Nociceptin/orphanin FQ prevents gastric damage induced by cold-restraint stress in the rat by acting in the periphery

The influence of peripheral nociceptin/orphanin FQ (N/OFQ) on cold restraint-induced gastric mucosal damage in the rat was investigated. Exposure to cold-restraint for 3 and 4h caused the formation of hemorrhagic lesions in the glandular portion of the stomach. N/OFQ dose-dependently decreased lesion formation, in the range 0.03-1 microg/kg/h i.p. Its effect was reversed by the selective NOP receptor antagonist [Nphe(1)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-101), 30 microg/kg/h ip. The selective NOP receptor agonist [(pF)Phe(4)Aib(7)Arg(14)Lys(15)]N/OFQ-NH(2) (UFP-112), 0.01-0.3 microg/kg/h i.p., similarly reduced lesion formation. Light and scanning electron microscopy confirmed the protective activity of N/OFQ. Cold-restraint stress causes a reduction in mucus content and in adhering mucus layer, partly counteracted by N/OFQ. These results suggest that N/OFQ counteracts acute stress-induced gastric mucosal damage by interacting with NOP receptor and by influencing mucous cell activity.

[TREK-1: a potential target for novel antidepressants]

The neurotransmitter serotonin (5-HT: 5-hydroxytryptamin) was suggested to be involved in the pathogenesis of depression as well as in the mechanisms of antidepressant treatments. However, the molecular mechanisms underlying the pathophysiology or treatment of depression are still poorly understood. A recent paper has shown that deletion of the two-pore domain potassium channel TREK-1 results in an antidepressant-like phenotype. TREK-1 -deficient mice behave as if they have been treated with an antidepressant drug, such as fluoxetine. Moreover, TREK-1-deficient mice showed a reduced elevation of corticosterone level under stress, an increased efficacy of 5-HT neurotransmission and an increased fluoxetine-induced neurogenesis in the hippocampus. Selective serotonin reuptake inhibitors (SSRIs) inhibited not only the 5-HT transporter but also the TREK-1 channel. In this article, we review the molecular and functional properties of the TREK-1 channel, which is a potential target for novel antidepressants.

Adaptation in the corticosterone and hyperthermic responses to stress following repeated stressor exposure

Previous studies have shown that repeated daily exposure to the same (homotypic) stressor results in habituation of the corticosterone (CORT) response. Others have found that the stress response to a more ethologically relevant stressor, social defeat, does not habituate and, in some cases, sensitisation has been observed. Similar observations have been noted when core temperature is examined. Although habituation and/or sensitisation have been reported during stressor exposure, little is known about the development of an anticipatory fever in response to daily stressor exposure. The aim of the present study was to compare systematically commonly used laboratory stressors (i.e. restraint, cage confinement and social defeat) using a common set of procedures and analyses. Specifically, we examined: (i) the development of an anticipatory fever to repeated (5 days) homotypic stressor exposure; (ii) the adaptation of the fever response during stressor exposure; and (iii) the resolution of the fever response to stressors presented at the same time each day. For comparison, adaptation of the CORT response was also examined to assess the degree to which habituation to repeated stressor exposure may represent a more general response observed across diverse physiological measures. Habituation was observed after restraint and cage confinement, but not observed in either the CORT or hyperthermic responses to repeated social defeat. Furthermore, no anticipatory fever response was observed with repeated exposure to restraint, cage confinement, or social defeat. These data suggest that habituation to repeated stressor exposure may not occur with all homotypic stressor paradigms. In addition, rats do not appear to entrain an anticipatory fever response to a stressor presented at the same time each day, at least not within 5-6 days of repeated exposure.

Quetiapine prevents anhedonia induced by acute or chronic stress

The role of atypical antipsychotics as add-on treatments and as primary mood stabilizers in different phases of bipolar disorder is an important current research area. Although in bipolar patients the main therapeutic indication of quetiapine (QTP) is the management of acute mania, several observations suggest that this agent may exert antidepressant as well as antimanic effects. However, in our knowledge, there are no preclinical studies supporting this hypothesis. Thus, the main goal of the present work was to evaluate the putative antidepressant effect of QTP (0.4, 2.0, or 10 mg/kg/day), in comparison to amitriptyline (AMI) (2 or 5 mg/kg/day), in rats exposed to acute or chronic stress. The administration of QTP, 2 mg/kg/day, prevents the onset of anhedonia in rats exposed to a 6-week chronic mild stress (CMS) protocol. The effect of QTP has a slow onset, beginning at week 5, and causes a complete recovery from anhedonia. In this respect, the effect of QTP is similar to that obtained after chronic administration of AMI 2 or 5 mg/kg/day. Our findings also indicate that a 6-week administration of QTP, 2 or 10 mg/kg/day, has protective effects against the onset of anhedonia caused by the exposure to an acute subthreshold stressful event in rats that have previously experienced the CMS procedure. The results suggest that QTP is able to prevent both the transient mood depression caused by acute stress and the long-lasting anhedonic state induced by exposure, over a period of weeks, to a variety of unpredictable mild stressors.

Mice lacking sulfonylurea receptor 2 (SUR2) ATP-sensitive potassium channels are resistant to acute cardiovascular stress

Adenosine triphosphate-sensitive potassium (K(ATP)) channels are thought to mediate the stress response by sensing intracellular ATP concentration. Cardiomyocyte K(ATP) channels are composed of the pore-forming Kir6.2 subunit and the regulatory sulfonylurea receptor 2 (SUR2). We studied the response to acute isoproterenol in SUR2 null mice as a model of acute adrenergic stress and found that the episodic coronary vasospasm observed at baseline in SUR2 null mice was alleviated. Similar results were observed following administration of a nitric oxide donor consistent with a vasodilatory role. Langendorff-perfused hearts were subjected to global ischemia, and hearts from SUR2 null mice exhibited significantly reduced infarct size (54+/-4 versus 30+/-3%) and improved cardiac function compared to control mice. SUR2 null mice have hypertension and develop cardiac hypertrophy. However, despite longstanding hypertension, fibrosis was absent in SUR2 null mice. SUR2 null mice were administered nifedipine to block baseline coronary vasospasm, and hearts from nifedipine-treated SUR2 null mice exhibited increased infarct size compared to untreated SUR2 null mice (42+/-3% versus 54+/-3%). We conclude that conventional sarcolemmal cardiomyocyte K(ATP) channels containing full-length SUR2 are not required for mediating the response to acute cardiovascular stress.

Involvement of sensory afferent fibers and lipid peroxidation in the pathogenesis of stress-induced gastric mucosa damage

Ablation of sensory nerves impairs healing of gastric ulcers, but the role of free radicals in the healing process has been little studied. The aim of our present investigations was to determine the participation of reactive oxygen species (ROS) in sensory nerve activity during WRS. Experiments were carried out on male Wistar rats and the number of gastric lesions was measured by planimetry. Colorimetric assays were used to determine gastric mucosal levels of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), as well as superoxide dismutase (SOD) activity. We found that capsaicin-inactivation of sensory nerves resulted in magnification of gastric mucosal damage induced by the WRS. In this process, oxidative stress occurs, as reflected by an increase of MDA and 4-HNE tissue concentrations (an index of lipid peroxidation), and a decrease of SOD activity, could play an important role. Pentoxyfilline-induced gastroprotection and hyperemia depends upon attenuation of the oxidative stress. This protection and hyperemia were, at least in part, attenuated by ASA. Afferent sensory fibers participate in the pathogenesis of ulcers. Lipid peroxidation plays an important role in this process.

No evidence for enhanced noise induced hearing loss after prenatal stress or dexamethasone

It was recently implied that prenatal stress and fetal exposure to glucocorticoids may interfere with hearing ability and noise induced hearing loss in adulthood. In the present study pregnant Wistar rats were stressed during gestation by Chronic Mild Stress (CMS, a variable schedule of different stressors) or by dexamethasone (a synthetic glucocorticoid, i.e. a pharmacological stressor). At birth, but not at weaning, the dexamethasone offspring exhibited significantly decreased body weight compared to both control offspring and progeny from dams exposed to CMS during pregnancy. As adults, male offspring were exposed to 105 dB sound pressure level (SPL) wide band noise either continuously for eight hours or for two hours per day on three consecutive days. Oto-acoustic emissions and auditory brainstem responses were recorded before and after exposure to noise. Neither prenatal chronic stress nor prenatal dexamethasone exposure was associated with significantly enhanced noise induced hearing loss compared to controls, and these results were consistent in both subsets of animals. Our data do not support previous reports that prenatal exposure to mild stress nor to dexamethasone is detrimental to the hearing organ per se. However, hearing may be modulated by prenatal stressors under certain circumstances, of which the timing and degree are probably the most important.

Chronic stress and insulin resistance-related indices of cardiovascular disease risk, part I: neurophysiological responses and pathological sequelae

Cardiovascular disease (CVD) is the leading cause of death and disability in the industrialized world, and the prevalence is increasing rapidly among developing nations. The rising prevalence of CVD worldwide may be attributed in large part to specific atherogenic changes in insulin resistance, adiposity, lipid profiles, and other indices of insulin resistance syndrome (IRS), a cluster of metabolic and hemodynamic abnormalities that are strongly predictive of CVD. A growing body of research suggests that chronic psychosocial stress and related factors significantly contribute to the pathogenesis of IRS-related abnormalities, associated insulin-resistant states, and CVD, in part by promoting dysregulation of the sympathoadrenal system and hypothalamic-pituitary-adrenal axis. In this article, we review the literature supporting the relationships between these factors, outline the neurophysiologic responses to chronic stress, and discuss the pathways by which chronic or recurrent psychosocial stress may lead to a destructive cascade of neuroendocrine, metabolic, inflammatory, and neuropsychological changes that fosters the development of IRS and, ultimately, CVD.

Effect of ovariectomy and female sex hormones administration upon gastric ulceration induced by cold and immobility restraint stress

OBJECTIVE

To investigate the protective effects of estrogen and progesterone administrations on gastric mucosal barrier of rats applied ovariectomy, cold and immobility stress.

METHODS

Seventy female Wistar rats, obtained from Medical Science Application and Research Center, Dicle University, Turkey on the year 2004, were divided into 10 separate groups (n=7). Nothing was applied to the animals of Group 1 (control); bilateral ovariectomy was performed on the animals of the Groups 2, 4, 5, 6, 7, 8, 9, and 10. Groups 5 and 6 was applied 5 mg/kg 17beta-estradiol and groups 7 and 8 was applied 10 mg/kg progesterone for 7 days. The animals in the Groups 9 and 10 were applied 2.5 mg/kg 17beta-estradiol and 5 mg/kg progesterone during 7 days. The animals in the groups 3, 4, 6, 8 and 10 were exposed to cold and immobility stress for 4 hours at 4degrees celsius.

RESULTS

The levels of mucus and phospholipids were decreased in the rats applied ovariectomy and stress as compared to the control groups (p<0.001). The increase determined the mucus and phospholipids levels in estrogen and progesterone administered rats as compared to stress applied group (p<0.001). While the cold and immobility stress causes important damages in gastric mucosa, estrogen and progesterone administrations has protective effects in ovariectomized rats.

CONCLUSION

The estrogen and progesterone administration prevents the stress that caused decrease in the levels of mucus and phospholipids, thus females are more resistant to gastric ulcer rather than males due to their sex hormones.

Foot shock stress prolongs the telogen stage of the spontaneous hair cycle in a non-depilated mouse model

BACKGROUND

There is an increasing evidence to indicate that stress can influence skin disease and cutaneous functions. Previous studies have shown that stress alters the murine hair cycle; however, these studies have been carried out by using mouse models in which the hair cycle is forcibly synchronized after depilation.

OBJECTIVE

To examine whether foot shock stress (FS) changes the spontaneous hair cycle in a non-depilated animal model, and to evaluate the role of mast cells and substance P (SP) in the influence of stress on the hair cycle.

METHODS

Changes in the spontaneous hair cycle and the inhibitory effects of a specific SP NK1 receptor antagonist were examined in non-depilated mice during 3-4 weeks of FS.

RESULTS

Foot shock stress prolonged the telogen stage of the hair cycle and delayed the induction of the subsequent anagen stage in the animal model. FS caused an increase in the ratio of de-granulated mast cells in the skin, an increase in the number of TUNEL-positive cells, and a decrease in the number of Ki67-positive cells. The NK1 receptor antagonist, WIN 62577, inhibited these stress responses.

CONCLUSION

Our results strongly support previous work, demonstrating that stress alters active hair-cycling in vivo through the action of SP.

Stress-related mucosal disease in the intensive care unit: an update on prophylaxis

Gastric ulcers have been known to develop in critically ill patients secondary to physiological stress since the 19th century. It is only relatively recently that stress ulcer prophylaxis has become an established routine practice in the intensive care unit. Numerous terms have been used to describe stress ulcers, but stress-related mucosal disease (SRMD) is commonly used. Significant morbidity and mortality in critically ill patients is caused by SRMD and related bleedings, but the incidence depends on the definition of bleeding. Pathophysiology of SRMD is multifactorial and involves a complex set of interactions that causes a breakdown of mucosal proactive defenses, leading to ulceration. Critically ill patients are at an increased risk for developing SRMD and subsequent bleeding secondary to several risk factors. To minimize stress-related mucosal bleeding, several regimens have been used. This article presents an update on the incidence, pathophysiology, risk factors, and prophylaxis of SRMD.

Cognitive activation theory of stress, sensitization, and common health complaints

According to the cognitive activation theory of stress (CATS), a formal system of systematic definitions, the term "stress" is used for stress stimuli, the stress experience, the nonspecific, general stress response, and the experience of the stress response. The stress response is normal, healthy, and necessary alarm. If sustained there may be a risk of illness and disease. The level and duration of the alarm depend on the expectancy of the outcome of stimuli and the specific responses available for coping. The most common health complaints are subjective health complaints like muscle pain, tiredness and mood changes. These are normal aches of short duration and low intensity for most people. For some the pains and complaints are substantial and longlasting with serious implications for functioning. There are no sharp or obvious limits in the distribution of health complaints, separating "normal" and endurable pain and complaints, and intolerable complaints that need professional help. These conditions are most often unspecific, and are the most common reason for encounters with health professionals, and the most frequent reason for sick leave and disability. There is a striking comorbidity for all these conditions. This may be explained by psychobiological sensitization within neural loops, maintained by sustained activation, which has been suggested as a mechanism for these conditions.

Prevention of gastrointestinal complications in the critically ill patient

Common pathophysiologic changes associated with critical illness directly contribute to the development of gastrointestinal (GI) complications. In addition, supportive interventions such as mechanical ventilation and vasopressors increase the risk of GI complications. Early, specific signs of GI complications are rarely present; therefore, because of late or missed diagnosis, morbidity and mortality related to these complications can be high. This article aims to review the pathophysiology of GI dysfunction and describe an approach to evaluate the abdomen in the critically ill patient. Risk can be limited by understanding individual patient characteristics, thoughtfully evaluating the risk-benefit profile of all interventions, and implementing preventive strategies.

[Gender differences in stress among physicians]

INTRODUCTION

It is difficult to evaluate gender differences in relation to health because occupation and position are different for males and females. It is therefore necessary to evaluate how health is affected for both genders with the same working conditions. The purpose of this study was to evaluate: 1) gender differences in relation to different stressors within daily life, working life and health, 2) how these stressors affect the correlation between stress and gender.

MATERIALS AND METHOD

A questionnaire was sent out in 2001 to a total of 1414 physicians; 707 males and 707 females. The response rate was 58%. Using SPSS, the answers were reviewed by gender differences in relation to selected stressors in daily life, working life and health. Finally, a logistic regression was run where the correlation between gender and stress was controlled for all significant stressors.

RESULTS

It was found that female physicians more often experience stressors in relation to daily life and health while male physicians experience stressors in relation to their working life. It was also shown that female physicians had more than twice the risk of being stressed on a daily basis compared to male physicians, when controlling for cohabitant/spouse working hours, own working hours, conflicting demands at work, the feeling of never having enough time for oneself and depression.

CONCLUSION

Female physicians had more than twice the risk of being stressed on a daily basis compared to their male colleagues, in spite of control for stressors in relation to daily life, working life and health.

[Gender and stress]

Stress is an independent risk factor for developing e.g. heart diseases and depression. There are marked gender differences which need to be examined in depth. Some of the explanation seems to be related to the traditional pattern of gender roles--men as breadwinners and women with responsibility for the family as well as paid work in addition to housework. But gender differences in biological factors also seem to play an important role in chronic stress and stress-related diseases. We need to know more about gender differences, but we can already incorporate the known ones in the prevention of stress-related disorders.

Apical and midventricular transient left ventricular dysfunction syndrome (tako-tsubo cardiomyopathy): frequency, mechanisms, and prognosis

BACKGROUND

The frequency and potential differences between patients with apical ("typical") and midventricular ("atypical") ballooning have not been described.

METHODS

Consecutive patients with the diagnosis of a troponin-positive acute coronary syndrome (ACS) were prospectively included into a registry (n = 3,265). Of those, 2,944 patients underwent left-heart catheterization and form the study population. Demographic, clinical, and angiographic data including assessment of microvascular dysfunction (Thrombolysis in Myocardial Infarction [TIMI] blush grade, corrected TIMI frame count), as well as clinical outcome were assessed in all patients.

RESULTS

In patients with troponin-positive ACS, the frequency of transient cardiomyopathy was 1.2% (35 of 2,944 patients). Typical apical wall motion abnormality was observed in 21 of 35 patients (60%), as compared to an atypical (midventricular) pattern in 14 of 35 patients (40%). Both groups did not differ regarding demographic, clinical, laboratory, or angiographic parameters. Scintigraphy and PET studies were performed in 17 of 35 patients (49%) with transient cardiomyopathy, and showed a strong correlation between location of wall motion abnormality and myocardial metabolism defects, with a significantly higher apical decrease in glucose uptake in patients with a typical pattern.

CONCLUSIONS

Transient cardiomyopathy affects approximately 1% of patients with a troponin-positive ACS. A typical apical wall motion abnormality is seen in only 60% of patients. Transient cardiomyopathy, also termed Tako-Tsubo cardiomyopathy, therefore should no longer be regarded as an exclusively apical ballooning syndrome, but rather a transient left ventricular dysfunction syndrome with an apical or midventricular pattern of wall motion abnormality.

Plasma concentration of selected neuropeptides in patients suffering from psoriasis

The aim of this study was to evaluate plasma levels of substance P (SP), calcitonin gene-related peptide (CGRP), vasoactive intestinal peptide (VIP) and neuropeptide Y (NPY) during psoriasis course.

METHODS

Seventy-three patients with psoriasis and 32 healthy volunteers were included. Detailed demographic and disease anamnesis was obtained from every patient. The disease severity was assessed using the Psoriasis Area and Severity Index score. Plasma levels of SP, CGRP, VIP and NPY were measured radioimmunologically.

RESULTS

Plasma levels of SP and NPY did not significantly differ between patients with psoriasis and controls (median SP: 52.8 and 57.9 pg/ml, respectively; P = 0.32; median NPY: 8.5 and 8.2 pg/ml, respectively; P = 0.67). CGRP plasma concentration was significantly elevated in psoriatic individuals both before (median 43.1 pg/ml) and after treatment (median 45.4 pg/ml), in comparison with healthy donors (median 13.5 pg/ml; P < 0.01 and P = 0.03, respectively). Treatment did not significantly influence plasma CGRP levels (P = 0.3). Median VIP plasma concentration in psoriatics before treatment was significantly higher compared with healthy controls (medians 66.9 and 60.1 pg/ml, respectively; P = 0.04), but the therapy resulted in significant decrease in VIP plasma level (median 19.0 pg/ml; P < 0.001). In psoriatic patients significant correlations were noted between NPY and VIP (R = 0.34; P < 0.01), and VIP and CGRP plasma levels, both before (R = 0.28; P = 0.03) and after the treatment (R = 0.44; P < 0.01).

CONCLUSIONS

Based on our results and previous literature data it could be suggested that neuropeptides may be involved in the development of psoriatic lesions.