Psychological and physiological responses to acute laboratory stressors in insulin-dependent diabetes mellitus adolescents and nondiabetic controls

Thirty 11- to 18-year old adolescents with insulin-dependent diabetes mellitus (IDDM) of at least 1-year duration and 15 nondiabetic controls were subjected to three laboratory stressors: a venipuncture and two public-speaking tasks. Half of the IDDM participants were in good metabolic control prior to the inception of the experiment and half were in poor control. The IDDM adolescents in poor control and the nondiabetics were matched to the well-controlled IDDM group on the basis of age, sex, and race. The two IDDM groups were also matched on disease duration. Self-report, behavioral, and physiological measures of anxiety or arousal were monitored during the stress.     

Depressive symptoms and attenuated physiological reactivity to laboratory stressors

There is evidence that depressive symptoms are associated with attenuated physiological reactivity to active stressors. However, it is not known whether blunted reactivity in depressed individuals is stressor-specific. We examined cardiovascular and electrodermal reactivity in non-clinical participants with varying levels of depressive symptoms to different active and passive stressors. Depressive symptoms were inversely related to both blood pressure and skin conductance reactivity during a public speaking task and the viewing of the speech video. However, no effects were found during a cold pressor task. Together these findings suggest that depressive symptoms are related to attenuated sympathetic nervous system reactivity in response to self-relevant stressors.     

Increased serotonin release in mice frontal cortex and hippocampus induced by acute physiological stressors

The effects of acute physiological stressors (5 s tail pinch, handling and forced swimming at +25 and +5 degrees C for 3 min each) on serotonin (5-HT) release in the mouse brain were investigated using in vivo microdialysis. The extracellular 5-HT levels were determined by a newly developed highly-sensitive and selective high-performance liquid chromatography method based on derivatization with benzylamine and fluorescence detection. The basal levels of 5-HT in 3 min microdialysates from the ventral hippocampus and frontal cortex were 0.68+/-0.21 and 0.75+/-0.28 fmol/6 microl (n=24), respectively. All three stressors caused an immediate, significant and reversible increase (handling: 150%; swimming: 240%) of extracellular 5-HT levels in both brain structures, suggesting a more dynamic role played by the serotonergic system in response to acute stress.     

Cardiovascular responses to psychological and physiological stressors during the menstrual cycle

Psychological and physical stress reactivity was studied in 15 females in two phases of the menstrual cycle (cycle days 5-7 and 24-26) and in 15 males. Each female was matched for age and time between sessions with a male. There was a significant phase-related difference in cardiovascular reactivity among the females. Females in the luteal phase reacted significantly more to the cold pressor but not to the mental arithmetic test. There were significant sex differences in systolic blood pressure, the males displaying higher levels during provocation, as well as during control conditions. The females were more reactive in heart rate to the mental stressor when changes from control conditions to stress were calculated. When the data were analyzed separately for smokers and non-smokers, there was a significant interaction between menstrual cycle phase and smoking. In the luteal phase, the female smokers were more reactive in systolic blood pressure than the non-smokers. The male smokers were more reactive than the non-smokers in diastolic blood pressure response to mental arithmetic, but not to the cold pressor test. Significantly higher levels of cortisol and aldosterone were found in the luteal phase as compared with the follicular phase. The cortisol levels were higher in the males than in the females in the follicular phase, whereas the female aldosterone concentrations in the luteal phase were higher than those of the males.     

Lactation and weaning effects on physiological and behavioral response to stressors

Two experiments tested the effects of lactation and weaning on heart rate (HR), corticosterone, and behavioral responses to stress in Wistar rats. In Experiment 1, HRs in lactating, weaning, and control animals were recorded for 10-min periods before, during, and after immobilization stress. Compared with control animals, lactating and weaning animals showed a diminished initial HR response. In addition, HRs of weaning animals failed to habituate and showed a delayed decline after stress termination. In Experiment 2, behaviors, HRs, and corticosterone levels in the elevated plus maze (EPM) were compared among lactating, weaning, and control animals. Compared with control animals, weaning animals exhibited more anxiety behaviors. Contrary to expectation, compared to the other two groups, lactating animals exhibited more closed-arm entries, although they may have been motivated by maternal behavior, rather than anxiety. Initial HR responses to the plus maze were attenuated in lactating animals. Corticosterone levels after the plus maze were lowest in the lactating dams and highest in the control animals. The results from these two experiments are consistent with effects of breast-feeding and weaning observed in humans. In general, lactation is associated with an attenuated initial HR response to stress, while weaning is associated with exacerbated response to stressors.     

Stress management training for hypertensives: Cognitive and physiological effects

The contribution of training procedures designed to alter individuals' psychological responses to stressful life stimuli to the reduction of blood-pressure levels of hypertensives was evaluated. The treatment consisted of a set of coping skill-building experiences. Forty-one black males, mildly to moderately hypertensive and under medical supervision in an outpatient cardiovascular unit of a veterans' hospital, participated. Subjects were randomly assigned to one of three groups: Cognitive Self-Management Training (CSM), Attention Placebo Control, and Current Clinic Conditions Control. The dependent measures were the State Anxiety Scale, Trait Anxiety Scale, Coping Strategic Inventory, systolic blood pressure, and diastolic blood pressure. Subjects in the CSM group reported significant increases in the use of cognitive coping strategies in their lives and demonstrated significant decreases in measured levels of state anxiety and systolic blood pressure. Promising reductions of diastolic blood pressure ratings were obtained as well.     

A pilot study of some associations between behavioural stressors and physiological processes in healthy men

Summary A study was made of the physiological effects of smoking, psychological stressors, heat, exercise, and fat ingestion on 12 healthy men. Repeated measurements were made of cardiovascular, neuroendocrine, enzyme, lipid, and other variables in all stressor situations. The main findings were that psychological stressors and exercise were associated with more and larger physiological changes than the other stressors, and widespread response differences in addition to those in lipids were identified between subgroups of seven normolipidaemic men and five hypertriglyceridaemic men.     

Nasal hyperreactivity to newspapers

Nasal hyperreactivity occurs quite frequently while reading newspapers. This study consisted of 15 patients with vasomotor rhinitis with such problems and six asymptomatic volunteers. All subjects were exposed to printing ink and paper dust from newspapers. The effect was registered by nasal symptom score and rhinomanometry. Patients with vasomotor rhinitis reacted upon exposure to paper dust but not to printing ink. This exposure had no effect on the control group. The results indicate that paper dust is the causative agent in hyperreactivity to newspapers.     

Effects of acute exposure to stressors on subsequent avoidance-escape behavior.

This paper attempts to show that severely stressful conditions can lead to a deficit in avoidance-escape responding by reducing noradrenergic activity in the brain. It is argued that this stress-induced neurochemical change explains more adequately an avoidance-excape deficit seen previously in dogs after severe inescapable shock than does the "learned helplessness" explanation originally offered for this effect. A series of six experiments are described that test the stress-neurochemical change explanation, which is called the "motor activation deficit" hypothesis. The first experiment showed that a brief exposure to cold swim, which reduced central noradrenergic activity but did not induce "learned helplessness," produced an avoidance-escape deficit similar to that observed after inescapable shock in the original "learned helplessness" studies. Subsequent experiments demonstrated that the deficit induced by cold swim was also similar to the original deficit in that it too dissipated with the passage of time and was reduced by pretraining animals in the correct response. Further experiments then showed that the deficit induced by cold swim was (a) aggravated by raising the height of the barrier between compartments in the shuttle box, and (b) did not occur if the avoidance-escape task used required little motor activity, both of the findings being predicted by the "motor activation deficit" hypothesis. Finally, an avoidance-escape deficit was produced by inescapable shock, and it was found that this stressor likewise did not impair avoidance-escape responding if the task required little skeletal activity, a result not predicted by the "learned helplessness" hypothesis. The paper concludes by discussing how the results presented in this paper, as well as in succeeding papers, support the "motor activation deficit" explanation for certain avoidance-escape deficits, defining the cases to which the explanation applies and discussing the neurotransmitters involved.     

Personality and physiological reactions to acute psychological stress

Stable personality traits have long been presumed to have biological substrates, although the evidence relating personality to biological stress reactivity is inconclusive. The present study examined, in a large middle aged cohort (N = 352), the relationship between key personality traits and both cortisol and cardiovascular reactions to acute psychological stress. Salivary cortisol and cardiovascular activity were measured at rest and in response to a psychological stress protocol comprising 5 min each of a Stroop task, mirror tracing, and a speech task. Participants subsequently completed the Big Five Inventory to assess neuroticism, agreeableness, openness to experience, extraversion, and conscientiousness. Those with higher neuroticism scores exhibited smaller cortisol and cardiovascular stress reactions, whereas participants who were less agreeable and less open had smaller cortisol and cardiac reactions to stress. These associations remained statistically significant following adjustment for a range of potential confounding variables. Thus, a negative personality disposition would appear to be linked to diminished stress reactivity. These findings further support a growing body of evidence which suggests that blunted stress reactivity may be maladaptive.     

Sympathetic arousal moderates self-reported physiological arousal symptoms at baseline and physiological flexibility in response to a stressor in generalized anxiety disorder

Compared to controls, individuals with generalized anxiety disorder (GAD) often fail to exhibit expected changes in physiological arousal in response to laboratory stressors. Nevertheless, individuals with GAD often report significant subjective arousal. We sought to assess the degree of sympathetic arousal in individuals with GAD and controls and the impact such arousal had on self-reported physiological arousal and response to an emotional challenge. Degree of baseline sympathetic arousal moderated the self-report of physiological arousal in non-comorbid GAD at baseline such that within this group, higher levels of sympathetic arousal predicted reports of heightened physiological arousal compared to controls. Overall, individuals with GAD exhibited no significant changes in arousal in response to the emotional challenge. However, basal sympathetic arousal moderated degree of change such that non-comorbid GAD participants low in baseline sympathetic arousal exhibited changes in arousal similar to controls in response to the stressor. That basal sympathetic arousal moderated both self-reported arousal at baseline and sympathetic response to a stressor suggests important physiological heterogeneity in GAD, wherein only those individuals with heightened tonic sympathetic arousal report accompanying symptoms and display diminished sympathetic reactivity.     

Behavioral and physiological effects of a beta blocker and relaxation therapy on mild hypertensives

In this industrial-based study we compared the blood pressure (BP)-lowering effectiveness of relaxation, a beta blocker, and the combined use of these two treatments in 47 untreated, mildly hypertensive blue collar steel workers. Using a randomized two by two factorial design, patients received either nadolol or placebo drug daily, and either a relaxation training or an education program, each lasting 8 weeks. A pre-intervention and post-intervention stress test measured response of heart rate and BP to mental and physical tasks. BP assessments were done at baseline, post-intervention, 1 month, and 3 month follow-up. Change in several self-report measures was determined. Results showed that beta blocker was more effective in lowering BP than placebo, but relaxation was not more effective in lowering BP than health education. The combined effect of beta blocker and relaxation was not superior to beta blocker alone. Compliance with relaxation practice was not superior to compliance with medication. We conclude that pharmacologic treatment is superior to the relaxation therapy tested.     

Significance of DopEcR,a G-protein coupled dopamine/ecdysteroid receptor,in physiological and behavioral response to stressors

Abstract

Organisms respond to various environmental stressors by modulating physiology and behavior to maintain homeostasis. Steroids and catecholamines are involved in the highly conserved signaling pathways crucial for mounting molecular and cellular events that ensure immediate or long-term survival under stress conditions. The insect dopamine/ecdysteroid receptor (DopEcR) is a dual G-protein coupled receptor for the catecholamine dopamine and the steroid hormone ecdysone. DopEcR acts in a ligand-dependent manner, mediating dopaminergic signaling and unconventional “nongenomic” ecdysteroid actions through various intracellular signaling pathways. This unique feature of DopEcR raises the interesting possibility that DopEcR may serve as an integrative hub for complex molecular cascades activated under stress conditions. Here, we review previously published studies of Drosophila DopEcR in the context of stress response and also present newly discovered DopEcR loss-of-function phenotypes under different stress conditions. These findings provide corroborating evidence that DopEcR plays vital roles in responses to various stressors, including heat, starvation, alcohol, courtship rejection, and repeated neuronal stimulation in Drosophila. We further discuss what is known about DopEcR in other insects and DopEcR orthologs in mammals, implicating their roles in stress responses. Overall, this review highlights the importance of dual GPCRs for catecholamines and steroids in modulating physiology and behavior under stress conditions. Further multidisciplinary studies of Drosophila DopEcR will contribute to our basic understanding of the functional roles and underlying mechanisms of this class of GPCRs.     

IL-1 receptors mediate persistent, but not acute, airway hyperreactivity to ozone in guinea pigs

Ozone exposure in the lab and environment causes airway hyperreactivity lasting at least 3 days in humans and animals. In guinea pigs 1 day after ozone exposure, airway hyperreactivity is mediated by eosinophils that block neuronal M(2) muscarinic receptor function, thus increasing acetylcholine release from airway parasympathetic nerves. However, mechanisms of ozone-induced airway hyperreactivity change over time, so that depleting eosinophils 3 days after ozone makes airway hyperreactivity worse rather than better. Ozone exposure increases IL-1beta in bone marrow, which may contribute to acute and chronic airway hyperreactivity. To test whether IL-1beta mediates ozone-induced airway hyperreactivity 1 and 3 days after ozone exposure, guinea pigs were pretreated with an IL-1 receptor antagonist (anakinra, 30 mg/kg, intraperitoneally) 30 minutes before exposure to filtered air or to ozone (2 ppm, 4 h). One or three days after exposure, airway reactivity was measured in anesthetized guinea pigs. The IL-1 receptor antagonist prevented ozone-induced airway hyperreactivity 3 days, but not 1 day, after ozone exposure. Ozone-induced airway hyperreactivity was vagally mediated, since bronchoconstriction induced by intravenous acetylcholine was not changed by ozone. The IL-1 receptor antagonist selectively prevented ozone-induced reduction of eosinophils around nerves and prevented ozone-induced deposition of extracellular eosinophil major basic protein in airways. These data demonstrate that IL-1 mediates ozone-induced airway hyperreactivity at 3 days, but not 1 day, after ozone exposure. Furthermore, preventing hyperreactivity was accompanied by decreased eosinophil major basic protein deposition within the lung, suggesting that IL-1 affects eosinophil activation 3 days after ozone exposure.     

A twin study of psychomotor and physiological responses to an acute dose of alcohol

A battery of psychomotor tasks and physiological measures was administered to 206 pairs of twins before alcohol and then three times at hourly intervals after they ingested a standard dose of ethanol (0.75 g/kg body weight). Repeat measurements were obtained for 41 of these pairs on a second occasion. Performance on motor coordination, standing steadiness, pursuit rotor, arithmetic computation, and reaction-time tasks deteriorated after alcohol, but decrements on the five tasks were generally independent of each other. Measurements of blood pressure, pulse rate, and skin temperature were all elevated following alcohol intake, but these responses were also uncorrelated. The variance in many of these measures increased after alcohol. An analysis of covariance structure revealed that most of this additional variance exposed by alcohol was genetic in origin, particularly for standing steadiness, pursuit rotor, arithmetic computation, and pulse rate. Up to 50% of the variance in body sway after alcohol was estimated to be due to genetic factors expressed only under the influence of alcohol. Although significant correlations were found with blood alcohol concentration, previous drinking experience, and the personality trait Extraversion, little of the genetic variance exposed by alcohol could be explained by these predictors. It is concluded that the sources of the considerable genetic variation affecting performance under alcohol must be sought elsewhere.This work was supported by the Australian Associated Brewers.     

Feline immunodeficiency virus predisposes cats to acute generalized toxoplasmosis.

This study was designed to examine the effects of a pre-existing, clinically asymptomatic feline immunodeficiency virus (FIV) infection on a primary challenge with Toxoplasma gondii. Parenteral challenge of FIV-infected cats with tachyzoites of the ME49 strain of T. gondii caused a precipitous drop in all lymphocytes (CD4+, CD8+, and B cells) and generalized severe toxoplasmosis. The predominant postmortem lesions included acute and often fatal interstitial pneumonia, dominated histologically by macrophages, and multifocal to coalescing hepatic necrosis. Immunohistochemistry revealed numerous T. gondii antigen and tachyzoites in macrophages and other cell types in the lung lesions. The proliferative response of peripheral blood mononuclear cells to specific (T. gondii antigen) and nonspecific (Concanavalin A) mitogens was defective in the dually infected cats, suggesting marked immunosuppression. In contrast to the dually infected cats, cats infected only with T. gondii developed a transient, mild clinical disease characterized by anorexia, lethargy, and multifocal chorioretinitis. Lymphocyte changes in T. gondii-infected cats included an early pan-lymphopenia followed by reestablishment of all lymphocyte subset profiles. These cats also showed a reduced proliferative response to Concanavalin A at 1 week after challenge, but a measurable in vivo response to T. gondii antigens, as evidenced by in vitro lymphocyte proliferation in the absence of a mitogenic stimulus. These results show that infection of cats with FIV-NCSU, markedly enhances their susceptibility to a primary T. gondii infection and provides a model to study the mechanisms of the underlying immunological defect(s) occurring early after HIV infection that may predispose individuals to development of acquired immunodeficiency syndrome and associated diseases.     

Social stressors,mental health,and physiological stress in an urban elite of young Afghans in Kabul

Afghanistan provides a unique setting in which to appraise psychosocial stress, given the context of persistent insecurity and widening economic inequality. In Kabul, people experience widespread frustrations, hinging on restricted opportunities for social advancement, education, and employment. We appraised social aspirations, every‐day stressors, psychosocial distress, and mental health problems for a random sample of 161 male and female students at Kabul University. The survey featured both existing and newly‐developed instruments (Self‐Reported Questionnaire SRQ‐20; Afghan Symptom Checklist; Afghan Daily Stressor Scale; and Social Aspirations and Frustrations), implementing both internationally‐used and culturally‐grounded measures of mental health assessment. We also included indicators of physical health (blood pressure, immune responses to Epstein‐Barr virus (EBV), C‐reactive protein, and body mass index), to map physiological function with reported psychosocial distress. This young, urban elite expressed major feelings of frustrations, related to physical, economic, social, and political stressors of day‐to‐day life in Kabul. There were striking gender differences for psychosocial and physiological markers of wellbeing; specifically, women showed poorer mental health (SRQ‐20, P = 0.01) and elevated EBV antibody titers (P = 0.003). Both diastolic blood pressure (P = 0.018) and EBV (P = 0.038) were associated with a subscale of family stressors among women, but not among men, consistent with women's social vulnerabilities to stressful family dynamics. This is the first study to integrate approaches from anthropology, cross‐cultural psychiatry, and human biology to document social stressors, psychosocial distress, and physiological wellbeing in the challenging setting of present‐day Afghanistan. Am. J.Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.     

Induction of hyperreactivity to endotoxin in mice by Coxiella burnetii

Intraperitoneal inoculation of mice with live or killed Coxiella burnetii phase I or phase II cells induced a marked hyperreactivity to the lethal effect of bacterial endotoxin and was accompanied by a marked hepatosplenomegaly. The degree and duration of hyperreactivity depended on the dose of C. burnetii administered and were higher with phase I than with phase II cells. Sensitization to the lethal effects of endotoxin and induction of splenomegaly by phase I C. burnetii cells also proceeded in the endotoxin-resistant C3H/HeJ strain of mice. Preincubation of C. burnetii cells with the corresponding immune serum significantly diminished the ability of phase I but not phase II cells to induce hyperreactivity to endotoxin.