dominants. Although the behavioral differences could have resulted from social stress of subordination, and dominant birds reached significantly higher levels of corticosterone during their response to acute stress compared to subordinates, there were no significant differences between dominants and subordinates in baseline levels or in the pattern of adrenocortical stress response. We find no evidence, therefore, to support the hypothesis that subordinate mountain chickadees maintain elevated baseline corticosterone levels whereas lower caching rates and inferior cache retrieval efficiency might contribute to reduced survival of subordinates commonly found in food-caching parids.
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PMID:The relationship between dominance, corticosterone, memory, and food caching in mountain chickadees (Poecile gambeli). 1312 80

Social stress is a common occurrence in our society that can negatively impact health. Therefore, we wanted to study the effects of a mild stressor designed to model social stress on seizure susceptibility and GABAA receptors in male and female rats. The mild chronic stress of individual housing consistently decreased bicuculline (but not pentylenetetrazol, PTZ) seizure thresholds by 10-15% in both sexes. Housing conditions did not alter the anticonvulsant activity of diazepam or ethanol, although the anticonvulsant effect of ethanol was significantly greater against PTZ-induced seizures. Experiments testing the addition of an acute restraint stress unmasked sex differences in seizure induction. The acute stress also selectively decreased the potency of GABA to modulate GABAA receptor-mediated chloride uptake in group-housed females. There were additional sex differences by housing condition for GABAA receptor-gated chloride uptake but no differences in [3H]flunitrazepam binding. We also found significant effects of sex and housing on ethanol-induced increases in corticosterone (CORT) levels. In summary, there were complex and sex-selective effects of mild chronic stress on seizure induction and GABAA receptors. Gaining a better understanding of mechanisms underlying interactions between sex and stress has important implications for addressing health concerns about stress in men and women.
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PMID:Sex differences in effects of mild chronic stress on seizure risk and GABAA receptors in rats. 1525 Dec 58

Depressive symptoms in the non-clinical range have been linked to increased health risks. Recent theorizing raises the possibility that heightened physiologic responses to acute stress and/or slowed stress recovery in individuals with depressive symptoms may contribute to increased risk. We investigated stress-induced catecholamine responses and recovery patterns using a modified version of the Trier Social Stress Test (15 min) with a sample of 52 healthy women and compared subgroups with high normal versus low scores on the Beck Depression Inventory (BDI, median split) to 29 women randomly assigned to a non-stressed control group. The BDI-high normal and BDI-low groups showed similar acute increases in epinephrine immediately post stressor, but only the BDI-high normal group remained significantly elevated above control group levels during the recovery period. No differences were found in norepinephrine responses. Elevations in BDI scores within the normal range may selectively predict slower physiological recovery following acute stress.
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PMID:Higher Beck depression scores predict delayed epinephrine recovery after acute psychological stress independent of baseline levels of stress and mood. 1529 85


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