Stress and the adaptive self-organization of neuronal connectivity during early childhood

Childhood chronic condition and subsequent self-reported internalizing and externalizing problems in adolescence: a birth cohort study

Chronic conditions are common in childhood. We investigated the associations of childhood chronic conditions reported by parents with subsequent self-reported internalizing and externalizing problems in adolescence. A sample of 6290 children (3142 boys and 3148 girls) with data on chronic condition reported by parents both at 7 and at 16 years of age was obtained from the Northern Finland Birth Cohort 1986 (NFBC 1986), which is a longitudinal 1-year birth cohort (n = 9432) from an unselected, regionally defined population. Internalizing and externalizing problems were measured at 8 years of age with Rutter Children's Behavioral Questionnaire by teachers and at 16 years of age with Youth Self-Report by adolescents. When studying the effects of history of chronic conditions on these problems at 16 years of age, childhood internalizing and externalizing problems and social relations were adjusted. A history of chronic condition predicted subsequent somatic complaints among all adolescents. Early-onset chronic conditions were related to subsequent externalizing (OR 1.35; 1.02-1.79) and attention problems (OR 1.33; 1.01-1.75) and later onset of chronic conditions with internalizing (OR 1.49; 1.22-1.82) and thought problems (OR 1.50; 1.18-1.92). The effect was specific for sex and the type of chronic condition.

CONCLUSION

Childhood chronic conditions predicted internalizing and externalizing problems in adolescence. To prevent poor mental health trajectories, children with chronic conditions during their growth to adolescence need early support and long-term monitoring.

WHAT IS KNOWN

• Childhood adversities increase the risk of mental disorders. • Internalizing and externalizing problems have been suggested for measuring childhood and adolescent psychopathologies.

WHAT IS NEW

• Having a chronic condition (CC) before the age of 7 or later but before the age of 16 had different outcomes in adolescence. The early onset predicted externalizing problems, whereas the late onset predicted internalizing problems and thought problems in adolescence. The risk of somatic complaints was increased regardless of CC onset time. These findings can reflect more restricted ability to mental processing in the younger children.

Intranasal oxytocin affects the stress response to social isolation in sheep

Oxytocin (OT) is a neuropeptide hormone that modulates several social behaviors and can affect the anxiety and stress response. The aim of this study was to determine if administration of intranasal OT affects the stress response to social isolation in sheep. Twenty adult Merino ewes were assigned to two groups; 1) Control group (CG, n = 10), which received an intranasal administration of isotonic saline and 2) Oxytocin-treated group (OTG, n = 10), which received an intranasal administration of OT (24 IU) 40 min before the animals were placed in the social isolation test. During the social isolation test (10 min), the behavior of the sheep was recorded, and blood samples were obtained before and after the test for the determination of cortisol, glucose and serum proteins, and heart rate and surface temperature were recorded. The OTG ewes had a higher cortisol concentration (P = 0.04) after social isolation, tended to vocalize more (P = 0.06) during isolation, and tended to have lower globulin concentrations (P = 0.10) than the CG ewes. Contrary to what we expected, the administration of intranasal OT increased the stress response to social isolation in ewes, which was evidenced by endocrine (greater increase in cortisol concentration), physiological (a tendency to present lower concentration of globulins in blood) and behavioral (a tendency to vocalize more) indicators. This study suggests that the administration of intranasal OT increased the stress response to isolation possibly by strengthening the social bond among ewes.

Relationships between mental health and diet during pregnancy and birth outcomes in a lower-middle income country: "Healthy mothers, healthy communities" study in Vanuatu

Poor maternal mental health during pregnancy is associated with adverse birth outcomes, including lower birthweight and gestational age. However, few studies assess both mental health and diet, which might have interactive effects. Furthermore, most studies are in high-income countries, though patterns might differ in low- and middle-income countries (LMICs).

OBJECTIVES

To analyze relationships between mental health and diet during pregnancy with birth outcomes in Vanuatu, a lower-middle income country.

METHODS

We assessed negative emotional symptoms of depression, anxiety, and stress (referred to as "distress") and dietary diversity during pregnancy, and infant weight and gestational age at birth, among 187 women. We used multivariate linear regression to analyze independent and interactive relationships between distress, dietary diversity, and birth outcomes, controlling for sociodemographic and maternal health covariates.

RESULTS

There were no direct linear relationships between dietary diversity or distress with infant birthweight or gestational age, and no curvilinear relationships between distress and infant outcomes. We observed interactive relationships between distress and dietary diversity on birthweight, explaining 2.1% of unique variance (P = .024). High levels of distress predicted lower birthweights among women with low dietary diversity. These relationships were not evident among women with moderate or high dietary diversity.

CONCLUSIONS

Relationships between mental health and diet might underlie inconsistencies in past studies of prenatal mental health and birthweight. Results highlight the importance of maternal mental health on birthweight in LMICs. Interactive relationships between mental health and diet might ultimately point to new intervention pathways to address the persistent problem of low birthweight in LMICs.

Neurocognitive Precursors of Substance Misuse Corresponding to Risk, Resistance, and Resilience Pathways: Implications for Prevention Science

Studies of substance misuse prevention generally focus on characteristics that typify risk, with the assumption that the prevalence of the problem will be optimally reduced by identifying, targeting, and reducing or eliminating risk factors. However, this risk-centered approach neglects variations in individual-level and environmental characteristics that portend differential pathways that are distinguishable by timing of substance use initiation (e.g., early versus delayed), the likelihood of use escalation versus eventual desistance, and enduring abstinence, despite exposure to significant risk factors. Considering the various underpinnings of these distinct substance use trajectories is critical to a more nuanced understanding of the effects, potency, and malleability of factors that are known to increase risk or confer protection. Here, we discuss three pathways relative to substance use patterns and predictors in the context of adversity, a well-known, highly significant influence on propensity for substance misuse. The first pathway is designated as "high risk" based on early onset of substance use, rapid escalation, and proneness to substance use disorders. Individuals who defy all odds and eventually exhibit adaptive developmental outcomes despite an initial maladaptive reaction to adversity, are referred to as "resilient." However, another categorization that has not been adequately characterized is "resistant." Resistant individuals include those who do not exhibit problematic substance use behaviors (e.g., early onset and escalation) and do not develop substance use disorders or other forms of psychopathology, despite significant exposure to factors that normally increase the propensity for such outcomes (e.g. trauma and/or adversity). In this paper, we apply this conceptualization of risk, resistance, and resilience for substance misuse to a more fine-grained analysis of substance use pathways and their corresponding patterns (e.g., non-use, initiation, escalation, desistance). The significance of the progression of neurocognitive functioning over the course of development is discussed as well as how this knowledge may be translated to make a science-based determination of intervention targets. This more encompassing theoretical model has direct implications for primary prevention and clinical approaches to disrupt risk pathways and to optimize long-term outcomes.

A developmentally informed perspective on the relation between stress and psychopathology: when the problem with stress is that there is not enough

A common tenet of several prominent theories of stress and psychopathology (e.g., stress exposure) is that experiencing high rates of life stressors is associated with greater risk for negative mental health outcomes. Although there has been substantial empirical support for this position, another possibility that has received considerably less attention to date is that early life stressors may share a curvilinear rather than monotonic relation with psychological well-being. In what has been termed the "steeling effect," "stress inoculation," and "antifragility," exposure to moderate stressors early in life may confer resilience to potential detrimental effects of later stressors. An interesting implication of this model is that low levels of early life stressors, relative to normatively moderate rates, may be associated with greater sensitivity to future stressors. The present article reviews preliminary evidence consistent with this possibility, drawing on behavioral and neurobiological studies in animal models, and the more modest literature on neurocognitive, psychological, and psychophysiological functioning in humans. Limitations of the clinical literature and possible directions for future research are discussed, including naturalistic longitudinal studies with clinical outcomes, and for research examining moderators and mechanisms, across multiple levels of analysis (e.g., cognitive, immunological, and neurobiological).

The Role of Prenatal Maternal Stress in Child Development

The notion that a woman's psychological state during pregnancy affects the fetus is a persistent cultural belief in many parts of the world. Recent results indicate that prenatal maternal distress in rodents and nonhuman primates negatively influences long-term learning, motor development, and behavior in their offspring. The applicability of these findings to human pregnancy and child development is considered in this article. Potential mechanisms through which maternal psychological functioning may alter development of the fetal nervous system are being identified by current research, but it is premature to conclude that maternal prenatal stress has negative consequences for child development. Mild stress may be a necessary condition for optimal development.

Effect of maternal job strain during pregnancy on infant neurodevelopment by gender at 6 and 12 months: Mothers and Children's Environmental Health (MOCEH) study

OBJECTIVES

Limited evidence is available regarding the association between prenatal job strain and infant neurodevelopment. Most studies used stress indicators other than job strain to explain the relationship between prenatal maternal stress and child development. The objective of this study was to investigate the association between maternal job strain during pregnancy and neurodevelopment in infancy.

METHODS

Mothers and Children's Environmental Health (MOCEH) study, an on-going prospective birth cohort study, has been conducted in South Korea since 2006. Job strain during pregnancy was measured using Korean version of Job Content Questionnaire (JCQ). Infant neurodevelopment was assessed using Korean Bayley Scale of Infant Development II (K-BSID-II) at 6 and 12 months of age. A total of 343 mother-child pairs that completed JCQ and K-BSID-II more than once were included. Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) defined in the K-BSID-II were used as outcome variables.

RESULTS

Compared to infants from mothers with low job strain, significant (p < 0.05) decreases in PDI were found in infants from mothers with active and passive job at 6 months of age. After stratification by infant sex, boys in the high strain group had a lower MDI score than boys in the low job strain group at 12 months. On the other hand, girls in the high strain and active groups had higher MDI scores than girls in the low job strain group at 12 months. PDI at 12 months also showed different results by sex. Boys in the high strain and passive job groups had lower PDI scores than boys in the low job strain group. However, such difference was not observed in girls.

CONCLUSIONS

The findings of this study suggest that prenatal job strain affects infant neurodevelopment in a gender-dependent manner.

Maternal stress in pregnancy: considerations for fetal development

There is significant current interest in the degree to which prenatal exposures, including maternal psychological factors, influence child outcomes. Studies that detect an association between prenatal maternal psychological distress and child developmental outcomes are subject to a number of interpretative challenges in the inference of causality. Some of these are common to many types of prenatal exposures that must necessarily rely on observational designs. Such challenges include the correlation between prenatal and postnatal exposures and the potential role of other sources of shared influence, such as genetic factors. Others are more specific to this area of research. These include confounding between maternal report of child outcomes and the maternal psychological attributes under study, difficulties in distinguishing maternal stress from more ubiquitous aspects of maternal personality, and the lack of association between cortisol and measures of maternal psychological stress. This article considers these methodological issues and offers an additional methodology focused on fetal neurobehavior for discerning potential mechanisms that may mediate associations between maternal psychological functioning and the developing fetal nervous system.

The mediating effect of depressive symptoms on the relationship between traumatic childhood experiences and drug use initiation

Stressful experiences such as childhood trauma and depressive symptoms have both been implicated in the initiation of drug use; however, longitudinal designs have not yet been used to elucidate their respective roles to better understand the causal sequence. In the present study, a sensitivity analysis was conducted using two mediation strategies to examine how this sequence may differ by various levels of statistical control, including (1) the standard mediational model in which the effect of lifetime traumatic stressors (Year 1) on the onset of drug use (Years 3 and 4) is mediated by levels of depressive symptoms (Year 2); and (2) a stronger test of causality such that the effect of lifetime traumatic stressors (Year 1) on the onset of drug use (Years 3 and 4) was mediated by changes in depressive symptoms (Year 1 to 2), measured by a residualized change score that controlled for levels in Year 1. Two types of trauma were studied in a community-based study of 489 Hispanic preadolescents (aged 10-12): (a) the number of lifetime traumatic stressors and (b) seven specific lifetime stressors. We also controlled for new onset traumatic stressors occurring between Years 1 and 2. Primary findings indicate that drug use initiation during early adolescence (e.g., ages 14-16) may not be tied to immediate proximal perturbations in risk factors, such as traumatic experiences and depressive symptoms. Rather, the effects of trauma on depression in this sample appear to be established earlier in childhood (ages 10-14 or younger) and persist in a relatively stable manner into middle adolescence when the risk for drug use may be heightened.

Evolutionary functions of early social modulation of hypothalamic-pituitary-adrenal axis development in humans

The hypothalamic-pituitary-adrenal axis (HPAA) is highly responsive to social challenges. Because stress hormones can have negative developmental and health consequences, this presents an evolutionary paradox: Why would natural selection have favored mechanisms that elevate stress hormone levels in response to psychosocial stimuli? Here we review the hypothesis that large brains, an extended childhood and intensive family care in humans are adaptations resulting from selective forces exerted by the increasingly complex and dynamic social and cultural environment that co-evolved with these traits. Variations in the modulation of stress responses mediated by specific HPAA characteristics (e.g., baseline cortisol levels, and changes in cortisol levels in response to challenges) are viewed as phenotypically plastic, ontogenetic responses to specific environmental signals. From this perspective, we discuss relations between physiological stress responses and life history trajectories, particularly the development of social competencies. We present brief summaries of data on hormones, indicators of morbidity and social environments from our long-term, naturalistic studies in both Guatemala and Dominica. Results indicate that difficult family environments and traumatic social events are associated with temporal elevations of cortisol, suppressed reproductive functioning and elevated morbidity. The long-term effects of traumatic early experiences on cortisol profiles are complex and indicate domain-specific effects, with normal recovery from physical stressors, but some heightened response to negative-affect social challenges. We consider these results to be consistent with the hypothesis that developmental programming of the HPAA and other neuroendocrine systems associated with stress responses may facilitate cognitive targeting of salient social challenges in specific environments.

Osteopathy and (hatha) yoga

Differences and points of contact between osteopathy and yoga as regards their history and practical application are outlined. Both seek to promote healing. Yoga seeks the attainment of consciousness; osteopathy aims for providing support to health. One fundamental difference is the personal involvement of the individual in yoga. Teacher and student alike are challenged to re-examine the attitudes of mind they have adopted toward their lives. Osteopathy generally involves a relatively passive patient while the osteopath is active in providing treatment. Practical examples are used to highlight points of contact between yoga and osteopathy. The text includes a discussion of the importance of physicality and a description of ways of using it in healing processes. Furthermore, processes of attaining consciousness are outlined. Possible reductionist misconceptions in yoga and osteopathy are also pointed out. Fundamental attitudes and focus that complement each other are presented, taking the concept of stillness as a particular example.

Prenatal stress and brain development

Prenatal stress (PS) has been linked to abnormal cognitive, behavioral and psychosocial outcomes in both animals and humans. Animal studies have clearly demonstrated PS effects on the offspring's brain, however, while it has been speculated that PS most likely affects the brains of exposed human fetuses as well, no study has to date examined this possibility prospectively using an independent stressor (i.e., a stressful event that the pregnant woman has no control over, such as a natural disaster). The aim of this review is to summarize the existing animal literature by focusing on specific brain regions that have been shown to be affected by PS both macroscopically and microscopically. These regions include the hippocampus, amygdala, corpus callosum, anterior commissure, cerebral cortex, cerebellum and hypothalamus. We first discuss the mechanisms by which the effects of PS might occur. In particular, we show that maternal and fetal hypothalamic-pituitary-adrenal (HPA) axes, and the placenta, are the most likely candidates for these mechanisms. We see that, although animal studies have obvious advantages over human studies, the integration of findings in animals and the transfer of these findings to human populations remains a complex issue. Finally, we show how it is possible to circumvent these challenges by studying the effects of PS on brain development directly in humans, by taking advantage of natural or man-made disasters and assessing the impact and consequences of such stressful events on pregnant women and their offspring prospectively.

Maternal psychosocial adversity during pregnancy is associated with length of gestation and offspring size at birth: evidence from a population-based cohort study

OBJECTIVE

To study in a large-scale cohort with prospective data the associations of psychosocial adversities during pregnancy with length of gestation and offspring size at birth.

METHODS

We defined a priori two types of psychosocial adversity during pregnancy: life stress (perceived burdens in major areas of life) and emotional symptoms (e.g. anxiety). Measures of offspring size at birth, including body weight, body length, abdominal and head circumference, were obtained from a national medical birth registry. We included in the analyses gestational age and offspring size at birth controlled for length of gestation; the latter was calculated by gestational-age-specific z scores (ZS) reported in 10(-3). We conducted multiple regression analyses adjusted for potential confounders to estimate the association between exposures and birth outcomes (n = 78017 pregnancies).

RESULTS

Life stress (per score increase by 1; range, 0-18) was associated with shorter length of gestation (days; B, -0.14; 95% confidence interval (CI), -0.19, -0.10), increased offspring body weight (ZS; B, 9.14; 95% CI, 4.99, 13.28), body length (ZS; B, 6.58; 95% CI, 2.39, 10.77), abdominal circumference (ZS; B, 9.96; 95% CI, 5.77, 14.16), and head circumference (ZS; B, 6.13; 95% CI, 1.95, 10.30). Emotional symptoms were associated with shorter length of gestation (days; B, -0.04; 95% CI, -0.07, -0.004) and decreased body length (ZS; B, -4.44; 95% CI, -7.57, -1.32) only.

CONCLUSIONS

Life stress and emotional symptoms both predicted a shorter length of gestation, while only life stress predicted an increased offspring size at birth controlled for length of gestation; yet, the associations were rather small. The fetoplacental-maternal unit may regulate fetal growth according to the type of psychosocial adversity and even increase fetal growth in response to maternal stress in major areas of life. This potentially reflects a basic principle of intrauterine human development in response to stress.

Epileptogenesis is increased in rats with neonatal isolation and early-life seizure and ameliorated by MK-801: a long-term MRI and histological study

Early-life stress has been shown to destabilize the homeostatic synaptic plasticity and compromise the developing brain to the later encountered insults. This study would determine the long-term epileptogenic effect of neonatal isolation (NI) on early-life seizure. There were five groups: normal rearing (NR) rats; NI rats; NR rats suffering from status epilepticus (SE) at P12 (NR-SE); NI-SE rats; NI-SE-MK801 rats. All adult rats were video monitored to detect behavioral seizures, examined with brain magnetic resonance imaging, and assessed for hippocampal NeuN-immunoreactive (NeuN-IR) cells. Behavioral seizures were detected in one of six NR-SE rats, all the NI-SE rats (eight of eight), and none in the NR, NI, or NI-SE-MK801 rats. High hippocampal T2 signal were only found in three of five NR-SE rats, five of six NI-SE rats, and one of five NI-SE-MK801 rats. There was a significant decrease in the number of hippocampal NeuN-IR cells in the NR-SE and NI-SE groups, compared with the NR group, and MK-801 treatment ameliorated the neuronal loss. Our results demonstrated that NI led to an increase in epileptogenesis in rat pups with early-life SE, and treatment with MK-801 could ameliorate brain injuries, indicating a critical role of N-methyl-d-aspartic acid receptor in the epileptogenic process.

Infusing neuroscience into the study and prevention of drug misuse and co-occurring aggressive behavior

The etiology of behavioral precursors to substance misuse and aggression is viewed from the perspective of a developmental, multifactorial model of complex disorders. Beginning at conception, genetic and environmental interactions have potential to produce a sequence of behavioral phenotypes during development that bias the trajectory toward high-risk outcomes. One pathway is theorized to emanate from a deviation in neurological development that predisposes children to affective and cognitive delays or impairments that, in turn, generate dysregulatory behaviors. The plasticity of these neurobiological systems is highly relevant to the prevention sciences; their functions are reliant upon environmental inputs and can be altered, for better or for worse, contingent upon the nature of the inputs. Thus, social contextual factors confer significant influence on the development of this neural network and behavioral outcomes by increasing risk for, or protecting (1) against, dysregulatory outcomes. A well-designed intervention can exploit the brain's plasticity by targeting biological and social factors at sensitive time points to positively influence emergent neurobiological functions and related behaviors. Accordingly, prevention research is beginning to focus on perturbations in developmental neural plasticity during childhood that increase the likelihood of risky behaviors and may also moderate intervention effects on behavior. Given that the more complex features of neurobiological functions underlying drug misuse and aggression (e.g., executive cognitive function, coping skills, affect regulation) do not coalesce until early adulthood when prefrontal-limbic brain networks consolidate, it is critical that mechanisms underlying developmental risk factors are identified. An empirically driven prevention approach, thus, may benefit from consideration of (i) the type, effect, and developmental timing of the environmental impact on the brain, and (ii) the type and effect on brain function, and developmental timing of the intervention. This translational approach promises to eventually offer some direction for the design of effective interventions to prevent drug misuse and concomitant aggression.

Repeated neonatal separation stress alters the composition of neurochemically characterized interneuron subpopulations in the rodent dentate gyrus and basolateral amygdala

Emotional experience during early life has been shown to interfere with the development of excitatory synaptic networks in the prefrontal cortex, hippocampus, and the amygdala of rodents and primates. The aim of the present study was to investigate a developmental "homoeostatic synaptic plasticity" hypothesis and to test whether stress-induced changes of excitatory synaptic composition are counterbalanced by parallel changes of inhibitory synaptic networks. The impact of repeated early separation stress on the development of two GABAergic neuronal subpopulations was quantitatively analyzed in the brain of the semiprecocial rodent Octodon degus. Assuming that PARV- and CaBP-D28k-expression are negatively correlated to the level of inhibitory activity, the previously described reduced density of excitatory spine synapses in the dentate gyrus of stressed animals appears to be "amplified" by elevated GABAergic inhibition, reflected by reduced PARV- (down to 85%) and CaBP-D28k-immunoreactivity (down to 74%). In opposite direction, the previously observed elevated excitatory spine density in the CA1 region of stressed animals appears to be amplified by reduced inhibition, reflected by elevated CaPB-D28k-immunoreactivity (up to 149%). In the (baso)lateral amygdala, the previously described reduction of excitatory spine synapses appears to be "compensated" by reduced inhibitory activity, reflected by dramatically elevated PARV- (up to 395%) and CaPB-D28k-immunoreactivity (up to 327%). No significant differences were found in the central nucleus of the amygdala, the piriform, and somatosensory cortices and in the hypothalamic paraventricular nucleus. Thus during stress-evoked neuronal and synaptic reorganization, a homeostatic balance between excitation and inhibition is not maintained in all regions of the juvenile brain.

Co-ruminating increases stress hormone levels in women

Same-sex friendships are an important source of social support and typically contribute to positive adjustment. However, there can be adjustment trade-offs if the friends co-ruminate (i.e., talk excessively about problems) in that co-rumination is related to having close friendships but also to increased internalizing symptoms. The current study utilized an experimental manipulation that elicited co-rumination in young women and thus mirrored an everyday response to stress. Observed co-rumination was associated with a significant increase in the stress hormone, cortisol (after controlling for self-reported co-rumination and for cortisol levels assessed before the discussion of problems). These findings suggest that co-rumination can amplify, rather than mitigate, the hormonal stress response to personal life stressors.

Adolescent neurological development and its implications for adolescent substance use prevention

Recent technological advancements have facilitated the study of adolescent neurological development and its implications for adolescent decision-making and behavior. This article reviews findings from the adolescent neurodevelopment and substance use prevention literatures. It also discusses how findings from these two distinct areas of adolescent development can complement each other and be used to build more developmentally appropriate interventions for preventing adolescent substance use. Specifically, a combination of child-centered and family-based strategies is advocated based on extant neurological and prevention literature. EDITORS' STRATEGIC IMPLICATIONS: Researchers are encouraged to take up the authors' challenge and study the links between adolescent neurological development/decision making ability and the long term efficacy of comprehensive interventions for preventing adolescent substance use.

Maternal psychological distress during pregnancy in relation to child development at age two

Concern exists that a constellation of negative maternal emotions during pregnancy generates persistent negative consequences for child development. Maternal reports of anxiety, pregnancy-specific and nonspecific stress, and depressive symptoms were collected during mid-pregnancy and at 6 weeks and 24 months after birth in a sample of healthy women with low risk pregnancies. Developmental assessment and cardiac vagal tone monitoring were administered to 94 children at age 2. Higher levels of prenatal anxiety, nonspecific stress, and depressive symptoms were associated with more advanced motor development in children after postnatal control for each psychological measure; anxiety and depression were also significantly and positively associated with mental development. Mild to moderate levels of psychological distress may enhance fetal maturation in healthy populations.

The effects of stress on muscarinic receptors. Heterologous receptor regulation: yes or no?

1 Stress is usually comprehended as an event affecting mainly the catecholaminergic system, the hypothalamo-pituitary-adrenocortical (HPA) axis and the receptor systems connected to these neurotransmitters/hormones. Other neurotransmitter/hormone systems can be affected too. Here we review the available data on the effects of different stressful stimuli (physical, chemical, psychological/social, cardiovascular, affecting multiple system) on muscarinic receptors (MR). 2 The data suppose the existence of specific mechanisms that regulate the signalization through MR during different type of stress. 3 Physical stressors (cold vs. heat) reveal opposite type of changes on peripheral-tissue MRs. Chemical stressors (oxidative stress) are tightly connected with MR and it is especially interesting that the sensitivity of MR to oxidative stress is subtype-specific. It is also suggested that heterologous regulation can occur with psychological/social stressors on the organism. Cardiovascular system-disturbing stressors cause imbalance between autonomic receptors or down-regulate MR in the peripheral tissue. Immobilization caused opposite effects on MR in the central nervous system and periphery, where the changes are supposed to be due to heterologous regulation between receptor systems. 4 In conclusion, some data indicate that in specific conditions MR are regulated as a consequence of other changes rather than as a primary effect of stress. On the contrary, in some situations, MR are the first targets to respond to the stress. 5 These findings on stress-induced activity of the cholinergic system and changes in muscarinic receptors support the view that stress is a specific response of the organism.

Behavioral and hypothalamic‐pituitary‐adrenal responses to anterodorsal thalami nuclei lesions and variable chronic stress in maternally separated rats

In maternally separated rats, variable chronic stress decreased the emotional reactivity and provoked a state of hypoactivity of the hypothalamic-pituitary-adrenal system at 3 months old but increased its activity after the open field test. The anterodorsal thalami nuclei control of the endocrine response under stress conditions was not manifested however its seems activate grooming behavior. The development of behavioral and endocrine response to stress is influenced by early postnatal environment. On the other hand, the anterodorsal thalami nuclei exert an inhibitory influence on the hypothalamic-pituitary-adrenal system under basal and stressful conditions. The aim of this work is to determine the magnitude of behavioral and hypothalamic-pituitary-adrenal responses to variable chronic stress in adult female rats with anterodorsal thalami nuclei lesions, previously isolated for 4.5 h daily during the first 3 weeks of life. The groups were: non-maternally separated sham and lesioned, maternally separated sham and lesioned with variable chronic stress with and without open field test. At 3 months old, under variable chronic stress, maternal separation provoked an increase in ambulation in sham and lesioned animals (P<0.01) but this parameter was not modified by lesion in either non-maternally separated or maternally separated groups. Neither the lesion nor the maternal separation changed the defecation and rearing parameter. Grooming behavior was lower in maternally separated lesioned rats (P<0.05). Under variable chronic stress maternal separation decreased adrenocorticotrophin hormone in comparison with non-maternally separated (P<0.001) and the lesion did not alter this response. Regarding corticosterone concentrations, maternal separation did not affect this hormone under variable chronic stress conditions and after the open field test there was an increase of this in both non-maternally separated and maternally separated sham and lesioned (P<0.001).

The contribution of perceived control of stressful life events and thought suppression to the symptoms of obsessive-compulsive disorder in both non-clinical and clinical samples

The two studies presented in this paper investigated the impact of controllable versus uncontrollable stressful life events (SLE) and low versus high thought suppression upon symptoms of obsessive-compulsive disorder (OCD) in both a non-clinical sample (Study 1) and a clinical sample (Study 2). The sample for Study 1 consisted of 269 undergraduate university students and the sample for Study 2 consisted of 91 participants obtained from the Obsessive Compulsive and Anxiety Disorders Foundation of Victoria, Australia. Participants in both studies were given identical questionnaires measuring anxiety, depression, thought suppression, OCD, and, the control, magnitude and number of SLEs suffered during the previous 18 months. In both studies, analysis of covariance (ANCOVA) followed by post hoc tests indicated that high OCD scores were associated with high thought suppression and low perceived control over high magnitude stressful life events relative to controls. The results suggest that high thought suppression coupled with low control over stressful life events may interact with other predisposing factors, such as genetic vulnerability to produce OCD symptoms.

Early maternal availability and prefrontal correlates of reward-related memory

Early emotional experiences affect developing brain systems that subsequently mediate adult learning and memory in rodents. Here we test for similar effects in squirrel monkeys (Saimiri sciureus) four years after disruptions in early maternal availability. These conditions were previously shown to generate differences in emotional behavior, hypothalamic-pituitary-adrenal stress physiology, and right ventral medial prefrontal volumes determined in adulthood by magnetic resonance imaging. This report identifies in the same monkeys variability in reward-related memory on tests with a spatial reversal. Adult monkeys that more often selected locations repeatedly rewarded before each reversal had larger right ventral medial prefrontal volumes, but not hippocampal nor dorsolateral prefrontal volumes on the left or right brain side. Differences in performance were also discerned after each spatial reversal. These findings indicate that maternal availability alters developing ventral medial prefrontal brain regions involved in reward-related memory.

Neonatal handling reduces the number of cells in the locus coeruleus of rats

Neonatal handling induces long-lasting effects on behaviors and stress responses. The objective of the present study was to analyze the effects of neonatal handling (from the 1st to the 10th day after delivery) on the number of cells and volume of locus coeruleus (LC) nucleus in male and female rats at 4 different ages: 11, 26, 35, and 90 days. Results showed significant reductions in the number of cells and the volume of the LC nucleus in neonatally handled males and females compared with nonhandled rats. Environmental stimulation early in life induced a stable structural change in a central noradrenergic nucleus, which could be one of the causal factors for the behavioral and hormonal alterations observed in adulthood.

Experience-dependent asymmetric variation in primate prefrontal morphology

Theories of human development suggest that experiences embedded in social relationships alter prefrontal brain systems that mediate emotional self-regulation. This study tests for experience-dependent effects on prefrontal gray and white matter volumes determined in 39 young adult monkeys (Saimiri sciureus) 4 years after conditions that modified early maternal availability. These conditions were previously shown to alter subsequent measures of emotional behavior, social propensities, and hypothalamic-pituitary-adrenal axis stress physiology. Here we identify significant differences in right but not left adult prefrontal volumes, with experience-dependent asymmetric variation most clearly expressed in ventral medial cortex measured in vivo by magnetic resonance imaging (MRI). Follow-up studies now need to determine whether maternal availability directly affects or interacts with subsequent experiences to alter prefrontal substrates of emotional processing and sensitivity to stress.

Chronic stress during prepubertal development: immediate and long-lasting effects on arterial blood pressure and anxiety-related behavior

The present work was undertaken to study the immediate and long-lasting effects of environmental stress during prepubertal life in rats with inherited stress-induced arterial hypertension (ISIAH) and normotensive Wistar rats on blood pressure (BP) levels and anxiety-related behavior. Two models of chronic stress (21-32 postnatal days) were used: repeated handling (HS) and unpredictable stress (US) of daily exposures to a variety of mild physical or psychoemotional stressors. Rats were tested just after the end of the chronic stress period and then at the age of 4 months. Chronic prepubertal stress did not affect the basal or stress-induced BP levels in young or adult Wistar rats. In ISIAH rats, chronic stress during the early phase of hypertension development did not accelerate its formation and did not augment its manifestation in adults. Moreover, the basal BP was decreased in young and adult ISIAH rats exposed to HS or US as compared to the age-matched controls. No long-lasting effect on BP elevation under acute stress in adults was found. Plasma corticosterone levels at resting and acute stress conditions were not changed in adult rats that had experienced prepubertal stress. Hypertensive rats proved to be less anxious in the elevated plus-maze test. The immediate effects of chronic stress were similar in the two rat strains: HS had an anxiolytic action while US stimulated anxiety. Long-lasting consequences depended on the rat strain: the anxiolytic effect of HS was retained in Wistar rats and US caused a greater anxiety in adult ISIAH rats. The data do not evidence that symptoms of anxiety are related to the development and maintenance of stress-sensitive arterial hypertension in ISIAH rats.

Immediate and long-lasting effects of chronic stress in the prepubertal age on the startle reflex

The immediate and long-lasting effects of two models of chronic stress during the prepubertal period of life (21-32 days) on the acoustic startle response (ASR) were studied in outbred Wistar normotensives and rats with inherited stress-induced arterial hypertension (ISIAH) derived from them. Chronic variable stress (CVS) and repeated handling were used as chronic treatment. The obtained data showed a significantly attenuated ASR and a greater magnitude of prepulse inhibition (PPI) in juvenile and adult ISIAH compared to Wistar rats. The immediate effects of prolonged stress on the ASR were genotype-dependent. Young ISIAH rats exposed to both types of prepubertal stimulation had higher ASR than the age-matched controls. No significant stress-induced changes in the ASR were found in young Wistar rats. The long-lasting consequences of prolonged prepubertal stress were similar in the two strains and were determined by the specificity of stress stimulation: chronic handling had no effect on the ASR, while CVS enhanced it. The long-lasting effect of CVS experienced in prepubertal life appears to produce ASR changes similar to those seen in patients with posttraumatic stress disorder (PTSD). The magnitude of PPI increased from early age to adulthood and it was tolerant to environmental influences. The two rat strains did not differ in the rate of short-term habituation to repeated acoustic stimuli, which was unaffected by prepubertal stress. Evidence was obtained indicating that genetic and environmental background in childhood may contribute to the truncation of the startle response.

Pathophysiologische und neuropsychologische Aspekte depressiver Störungen

Zusammenfassung: Bei depressiven Störungen sind zahlreiche neurobiologische Auffälligkeiten dokumentiert. Aufschluß darüber geben Untersuchungen bei primärer Depression sowie Untersuchungen bei depressiven Störungen, die sich im Zusammenhang mit Hirnschädigungen, wie etwa Schlaganfällen, manifestieren. Ebenfalls lassen neuropsychologische Befunde Rückschlüsse auf pathophysiologische Mechanismen zu. Vieles deutet darauf hin, daß es bei depressiven Störungen zu einer Störung eines komplexen neuronalen Netzwerkes kommt, insbesondere unter Beteiligung präfrontaler cortikaler Strukturen, der Amygdala und der Basalganglien sowie ihrer monoaminergen Afferenzen aus Hirnstamm und pontinem Tegmentum. Der Befund eines reduzierten Hippokampusvolumens bei Subtypen der Depression geht möglicherweise auf einen Hypercortisolismus zurück. Neurobiologische Auffälligkeiten stellen einen wichtigen Anknüpfungspunkt für antidepressive Therapien dar. Insgesamt ist die Depression als eine psychobiologische Störung konzeptualisierbar, bei der biologische und psychologische Faktoren eng miteinander verzahnt sind.

Disturbance of neuronal plasticity is a critical pathogenetic event in Alzheimer's disease

Brain areas affected by AD pathology are primarily those structures that are invovled in the regulation of "higher brain functions". The functions these areas subserve such as learning, memory, perception, self-awareness, and consciousness require a life-long re-fittng of synaptic contacts that allows for the acquistion of new epigenetic information, a process based on a particularly high degree of structural plasticity. Here, we outline a hypothesis that it is the "labile state fo differentiation" of a subset of neurons in the adult brain that allows for ongoing neuroplastic processes after development is completed but at the same time renders these neurons particularly vulnerable. Mechanisms of molecular and cellular control of neuronal differentiation and proliferation might, thus, not only play a role during development but critically involved in the pathogenesis of neurodegeneration.

Alzheimer's disease as a disorder of mechanisms underlying structural brain self-organization

Mental function has as its cerebral basis a specific dynamic structure. In particular, cortical and limbic areas involved in "higher brain functions" such as learning, memory, perception, self-awareness and consciousness continuously need to be self-adjusted even after development is completed. By this lifelong self-optimization process, the cognitive, behavioural and emotional reactivity of an individual is stepwise remodelled to meet the environmental demands. While the presence of rigid synaptic connections ensures the stability of the principal characteristics of function, the variable configuration of the flexible synaptic connections determines the unique, non-repeatable character of an experienced mental act. With the increasing need during evolution to organize brain structures of increasing complexity, this process of selective dynamic stabilization and destabilization of synaptic connections becomes more and more important. These mechanisms of structural stabilization and labilization underlying a lifelong synaptic remodelling according to experience, are accompanied, however, by increasing inherent possibilities of failure and may, thus, not only allow for the evolutionary acquisition of "higher brain function" but at the same time provide the basis for a variety of neuropsychiatric disorders. It is the objective of the present paper to outline the hypothesis that it might be the disturbance of structural brain self-organization which, based on both genetic and epigenetic information, constantly "creates" and "re-creates" the brain throughout life, that is the defect that underlies Alzheimer's disease (AD). This hypothesis is, in particular, based on the following lines of evidence. (1) AD is a synaptic disorder. (2) AD is associated with aberrant sprouting at both the presynaptic (axonal) and postsynaptic (dendritic) site. (3) The spatial and temporal distribution of AD pathology follows the pattern of structural neuroplasticity in adulthood, which is a developmental pattern. (4) AD pathology preferentially involves molecules critical for the regulation of modifications of synaptic connections, i.e. "morphoregulatory" molecules that are developmentally controlled, such as growth-inducing and growth-associated molecules, synaptic molecules, adhesion molecules, molecules involved in membrane turnover, cytoskeletal proteins, etc. (5) Life events that place an additional burden on the plastic capacity of the brain or that require a particularly high plastic capacity of the brain might trigger the onset of the disease or might stimulate a more rapid progression of the disease. In other words, they might increase the risk for AD in the sense that they determine when, not whether, one gets AD. (6) AD is associated with a reactivation of developmental programmes that are incompatible with a differentiated cellular background and, therefore, lead to neuronal death. From this hypothesis, it can be predicted that a therapeutic intervention into these pathogenetic mechanisms is a particular challenge as it potentially interferes with those mechanisms that at the same time provide the basis for "higher brain function".

Homeostatic biophasal conscious regulation

A new theory on consciousness is presented. According to our neuroscientific model, focal awareness is the result of neurophysiological patterns of voluntary or involuntary information, registration, storage and retrieval performed in accordance with organismic biphasal homeostatic rules and regulations that follow the demand-supply principle. The information-processing operation consists of three major elements: 1. Involuntary activated 'inherited schematic representation' (ISR) programs that monitor homeostatic negative feedback programs and remain inert during the storage period; 2. Voluntary activated 'acquired engram linkage' (AEL) programs that monitor the preferential self-efforts designed to maintain homeostasis and dynamic adaptational survival; this information remains fixed in the storage reservoir; and 3. Outer, nonselective sources of activation that derive from the assembly of the sensory information system. Consciousness is limited by the microneurostructural boundaries of 'conscious instrument panel' (CIP) needed to handle this unique biological experience. At any unit of time, the conscious subjectively identifies states of pleasure (first phase of homeostasis maintenance) or displeasure (second phase of homeostasis) which are associated with the alarm subsystem of the 'organismic defense system' (ODS).Thus, consciousness is a form of neurophysiological activity that excludes unconscious existence in order to monitor information. This model promotes our understanding of the biological essences of consciousness.

The stress-reaction process and the adaptive modification and reorganization of neuronal networks

On the basis of a comprehensive definition of the stress-reaction process (SRP), the neurobiological and psychological consequences of this process, which are elicited by either controllable or uncontrollable stress, are described. We conclude that controllable stress triggers the stabilization and facilitation of neuronal networks involved in the generation of appropriate patterns of appraisal and coping, whereas uncontrollable stress favors the extinction of inappropriate patterns and the reorganization of neuronal connections underlying certain inappropriate behaviors. Both controllable and uncontrollable stress-reaction processes are therefore inherent challenges to the development and essential prerequisites of the adaptation of an individual's behavior to the demands of the ever-changing external world. The overabundance, as well as the lack, of either kind of SRP may lead to different psychodevelopmental failures and psychiatric disturbances.