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PubMed2001

LEDGF binds to heat shock and stress-related element to activate the expression of stress-related genes.

We have investigated the mechanism by which LEDGF protects cells against environmental stress. Our earlier report showed that a low level of LEDGF was present in the nucleus of most cell types and significant elevation of LEDGF level was induced by heat and oxidative stress. The cells overexpressing LEDGF-activated expression of heat shock proteins and enhanced survival of many cell types. Here we show that LEDGF binds to heat shock element (HSE) and stress-related regulatory element (STRE) to activate the expression of stress-related genes (Hsp27 and alphaB-crystallin). Apparently, HSE and STRE are present in promoters of many stress-related genes. Elevation of many stress-related proteins (STRPs) induced by LEDGF may protect cells against environmental stress. In yeast, it has been demonstrated that a single stress can activate the expression of multiple STRPs. This is known as "cross-protection," and now similar mechanism has been found in mammalian cells and LEDGF plays a vital role in it.

Base Sequence↗
PubMed1998

The effects of psychological stress on humans: increased production of pro-inflammatory cytokines and a Th1-like response in stress-induced anxiety.

There is some evidence that, in humans and experimental animals, psychological stress may suppress or enhance immune functions, depending on the nature of the stressor and the immune variables under consideration. The possibility that psychological stress may affect the production of pro-inflammatory and immunoregulatory cytokines was investigated in 38 medical students, who had blood samplings a few weeks before and after as well as one day before an academic examination. Psychological stress significantly increased the stimulated production of tumour necrosis factor alpha (TNF-alpha), interleukin 6 (IL-6), IL-1 receptor antagonist (IL-1Ra), interferon gamma (IFN-gamma) and IL-10. Students with high stress perception during the stressful condition had a significantly higher production of TNF-alpha, IL-6, IL-1Ra and IFN-gamma than students with a low-stress perception. Students with a high anxiety response had a significantly higher production of IFN-gamma and a lower production of the negative immunoregulatory cytokines, IL-10 and IL-4, than students without anxiety. These findings suggest that, in humans, changes in the production of the pro-inflammatory cytokines, TNF-alpha, IL-6 and IFN-gamma, and negative immunoregulatory cytokines, IL-10 and IL-4, take part in the homeostatic responses to psychological stress and that stress-induced anxiety is related to a T-helper-1-like response.

Adult↗
PubMed1993

The prevention of cataract caused by oxidative stress in cultured rat lenses. II. Early effects of photochemical stress and recovery.

Previous work has demonstrated that photochemically induced oxidative stress generated with 4 microM riboflavin in a 4% oxygen atmosphere utilizing daylight type radiation is capable of causing cataract in cultured rat lenses. Such cataract is prevented by the GSH peroxidase type mimic, AL-3823A. Examination of the early stages of cataract formation produced by short-term oxidative stress and recovery is now reported. A 24-hr oxidative stress, under the above conditions, causes loss of transparency, particularly in the equatorial region, increased hydration, loss of glyceraldehyde-3-PO4 dehydrogenase activity, oxidation of non-protein thiol and a decrease in 86Rb and [14C]choline uptake and ATP levels. Examination of recovery of these parameters during a 72-hr period indicates, in most cases, little or no reversal of oxidative damage. Hydration and loss of non-protein thiol continued during the recovery period. The presence of AL-3823A during the stress period prevented change in all parameters. Transport systems appear to be particularly vulnerable to this type of oxidative stress losing 50% or more activity within 4 hr. Even after a 2-hr stress, choline transport did not recover even though, under these conditions, ATP levels had only decreased slightly. Cytosolic components such as non-protein thiol and glyceraldehyde-3-PO4 dehydrogenase also showed little change after a 4-hr insult. 86Rb efflux experiments indicated no change in permeability during a 24-hr stress period. The overall conclusion from these studies is that a 24-hr oxidative stress which appears to reflect physiological conditions existing during cataract development, causes extensive, irreversible damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Work stress, nonwork stress, and health.

This paper examines the interface between work stress and nonwork stress and how it relates to health. Results indicate that the way people feel at work is largely a function of conditions at work. Similarly, the way people feel outside of work is largely a function of things that occur outside the job. Both work and nonwork stress are independently associated with physical and mental health, although the relationship between nonwork stress and health is slightly stronger. Excessive demands or stresses in one domain can interfere with life in the other. Such conflict operates equally in both directions. When present it can be an added source of stress and adversely affect health. Taken together these findings suggest that the stress people experience at work is not simply a reflection of their "personal problems." This has implications for the design of health promotion and stress prevention programs in the workplace.

Adult↗
PubMed2005

Initial stress-kick is required for fluid shear stress-induced rate dependent activation of bone cells.

The shear stress induced by the loading-mediated flow of interstitial fluid through the lacuno-canalicular network is a likely stimulus for bone cell adaptive responses. Furthermore, the magnitude of the cellular response is related to the rate of mechanical loading rather than its magnitude. Thus, bone cells might be very sensitive to sudden stress-kicks, as occuring e.g., during impact loading. There is evidence that cells change stiffness under stress, which might make them more sensitive to subsequent loading. We studied the influence of a stress-kick on the mechanosensitivity of MC3T3-E1 osteoblast-like cells under different peak shear rate conditions, as measured by nitric oxide production. MC3T3-E1 bone cells were treated with steady or pulsating fluid shear stress (PFSS) for 5 min with different peak rates (9.70, 17.5, and 22.0 Pa Hz) using varying frequencies (5 and 9 Hz), and amplitudes (0.70 and 0.31 Pa). PFSS treatment was done with or without fluid flow pretreatment phase, which removed the initial stress-kick by first applying a slow fluid flow increase. Nitric oxide production in response to fluid shear stress was rate dependent, but necessitated an initial stress-kick to occur. This suggests that high-rate stimuli condition bone cells to be more sensitive for high-frequency, low-amplitude loads.

Bone Marrow Cells↗
PubMed1992

Relationships between thermotolerance, oxidative stress responses and induction of stress proteins in human tumour cell lines.

Thermotolerance, resistance to oxidative stress and induction of stress proteins were examined in a panel of 10 human tumour cell lines. An inverse relationship was indicated between intrinsic thermotolerance (cell survival after treatment at 43.5 degrees for 3 hr) and thermotolerance induced by pretreatment at 42.5 degrees for 30 min. Similar levels of induction of hsp 70 were found in cell lines with high or low levels of intrinsic thermotolerance; induction of other stress proteins could not be detected. Cell survival following treatment with H2O2 correlated with that following streptonigrin treatment (P < 0.05). Pretreatment with buthionine sulphoximine or diamide synergistically increased the toxicity of heat, H2O2 and streptonigrin whereas reduced glutathione had the reverse effect. No direct correlation was found, however, between tolerance to heat and to oxidative stress, and hsp 70 was not induced by the latter. The stress protein heme oxygenase, detected by immunoblotting with the monoclonal antibody HO, was induced by H2O2 in melanoma cell lines but not in HeLa. Cadmium and arsenite ions, however, readily induced heme oxygenase in HeLa, indicating that in these cells induction of heme oxygenase by oxidative stress involves a different mechanism. Overall, the results suggest that tolerance to heat or oxidative stress in these cell lines may not necessarily be associated with the induction of heat shock proteins or heme oxygenase but that cell survival after both types of stress depends to a certain extent on cellular sulphydryls.

Adaptation, Physiological↗
PubMed1986

Relationships between sexual activity, plasma testosterone, and the volume of the sexually dimorphic nucleus of the preoptic area in prenatally stressed and non-stressed rats.

The sexually dimorphic nucleus of the preoptic area (SDN-POA) has recently been shown to be reduced in cross-sectional area in prenatally stressed male rats. As masculine copulatory behavior is also reduced in prenatally stressed animals, the present study was designed to test a possible relationship between the entire volume of the SDN-POA and masculine sexual activity in both prenatally stressed and control adult male rats. We report here that prenatally stressed adult males have significantly reduced SDN-POA volumes, reduced levels of sexual activity and lower plasma testosterone levels as compared to control animals. Additionally, however, a strong positive relationship was demonstrated between SDN-POA volume and sexual activity in both stressed and control animals. SDN-POA volumes of sexually active animals from stressed and control groups are approximately equal. SDN-POA volumes of sexually non-active animals are also equal and are about two times smaller than those of sexually active animals, either stressed or control. Similar correlations are reported between SDN-POA volume and testosterone level, and between testosterone level and sexual activity. It is concluded that (1) SDN-POA volume is predictive of sexual activity in both stressed and control male rats, (2) there is a relationship between SDN-POA volume and plasma testosterone level, and (3) the SDN-POA likely has multiple roles in the circuitry underlying masculine reproductive processes and hormone regulation.

Animals↗
PubMed1992

Stress-induced sensitization to amphetamine and morphine psychomotor effects depend on stress-induced corticosterone secretion.

Repeated exposure to stressful situations has been shown to increase individual reactivity to addictive drugs. However, the biological factors involved in such stress-induced changes are largely unknown. In this study, we investigated the role of corticosterone in the effects of restraint stress on the response to psychostimulants and opioids. The effects of repeated stress on amphetamine- and morphine-induced locomotor activity were compared in: (i) animals with an intact hypothalamo-pituitary-adrenal (HPA) axis; (ii) animals in which stress-induced corticosterone secretion was blocked by adrenalectomy, but who received exogenous corticosterone from a subcutaneous implant. The implanted pellets (50 mg) slowly release corticosterone producing a stable plasma level within the normal physiological range over a period of 20 days. Restraint stress increased the locomotor response to both amphetamine (1.5 mg/kg i.p.) and morphine (2 mg/kg s.c.) in animals with an intact HPA axis, but not in animals in which stress-induced corticosterone secretion was suppressed. These results suggest that corticosterone secretion may be one of the mechanisms by which repeated stress amplifies behavioral responses to amphetamine and morphine. Since an enhanced locomotor reactivity to addictive drugs has been found to be frequently associated with an enhanced vulnerability to drug self-administration, these findings point to a role for glucocorticoids in the susceptibility to drug abuse.

Adrenal Glands↗
PubMed1994

The habituation of brainstem catecholaminergic groups to chronic daily restraint stress is stress specific like that of the hypothalamo-pituitary-adrenal axis.

It has previously been shown that immobilization and ether stress induce activation of the hypothalamo-pituitary-adrenal (HPA) axis and that this activation occurs subsequent to activation of brain stem catecholaminergic neurones. In the present study we have investigated whether the brain stem catecholaminergic (CA) neurons show habituation to chronic daily intermittent exposure to the same restraint stress comparable to that of the HPA axis. The level of activity of the brainstem CA groups was estimated by measurement in tissue punches of content of 3,4-dihydroxyphenylacetic acid (DOPAC), a side metabolite of noradrenaline and adrenaline biosynthesis which has been shown to be a reliable index of the stress-induced activation of the CA groups. The level of activity of the HPA axis was determined by measurement of plasma corticosterone and adrenocorticotropic hormone (ACTH) levels. The animals were submitted to a 15 min restraint stress daily. They were sacrificed at the end of the stress session on day 3, 5 and 10. The ACTH response to the acute restraint stress whilst unchanged on day 3 was significantly decreased on day 5 (-54%) and day 10 (-70%) compared to the response in naive rats. The approximately twofold increase in DOPAC level induced by acute restraint stress in the so-called CA medullary group A1/C1 of naive rats was reduced in daily restraint rats on day 5 (-22%) and day 10 (-30%) but was unchanged on day 3. A small (-20%) decrease of the stress-induced DOPAC response in the A2/C2 CA group and locus coeruleus was also observed on day 10.(ABSTRACT TRUNCATED AT 250 WORDS)

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

Effects of prenatal stress on vulnerability to stress in prepubertal and adult rats.

This study investigated the hypotheses that unpredictable prenatal stress has effects on the offspring, similar to those induced by perinatal administration of glucocorticoids and increases the vulnerability to stressful situations at adulthood. Rats were exposed to random noise and light stress throughout pregnancy. Offspring were tested for the development of spontaneous alternation behavior (SA) and at adulthood, their response to novel or aversive situations, open field, extinction and punishment following acquisition of an appetitive response and two-way active avoidance, were assessed. In prenatally stressed rats, the development of SA was significantly delayed. On repeated exposure to an open field they were less active; control rats had elevated plasma corticosterone (CCS) on days 2 and 4 of open field exposure, while prenatally stressed rats had significantly raised plasma CCS after each exposure (days 1-8). Furthermore, punishment-induced suppression of an appetitive response was enhanced. Acquisition of active avoidance was faciliated in female but reduced in male prenatally stressed offspring. It is suggested that random prenatal noise and light stress may cause impairment of development of hippocampal function which lasts into adulthood. This impairment is manifested as an increase in vulnerability and a decrease in habituation to stressful stimuli.

Animals↗
PubMed1995

The degree of protection provided to neuronal cells by a pre-conditioning stress correlates with the amount of heat shock protein 70 it induces and not with the similarity of the subsequent stress.

A mild thermal stress protects primary cultures of dorsal root ganglion (DRG) neurons against a subsequent lethal heat stress as well as to a lesser extent against a subsequent lethal ischaemia. In contrast, a mild ischaemic stress protects DRG neurons only against a subsequent severe thermal stress and not against severe ischaemia. A greater induction of heat shock protein (hsp) synthesis was observed in these cells following mild temperature stress compared to mild ischaemia. This suggests that the protective effect observed is dependent on hsp synthesis resulting in the observed cross-protective effect and does not involve a particular pre-stress specifically protecting against a subsequent, more severe application of the same stress. Moreover, a particular level of hsp induction produces a better protective effect against lethal heat stress than against lethal ischaemia.

Animals↗
PubMed2004

Stress doses of hydrocortisone, traumatic memories, and symptoms of posttraumatic stress disorder in patients after cardiac surgery: a randomized study.

BACKGROUND: Traumatic experiences associated with cardiac surgery (CS) can result in traumatic memories and posttraumatic stress disorder (PTSD). Because it is known that subjects who develop PTSD often show sustained reductions in circulating cortisol concentrations, we performed a prospective, randomized study to examine whether exogenously administered stress doses of hydrocortisone during the perioperative period of CS reduces the long-term incidence of chronic stress and PTSD symptoms. METHODS: Patients (n = 91) were prospectively randomized to receive either stress doses of hydrocortisone or standard treatment during the perioperative period of CS. Of 48 available patients at 6 months after CS, 26 had received stress doses of hydrocortisone and 22 standard treatment. Traumatic memories and PTSD symptoms were diagnosed with previously validated questionnaires. RESULTS: As compared with patients after standard therapy, patients from the hydrocortisone group had significantly lower chronic stress symptom scores (p <.05). There was no significant difference regarding the number or type of traumatic memories between the hydrocortisone and the standard treatment groups. CONCLUSIONS: Stress doses of hydrocortisone in patients undergoing CS are associated with a lower intensity of chronic stress and PTSD symptoms at 6 months after CS.

Aged↗
PubMed2006

The sound of stress: blunted cortisol reactivity to psychosocial stress in tinnitus sufferers.

Clinical observations suggest that tinnitus is modulated by stress. However, there is little empirical data to support the link between stress and tinnitus. In this study, we measured the stress hormone cortisol to examine the reactivity of the hypothalamic-pituitary-adrenal (HPA) axis in tinnitus participants as well as in healthy controls without tinnitus. Eighteen participants with tinnitus and 18 controls without tinnitus were exposed to the Trier Social Stress Task and cortisol sampling and subjective ratings were obtained at regular intervals. Tinnitus participants displayed a blunted cortisol response to psychosocial stress, in comparison with healthy controls who had a typical cortisol release about 30 min after the beginning of the experiment. The blunted cortisol response displayed by the tinnitus participants suggests that they have an anomaly along the HPA axis. Their cortisol response is similar to that found in other bodily stress-related diseases and thus suggests that tinnitus is related to stress. However, tinnitus intensity might not be modulated by stress in a concurrent manner.

Aged↗
PubMed2005

The perfect time to be stressed: a differential modulation of human memory by stress applied in the morning or in the afternoon.

We measured the effects of a stressful experience on memory for emotionally arousing and neutral material learned after exposure to a stressor which induces a significant increase in corticosteroid stress hormones. Because memory performance can be influenced by circadian changes in corticosteroid levels, subjects were tested either in the morning or in the afternoon. Nineteen healthy men (9 in the morning group and 10 in the afternoon group) were submitted to a psychological stress task before viewing a story composed of emotionally negative and neutral segments, while another 20 healthy males (10 in the morning group and 10 in the afternoon group) viewed the story without being exposed to the psychological stressor. Salivary cortisol levels were measured before and after the stressor. Memory performance was assessed by a one week post learning delayed recall. Results show that stress-induced increases in salivary cortisol levels impaired delayed free recall of emotionally arousing material in the morning group, but not in the afternoon group. There was no effect of stress on memory for neutral material. Altogether, these findings suggest that stressing participants in the morning, at a time of high circulating levels of corticosteroids, over stimulated the corticosteroid receptors in the brain, impairing declarative memory for emotionally arousing material unrelated to the stressor. These findings suggest that the experimental context, i.e., time of day at which the experiment occurs, the nature of the to-be-remembered material (remembering the stressful event itself or material unrelated to the stressor) and the valence of the to-be-remembered material (emotionally arousing vs. neutral), modulates the effects of stress on human declarative memory.

Adolescent↗
PubMed2001

The effect of stress doses of hydrocortisone during septic shock on posttraumatic stress disorder in survivors.

BACKGROUND: Exposure to intense physical and psychological stress during septic shock can result in posttraumatic stress disorder in survivors. Patients with chronic posttraumatic stress disorder often show sustained reductions in serum cortisol concentration. This investigation examines whether increasing serum cortisol levels with hydrocortisone treatment during septic shock reduces the incidence of posttraumatic stress disorder in survivors. METHODS: Patients (n = 20) were recruited from a prospective, randomized double-blind study on the hemodynamic effects of hydrocortisone during septic shock. Eleven patients had received placebo and nine stress doses of hydrocortisone. Posttraumatic stress disorder was diagnosed 31 months (median) after intensive care unit discharge using SCID-IV (DSM-IV-criteria). Furthermore, the number of categories of traumatic memory from ICU treatment was determined in both groups at that time. RESULTS: Only one of nine patients from the hydrocortisone group developed posttraumatic stress disorder, compared with seven of 11 patients in the placebo group (p =.02). There was no significant difference with regard to the number of categories of traumatic memory between the hydrocortisone and placebo groups. CONCLUSIONS: The administration of hydrocortisone during septic shock in a dosage similar to the endogenous maximal production rate was associated with a lower incidence of posttraumatic stress disorder in long-term survivors, which seems to be independent of the number of categories of traumatic memory.

Adult↗
PubMed2001

Stress may add bite to appetite in women: a laboratory study of stress-induced cortisol and eating behavior.

To date, there are few known predictors of stress-induced eating. The purpose of this study was to identify whether physiological and psychological variables are related to eating after stress. Specifically, we hypothesized that high cortisol reactivity in response to stress may lead to eating after stress, given the relations between cortisol with both psychological stress and mechanisms affecting hunger. To test this, we exposed fifty-nine healthy pre-menopausal women to both a stress session and a control session on different days. High cortisol reactors consumed more calories on the stress day compared to low reactors, but ate similar amounts on the control day. In terms of taste preferences, high reactors ate significantly more sweet food across days. Increases in negative mood in response to the stressors were also significantly related to greater food consumption. These results suggest that psychophysiological response to stress may influence subsequent eating behavior. Over time, these alterations could impact both weight and health.

Adult↗
PubMed1998

Prolonged stress-induced elevation in plasma corticosterone during pregnancy in the rat: implications for prenatal stress studies.

Experiments were conducted to test the hypothesis that exposure to uncontrollable stress during pregnancy results in a heightened elevation of plasma glucocorticoids. Rats were exposed to uncontrollable electric tail shocks every other day during the 3 weeks of pregnancy. Plasma corticosterone concentrations in stressed dams increased significantly from gestation days 4 to 20. Importantly, this increase in plasma corticosterone occurred 24- and 48-h after exposure to stress suggesting a prolonged elevation in stress-induced glucocorticoid secretion. In addition, the stress-induced rise in plasma corticosterone was accompanied by a significant decrease in maternal levels of corticosteroid binding globulin which suggests increased circulating levels of free corticosterone. Significant stress-induced elevations in plasma corticosterone also occurred in fetuses that were examined on gestation day 20. Furthermore, a significant positive correlation was found between maternal and fetal plasma corticosterone. Results demonstrate that repeated exposure to uncontrollable stress increases plasma concentrations of glucocorticoids throughout pregnancy. In the unbound state, corticosterone may be highly effective in producing alterations in brain development of offspring. These data have important implications for understanding the process underlying the effects of prenatal stress.

Animals↗
PubMed1999

Defeat is a major stressor in males while social instability is stressful mainly in females: towards the development of a social stress model in female rats.

Social stress models appear useful in elucidating the interrelationship between stress, mood disorders, and drug efficacy. However, reliable social stress models for females are virtually lacking. The aim of this study was to determine stress-related consequences of (a) defeat in aggressive encounters and (b) social instability, in male and female rats. Defeat in male and female subjects was induced by aggressive male residents and female residents made aggressive by surgery (mediobasal hypothalamic lesion [MBHL]), respectively. Aggressiveness of resident males and resident MBHL females was remarkably similar. Alternating isolation and mixed-sex crowding phases with membership rotation were used to induce social instability. Aggression was kept low in the latter paradigm by manipulating crowding group composition. Defeat stress reduced weight gain, and increased both adrenals and plasma corticosterone in males. Only adrenal weight was affected in females. Social instability reduced weight gain, and induced thymus involution, adrenal hypertrophy and elevated plasma corticosterone levels in females. Only weight gain and thymus weights were affected in males. It is concluded that defeat stresses males more than females, while social instability is more stressful for females than for males, if aggressive contacts are low. It is suggested that the social instability model is a good model of social stress in females.

Aggression↗