摘要:

Physiological and morphological parameters of optic nerve lesions followed by functional recovery are discussed in detail. To study functional and/or morphological recovery processes, a recently developed model of the ‘graded optic nerve crush’ is compared with other models of lesioning. It is concluded that the optic nerve crush model is a valuable tool when studying brain repair mechanisms. First results show that functional recovery depends on the initial preservation of a sufficiently large population of ganglion cells in the retina. It takes place despite the progressive loss of retinal ganglion cells during the recovery per

ISSN:0302-282X    

DOI:10.1159/000119001

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The stress response should be regarded as an alarm system, occurring whenever there is something missing. Lack of information (uncertainty), and the absence or loss of control produce alarm, presence of information and control (coping), or cognitive defence mechanisms (distorted stimulus expectancies) reduce the alarm. Both immune and endocrine parameters of stress are dampened by defence and coping. Biologically, these two mechanisms have different time axes. While coping is related to the fast catecholamine response, defence is related to the slower pituitary-adrenal response. The role of cortisol seems to be to suppress and dampen the acute stress response in the later phase, once it has been elicited. The relation between stress and health depends on the stress-dampening mechanisms, on how the alarm is turned off, why it sometimes seems to be left on, and what the consequences really are of leaving the alarm on.

ISSN:0302-282X    

DOI:10.1159/000119002

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The aim of the present experiment is to evaluate heart rate variability (HRV) and cortisol as indices of mental workload in a complex environment. Heart rate was continuously recorded during flight scenarios that differed in difficulty. The HRV nicely reflected the changes in difficulty. The results support the idea that HRV is a sensitive index for mental workload when tasks are highly demanding and subjects are motivated to exert additional effort whenever the task becomes more demanding. Cortisol was only slightly increased on the experimental day compared to the training day. On the experimental day, post-task levels did not differ from pre-task levels. The level of cortisol in saliva was, however, related to overall task performance. Subjects who had a high level of cortisol had a low level of performance.

ISSN:0302-282X    

DOI:10.1159/000119003

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

This paper describes a protocol for induction of moderate psychological stress in a laboratory setting and evaluates its effects on physiological responses. The ‘Trier Social Stress Test’ (TSST) mainly consists of an anticipation period (10 min) and a test period (10 min) in which the subjects have to deliver a free speech and perform mental arithmetic in front of an audience. In six independent studies this protocol has been found to induce considerable changes in the concentration of ACTH, cortisol (serum and saliva), GH, prolactin as well as significant increases in heart rate. As for salivary cortisol levels, the TSST reliably led to 2- to 4-fold elevations above baseline with similar peak cortisol concentrations. Studies are summarized in which TSST-induced cortisol increases elucidated some of the multiple variables contributing to the interindividual variation in adrenocortical stress responses. The results suggest that gender, genetics and nicotine consumption can influence the individual’s stress responsiveness to psychological stress while personality traits showed no correlation with cortisol responses to TSST stimulation. From these data we conclude that the TSST can serve as a tool for psychobiological res

ISSN:0302-282X    

DOI:10.1159/000119004

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

In a placebo-controlled double-blind study described by Rammsayer and co-workers in this volume, we investigated the influence of decreased body core temperature (BCT) on responses of cortisol and the immune system. As described in the first paper, the decrease in BCT was achieved by: (a) exposure to ambient cold temperature of 5 °C for 20 min (CT group), or (b) application of a 5HT-1a agonist under normal temperature conditions (5HT group). A third group serving as control was exposed to normal temperature and placebo (NT group). The decrease of BCT seen in both CT and 5HT was accompanied by an increase in cortisol. This seemed to be due to stress experience in the CT group and to the pharmacological challenge in the 5HT group. The number of peripheral CD4+ cells was reduced in both experimental groups. This was not mediated by decreased BCT. In the CT group the reduction of CD4+ cells showed no relationship to changes in cortisol. However, in the 5HT group cortisol could be demonstrated to be the mediator of changes in peripheral CD4+ cells

ISSN:0302-282X    

DOI:10.1159/000119005

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Emotional stress is often followed by increased susceptibility to infections. Natural killer (NK) cells play a major role in the immediate immune response controlling this susceptibility. In this study on 45 first-time parachutists, it is demonstrated that highly controlled psychological stress increased psychophysiological variables, enhanced the secretion of sympathetic-adrenal hormones and also led to a significant increase of NK cells and their cytotoxic activity followed by a decrease below starting values. This immunological alteration is correlated with the secretion of noradrenaline during the emotional strain. Quick mobilization of these cytotoxic effector cells is suggested as a major mechanism for the effective adaptation of the immune system to stress situations.

ISSN:0302-282X    

DOI:10.1159/000119006

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

The effect of immobilization and light-dark cycle on the serotoninergic system of the n. raphe dorsalis and on the distribution of blood lymphocyte subpopulations was studied in the rat. As was shown by in vivo voltammetry, 10 min immobilization enhanced serotonin metabolism with a maximum 15 min after immobilization. The distribution of the blood lymphocytes into subpopulations was also affected: pan-T and T helper lymphocytes were reduced during immobilization and reached minimum values after 20 min recovery. The circadian rhythms of serotonin metabolism and the distribution of pan-T and T helper cells exhibited a slight phase shift if compared with each other.

ISSN:0302-282X    

DOI:10.1159/000119007

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Social interactions as a consequence of the social position represent stressful conditions for the individual. Manipulation of social conditions or forming long-term social hierarchies by colony aggregation allow to investigate the regulation of immune defense mechanisms under seminatural circumstances. The present paper describes the effects of dyadic social interaction in male rats with or without direct aggressive interactions on some indices of humoral and cellular immunity. In addition, for comparative and reference purposes, in one experiment the conventional stressor of inescapable footshock was used as well. Primary humoral immune response to sheep red blood cell antigen is suppressed by repeated experience of both defeat and inescapable footshock. At individual level the social stressor is as effective as the conventional stressor of inescapable footshock, less individual rats show suppression following the social than after the conventional stress. The social stressors, i.e. being exposed to a resident or intruder of the territory, facilitate lymphocyte proliferation in the spleen by the mitogen ConA and PHA independently of the presence or absence of direct aggressive interaction. Finally, the different social stressors have some impact on the lymphocyte subpopulation in the spleen. Social stimulation without aggressive interactions increases the relative number of Thelper cells, whereas defeat leads to an increase in the Tsuppressor/cytotoxic subpopulation. The data suggest multiple and differential effects of social stress on immune system functioning in the rat. Individual characteristics of the coping with stress, the social environment, and the immune indices under investigation determine the magnitude and direction of the changes in immune functioning.

ISSN:0302-282X    

DOI:10.1159/000119008

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

An overview of the most important features of the two distinct types of individuals which normally co-occur in an unselected population of Wistar rats is given. It reveals that the overall make-up and reactivity of the brain, as well as the endocrinological and immunological systems differ completely between the two types of individuals. Each of these types of individuals has its own individual-specific hardware and software to cope with challenges from the internal or external environment, requires its own optimal niche, and is vulnerable for its own set of stressors.

ISSN:0302-282X    

DOI:10.1159/000119009

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Fever is induced by interactions of bacterial pyrogens with cells from the immune system, which subsequently release a cascade of cytokines. After intramuscular injection of lipopolysaccharide (LPS) from E. coli, increased amounts of tumor necrosis factor (TNF) and interleukin-6 (IL-6) can be measured in blood plasma and in perfusates of the anterior hypothalamus, where body temperature is regulated. These substances are therefore candidates to be involved in the modification of thermoregulatory structures leading to the febrile rise in body temperature. This increase of body temperature is limited and sometimes even prevented by the actions of endogenous antipyretic neuropeptides like arginine vasopressin (AVP), adrenocorticotropin (ACTH) and melanocyte-stimulating hormones (MSHs) liberated within the brain or systemically during fever. For AVP, most experimental evidence confirms antipyretic pathways from the hypothalamic paraventricular nucleus to the septal area of the limbic system, which are activated during fever and by several stressful stimuli. Fever and endogenous antipyresis are interconnected and result from interactions between the immune system and the central nervous system.

ISSN:0302-282X    

DOI:10.1159/000119010

出版商:S. Karger AG    

年代:1993

数据来源: Karger