Changes In Stress Hormone Levels Research Articles

Effects of noise exposure on stress hormone changes during task performance in young Korean men: quasi-experimental study

ABSTRACT Numerous studies have suggested that noise exposure might be associated with changes in stress hormone levels. However, quantitative evidence for these effects in humans is rare and remains controversial. This study aimed to investigate the acute effects of exposure to noise and its different levels on stress hormone changes in task performance. Quasi-experimental noise exposure environment was established for 90 male university student volunteers in their twenties, and each was exposed to different noise levels during task performance. The stress hormones tested included cortisol, adrenocorticotropic hormone (ACTH), adrenaline, and noradrenaline. A one-way ANOVA was performed to investigate differences in hormone levels measured in the three groups according to the noise exposure levels (35, 45, or 75 dB). Analysis of covariance (ANCOVA) was used to adjust for confounding factors that might affect hormone levels. After adjusting for confounders, significant exposure-dependent differences were found in hormone levels in salivary cortisol, serum cortisol, serum ACTH, and serum adrenaline. The amount of hormonal increase in 75 dB exposure group compared to 35 or 45 dB groups was detected. Similar results were also seen in the rate of change analysis. Our findings indicate that short-term noise exposure during task performance elevates stress hormone levels. Further, the extent of stress hormone alterations varies with noise exposure levels. Changes in hormone levels are an objective measure that may be used to identify health effects and stress responses in various noise environments.

Noise Exposure and Stress Hormone Levels:A Review

Noise is one of the most common environmental hazards to which people are exposed,and the exposure to noise can cause not only hearing but also non-hearing damage.Although noise under safety limits may not affect the auditory system,it can cause changes in stress hormone levels,which is harmful to health.However,the current studies about the impact of noise on health mainly focus on the auditory system,and little is known about the relationship between noise and stress hormone levels.Therefore,this paper reviews the studies involving noise exposure and stress hormone levels,aiming to provide ideas for strengthening the prevention and control of noise hazards.

Аssessment of the antinociceptive efficacy of varieties of multimodal low-opioid general anesthesia during laparoscopic renal surgery

The main premise for the emergence of the concept of low-opioid general anesthesia was the phenomenon of the formation of drug/opioid dependence in patients undergoing surgery under multicomponent anesthesia with high doses of narcotic analgesics (opioids). Opioids were used as the main analgesics and in the postoperative period. The above factors contributed to the development of opiate addiction in operated patients in the late postoperative period. The mass nature of this phenomenon has become one of the most urgent problems in modern anesthesiology.
 Our study aimed to evaluate the antinociceptive/antistress efficacy of 3 types of low-opioid multimodal general anesthesia in laparoscopic renal surgery.
 Methods. Eighty patients who had undergone laparoscopic renal surgery under 3 types of general anesthesia were included in this prospective cohort study. All patients were operated under general anesthesia with tracheal intubation. Induction: intravenous (IV) propofol 2 mg/kg, fentanyl 1.5-2 μg/kg, atracurium 0.6 mg/kg. Maintenance of anesthesia: sevoflurane (MAC - 1.44±0.25% by volume). In group 1 (control group n = 26), analgesia was provided with fentanyl 3,89±2.03 μg/kg/h. In group 2 (n = 25), multimodal low-opioid general anesthesia was performed with fentanyl 1.76±1.2 μg/kg/h and IV lidocaine 1.5 mg/kg/h and subanesthetic doses of ketamine. In group 3 (n = 29), multimodal anesthesia with low opioids was performed with fentanyl 2.38±1.01 μg/kg/h in combination with dexmedetomidine 0.7 μg/kg/h. The efficacy of antinociceptive protection was assessed by the dynamics of changes in stress hormone levels, hemodynamic parameters, and blood glucose concentration.
 Results. The mean total dose of fentanyl used throughout the anesthetic period was: 369,23±83,75 μg in group 1, 216,0±47,26 μg in group 2, and 272,41±58,14 μg in group 3 (p < 0.001). Mean cortisol levels were significantly different before and after surgery in groups 1 and 2: 371,0±161,61 nmol/l vs 562,72±226,87 nmol/l (p < 0.01) and 531,08±218,02 nmol/l vs 831,33±235,32 nmol/l (p < 0.01), respectively. In group 3, we did not detect any statistical difference: 393,51±134,69 nmol/l and 436,37±188,09 nmol/l, respectively (p > 0.05). The mean level of adrenocorticotropic hormone increased significantly after surgery in all studied groups: 111.86% in group 1 (p < 0.01), 122.02% (p < 0.01) in group 2 and 78.59% (p < 0.01) in group 3. Blood glucose levels in the postoperative (p/o) period did not exceed 6,16±1,67 mmol/l (p > 0.05) in all groups. Hemodynamic parameters and BIS, which were maintained within 44±6.4%, indicated the adequacy of anesthesia and analgesia in the study groups.
 In group 1, 8 of 26 patients required additional analgesia with opioids during the p/o period (pain intensity on the VAS scale exceeded 4 points). In group 2 and group 3, 4 patients each required opioid analgesia, 16% and 15.38%, respectively. The next day after surgery, all patients were mobilized (sitting in bed, walking). Markers of renal function were also within normal range in all patients.
 Conclusion. The use of low-opioid multimodal anesthesia with IV lidocaine or dexmedetomidine during laparoscopic renal surgery provides an adequate anesthetic/antinociceptive effect. The use of dexmedetomidine in multimodal general anesthesia provides the greatest antinociceptive protection and reduces the stress response to surgery.

Influence of Comprehensive Lifestyle Intervention (LSI) Program on Health, Fatigue, and Quality of Life in Middle-Aged Women.

Middle age is one of the most important times in a woman's life, and it is a time when multiple changes occur that affect the body and health. The study aimed to investigate the efficacy of a comprehensive lifestyle intervention (LSI) program, including stress management, on middle-aged women's physical, physiological, and mental health. A total of 40 middle-aged women participated in a short-term LSI program, nutrition, exercise, and mental and physical management with various experiential activities. Physical measurements, biochemical indicators, stress hormones, chronic fatigue, and quality of life indicators were evaluated to interpret the clinical efficacy of the program. LSI program significantly improved satisfaction and quality of life in participants. Total chronic fatigue scores reduced significantly compared to scores before the start of the program. Moreover, fat mass and body fat were reduced without loss of muscle mass. Further, blood pressure and triglyceride levels significantly decreased after completing the LSI program. However, changes in stress hormone levels remained insignificant. Adoption of LSI in middle-aged women demonstrated positive implications of the program. LSI efficiently regulates body fat, fat mass, fatigue, hypertension, and triglyceride levels which play a critical role in determining the quality of life. Thus, the LSI program could spread healthy lifestyles among middle-aged women.

Improved interhemispheric connectivity after stress during lexical decision making

Functional hemispheric asymmetries emerge as the left and the right hemisphere are dominant for different aspects of task processing. However, the hemispheres do not work independent of each other but share information through the corpus callosum. The integration of information across the corpus callosum is dependent on its structural integrity and functionality. Several hormones, like estradiol and progesterone, can influence this function. Since earlier work has demonstrated that long-term changes in stress hormone levels are accompanied by changes in hemispheric asymmetries in several mental disorders, the aim of the current study was to investigate whether acute stress and the associated changes in stress hormone levels also affect information transfer across the corpus callosum. For this purpose, we collected EEG data from 51 participants while completing a lexical decision task and a Poffenberger paradigm twice, once after stress induction with the Trier Social Stress Test and once after a control-condition. While there were no differences in interhemispheric transfer between the stress and the non-stress condition in the Poffenberger paradigm, we observed shorter latencies to stimuli in the left visual field in the left hemisphere at the CP3-CP4 electrode pair after stress. These results suggest that the transfer of lexical material from the right to the left hemisphere was quicker under stress. Stress may increase callosal excitability and lead to more efficient signal transfer across the corpus callosum between language related areas. Future studies using pharmacological intervention are needed to further examine cooperation of the hemispheres under stress in more detail.

Stress as a mnemonic filter: Interactions between medial temporal lobe encoding processes and post-encoding stress.

Acute stress has been shown to modulate memory for recently learned information, an effect attributed to the influence of stress hormones on medial temporal lobe (MTL) consolidation processes. However, little is known about which memories will be affected when stress follows encoding. One possibility is that stress interacts with encoding processes to selectively protect memories that had elicited responses in the hippocampus and amygdala, two MTL structures important for memory formation. There is limited evidence for interactions between encoding processes and consolidation effects in humans, but recent studies of consolidation in rodents have emphasized the importance of encoding "tags" for determining the impact of consolidation manipulations on memory. Here, we used functional magnetic resonance imaging in humans to test the hypothesis that the effects of post-encoding stress depend on MTL processes observed during encoding. We found that changes in stress hormone levels were associated with an increase in the contingency of memory outcomes on hippocampal and amygdala encoding responses. That is, for participants showing high cortisol reactivity, memories became more dependent on MTL activity observed during encoding, thereby shifting the distribution of recollected events toward those that had elicited relatively high activation. Surprisingly, this effect was generally larger for neutral, compared to emotionally negative, memories. The results suggest that stress does not uniformly enhance memory, but instead selectively preserves memories tagged during encoding, effectively acting as mnemonic filter. © 2016 Wiley Periodicals, Inc.

Preservation of gastric functional activity by the herbal preparation STW 5 in functional dyspepsia in a novel stress model

The present study aims to show whether the beneficial effects of the herbal preparation STW 5 (Iberogast®) in functional dyspepsia (FD) could be partly due to preservation of gastric emptying and function. STW 5 consists of standardized extracts of Iberis amara, Melissa officinalis, Matricaria recutita, Carum carvi, Mentha x piperita, Angelica archangelica, Silybum marianum, Chelidonium majus, and Glycyrrhiza glabra. We recently established a novel model of FD resembling the clinical situation [1] where FD is attributed to emotional stress in early life [2], followed by exposure to stress in later life [3]. Rats were subjected to neonatal maternal separation at intervals during the first 3 weeks of birth followed by restraint stress in adulthood. Restraining sessions were carried out 90 min/day for 1 week during which they were given STW 5 in daily doses of 2 and 5 ml/kg p.o. One day after the last session, gastric emptying time was determined using a phenol red meal [4]. Stressed rats showed marked delay in gastric emptying, an effect which was counteracted dose dependently by STW 5. We further tried to correlate changes in gastric emptying with changes in stress hormone levels and gastric reactivity towards smooth muscle stimulants and relaxants. We had shown earlier that giving STW 5 ahead of stress prevented changes in fundus strip sensitivity to carbachol, serotonin, adrenaline and KCl. In the present work we extend our findings by giving STW 5 alongside with stress. STW 5 prevented the rise in corticosterone and changes in fundus sensitivity to these agents induced by the model. The preservation of gastric functional activity by STW 5 in the face of stress contributes to our understanding of its beneficial use in FD [5].

Effects of leisure activities at home on perceived care burden and the endocrine system of caregivers of dementia patients: a randomized controlled study.

Psychological stress associated with caregiving is thought to underlie the high incidence of hypertension, ischemic heart disease, and mortality, as well as reduced immune function, among caregivers of dementia patients. Here, we examined the effects of periodic leisure activities performed by caregivers of dementia patients with care recipients at home on perceived care burden and levels of stress hormones. Participants were 42 caregivers aged ≥ 65 years of patients diagnosed with Alzheimer's dementia. They were randomly assigned to intervention and non-intervention groups. The intervention group underwent a leisure activity program (30 min/3 times/week for 24 weeks) with the care recipient, and the control group underwent normal care activities. The Zarit Burden Interview (ZBI) score, a subjective indicator of care burden, significantly decreased after intervention in the intervention group (p < 0.05), whereas no difference was observed in the control group. No significant changes were observed in adrenaline, noradrenaline, dopamine, and cortisol levels in both groups. The lack of changes in stress hormone levels despite a decrease in subjective care burden in the intervention group might be explained by the effects of the chosen leisure activity on the neuroendocrine system. Our findings suggest that periodic leisure activities can reduce perceived care burden among caregivers of dementia patients. However, in order to evaluate accurately the effects of leisure activities of the present study, long-term follow-up of both caregivers and care recipients is necessary. The Nagoya University Department of Medicine Ethics Committee Clinical Trials Registry Number is 1290.

Functional changes in neutrophils and psychoneuroendocrine responses during 105 days of confinement.

The innate immune system as one key element of immunity and a prerequisite for an adequate host defense is of emerging interest in space research to ensure crew health and thus mission success. In ground-based studies, spaceflight-associated specifics such as confinement caused altered immune functions paralleled by changes in stress hormone levels. In this study, six men were confined for 105 days to a space module of ~500 m(3) mimicking conditions of a long-term space mission. Psychic stress was surveyed by different questionnaires. Blood, saliva, and urine samples were taken before, during, and after confinement to determine quantitative and qualitative immune responses by analyzing enumerative assays and quantifying microbicide and phagocytic functions. Additionally, expression and shedding of L-selectin (CD62L) on granulocytes and different plasma cytokine levels were measured. Cortisol and catecholamine levels were analyzed in saliva and urine. Psychic stress or an activation of the psychoneuroendocrine system could not be testified. White blood cell counts were not significantly altered, but innate immune functions showed increased cytotoxic and reduced microbicide capabilities. Furthermore, a significantly enhanced shedding of CD62L might be a hint at increased migratory capabilities. However, this was observed in the absence of any acute inflammatory state, and no rise in plasma cytokine levels was detected. In summary, confinement for 105 days caused changes in innate immune functions. Whether these changes result from an alert immune state in preparation for further immune challenges or from a normal adaptive process during confinement remains to be clarified in future research.

Changes in stress hormone levels with the application of vibrations before resistance exercises at different intensities

[Purpose] The purpose of the present study was to determine whether vibrations should be applied before resistance exercises by examining changes in stress hormone levels with vibrations applied before different exercise intensities. [Subjects] Eighteen male subjects in their 20s were included, and were randomly divided into one-repetition maximum (1RM) 50% group (50% RMG, n = 6), 1RM 70% group (70%RMG, n = 6), and 1RM 90% group (90% RMG, n = 6). [Methods] Three sets of Smith squats were performed at 1RM 50%, 70%, and 90% according to resistance intensities, and vibrations were applied for 1 min at a fixed frequency of 30 Hz before each set. Epinephrine, norepinephrine, and dopamine stress hormone levels were analyzed. [Results] Epinephrine levels were significantly higher immediately after exercise than at rest in the 50%RMG; however, no significant changes were noted in the 70%RMG and 90%RMG. Norepinephrine levels were significantly higher immediately after exercise than at rest in all three groups. However, no significant changes in dopamine levels were noted in the three groups. [Conclusion] The application of vibrations at a frequency of 30 Hz before 70%RM and 90%RM resistance exercises suppressed increases in the stress hormone epinephrine levels immediately after exercise.

Corticosterone and corticotropin-releasing factor acutely facilitate gamma oscillations in the hippocampus in vitro.

Stressful experiences do not only cause peripheral changes in stress hormone levels, but also affect central structures such as the hippocampus, implicated in spatial orientation, stress evaluation, and learning and memory. It has been suggested that formation of memory traces is dependent on hippocampal gamma oscillations observed during alert behaviour and rapid eye movement sleep. Furthermore, during quiescent behaviour, sharp wave-ripple (SW-R) activity emerges. These events provide a temporal window during which reactivation of memory ensembles occur. We hypothesized that stress-responsive modulators, such as corticosterone (CORT), corticotropin-releasing factor (CRF) and the neurosteroid 3α, 21-dihydroxy-5α-pregnan-20-one (THDOC) are able to modulate gamma oscillations and SW-Rs. Using in vitro hippocampal slices, we studied acute and subacute (2 h) impact of these agents on gamma oscillations in area cornu ammonis 3 of the ventral hippocampus induced by acetylcholine (10 μm) combined with physostigmine (2 μm). CORT increased the gamma oscillations in a dose-dependent fashion. This effect was mediated by glucocorticoid receptors. Likewise, CRF augmented gamma oscillations via CRF type 1 receptor. Lastly, THDOC was found to diminish cholinergic gamma oscillations in a dose-dependent manner. Neither CORT, CRF nor THDOC modulated gamma power when pre-applied for 1 h, 2 h before the induction of gamma oscillations. Interestingly, stress-related neuromodulators had rather mild effects on spontaneous SW-R compared with their effects on gamma oscillations. These data suggest that the alteration of hippocampal gamma oscillation strength in vitro by stress-related agents is an acute process, permitting fast adaptation to new attention-requiring situations in vivo.

No Effects of Psychosocial Stress on Intertemporal Choice

Intertemporal choices - involving decisions which trade off instant and delayed outcomes - are often made under stress. It remains unknown, however, whether and how stress affects intertemporal choice. We subjected 142 healthy male subjects to a laboratory stress or control protocol, and asked them to make a series of intertemporal choices either directly after stress, or 20 minutes later (resulting in four experimental groups). Based on theory and evidence from behavioral economics and cellular neuroscience, we predicted a bidirectional effect of stress on intertemporal choice, with increases in impatience or present bias immediately after stress, but decreases in present bias or impatience when subjects are tested 20 minutes later. However, our results show no effects of stress on intertemporal choice at either time point, and individual differences in stress reactivity (changes in stress hormone levels over time) are not related to individual differences in intertemporal choice. Together, we did not find support for the hypothesis that psychosocial laboratory stressors affect intertemporal choice.

Nature of Pre-Earthquake Phenomena and their Effects on Living Organisms.

Simple SummaryEarthquakes are invariably preceded by a period when stresses increase deep in the Earth. Animals appear to be able to sense impending seismic events. During build-up of stress, electronic charge carriers are activated deep below, called positive holes. Positive holes have unusual properties: they can travel fast and far into and through the surrounding rocks. As they flow, they generate ultralow frequency electromagnetic waves. When they arrive at the Earth surface, they can ionize the air. When they flow into water, they oxidize it to hydrogen peroxides. All these physical and chemical processes can have noticeable effects on animals.Earthquakes occur when tectonic stresses build up deep in the Earth before catastrophic rupture. During the build-up of stress, processes that occur in the crustal rocks lead to the activation of highly mobile electronic charge carriers. These charge carriers are able to flow out of the stressed rock volume into surrounding rocks. Such outflow constitutes an electric current, which generates electromagnetic (EM) signals. If the outflow occurs in bursts, it will lead to short EM pulses. If the outflow is continuous, the currents may fluctuate, generating EM emissions over a wide frequency range. Only ultralow and extremely low frequency (ULF/ELF) waves travel through rock and can reach the Earth surface. The outflowing charge carriers are (i) positively charged and (ii) highly oxidizing. When they arrive at the Earth surface from below, they build up microscopic electric fields, strong enough to field-ionize air molecules. As a result, the air above the epicentral region of an impending major earthquake often becomes laden with positive airborne ions. Medical research has long shown that positive airborne ions cause changes in stress hormone levels in animals and humans. In addition to the ULF/ELF emissions, positive airborne ions can cause unusual reactions among animals. When the charge carriers flow into water, they oxidize water to hydrogen peroxide. This, plus oxidation of organic compounds, can cause behavioral changes among aquatic animals.

Do stress hormones connect environmental effects with behavior in the forced swim test?

Forced swim test (FST) is a widely used test for antidepressant development. Depression is a stress related disease, as hormones of the stress-axis can modify mood. However it is not clear, how the appearance of depressive-like behavior (floating) in FST is connected with changes in the stress-hormone levels. We hypothesized, that different manipulations would alter the behavior through changes in stress-hormone levels. First the effect of environmental alterations was studied. Increasing water-temperature enhanced floating time together with a decrease in adrenocorticotropin levels. During the dark phase of the day rats spent more time with floating independently from the actual lighting. Neither the phase nor the actual lighting had significant effect on adrenocorticotropin concentrations with higher corticosterone levels during the dark phase. At greater water depth rats float less but the size of animals had no effect. Water depth did not influence adrenocorticotropin and corticosterone responses, but the size of the rats significantly affected both factors. Secondly, administration of imipramine reduced floating and adrenocorticotropin level without affecting corticosterone. Despite the known connection between depression and stress we did not find a correlation between floating behavior and hormone levels. As an alternative mechanism imipramine-induced heart rate and core body temperature decrease was found by telemetric approach. This study is the first summary in rats examining the effect of wide range of environmental alterations during FST. It seems likely that both brain monoamines and stress-axis take part in the development of depression, but these pathways are regulated independently.

Bidirectional regulation of stress responses by galanin in mice: Involvement of galanin receptor subtype 1

The neuropeptide galanin has been shown to play a role in psychiatric disorders as well as in other biological processes including regulation of pain threshold through interactions with three G-protein coupled receptors, galanin receptor subtypes 1–3 (GalR1−3). While most of the pharmacological studies on galanin in stress-related disorders have been done with rats, the continuous development of genetically engineered mice involving galanin or its receptor subtype(s) validates the importance of mouse pharmacological studies. The present study on mice examined the homeostatic, endocrinological and neuroanatomical effects of the galanin, injected intracerebroventricularly (i.c.v.), in regulation of stress responses after restraint stress. Furthermore, the roles of GalR1 on these effects were studied using GalR1 knockout (KO) mice. The core body temperature and the locomotor activity were monitored with radio telemetry devices. Galanin (i.c.v.) decreased locomotor activity and exerted a bidirectional effect on the restraint stress–induced hyperthermia; a high dose of galanin significantly attenuated the stress-induced hyperthermic response, while a low dose of galanin moderately enhanced this response. The bidirectional effect of galanin was correlated with changes in stress hormone levels (adrenocorticotropic hormone and corticosterone). To neuroanatomically localize the effects of galanin on stress response, cFos immunoreactivity was assessed in galanin receptor rich areas; paraventricular nucleus (PVN) of the hypothalamus and the locus coeruleus (LC), respectively. A high dose of galanin significantly induced cFos activity in the LC but not in the PVN. In GalR1KO mice, a high dose of galanin failed to induce any of the above effects, suggesting the pivotal role of GalR1 in decreased locomotor activity and stress-resistant effects caused by galanin i.c.v. injection studied here.

Alterations in the Brain–Gut Axis Underlying Visceral Chemosensitivity in Nippostrongylus brasiliensis-Infected Mice

Visceral hypersensitivity, a hallmark of irritable bowel syndrome, is generally considered to be mechanosensitive in nature and mediated via spinal afferents. Both stress and inflammation are implicated in visceral hypersensitivity, but the underlying molecular mechanisms of visceral hypersensitivity are unknown. Mice were infected with Nippostrongylus brasiliensis (Nb) larvae, exposed to environmental stress and the following separate studies performed 3-4 weeks later. Mesenteric afferent nerve activity was recorded in response to either ramp balloon distention (60 mm Hg), or to an intraluminal perfusion of hydrochloric acid (50 mmol/L), or to octreotide administration (2 micromol/L). Intraperitoneal injection of cholera toxin B-488 identified neurons projecting to the abdominal viscera. Fluorescent neurons in dorsal root and nodose ganglia were isolated using laser-capture microdissection. RNA was hybridized to Affymetrix Mouse whole genome arrays for analysis to evaluate the effects of stress and infection. In mice previously infected with Nb, there was no change in intestinal afferent mechanosensitivity, but there was an increase in chemosensitive responses to intraluminal hydrochloric acid when compared with control animals. Gene expression profiles in vagal but not spinal visceral sensory neurons were significantly altered in stressed Nb-infected mice. Decreased afferent responses to somatostatin receptor 2 stimulation correlated with lower expression of vagal somatostatin receptor 2 in stressed Nb-infected mice, confirming a link between molecular data and functional sequelae. Alterations in the intestinal brain-gut axis, in chemosensitivity but not mechanosensitivity, and through vagal rather than spinal pathways, are implicated in stress-induced postinflammatory visceral hypersensitivity.

Increase in epinephrine excretion is associated with cognitive decline in elderly men: MacArthur studies of successful aging

High stress hormone levels are associated with increased risk of cognitive decline in elderly individuals. However, the effect of late-life changes in stress hormone levels on cognitive decline risk has not been examined. Our objective was to investigate whether increase over time in urinary epinephrine excretion in older adults was associated with subsequent cognitive decline. Measurements were made on 154 high-functioning men and women, 70-79 years of age, in 1988, 1991, and 1995. Twelve-hour overnight urinary excretion of epinephrine (normalized by creatinine excretion to adjust for body size) was recorded in 1988 and 1991. Cognitive functioning was assessed in 1991 and 1995 by summary scores based on standard tests of language, memory, abstraction, spatial recognition, and spatial construction. Compared to individuals whose epinephrine excretion decreased between 1988 and 1991, the individuals whose epinephrine excretion increased over the same period had greater subsequent declines in summary cognitive scores between 1991 and 1995. After adjusting for baseline epinephrine, baseline cognitive function, and relevant covariates, and stratifying by gender, increases in urine epinephrine were positively associated with cognitive decline only in men. We conclude that increase in urinary excretion of epinephrine predicts subsequent cognitive decline in older men.

Opposite effects of mild and severe stress on in vitro activation of rat peripheral blood lymphocytes

The effects of short-term handling and different durations of immobilization on serum levels of catecholamines, ACTH, prolactin, and corticosterone and in vitro functions of lymphocytes were examined in rats. The results show that changes in the immune response of peripheral blood lymphocytes (PBL) depend on the intensity of the stressor: Short (1 min) handling of cannulated rats induced an enhanced stimulation of PBL to respond to T and B cell mitogens, whereas immobilization of the same animals led to suppression, dependent on the time this stressor was applied. The decrease in the mitogen reactivity of PBL after 120 min of immobilization was reversible within 24 h, and could be largely prevented by adrenalectomy, confirming that factors released by this gland are mainly responsible for immunosuppression. In contrast to PBL, spleen cells showed an enhanced mitogen response to immobilization and adrenalectomy, indicating that the immune response is differently regulated in the various compartments of the immune system. Possible correlations of the various effects with changes in stress hormone levels are discussed.