Coping and immunosuppression: inescapable but not escapable shock suppresses lymphocyte proliferation

Neuropeptides: conductors of the immune orchestra

There is increasing evidence for a bidirectional communications system between the immune system and the brain. Many of the substances involved in this communication appear to be neuropeptides. These findings have given biochemical validity to the clinical and epidemiological studies that have suggested that psychosocial factors can modulate the response to infections and neoplasms.

Explanatory style and illness

Explanatory style is an individual difference that influences people's response to bad events. The present article discusses the possibility that a pessimistic explanatory style makes illness more likely. Several studies suggest that people who offer internal, stable, and global explanations for bad events are at increased risk for morbidity and mortality. We tentatively conclude that passivity, pessimism, and low morale foreshadow disease and death, although the process by which this occurs is unclear.

Wellness health care and the architectural environment

The stress management-wellness health care environment is emerging as a distinct facility type in the 1980s. Yet the idea is not a new one, with roots based in the Greek Asklepieon dating from 480 B.C. This and later Western transformations for health promotion embraced the therapeutic amenity inherent in meditation, solace and communality with nature based on the premise that the need for refuge from the stress inherent in one's daily life is deep-rooted in humans. A two-phase study is reported on wellness health care provider priorities, relative to the architectural features of stress-wellness centers. Representatives of 11 health care organizations responded to a telephone survey questionnaire, and 128 respondents completed a user needs questionnaire. Four major issues were addressed: image and appearance, location and setting, services provided and costs, and patterns of use. Convenience to one's place of work, a balanced mixture of clinical and nonclinical programs, a noninstitutional retreat-like environment, and membership cost structures were found to be major user considerations with respect to planning and design concepts for wellness health care environments. Directions for further research are discussed.

A benzodiazepine receptor inverse agonist inhibits stress-induced ulcer formation

The effects of a benzodiazepine receptor inverse agonist (FG 7142) on gastric ulcer formation were studied in restrained rats. FG 7142 (10-50 mg/kg) reduced in a dose-dependent fashion both the number and cumulative length of gastric ulcers elicited by restraint for 2 hr at 4 degrees C, but did not affect ulcer formation in unrestrained animals maintained in this environment. FG 7142 also reduced gastric ulcer formation in restrained rats maintained at 22 degrees C for 5 hr. The ability of FG 7142 to reduce restraint-stress induced gastric ulcer formation was blocked by the benzodiazepine receptor antagonist ZK 93426 and the beta-adrenoceptor antagonist propranolol. These findings suggest that FG 7142 produces a benzodiazepine-receptor mediated reduction in gastric ulcer formation, which may result from its ability to increase activity of the sympathetic nervous system.

Effect of diazepam on brain neurotransmitters, plasma corticosterone, and the immune system of stressed rats

Rats were treated with injections of diazepam (1 or 10 mg/kg) and stressed by restraint lasting 3 hours. This was performed once or, in animals immunized with sheep erythrocytes, repeatedly for 4 consecutive days. After repeated stress and/or diazepam treatment, the levels of brain noradrenalin decreased in all treated groups. Although both treatments (stress and diazepam) diminished the 5-hydroxytryptamine (5-HT)/5-hydroxyindoleacetic acid (5-HIAA) ratio, treatment with either dose of diazepam prevented the stress-induced fall of this ratio. The activity of hypothalamic glutamate decarboxylase, the enzyme taking part in GABA synthesis, was affected neither by the acute nor by repeated stress and/or diazepam treatment. The levels of plasma corticosterone were enhanced in all stressed rats, with and without drug. This finding was in accordance with the enhanced weights of adrenal glands in repeatedly stressed rats. The tendency to a corticosterone rise after repeated treatment with diazepam, 10 mg/kg, coincided with the enhanced weights of adrenal glands in these animals. The plaque-forming cell (PFC) response was reduced in all stressed animals and in animals treated with diazepam, 10 mg/kg. Accordingly, high doses of diazepam given repeatedly to rats are immunosuppressive, achieving this effect presumably by an enhancement of glucocorticoid secretion. Neither the low nor the high doses of diazepam affect the stress-induced enhancement of hypothalamohypophysial-adrenal axis activity and consecutive immunosuppression.

Modulation of the immune response by emotional stress

The influence of mild, emotional stress was investigated for its effect on the immune system by subjecting rats to the one-trial-learning passive avoidance test. The reactivity of the immune system was tested by determining the proliferative response after mitogenic stimulation in vitro as well as the capacity to generate a primary antibody response in vivo after immunization with sheep red blood cells. Our results demonstrate that exposure of rats to a single electric footshock (learning trial) or habituation to the passive avoidance apparatus, induces an increase of the immune response in vitro and in vivo. Thus, emotional stimuli seem to facilitate immunological responsiveness. However, when the animal is confronted with a conflict situation, as tested by the retention of the avoidance response after a single learning trial, the initially enhanced reactivity of the immune system decreases. It is concluded that the immune system is capable of reacting specifically and immediately to distinct psychological stimuli.

Aging and health: effects of the sense of control

The relation between health and a sense of control may grow stronger in old age. This could occur through three types of processes: experiences particularly relevant to control may increase markedly in old age; the association between control and some aspect of health may be altered by age; and age may influence the association between control and health-related behaviors or the seeking of medical care. Studies show that there are detrimental effects on the health of older people when their control of their activities is restricted; in contrast, interventions that enhance options for control by nursing home patients promote health. With increasing age, however, variability in preferred amounts of control also increases, and sometimes greater control over activities, circumstances, or health has negative consequences including stress, worry, and self-blame. Mechanisms mediating the control-health relation include feelings of stress, symptom labeling, changes in the neuroendocrine and immune systems, and behavior relevant to health maintenance.

Impairment of immune function after cessation of long-term chronic stress

A pronounced impairment of mitogen-induced proliferation of splenic lymphocytes was observed in Fischer-344 male rats 1 month after termination of exposure of the animals to stress. The stress model used in these experiments was random schedules of a signaled, escapable electric foot-shock stress for 2-4 h/day over a period of 6 months. The magnitude of the observed immunosuppression correlated positively with the total, cumulative stress exposure received by the animals. The effect was not secondary to changes in the percentage of splenic T lymphocytes in stressed, compared to control rats. Also, at the time of sacrifice, plasma levels of corticosterone were comparable in experimental and control animals. Therefore, the immunosuppression observed 1 month after the last stress session cannot be attributed to pituitary-adrenocortical hyperactivity, at the time of sacrifice. These results provide the first evidence that stress-induced immunosuppression is not restricted to the period of exposure to the stress. This finding may contribute to a better understanding of the suggested association between stressful life events and increased susceptibility to disease in humans.

Psychotherapy research: physiological measures and intrapsychic events

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Effect of 7,12-dimethylbenz[a]anthracene-induced mammary carcinogenesis on the opioid peptide levels in the rat central nervous system

Mammary tumors were induced in female Sprague-Dawley rats by giving a single oral dose of 20 mg 7,12-dimethylbenz[a]anthracene (DMBA). Animals were killed after full development of tumors 4 months after the ingestion of DMBA. Opioid peptides in various tissues were estimated by radioimmunoassay (RIA). Tumor-bearing rats (n = 5) had higher (P less than 0.05) contents of beta-endorphin in pituitary (+60%), striatum (+52%) and midbrain (+85%) compared to animals with no tumors. However, tumor-bearing rats showed a decrease of 35% in striatal met-enkephalin content. Dynorphin level decreased (P less than 0.05) in pituitary (-49%) and hypothalamus (-29%) of tumor-bearing rats. Thus for the first time, we report the alteration in the level of these neuropeptides during the process of chemical carcinogenesis.

Modification of the antitumor action of Corynebacterium parvum by stress

Social grouping and isolation of mice, in the presence of an acute stressor, were found to differentially affect the antitumor action of the immunological adjuvant Corynebacterium parvum. Socially grouped DBA/2j mice were injected intradermally with P815 mastocytoma ascites cells. Half the mice had a threshold dose of C. parvum admixed with the P815 cells. Half the mice in each of those conditions were given acute, inescapable electric footshock. In a second experiment, the stressed mice were socially isolated prior to the acute stress. Tumor growth itself was not affected by the stress procedures. C. parvum inhibited tumor growth in non-stressed and socially isolated, stressed mice. However, social grouping selectively negated the C. parvum effect resulting in tumor growth and mortality equivalent to mice not given the adjuvant. Psychological factors may be important to the development of concomitant immunity and the efficacy of immunotherapies.

Modulation of human T-cell suppressor activity by beta endorphin and glycyl-L-glutamine

beta-endorphin (10(-7) M) induced suppressor cell activity in human peripheral blood lymphocyte cultures comparable to that of concanavalin A (Con A) (60 micrograms/ml). beta-endorphin and Con A, when used together during the induction portion of the suppressor assays, displayed synergistic activity. In contrast, glycyl-L-glutamine, the carboxy terminal dipeptide of beta-endorphin, inhibited development of Con A induced suppressor activity. It appears that the previously reported suppressive effects of beta-endorphin on immune function may be achieved by activation of specific suppressor T cell populations.

Changes in brain serotonin levels affect leukocytes, lymphocytes, T-cell subpopulations and natural killer cell activity in rats

The intraventricular injection of 5,6-dihydroxytryptamine into desipramine-treated rats caused a marked reduction in serotonin levels 5 and 10 days after treatment without significantly affecting catecholamine levels. In these animals, total leukocytes were increased and lymphocytes decreased. The number of helper T-cells (W3/25+) was significantly decreased after 5 days, whereas the numbers of total T-cells (W3/13+) and suppressor T-cells (MRC OX8) were increased after 10 days. The percentages of total T-cells, helper T-cells and suppressor T-cells were significantly reduced after 5 days. Natural killer cell (NK) activity was markedly reduced after 5 days. This finding suggests that central serotonin-containing neurons might be involved in the regulation of certain parts of the peripheral immune system.

Distress and DNA repair in human lymphocytes

This research assessed differences in DNA repair in lymphocytes from high- and low-distressed individuals. A median split on Minnesota Multiphasic Personality Inventory (MMPI) Scale 2 divided 28 newly admitted nonpsychotic psychiatric inpatients into high- and low-distress subgroups. The high-distress subgroup had significantly poorer DNA repair in lymphocytes exposed to X-irradiation than low-distress subjects. We also found that lymphocytes obtained from this psychiatric sample had significantly poorer DNA repair than lymphocytes from nonpsychiatric control subjects when compared 5 hr after X-irradiation. A high level of distress therefore appears to be associated with significant dysfunctional differences at the molecular level which may have important implications for health. These data provide evidence for a direct pathway through which distress could influence the incidence of cancer.

Involvement of peripheral and central catecholamine systems in neural-immune interactions

In this review, we have attempted to delineate the current state of knowledge of the relationships between the immune system and one chemically specific component of the nervous system, the noradrenergic system, both in the brain and the periphery. We have discussed recent work describing the presence of noradrenergic innervation in lymphoid tissues in the major lymphatic organs. Our findings demonstrate clearly that the regions in which lymphocytes (mainly T cells) reside, and through which they recirculate, receive direct sympathetic neural input. The immune system can, therefore, be considered 'hard-wired' to the brain. The evidence for receptors on cells of the immune system capable of receiving signals from the brain is discussed. The significance of this 'hard-wiring' to the function of the immune system is considered, both with regard to the effect of its disruption on immune responses, and to the direct and indirect effects of sympathetic neurotransmitter substances on lymphocytes and their behavior in vitro and in vivo. Finally, our detailed analysis of changes occurring in central noradrenergic pathways as a result of stimulation of the immune system leads to an emerging picture of feedback loops from the immune system to the brain. Such circuits employ endocrine, and probably autonomic, outflow to modulate and regulate immune responses.

Neuroimmunomodulatory interactions of norepinephrine and serotonin

Monoamine neuroleptics alter rodents responses to immunization, suggesting that norepinephrine (NE) and serotonin (5HT) are neuroimmunomodulatory in these animals. Although endocrine factors participate in their mechanism(s) of action, recent studies suggest that NE and 5HT also interact more directly with immunocompetent cells. This review provides an overview of evidence for a direct regulatory link between the nervous and immune systems and further speculates on the process by which NE and 5HT realize in part, their neuroimmunomodulatory potential. Anatomical data show that noradrenergic fibers of the sympathetic nervous system innervate lymphoid organs providing a channel of communication between neurons and lymphocytes. Presumably neural signals transmitted by NE are received by platelets that in turn, transduce them via 5HT into immunomodulatory messages. It is proposed that NE alters the capacity of platelets to sequester and/or catabolize 5HT, thus regulating its physiologically active pool in the plasma. Macrophages possess a 5HT uptake system, the kinetic properties of which make them sensitive to changes in plasma levels of the amine. Thus, through its ability to regulate plasma levels of 5HT, an immunosuppressive amine with access to macrophages, the nervous system can influence cells involved in antigen recognition. Support for this hypothetical immunomodulatory mechanism is gleaned from clinical and experimental studies. For example, individuals suffering emotional trauma are more susceptible than others to developing physical illness. It is of interest that platelet 5HT pharmacodynamics are often abnormal in patients with psychological disorders characterized by catecholamine deficits. Similar platelet changes have been achieved experimentally by treating rats with catecholamine antimetabolites. Additional support for the hypothesis derives from aging research since 'monoamine imbalance' and immune dysfunction are co-characteristics of senescence. In aging rodents and humans, central catecholamine deficits are associated with a decreased platelet affinity for 5HT and an increased plasma content of 5HT. Thus, emotional, spontaneous (age-related), or experimental changes in monoamine homeostasis have the potential to increase the risk of disease in affected individuals. Perhaps part of this effect results from endocrine perturbations associated with the trauma. However, a direct interaction between the nervous and immune systems involving monoamines is also possible, and a need for future study of this potentially significant mechanism for neuroimmunomodulation is indicated.

Coping and seizure susceptibility: control over shock protects against bicuculline-induced seizures

Rats were either given 80 escapable shocks, yoked inescapable shocks, restraint or given no treatment. Two hours later all subjects received i.p. injection of bicuculline (4, 6 or 8 mg/kg) and were immediately tested for latency to initial myoclonic jerk and clonus. The latency to clonic convulsion was dramatically affected by prior shock treatment, and the direction of this change depended upon the escapability/inescapability of the shock. Subjects that were given escapable shock showed a delay of onset to seizure, while subjects inescapably shocked demonstrated a decreased latency to clonus in comparison to restrained and naive controls. It was also demonstrated that if the subjects were tested immediately following a stress experience, both the 80 escapable and inescapable shock condition protected against bicuculline-induced seizures in comparison to the control condition. Finally Experiment 2 confirmed a previous finding that less stress, i.e., 20 inescapable shocks, protects against seizures when the animals are challenged with bicuculline either immediately or 2 h later. Our suggestion is that control over stress may facilitate GABAergic transmission, and this may be the mechanism whereby coping protects against the behavioral and physiological disruption produced by exposure to a stressor.

Stress, loneliness, and changes in herpesvirus latency

This study used a prospective design to examine the influence of examination stress and loneliness on herpesvirus latency as measured by changes in antibody levels to three herpesviruses, Epstein-Barr virus (EBV), Herpes simplex type I (HSV-1), and cytomegalovirus (CMV). Three blood samples were obtained from 49 first-year medical students, with the first sample drawn 1 month before final examinations, the second on the first day of final examinations, and the third during the first week after their return from summer vacation. A median split on the UCLA Loneliness Scale divided subjects into high- and low-scoring loneliness groups. There were significant changes in the antibody titers to all three herpesviruses across the sample points, with the lowest levels found in the third (low stress) sample. High-loneliness subjects had significantly higher EBV antibody titers than low-loneliness subjects. These data suggest that stress-related immunosuppression can significantly modulate herpesvirus latency.

Psychic distress and the immune response

This minireview surveys recent progress in the field of immunoregulation by the central nervous system. Representative findings from human and animal studies show evidence for significant immunosuppression in states of psychic distress. Mechanisms of immunomodulation are discussed in light of data implicating neuroendocrine, genetic, neuroanatomical, and learning factors. Evidence for reciprocal modulation of immune and nervous systems is considered. A simple hierarchical model proposes traits that are acted on by environment and experience to produce chronic states of mental health vs. psychic distress; these states determine baseline immunocompetence and response to afferent signals during acute immune challenge. Multidisciplinary interest in psychoneuroimmunology has accelerated the rate of inquiry into the mechanistic details of immunoregulation and has generated new appreciation for the pervasive effects of mental status on physiologic homeostasis.