Time-dependent effects of peer separation on lymphocyte proliferation responses in juvenile squirrel monkeys

Infant cortisol stress-response is associated with thymic function and vaccine response

Stress can impair T cell-mediated immunity. To determine if infants with high stress responses had deficits in T-cell mediated immunity, we examined the association of pain-induced cortisol responsiveness with thymic function and vaccine responses in infants. This study was performed among 306 (male = 153 and female = 153) participants of a randomized, controlled trial examining the effect of neonatal vitamin A supplementation on immune function in Bangladesh (NCT01583972). Salivary cortisol was measured before and 20 min after a needle stick (vaccination) at 6 weeks of age. The thymic index (TI) was determined by ultrasonography at 1, 6, 10 and 15 weeks. T-cell receptor excision circle and blood T-cell concentrations were measured at 6 and 15 weeks. Responses to Bacillus Calmette-Guérin (BCG), tetanus toxoid, hepatitis B virus and oral poliovirus vaccination were assayed at 6 and 15 weeks. Cortisol responsiveness was negatively associated with TI at all ages (p < .01) in boys only, was negatively associated with naïve helper T-cell concentrations in both sexes at both 6 (p = .0035) and 15 weeks (p = .0083), and was negatively associated with the delayed-type hypersensitivity (DTH) skin test response to BCG vaccination at 15 weeks (p = .034) in both sexes. Infants with a higher cortisol response to pain have differences in the T-cell compartment and a lower DTH response to vaccination. Sex differences in the immune system were seen as early as 6 weeks of age in these healthy infants.

Stress coping stimulates hippocampal neurogenesis in adult monkeys

Coping with intermittent social stress is an essential aspect of living in complex social environments. Coping tends to counteract the deleterious effects of stress and is thought to induce neuroadaptations in corticolimbic brain systems. Here we test this hypothesis in adult squirrel monkey males exposed to intermittent social separations and new pair formations. These manipulations simulate conditions that typically occur in male social associations because of competition for limited access to residency in mixed-sex groups. As evidence of coping, we previously confirmed that cortisol levels initially increase and then are restored to prestress levels within several days of each separation and new pair formation. Follow-up studies with exogenous cortisol further established that feedback regulation of the hypothalamic-pituitary-adrenal axis is not impaired. Now we report that exposure to intermittent social separations and new pair formations increased hippocampal neurogenesis in squirrel monkey males. Hippocampal neurogenesis in rodents contributes to spatial learning performance, and in monkeys we found that spatial learning was enhanced in conditions that increased hippocampal neurogenesis. Corresponding changes were discerned in the expression of genes involved in survival and integration of adult-born granule cells into hippocampal neural circuits. These findings support recent indications that stress coping stimulates hippocampal neurogenesis in adult rodents. Psychotherapies designed to promote stress coping potentially have similar effects in humans with major depression.

Interakciós szinkronitás az interperszonális adaptációban

Az utóbbi idők pszichológiai szakirodalma gyakran említi és elemzi az interakciós szinkronitás fogalmát. A gazdag elméleti és kutatási eredmények áttekintését azonban hátráltatja az egységes definíció hiánya, ami többek között arra vezethető vissza, hogy a fogalom a mind újabb eredmények - és az azzal párhuzamos szemléletváltás - hatására jelentős változáson ment keresztül. Az interakciós szinkronitás jelenségeinek megértéséhez tehát első lépésben a fogalom jelentésének tisztázása szükséges. A fogalom meghatározása után kísérletet teszek az interakciós szinkronitás személyközi alkalmazkodásban betöltött szerepének felvázolására. A cikk evolúciós pszichológiai szemléletű, mivel ez a megközelítés az interakciós szinkronitás jelenségeinek leírása mellett azok eredetével, mechanizmusaival és funkcióival is foglalkozik, s így elősegíti e jelenségek - szoros emberi kapcsolatokban, a fizikai és pszichés egészségben betöltött - szerepének jobb megértését.

Effects of maternal deprivation on adrenal and behavioural responses in rats with anterodorsal thalami nuclei lesions

There is evidence that repeated maternal isolation of neonatal rats may influence both emotional behavior and Hypothalamic-Pituitary Adrenal (HPA) activity. On the other hand the Anterodorsal Thalami Nuclei (ADTN) exerts an inhibitory influence on the hypophyso-adrenal system under basal and stressful conditions. In the present work we investigated whether neonatal maternal deprivation produces long term effects on the ADTN regulation of behavioral patterns (open field test) and on HPA axis activity. Specifically, we sought to determine whether adult female rats with ADTN lesions, previously isolated for 4.5 hours daily during the first 3 weeks of life, react in endocrinologically and behaviourally distinct manner as compared to controls. The examined groups were: non maternally deprived (NMD)/sham lesioned, NMD/lesioned, maternally deprived (MD)/sham lesioned, MD/lesioned with and without the open field test. At 3 months MD/sham lesioned animals showed a marked decrease in ambulation (P < 0.01), and with ADTN lesion, the rearing values were lower (P < 0.01) and grooming higher (P < 0.05) than NMD. This last data would indicate a high emotional index. Regarding the activity of the HPA axis, maternal deprivation induced a significant decrease in plasma ACTH concentration both in sham and lesioned animals (P < 0.001), and plasma Corticosterone (C) increased in sham animals (P < 0.001). This data would indicate a higher sensitivity of the adrenal glands. After the open field test ACTH and C were different between deprived and non-deprived animals depending on the ADTN lesion. Taking into consideration the increase of ACTH levels in sham lesioned MD animals exposed to the test, we could conclude that this new situation was a stressful situation. Finally in the present work, it was very difficult to relate the behavioral parameters with the endocrine data. It is known that depending on the context, corticosteroids may produce opposite effects on emotional behavior via different receptors in the brain.In summary, neonatal maternal deprivation induced alterations of behavioral patterns and affected the ADTN inhibitory influence on ACTH and C secretion.

Effects of separation and separation with supplemental stroking in BALb/c infant mice

The purpose of this pilot study was to investigate selected stress, immune, and growth consequences of maternal separation and separation with supplemental stroking in neonatal BALB/c infant mice and their dams. Three groups of 5 litters each (7 pups per litter) were studied. Control litters were undisturbed. Separated litters experienced 3 h of daily maternal deprivation on postnatal days 6 to 10. Separated/stroked litters were separated also, but for 2 h, which was then followed by 1 h of stroking with a wet paintbrush to simulate maternal tactile stimulation. After the experimental period, all animals were returned to the nest and left undisturbed for 5 additional days. One pup from each litter was sacrificed on postnatal days 6, 8, 10, and 15. Spleens and thymuses were removed, weighed, and homogenized for cell sorting, cytokine analysis, and proliferation studies. Blood was drawn for corticosterone levels and hematocrit. Hematocrits and thymus weights were lower in separated mice, suggesting decreased growth and protein synthesis. Separated/stroked pups had increased splenic proliferation responses to conconavalin A and phytohemagglutinin at day 15. Separated dams' proliferative response to ConA was lower than control dams at day 15. Day 15 decreases in thymic CD8 cells occurred in pups, with an increased thymic H:S ratio in separated pups. CD90 cells were higher at day 15 in separated/stroked pups as were CD25s at day 10 in spleen and thymus. However, gene expression of cytokines was not measurable in spleen and thymic cells, with the exception of gamma-IFN in separated/stroked animals. Pooled organ homogenates were used in this preliminary work, and further studies are needed to more precisely analyze the stress, immune, and growth effects of these interventions.

Close proximity of the heterosexual partner reduces the physiological and behavioral consequences of novel-cage housing in black tufted-ear marmosets (Callithrix kuhli)

The present studies assessed the extent to which heterosexual pairmates could buffer marmosets (Wied's black tufted-ear marmoset, Callithrix kuhli) against stress. Six male and six female marmosets from established groups were exposed to two experimental manipulations together with a control condition. Each condition lasted a total of 4 days. For the two experimental conditions, animals were removed from the family group and housed in a novel cage for 48 h in either the presence or the absence of the heterosexual pairmate. During the 48-h novel-cage housing period and for 48 h upon reunion of the subjects with the family group, concentrations of urinary cortisol were measured in the first void sample of the day and behavioral observations were conducted. When animals were housed alone in a novel cage they exhibited significant elevations in levels of urinary cortisol after 24 and 48 h of novel-cage exposure. In contrast, when marmosets were housed in the novel cage in the presence of the pairmate, levels of urinary cortisol did not change across the 4-day period. The presence of the social partner also reduced the behavioral manifestations of exposure to novelty. Upon reunion with the family group, animals that had been housed in the novel cage alone spent significantly more time in close proximity to the pairmate than animals that had been housed with the partner. A second experiment was conducted to determine the effect that separation from the pairmate, only (independent of any effects of novelty), had on levels of cortisol. Concentrations of urinary cortisol were measured in subjects housed in the familiar home cage, but in the absence of the pairmate, over a 48-h period and compared to concentrations of excreted cortisol immediately prior to separation. Separation from the pairmate did not elevate cortisol levels when the subject was housed in the home cage, suggesting that elevated cortisol levels in animals housed alone in the novel cage were in response to novelty exposure rather than to separation from the pairmate. Since the physical presence of the heterosexual partner reduced the physiological and behavioral effects of novel-cage housing, social attachments might function as homeostatic regulators of HPA function in marmosets.

Neuroendocrine correlates of separation stress in the Siberian dwarf hamster (Phodopus sungorus)

Siberian dwarf hamsters form monogamous male-female pair bonds. Disruption of the pair bond results in increases in body mass and behavioral alterations similar to profiles seen in human atypical depression. We examined behavioral and neuroendocrine correlates associated with separation of the male from his mate. Animals were paired (n = 28 pairs) for 3 weeks, then 15 pairs were separated and 13 pairs remained as controls. Behaviors of the males were observed in a novel environment following 3 weeks of pairing and 4 weeks of separation. The 5-min behavioral test monitored exploratory, territorial behavior, and locomotor activity. Separated males showed a significant increase in body mass (p < 0.01). paralleled by an increase in food consumption (p < 0.01). Separated males had decreased seminal vesicle mass (p < 0.05) and testicular mass (p < 0.05). Behavioral analysis revealed that separated males showed no significant differences in grooming, scent-marking, alert on 2 feet, or escape behavior when compared to paired males. Separated males did show significant increases in inactivity (p < 0.05). Plasma cortisol levels were significantly increased in separated animals (p < 0.05), but there were no significant effects on testosterone. Resting levels of plasma norepinephrine and epinephrine were less in separated males, but this was significant only for norepinephrine (p < 0.05). In conclusion, separation stress was accompanied by increased hypothalamic-pituitary-adrenal axis function and decreased peripheral sympathetic nervous system activity and decreased reproductive profiles.

Psychological disturbance alters thymic and adrenal hormone secretion in a parallel but independent manner

Thymosin-alpha 1 (thymosin alpha 1) and cortisol levels were evaluated in juvenile squirrel monkeys to investigate the influence of psychological disturbance on thymic and adrenal hormone activity. Hormone levels were assessed in peripheral circulation following removal of monkeys from their social group to establish the time course of thymosin and cortisol alterations. Thymosin alpha 1 was significantly decreased after social separation in association with increased adrenocortical activity, especially during the first day after being housed alone. The temporal pattern suggested that both hormone systems are involved in the acute inhibition of functional immunity observed following this type of psychological disturbance. A second study verified that the decrement in thymosin alpha 1 levels was replicable and also sensitive to psychosocial factors that influence the level of induced disturbance. In addition, changes in thymosin secretion could be attenuated partially by pharmacological inhibition of the cortisol response and opiate hormone action. Nevertheless, the decrease in thymosin alpha 1 secretion did not appear to be a secondary consequence of adrenocortical secretion, and instead probably emanates from a general shift in neuroendocrine activity.

A role for CRH and the sympathetic nervous system in stress-induced immunosuppression

Central CRH coordination of the behavioral and physiologic sequelae of stress has been well established, and so it is parsimonious to suggest that CRH might also coordinate the immunologic sequelae. The studies presented here lend support to this suggestion. CRH administration into the brain was shown to modulate aspects of both cellular and humoral immune function, and the inhibition of CRH release in the brain following stress inhibited stress-associated immunosuppression. The effects of CRH appear to be mediated by the sympathetic branch of the autonomic nervous system, as chemical sympathectomy and pharmacological blockade of beta-adrenergic receptors both reversed the effects of CRH on immune function. In contrast, removal of the adrenal glands did not alter the immunologic effects of CRH. These links among CRH in the brain, sympathetic activation, and immune function suggest the possibility that immune function may be altered in other conditions characterized by elevated sympathetic tone, such as depression and aging, and that these alterations may be attributed to CRH dysregulation in the brain. These studies shed light on the intricate relationship between the brain and the immune system, and also illuminate its complexity. The differential regulation of CRH in the brain and the periphery is one example of the latter. These findings also set the stage for potential clinical intervention with CRH antagonists, for example, to treat compromised immune function associated with chronic stress, depression, or aging.

Psychobiologic reactivity to stress and childhood respiratory illnesses: results of two prospective studies

Psychological stress is thought to undermine host resistance to infection through neuroendocrine-mediated changes in immune competence. Associations between stress and infection have been modest in magnitude, however, suggesting individual variability in stress response. We therefore studied environmental stressors, psychobiologic reactivity to stress, and respiratory illness incidence in two studies of 236 preschool children. In Study 1, 137 3- to 5-year-old children from four childcare centers underwent a laboratory-based assessment of cardiovascular reactivity (changes in heart rate and mean arterial pressure) during a series of developmentally challenging tasks. Environmental stress was evaluated with two measures of stressors in the childcare setting. The incidence of respiratory illnesses was ascertained over 6 months using weekly respiratory tract examinations by a nurse. In Study 2, 99 5-year-old children were assessed for immune reactivity (changes in CD4+, CD8+, and CD19+ cell numbers, lymphocyte mitogenesis, and antibody response to pneumococcal vaccine) during the normative stressor of entering school. Blood for immune measures was sampled 1 week before and after kindergarten entry. Environmental stress was indexed with parent reports of family stressors, and a 12-week respiratory illness incidence was measured with biweekly, parent-completed symptom checklists. The two studies produced remarkably similar findings. Although environmental stress was not independently associated with respiratory illnesses in either study, the incidence of illness was related to an interaction between child care stress and mean arterial pressure reactivity (beta = .35, p < .05) in Study 1 and to an interaction between stressful life events and CD19+ reactivity (beta = .51, p < .05) in Study 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Stressors, stress and stress consequences during long-duration manned space missions: a descriptive model

Keeping crew members in good health is a major factor in the success or failure of long-duration manned space missions. Among the many possible agents that can affect the crew's general well-being, stress is certainly one of the most critical because of its implications on human health and performance, both physical and mental. Nevertheless, very few studies have been performed on this fundamental issue and none of them has addressed it in its entirety, considering its diverse physical and psychological aspects. In this work, a descriptive model is proposed to expound the mechanism and sequence of events which mediate stress. A critical analysis of the information provided by past manned spaceflights and by dedicated research performed in analogous environments is presented, and an extrapolation of the available data on human stress in such extreme conditions is proposed. Both internal and external stressors have been identified, at physical and psychosocial levels, thus providing the basis for their early detection and preventive reduction. The possible negative consequences of stress that may lead to disease in crewmembers are described. Finally, the most effective instruments which may be of help in reducing space-related human stress and treating its negative consequences are suggested.

Influence of early life events on immune reactivity in adult mice

The effects of postnatal manipulations on different immune parameters were investigated in adult female mice. Postnatal stress consisted of a 15-min daily exposure to clean bedding (temperature maintained at 35 degrees C) for the first 2 weeks of life in the absence of the mother but in the presence of littermates. Controls were unhandled until weaning. At 60 days of age, female mice stressed during postnatal development showed enhanced immune reactivity as assessed by NK-cell activity and T-cell mitogenesis in comparison with unhandled mice. By contrast, B-lymphocyte proliferation induced by lipopolysaccharide (LPS) was not affected by alterations of postnatal environment. Furthermore, the association between immune reactivity and behavioral lateralization observed in adult mice was not altered by postnatal stress.