Brain-corticosteroid hormone dialogue: slow and persistent

The impact of daily affective touch on cortisol levels in institutionalized & fostered children

Institutionalized children are often deprived of affective touch. Such tactile deprivation often leads to constant stress, as measured by the levels of salivary cortisol. We report here the impact of an affective touch program, optimized to activate a specific population of unmyelinated mechanosensitive nerves in the skin called c-tactile afferents (CT) on stress resistance. Two populations of children (age 4-10) were recruited: (i) a cohort living in an orphanage and (ii) a fostered cohort. Both groups received the affective touch program daily for 10-15 min for 5-6 weeks. A cohort of age-matched children living in a family environment acted as a control group and did not receive any instructions for tactile stimulation. Salivary cortisol was collected at the beginning (T1) and at the end (T2) of the study in all three groups. For institutionalized and fostered children there was a significant improvement in the level of cortisol (p < 0.0001) between T1 and T2, which is manifested in the balancing cortisol levels: a decrease where it was elevated and an increase, where the critically low level testified to the distress of the child. Balancing cortisol levels is a process of recovery to normal values, which indicates the restoration of neurohumoral mechanisms of stress regulation. The effect of balancing cortisol levels was more pronounced in the group of fostered children compared to the group of orphanage children (p = 0.0326). The children in the control group had no significant differences.

Neural circuits for the adaptive regulation of fear and extinction memory

The regulation of fear memories is critical for adaptive behaviors and dysregulation of these processes is implicated in trauma- and stress-related disorders. Treatments for these disorders include pharmacological interventions as well as exposure-based therapies, which rely upon extinction learning. Considerable attention has been directed toward elucidating the neural mechanisms underlying fear and extinction learning. In this review, we will discuss historic discoveries and emerging evidence on the neural mechanisms of the adaptive regulation of fear and extinction memories. We will focus on neural circuits regulating the acquisition and extinction of Pavlovian fear conditioning in rodent models, particularly the role of the medial prefrontal cortex and hippocampus in the contextual control of extinguished fear memories. We will also consider new work revealing an important role for the thalamic nucleus reuniens in the modulation of prefrontal-hippocampal interactions in extinction learning and memory. Finally, we will explore the effects of stress on this circuit and the clinical implications of these findings.

Developmental and adult stress: effects of steroids and neurosteroids

In humans, exposure to early life adversity has profound implications for susceptibility to developing neuropsychiatric disorders later in life. Studies in rodents have shown that stress experienced during early postnatal life can have lasting effects on brain development. Glucocorticoids and sex steroids are produced in endocrine glands and the brain from cholesterol; these molecules bind to nuclear and membrane-associated steroid receptors. Unlike other steroids that can also be made in the brain, neurosteroids bind specifically to neurotransmitter receptors, not steroid receptors. The relationships among steroids, neurosteroids, and stress are multifaceted and not yet fully understood. However, studies demonstrating altered levels of progestogens, androgens, estrogens, glucocorticoids, and their neuroactive metabolites in both developmental and adult stress paradigms strongly suggest that these molecules may be important players in stress effects on brain circuits and behavior. In this review, we discuss the influence of developmental and adult stress on various components of the brain, including neurons, glia, and perineuronal nets, with a focus on sex steroids and neurosteroids. Gaining an enhanced understanding of how early adversity impacts the intricate systems of brain steroid and neurosteroid regulation could prove instrumental in identifying novel therapeutic targets for stress-related conditions.

Poverty, Caregiving, and HPA-Axis Activity in Early Childhood

The association between poverty and the activity of the hypothalamic pituitary adrenal (HPA) axis in early childhood is well established. Both ecological and transactional theories suggest that one way in which poverty may influence children's HPA-axis activity is through its effects on parents' behaviors, and over the past three decades a substantial literature has accumulated indicating that variations in these behaviors are associated with individual differences in young children's HPA-axis activity. More recent research suggests that non-parental caregiving behaviors are associated with HPA-axis activity in early childhood as well. Here we systematically review the literature on the association between both parental and non-parental caregiving behaviors in the context of poverty and the activity of the HPA-axis in early childhood. We conclude by noting commonalities across these two literatures and their implications for future research.

Childhood Sexual Abuse and Indicators of Immune Activity: A Systematic Review

Background: Childhood sexual abuse (CSA) is a prevalent subtype of early life stress associated with changes in immunological and neuroendocrine systems leading to inflammatory responses of the organism and increasing several inflammatory and immune markers. We aimed to conduct a systematic review concerning the association between CSA and indicators of immune activity. Methods: We conducted a search for articles in PubMed, Scopus, PsycINFO, and Web of Science, using the key words: ("Child sexual abuse" OR "childhood maltreatment" OR "sexual violence" OR "posttraumatic stress disorder" OR "rape") AND ("cytokines" OR "inflammatory markers" OR "interleukin" OR "tumor necrosis factor" OR "C-reactive protein"). PRISMA guidelines were used in order to improve the quality of this research, and MeSH terms were used in PubMed. Results: A total of 3,583 studies were found and, after application of the exclusion criteria, 17 studies were included in this review. Most studies reported an increase of inflammatory activity associated with the presence of early abuse. IL-6, TNF- α, and C-reactive protein were the most frequently analyzed markers and some studies showed higher levels in individuals that suffered CSA compared with controls, although the results were heterogeneous, as was the assessment of CSA, repeated trauma, and time of occurrence. It was not possible to perform a meta-analysis because the results were diversified. Conclusion: CSA is associated with changes in inflammatory markers levels. Improving the assessment of subtypes of trauma is important to further understand the complex correlations of CSA and its biological consequences such as psychiatric and physical illness in later life.

Effects of Neonatal Dexamethasone Exposure on Adult Neuropsychiatric Traits in Rats

The effects of early life stress in utero or in neonates has long-term consequences on hypothalamic-pituitary-adrenal (HPA) stress axis function and neurodevelopment. These effects extend into adulthood and may underpin a variety of mental illnesses and be related to various developmental and cognitive changes. We examined the potential role of neonatal HPA axis activation on adult psychopathology and dopamine sensitivity in the mature rat using neonatal exposure to the synthetic glucocorticoid receptor agonist and stress hormone, dexamethasone. We utilized a comprehensive battery of assessments for behaviour, brain function and gene expression to determine if elevated early life HPA activation is associated with adult-onset neuropsychiatric traits. Dexamethasone exposure increased startle reactivity under all conditions tested, but decreased sensitivity of sensorimotor gating to dopaminergic disruption–contrasting with what is observed in several neuropsychiatric diseases. Under certain conditions there also appeared to be mild long-term changes in stress and anxiety-related behaviours with neonatal dexamethasone exposure. Electrophysiology revealed that there were no consistent neuropsychiatric abnormalities in auditory processing or resting state brain function with dexamethasone exposure. However, neonatal dexamethasone altered auditory cortex glucocorticoid activation, and auditory cortex synchronization. Our results indicate that neonatal HPA axis activation by dexamethasone alters several aspects of adult brain function and behaviour and may induce long-term changes in emotional stress-reactivity. However, neonatal dexamethasone exposure is not specifically related to any particular neuropsychiatric disease.

Effects of age and maternal reactivity on the stress response of the pituitary-adrenocortical axis and the sympathetic nervous system in neonatal pigs

The study was conducted to investigate the adreno cortical capacity after injection of ACTH and the sensitivity of the pituitary and the adrenal to immobilization in neonatal pigs at different ages. Furthermore, the endocrine reactivity of the offspring was compared with the stress reactivity of their mothers. Four piglets were selected from each of six different litters and subjected to an immobilization test and an adrenal function test using synthetic ACTH1-24 at the ages of 7, 21 and 35 days; the six sows were also subjected to restraint and an ACTH stimulation test. Plasma β-endorphin, norepinephrine and epinephrine concentrations were measured in blood samples taken 2 min after restraint and cortisol concentrations were measured 60 min after ACTH administration. A highly sensitive adrenal response was demonstrated in both sows and piglets and adrenal reactivity showed also a considerable consistency over time within sows. In neonatal pigs, the cortisol response to ACTH was greatest on day 7 and decreased up to day 35. Plasma epinephrine and norepinephrine levels after the 2-min immobilization were also higher at day 7 compared with the other ages (P < 0·01). Piglets from sows, classified as high reacting according to their cortisol or epinephrine response, also showed significantly higher cortisol levels after ACTH challenge at all ages and significantly higher epinephrine levels after restraint at day 7 than piglets from low reacting sows. The results show an age-related change of pituitary-adrenocortical and sympatho-adrenomedullary responses in neonatal pigs and an absence of a stress hyporesponsive period at all ages studied. The results also indicate different levels of excitability in the offspring depending on the maternal stress reactivity.

Diurnal cortisol rhythm is associated with increased risky decision-making in older adults

Although past research has suggested a link between chronic stress and both physical and mental well-being in older adults, less is known about the degree to which neuroendocrine markers of stress are associated with higher-order cognitive processes such as decision-making. In a sample of healthy older adults (55-85 years), we tested the degree to which variation in the diurnal cortisol rhythm, an index of hypothalamic-adrenal-pituitary axis dynamics, was related to differences in risky decision-making. We found that diurnal cortisol fall predicted performance on the Cups Task, a risky decision-making task that independently tests risk-taking to achieve gains and risk-taking to avoid losses. For potential gains, we found that greater risk-taking was associated with lower diurnal cortisol fall, independent of age or sex of the participant. For risks to avoid potential losses, we found that lower diurnal fall was associated with suboptimal decision-making for men only. Compared with males with more typical diurnal fall, those who displayed lower diurnal fall made more risky choices and demonstrated lower sensitivity to the expected value of the risky choice. We integrate these results with the extant literature on the effects of stress on decision-making and cognitive aging.

Preliminary associations between childhood neglect, MIF, and cortisol: potential pathways to long-term disease risk

The study examined Hypothalamus-Pituitary-Adrenal (HPA) axis and inflammatory signaling in 206 youth with histories of prenatal drug exposure and self-reported histories of maltreatment. Youth with histories of severe neglect showed elevated levels of cortisol, the end product of the HPA axis, in comparison to youth with lower or minimal levels of neglect. Histories of severe neglect also were associated with increased levels of Macrophage Migration Inhibitory Factor (MIF), a cytokine known to be intricately involved in HPA axis regulation. Salivary MIF levels also were positively associated with youth age and prenatal drug exposure. These MIF and cortisol alterations may signal pathophysiological disruptions in the neuro-endocrine and immune systems, which may lead to trajectories of increased disease risk among vulnerable youth. Our findings also provide preliminary support for the validity and reliability of a noninvasive salivary assessment of MIF.

Effects of adverse early-life events on aggression and anti-social behaviours in animals and humans

We review the impact of early adversities on the development of violence and antisocial behaviour in humans, and present three aetiological animal models of escalated rodent aggression, each disentangling the consequences of one particular adverse early-life factor. A review of the human data, as well as those obtained with the animal models of repeated maternal separation, post-weaning social isolation and peripubertal stress, clearly shows that adverse developmental conditions strongly affect aggressive behaviour displayed in adulthood, the emotional responses to social challenges and the neuronal mechanisms activated by conflict. Although similarities between models are evident, important differences were also noted, demonstrating that the behavioural, emotional and neuronal consequences of early adversities are to a large extent dependent on aetiological factors. These findings support recent theories on human aggression, which suggest that particular developmental trajectories lead to specific forms of aggressive behaviour and brain dysfunctions. However, dissecting the roles of particular aetiological factors in humans is difficult because these occur in various combinations; in addition, the neuroscientific tools employed in humans still lack the depth of analysis of those used in animal research. We suggest that the analytical approach of the rodent models presented here may be successfully used to complement human findings and to develop integrative models of the complex relationship between early adversity, brain development and aggressive behaviour.

Early life trauma and attachment: immediate and enduring effects on neurobehavioral and stress axis development

Over half a century of converging clinical and animal research indicates that early life experiences induce enduring neuroplasticity of the HPA-axis and the developing brain. This experience-induced neuroplasticity is due to alterations in the frequency and intensity of stimulation of pups' sensory systems (i.e., olfactory, somatosensory, gustatory) embedded in mother-infant interactions. This stimulation provides "hidden regulators" of pups' behavioral, physiological, and neural responses that have both immediate and enduring consequences, including those involving the stress response. While variation in stimulation can produce individual differences and adaptive behaviors, pathological early life experiences can induce maladaptive behaviors, initiate a pathway to pathology, and increase risk for later-life psychopathologies, such as mood and affective disorders, suggesting that infant-attachment relationships program later-life neurobehavioral function. Recent evidence suggests that the effects of maternal presence or absence during this sensory stimulation provide a major modulatory role in neural and endocrine system responses, which have minimal impact on pups' immediate neurobehavior but a robust impact on neurobehavioral development. This concept is reviewed here using two complementary rodent models of infant trauma within attachment: infant paired-odor-shock conditioning (mimicking maternal odor attachment learning) and rearing with an abusive mother that converge in producing a similar behavioral phenotype in later-life including depressive-like behavior as well as disrupted HPA-axis and amygdala function. The importance of maternal social presence on pups' immediate and enduring brain and behavior suggests unique processing of sensory stimuli in early life that could provide insight into the development of novel strategies for prevention and therapeutic interventions for trauma experienced with the abusive caregiver.

Adolescent stress-induced epigenetic control of dopaminergic neurons via glucocorticoids

Environmental stressors during childhood and adolescence influence postnatal brain maturation and human behavioral patterns in adulthood. Accordingly, excess stressors result in adult-onset neuropsychiatric disorders. We describe an underlying mechanism in which glucocorticoids link adolescent stressors to epigenetic controls in neurons. In a mouse model of this phenomenon, a mild isolation stress affects the mesocortical projection of dopaminergic neurons in which DNA hypermethylation of the tyrosine hydroxylase gene is elicited, but only when combined with a relevant genetic risk for neuropsychiatric disorders. These molecular changes are associated with several neurochemical and behavioral deficits that occur in this mouse model, all of which are blocked by a glucocorticoid receptor antagonist. The biology and phenotypes of the mouse models resemble those of psychotic depression, a common and debilitating psychiatric disease.

Have studies of the developmental regulation of behavioral phenotypes revealed the mechanisms of gene-environment interactions?

This review addresses the recent convergence of our long-standing knowledge of the regulation of behavioral phenotypes by developmental experience with recent advances in our understanding of mechanisms regulating gene expression. This review supports a particular perspective on the developmental regulation of behavioral phenotypes: That the role of common developmental experiences (e.g. maternal interactions, peer interactions, exposure to a complex environment, etc.) is to fit individuals to the circumstances of their lives within bounds determined by long-standing (evolutionary) mechanisms that have shaped responses to critical and fundamental types of experience via those aspects of gene structure that regulate gene expression. The phenotype of a given species is not absolute for a given genotype but rather variable within bounds that is determined by mechanisms regulated by experience (e.g. epigenetic mechanisms). This phenotypic variation is not necessarily random, or evenly distributed along a continuum of description or measurement, but often highly disjointed, producing distinct, even opposing, phenotypes. The potentiality for these varying phenotypes is itself the product of evolution, the potential for alternative phenotypes itself conveying evolutionary advantage. Examples of such phenotypic variation, resulting from environmental or experiential influences, have a long history of study in neurobiology, and a number of these will be discussed in this review: neurodevelopmental experiences that produce phenotypic variation in visual perception, cognitive function, and emotional behavior. Although other examples will be discussed, particular emphasis will be made on the role of social behavior on neurodevelopment and phenotypic determination. It will be argued that an important purpose of some aspects of social behavior is regulation of neurobehavioral phenotypes by experience via genetic regulatory mechanisms.

Stress-induced dynamic routing of hippocampal connectivity: a hypothesis

Recent observations have caused a drastic shift in the conception of the hippocampus as a homogeneous structure that subserves cognitive functions, either spatial maps or short term episodic memory, to a structure that is associated with both cognitive and emotional functions. In fact, the assignment of cognitive functions to the hippocampus is restricted to its dorsal sector. In contrast, the ventral hippocampus (VH) appears to be associated with control of behavioral inhibition, stress and emotional memory, but not with strictly cognitive functions. Curiously, the VH but not the dorsal hippocampus (DH) is associated with the development of affective disorders. In line with these collective observations, we and others have found that the ability to evoke a sustained long term potentiation (LTP), a cellular correlate of learning and memory, is much lower in the VH compared to the DH. Strikingly, acute stress as well as direct exposure to corticosterone affect DH and VH in an opposite manner; causing facilitation of LTP in the VH and its suppression in the DH. This double dissociative action results from activation of different steroid receptor species in the DH and VH. Since the DH and VH differ in efferent connectivity, and since the strength of LTP can be considered as an indicator of strength of synaptic connectivity, these results suggest that stress regulates the routes by which the hippocampus is functionally linked to the rest of the brain such that under stress, the ventral route to the amygdala is enabled while the dorsal route to the neocortex is suppressed. This selective routing may underlie the complex outcome of stress on hippocampal and amygdala physiology and behavior.

Potential programming of dopaminergic circuits by early life stress

Stress and high levels of glucocorticoids during pre- and early postnatal life seem to alter developmental programs that assure dopaminergic transmission in the mesolimbic, mesocortical, and nigrostriatal systems. The induced changes are likely to be determined by the ontogenetic state of development of these brain regions at the time of stress exposure and their stability is associated with increased lifetime susceptibility to psychiatric disorders, including drug addiction. This article is intended to serve as a starting point for future studies aimed at the attenuation or reversal of the effects of adverse early life events on dopamine-regulated behaviors.

Threat-detection in child development: an evolutionary perspective

Evidence for developmental aspects of fear-targets and anxiety suggests a complex but stable pattern whereby specific kinds of fears emerge at different periods of development. This developmental schedule seems appropriate to dangers encountered repeatedly during human evolution. Also consistent with evolutionary perspective, the threat-detection systems are domain-specific, comprising different kinds of cues to do with predation, intraspecific violence, contamination-contagion and status loss. Proper evolutionary models may also be relevant to outstanding issues in the domain, notably the connections between typical development and pathology.

Early life stress, the development of aggression and neuroendocrine and neurobiological correlates: what can we learn from animal models?

Early life stress (child and adolescent abuse, neglect and trauma) induces robust alterations in emotional and social functioning resulting in enhanced risk for the development of psychopathologies such as mood and aggressive disorders. Here, an overview is given on recent findings in primate and rodent models of early life stress, demonstrating that chronic deprivation of early maternal care as well as chronic deprivation of early physical interactions with peers are profound risk factors for the development of inappropriate aggressive behaviors. Alterations in the hypothalamic-pituitary-adrenocortical (HPA), vasopressin and serotonin systems and their relevance for the regulation of aggression are discussed. Data suggest that social deprivation-induced inappropriate forms of aggression are associated with high or low HPA axis (re)activity and a generally lower functioning of the serotonin system in adulthood. Moreover, genetic and epigenetic modifications in HPA and serotonin systems influence the outcome of early life stress and may even moderate adverse effects of early social deprivation on aggression. A more comprehensive study of aggression, neuroendocrine, neurobiological and (epi)genetic correlates of early life stress using animal models is necessary to provide a better understanding of the invasive aggressive deficits observed in humans exposed to child maltreatment.

Differential modulation of long-term depression by acute stress in the rat dorsal and ventral hippocampus

The ventral hippocampus (VH) was recently shown to express lower-magnitude long-term potentiation (LTP) than the dorsal hippocampus (DH). An exposure to acute stress reversed this difference, and VH slices from stressed rats expressed larger LTP than controls, whereas LTP in the DH was suppressed by stress. We have now used long-term depression (LTD)-generating trains of stimulation to examine whether this differential LTP reflects a genuine difference in synaptic modifiability between the two sectors of the hippocampus. Surprisingly, slices of DH and VH express similar magnitudes of LTD. However, while prior stress enhanced LTD in the DH, it actually converted LTD to slow-onset, robust LTP in the VH. These two effects of stress on LTD were blocked by glucocorticosterone receptor (GR) and mineralocorticosterone receptor (MR) antagonists, respectively. Acute exposure of slices to a GR agonist dexamethasone facilitated LTD in slices of both DH and VH, while activation of MRs by aldosterone converted LTD to LTP in both regions. Thus, differential activation of the two species of corticosterone receptors determines the ability of the two sectors of the hippocampus to undergo plastic changes in response to LTD-inducing stimulation.

Early experience and the development of stress reactivity and regulation in children

Children who spend early portions of their lives in institutions or those maltreated in their families of origin are at risk for developing emotional and behavioral problems reflecting disorders of emotion and attention regulation. Animal models may help explicate the mechanisms producing these effects. Despite the value of the animal models, many questions remain in using the animal data to guide studies of human development. In 1999, the National Institute of Mental Health in the United States funded a research network to address unresolved issues and enhance translation of basic animal early experience research to application in child research. Professor Seymour Levine was both the inspiration for and an active member of this research network until his death in October of 2007. This review pays tribute to his legacy by outlining the conceptual model which is now guiding our research studies.

Differential corticosteroid modulation of inhibitory synaptic currents in the dorsal and ventral hippocampus

Corticosterone has been known to mediate the effects of stress on cognitive functions associated with the hippocampus. Acting at mineralocorticosteroid receptors (MRs) and glucocorticosteroid receptors (GRs), corticosterone exerts several effects in the hippocampus and elsewhere. Assuming that there are major functional differences between the dorsal hippocampus (DH) and ventral hippocampus (VH), and that these may be regulated by local interneurons, we analyzed the action of corticosterone on inhibitory synaptic currents in patch-clamped pyramidal neurons, recorded in acute slices of DH and VH. Corticosterone, through activation of MRs, reduced the frequency of spontaneous IPSCs in VH but not in DH neurons, and markedly suppressed paired-pulse facilitation of evoked inhibitory synaptic currents. These effects were mimicked by aldosterone, an MR agonist, and were blocked by an MR antagonist. In contrast, corticosterone caused an increase in the magnitude of IPSCs in both the DH and VH via its activation of GRs. This effect was mimicked by a GR agonist, dexamethasone, which produced a slow-onset, large potentiation reaching a peak within 45-60 min after onset of perfusion, and was blocked by a GR antagonist. The amplitude of mIPSCs was markedly increased by the GR agonist, indicating a synaptic locus of effect. These results indicate that corticosterone has a dual action, which may underlie the differential functional effects of stress hormones in the DH and VH.

The effect of 'two hit' neonatal and young-adult stress on dopaminergic modulation of prepulse inhibition and dopamine receptor density

BACKGROUND AND PURPOSE

A combination of early neurodevelopmental insult(s) and young-adult stress exposure may be involved in the development of schizophrenia. We studied prepulse inhibition (PPI) regulation in rats after an early stress, maternal deprivation, combined with a later stress, simulated by chronic corticosterone treatment, and also determined whether changes in brain dopamine receptor density were involved.

EXPERIMENTAL APPROACH

Rats were subjected to either 24 h maternal deprivation on postnatal day 9, corticosterone treatment from 8 to 10 weeks of age, or both. At 12 weeks of age, the rats were injected with 0.1, 0.3 or 1.0 mg.kg(-1) of apomorphine or 0.5 or 2.5 mg.kg(-1) of amphetamine and PPI was determined using automated startle boxes. Dopamine D(1) and D(2) receptor levels were assessed in the nucleus accumbens and caudate nucleus using receptor autoradiography.

KEY RESULTS

Young-adult treatment with corticosterone resulted in attenuated disruption of PPI by apomorphine and amphetamine. In some rats, maternal deprivation resulted in reduced baseline PPI which added to the effect of corticosterone treatment. There was no down-regulation of dopamine D(1) or D(2) receptors.

CONCLUSIONS AND IMPLICATIONS

These results confirm and extend our finding of an inhibitory interaction of developmental stress on dopaminergic regulation of PPI. No corresponding changes in dopamine receptor density were observed in brain regions with a major involvement in PPI regulation, suggesting long-lasting desensitization of dopamine receptor signalling or indirect changes in PPI regulation.

Early care experiences and HPA axis regulation in children: a mechanism for later trauma vulnerability

Post-traumatic stress disorder (PTSD) is associated with functional abnormalities of the hypothalamic-pituitary-adrenocortical (HPA) axis. Emerging evidence suggests that failures in social regulation of the HPA axis in young children manifested as neglectful or abusive care may play a role in shaping cortico-limbic circuits involved in processing experiences threatening experiences encountered later in life. Low cortisol levels, particularly near the peak of the diurnal rhythm, have been reported in abused, neglected and deprived children. Thus early imprinting effects of parenting quality on the HPA system regulation may be one of the mechanisms causing heightened risk of PTSD in responses to later trauma. However there is also evidence that the altered patterns of cortisol production seen in the context of early adverse care are not permanent, and remit once the care children receive improves. What awaits study is whether periods of atypical cortisol levels and altered HPA function early in life, even if transient, impact brain development in ways that heighten vulnerability to PTSD in response to traumas experienced later.

Early deprivation and home basal cortisol levels: a study of internationally adopted children

Animal studies reveal that early deprivation impairs regulation of the hypothalamic-pituitary-adrenocortical (HPA) axis, potentially increasing vulnerability to stressors throughout life. To examine early deprivation effects on basal HPA axis activity in humans, basal cortisol levels were examined in 164 internationally adopted children who had experienced varying degrees of preadoption deprivation. Duration of institutional care, age at adoption, and parent ratings of preadoption neglect indexed a latent factor of Deprived Care. Adoption measures of height and weight standardized to World Health Organisation norms indexed a latent factor of Growth Delay that was viewed as another reflection of deprivation. Cortisol samples were collected 3.3-11.6 years postadoption (Md = 7.3 years) at home on 3 days approximately 30 min after wakeup and before bedtime. Both early a.m. levels and the decrease in cortisol across the day were examined. A structural equation model revealed that preadoption Deprived Care predicted Growth Delay at adoption and Growth Delay predicted higher morning cortisol levels and a larger diurnal cortisol decrease.

Attenuated disruption of prepulse inhibition by dopaminergic stimulation after maternal deprivation and adolescent corticosterone treatment in rats

The development of schizophrenia may include an early neurodevelopmental stress component which increases vulnerability to later stressful life events, in combination leading to overt disease. We investigated the effect of an early stress, in the form of maternal deprivation, combined with a later stress, simulated by chronic periadolescent corticosterone treatment, on behaviour in rats. Acute treatment with apomorphine caused disruption of prepulse inhibition (PPI) in controls and in rats that had undergone either maternal deprivation or corticosterone treatment, but was surprisingly absent in rats that had undergone the combined early and late stress. Amphetamine treatment significantly disrupted PPI in both non-deprived groups, but was absent in both maternally deprived groups. The serotonin-1A receptor agonist, 8-OH-DPAT, induced a significant disruption of PPI in all groups. Amphetamine-induced locomotor hyperactivity was similar in all groups. These results show an inhibitory interaction of early stress, caused by maternal deprivation, combined with 'adolescent' stress, simulated by corticosterone treatment, on dopaminergic regulation of PPI. The altered effects of apomorphine and amphetamine could indicate differential changes in dopamine receptor signalling leading to functional desensitisation, or altered modulation of sensory gating in the nucleus accumbens by limbic structures such as the hippocampus.

Striking variations in corticosteroid modulation of long-term potentiation along the septotemporal axis of the hippocampus

The ability to express long-term potentiation (LTP) of reactivity to afferent stimulation along the septotemporal axis was explored in transverse rat hippocampal slices. The ventral pole of the hippocampus (VH) was found to be much impaired in ability to express LTP compared with the rest of the hippocampus. An exposure to acute stress before the rat was killed reversed this trend, and slices from VH now expressed a large LTP, whereas in the rest of the hippocampus, it was much suppressed. The enhanced LTP in VH was mediated by activation of a mineralocorticoid receptor (MR), whereas the suppressed LTP was mediated by activation of a glucocorticoid receptor, and indeed selective agonists of the respective steroid receptors mimicked the effects of stress, whereas selective antagonists blocked them. The MR-enhanced LTP in VH was not mediated by activation of the NMDA receptor but by enhancement of voltage-gated calcium channels. Because the VH has an unique efferent system to the hypothalamus, these results indicate that stress may activate this system while suppressing the ability of the rest of the hippocampus to express plastic properties under stressful conditions.

The neurobiology of stress and development

Stress is a part of every life to varying degrees, but individuals differ in their stress vulnerability. Stress is usefully viewed from a biological perspective; accordingly, it involves activation of neurobiological systems that preserve viability through change or allostasis. Although they are necessary for survival, frequent neurobiological stress responses increase the risk of physical and mental health problems, perhaps particularly when experienced during periods of rapid brain development. Recently, advances in noninvasive measurement techniques have resulted in a burgeoning of human developmental stress research. Here we review the anatomy and physiology of stress responding, discuss the relevant animal literature, and briefly outline what is currently known about the psychobiology of stress in human development, the critical role of social regulation of stress neurobiology, and the importance of individual differences as a lens through which to approach questions about stress experiences during development and child outcomes.

Transcriptional regulation of intronic calcium-activated potassium channel SK2 promoters by nuclear factor-kappa B and glucocorticoids

Small-conductance Ca(2+)-activated K(+) channels (SK) of the SK2 subtype are widely expressed in the central nervous system where they contribute to the control of neuronal excitability. Two SK2 isoforms, SK2-S and SK2-L, the latter representing an N-terminally extended protein of SK2-S, are expressed in similar patterns in the brain. However, our understanding of mechanisms by which the expression of SK2 is regulated is limited. We identified one functional glucocorticoid response element (GRE) at position -2248 bp and two functional nuclear factor-kappB (NF-kappaB) response elements at positions -1652 and -1586 bp in the SK2-S promoter. An increase in SK2-S promoter activity was observed in PC12 cells transiently transfected with a wild-type SK2-S promoter-luciferase reporter gene construct and treated with aldosterone or dexamethasone. The mineralocorticoid receptor (MR) antagonist spironolactone or the glucocorticoid receptor (GR) antagonist mifepristone fully inhibited aldosterone or dexamethasone activation of the SK2-S promoter, respectively. SK2-S promoter activity was also induced by the cell-permeable ceramide analog, N-acetylsphingosine (C2-ceramide). Antisense oligonucleotides directed to NF-kappaB p65 or p50 suppressed SK2-S transcription induced by C2-ceramide. Deletion studies showed that only the -1586 bp NF-kappaB binding site was necessary for maximum C2-ceramide response. Finally, we showed that activation of GRs but not of MRs repressed the NF-kappaB-mediated induction of SK2-S transcription. These findings suggest a possible transcriptional cross talk between GRs and NF-kappaB in the intronic promoter regulation of SK2-S channel gene transcription.

Age-related differences in glucocorticoid receptor mRNA levels in the human brain

Glucocorticoids and their receptors (GRs) are implicated in dynamic cognitive and neuroendocrine processes mediated by the prefrontal cortex and hippocampus. Additionally, a primary defect in forebrain GR levels can mimic symptoms of depression. We hypothesized that changes in GR mRNA levels may occur in the human brain across the life span thus positioning GR to differentially influence behavior and disease susceptibility. Following in situ hybridization with a riboprobe for human GR mRNA, we employed quantitative film autoradiography to measure expression levels in the prefrontal cortex and hippocampus in five age groups (infants, adolescents, young adults, adults, and aged) and in primary visual and visual association cortices for comparison. We detected a main effect of age group on cortical, but not hippocampal GR mRNA, with greater cortical expression in adolescents and adults than in infants or the aged. Increased GR mRNA in prefrontal cortex during adolescence and adulthood suggests that human GR-mediated forebrain regulation of cognition and the neuroendocrine stress response may be more salient during late maturation and at maturity.

Maternal deprivation increases vulnerability to morphine dependence and disturbs the enkephalinergic system in adulthood

Maternal deprivation can trigger long-lasting molecular and cellular modifications in brain functions and might facilitate the appearance of pathogenic behaviors. This study focuses on the vulnerability to develop morphine dependence in adult rats that were separated from their mother and littermates for 3 h per day for 14 d after birth and examines the adaptive changes in the enkephalinergic pathways. Place-preference conditioning was observed with 2 mg/kg morphine in deprived rats, whereas 5 mg/kg morphine was necessary to induce conditioning in nondeprived animals. A prolonged morphine conditioning was shown in deprived rats. A strong increase in oral morphine self-administration behavior and preference was observed in deprived rats. Only a very slight increase in preference for sucrose solution, a more ethological reinforcer known to interact with the opioid system, was shown in deprived rats. These results indicate that this postnatal environment change leads to a hypersensitivity to the reinforcing properties of morphine and to the development of morphine dependence. A significant decrease in preproenkephalin mRNA expression was observed in the nucleus accumbens and the caudate-putamen nucleus of deprived rats. The basal extracellular levels of the Met-enkephalin-like immunoreactivity in the nucleus accumbens were significantly lower in deprived rats when compared with nondeprived animals, whereas no change in mu-opioid receptor binding occurred. These results strongly support that maternal deprivation leads to a basal hypoactivity of the enkephalinergic system and hypersensitivity to morphine effects. Together, our results suggest that maternal deprivation in pups likely represents a risk factor for morphine dependence in adult rats.

Maternal deprivation increases behavioural reactivity to stressful situations in adulthood: suppression by the CCK2 antagonist L365,260

RATIONALE

Maternal deprivation can result in long-term impairment of neuronal functions and in the development of long-lasting behavioural disorders.

OBJECTIVES

This study analysed the effects of a selective cholecystokinin-2 (CCK2) antagonist, 3R-(+)-N-(2,3-dihydro-1methyl-2-oxo-5-phenyl-1H-1,4-benzodiazepin-3yl)-N'-(3-methyl phenyl) urea (L365,260), in anxiety- and stress-related behaviours of adult rats that were deprived (D) from their mother and littermates for 3 h everyday during 14 days after birth.

METHODS

The behaviour was studied in actimeter, in open field and after food and water deprivation. Corticosterone plasma levels were quantified after food and water deprivation. The effects of L365,260 were studied in the behavioural changes observed in D rats.

RESULTS

No differences in circadian motor activity between non-deprived (ND) and D rats were observed. D rats showed a 50% decrease in their number of visits to the central (aversive) part of the open field compared to ND rats. This effect was suppressed by L365,260. After 20 h of food and water deprivation, an increase in plasma corticosterone was observed in D and ND rats. However, the raise of corticosterone secretion in D rats was dramatically increased (300%) compared to ND rats, indicating a hypersensitised state revealed by this stressful situation. Consumption of sucrose solution (1%) was higher for D rats than for ND rats after food and water deprivation. Sucrose consumption returned to control values following L365,260 treatment.

CONCLUSIONS

These results suggest that maternal deprivation led to an increase in anxiety and stress reactivity in adulthood. We propose that these long-lasting changes are partly dependent on CCKergic transmission involving the activation of CCK2 receptors.

Delayed effects of early stress on hippocampal development

Early maternal separation has been shown in animal models to produce enduring morphological changes in the hippocampus and other brain structures, which may not become evident until adulthood. Postnatally, the trajectory of overproduction and pruning of axons, dendrites, synapses and receptors shapes the brain between puberty and adulthood. The objective of the study was to ascertain whether this normal trajectory was affected by repeated maternal separation. Rat pups were separated from their mother for 4 h a day between postnatal days 2 and 20 (ISO group), and compared to rat pups that remained with their mother in the animal facilities (AFR group) and were exposed to minimal handling. Immunoreactivity to synaptophysin was quantified in the hippocampus CA1 and CA3, amygdala, and prefrontal cortex using optical densitometry (OD) at 25, 40, 60, 80, and 100 days in male and female rats. Synaptophysin OD increased dramatically in CA1 and CA3 between 25 and 60 days in the AFR group and fell by the same degree between 60 and 100 days, showing the expected sequence of overproduction and pruning. No difference between groups in synaptophysin OD was observed at 25 and 40 days. However, at day 60 synaptophysin was 34-36% lower in CA1 and CA3 of the ISO group, and remained 24-26% lower at 100 days. Early isolation produced no enduring reduction in synaptophysin OD in the amygdala or prefrontal cortex. Overall, these results suggest that early maternal separation produced a regionally specific delayed effect on the structure of the hippocampus by attenuating rates of synaptic development.

Genetic background, nature of event, and time of exposure to event direct the phenotypic expression of a particular genotype

The aim of this study was to investigate the differential long-term after-effects on the apomorphine-susceptibility in the apomorphine-susceptible (APO-SUS) and apomorphine-unsusceptible (APO-UNSUS) rats of either a saline injection (a mild stressor) or a clonidine-injection (a moderate stressor) applied around the onset of the stress-hypo-responsive-period (SHRP) on postnatal day (PND) 2, 4, 6 or 9. The present study shows that an injection of saline on PND 2 decreases the apomorphine-induced gnawing score in adult APO-SUS rats, but increases this score in adult APO-UNSUS rats; clonidine given on this day has no effect. An injection of saline on PND 4 decreases the apomorphine score in adult APO-SUS rats, but has no effect in adult APO-UNSUS rats. An injection of clonidine on PND 4 counteracts the long-term after-effects of a saline injection on this PND in adult APO-SUS rats, but has no effect in adult APO-UNSUS rats. Finally, an injection of clonidine on PND 9 has no effect on the apomorphine score in adult APO-SUS rats, but increases this score in adult APO-UNSUS rats; saline given on this day has no effect. It is concluded that the long-term after-effects of early postnatal stressors depend on the interrelationship between, rather than the separate impact of, the genetic background of the rat, the nature of the event, and time of exposure to the event, thereby implying that these factors direct the phenotypic expression of a particular genotype at adult age.

Genomic and non-genomic effects of glucocorticoids on aggressive behavior in male rats

An increasing body of evidence suggests that glucocorticoids--besides their well-known genomic effects--can affect neuronal function via mechanisms that do not involve the genome. Data obtained mainly in amphibians and birds suggest that such mechanisms play a role in the control of behavior. Acute glucocorticoid treatments increase aggressive behavior in rats, but the mechanism of action has not been investigated to date. To clarify the issue, we have assessed the aggressiveness of male rats after treating them with the corticosterone synthesis inhibitor metyrapone, corticosterone, and the protein synthesis inhibitor cycloheximide. Metyrapone applied intraperitoneally (i.p.) decreased the aggressiveness of residents faced with smaller opponents. Corticosterone administered i.p. 20 or 2 min before a 5-min encounter abolished these changes irrespective of the delay of behavioral testing. Thus, the effects of glucocorticoids on aggressive behavior occurred in less than 7 min (the delay and duration of testing taken together), and lasted more than 25 min. Corticosterone applied centrally (infused into the right lateral ventricle) also stimulated aggressive behavior rapidly, which shows that the effect was centrally mediated. The protein synthesis inhibitor cycloheximide did not affect the aggression-promoting effects of corticosterone when the hormone was injected 2 min before the aggressive encounter. Surprisingly, however, the effects were completely abolished when the hormone was injected 20 min before the encounter. These data suggest that glucocorticoids rapidly increase aggressive behavior via non-genomic mechanisms. In later phases of the aggressive encounter, aggressive behavior appears to be stimulated by genomic mechanisms.

Manipulations during the second, but not the first, week of life increase susceptibility to cocaine self-administration in female rats

We compared the effects of manipulations during week 1 vs week 2 of life on the propensity to self-administer cocaine. Pups received daily subcutaneous saline injections, were handled briefly, or remained undisturbed during their respective treatment periods. Animals handled during the second week of life exhibited increased locomotor response to novelty when tested on postnatal day (PND) 48, compared to all other groups. Rats were implanted with jugular catheters on PND 70 and then given the opportunity to self-administer (0.125 mg/kg/infusion) cocaine for 5 consecutive days (1 h sessions). The dose was then raised to 0.25 mg/kg/infusion for 5 days and to 0.5 mg/kg/infusion for the final 5 days of testing. Only animals manipulated during the second week of life acquired drug-taking behavior. These effects were both stimulus- and gender-specific. Females handled during the second week of life acquired cocaine self-administration (SA) at the lowest dose, and females injected during the second week of life acquired at the intermediate dose. Males injected during the second week of life showed a similar, but more variable, drug-taking pattern. There were no group differences in serum corticosterone response to novelty, although relative to undisturbed animals and those manipulated in the first week of life, female animals manipulated during the second week of life had lower basal expression of hippocampal glucocorticoid receptor mRNA in adulthood. We conclude that the second week of life in the rodent is a sensitive period during which manipulations result in a more vulnerable phenotype for the acquisition of cocaine SA.

[Neurobiological impact of separating mothers from newborns in rodents]

Numerous animal models of early stress are currently being developed because early stress results in long-term disruptions of neuronal functions and the development of long-term behavioral disorders. These models should allow to study the concept of vulnerability applied to psychiatric disorders. The fundamental importance of the bond between the mother and the offsprings, in all mammalian species, for the development of the new-born, point to the great interest of animal models of mother/pups separation. Long periods of deprivation tend to result in anxiety, depressive-like behaviors and drug addiction in adult rats. Neurobiological studies have shown that several neuronal systems, in particular neuropeptidergic systems in the limbic structures of the brain, are disrupted, possibly due to the effects of early stress on neurodevelopment. Models evaluating the impact of early environmental factors should help to improve the prevention and prediction of psychiatric disorders and to develop new therapeutic strategies.

Impact of maternal deprivation on brain corticotropin-releasing hormone circuits: prevention of CRH receptor-2 mRNA changes by desipramine treatment

Corticotropin-releasing hormone (CRH) acts within the brain and pituitary to coordinate the overall endocrinological and behavioral stress response. From postnatal day (PND) 4 to 14, the infant rat displays minimal adrenal response to mild stress. However, maternal deprivation alters the pituitary-adrenal system such that the infants become responsive to specific stimuli. We hypothesized that maternal deprivation would also affect CRH brain circuits. Since tricyclic antidepressants have been shown to decrease the adrenal response to stress in adult rats, we hypothesized that CRH-related changes induced by maternal deprivation would be prevented by this treatment. Thus, we investigated CRH-related molecules on animals that were maternally deprived on PND 13 compared with nondeprived animals. We found that maternal deprivation caused alterations in the gene expression of both CRH receptors (CRHr) 1 and 2 in specific brain regions, and that some of these effects were augmented by chronic isotonic saline injections. There was a significant increase in CRH, CRHr1, and r2 mRNA in the cortex. In amygdala, CRHr1 and r2 mRNAs were decreased. CRHr2 mRNA was also decreased in the ventromedial nucleus of the hypothalamus, whereas an increase was detected in the hippocampal pyramidal cells. One week of desipramine (DES) administration preceding the maternal deprivation event prevented all the deprivation-induced changes in CRHr2 mRNA, regardless of the direction of the original change. We also found that chronic injection treatments enhanced the adrenocortical response and improved the efficiency of negative feedback in maternal deprivation animals. These results demonstrate that maternal deprivation elicits modifications of CRH brain circuits in a site-specific manner, and that the regulation of CRHr2 gene expression is mediated by mechanisms different from those involved with the modulation of CRHr1 in the infant rat.

Long-term neurobehavioural impact of the postnatal environment in rats: manipulations, effects and mediating mechanisms

The major characteristics of the postnatal environment of the rat pup are its mother and littermates. The pup, which is poorly developed at birth, matures rapidly in this environment, and regulates the behaviour and physiology of the dam and littermates, as well as vice versa. The study of the impact of the rat's postnatal environment on its long-term neurobehavioural development is of fundamental importance. In fact, it is one of the major examples--at the interface of the biological, social and medical sciences--of animal models for the study of the interaction between the environment and the genome in both the acute and chronic regulation of the phenotype. Specific experimental manipulations of the rat postnatal environment have been demonstrated to exert robust and marked effects on neurobiological, physiological and behavioural phenotypes in adulthood. In the present review we present some of the major findings, including some original data, and discuss what these existing data can tell us about the long-term neurobehavioural effects of the postnatal environment in rats, the external and internal mechanisms that mediate these effects, and the most appropriate directions for future basic and applied research in this area.

Maternal behavior in F344/N and LEW/N rats. Effects on carrageenan-induced inflammatory reactivity and body weight

Inbred Fischer (F344/N) and Lewis (LEW/N) rats differ on a myriad of behavioral and physiological endpoints, such as inflammatory, startle and drug responsivity. These differences point to underlying genetic differences between the strains. However, genetic models of hypertension have shown the importance of the maternal environment in the development of high blood pressure, suggesting that maternal influences might also play a role in adult phenotypes of the LEW/N and F344/N strains. This was tested in the present series of experiments in which the effects of crossfostering on carrageenan-induced inflammation and on body weight were examined in the two strains. Following the demonstration that the two strains differed in maternal behavior (Experiment 1), which was independent of the pup being reared (Experiment 2), crossfostered and in-fostered pups from the LEW/N and F344/N strains were injected with carrageenan (at 60 days of age) and subsequently assessed for the accumulation of exudate in response to the injection. Body weights were also monitored from birth through 60 days of age. Although crossfostering affected body weight of the two strains, specifically, reducing weights in LEW/N pups reared by F344/N dams and increasing weights of F344/N pups reared by LEW/N dams, crossfostering did not affect inflammatory reactivity to carrageenan. Specifically, LEW/N pups had a greater level of exudate than F344/N pups, independent of the conditions under which they were reared, suggesting that differences in the inflammatory response between these two strains are under a high degree of genetic control. These results were discussed in terms of genetic factors mediating the early form of immune reactivity induced by carrageenan.

Psychiatric disorders associated with Cushing's syndrome. Epidemiology, pathophysiology and treatment

Cushing's syndrome is caused by a chronic excess of glucocorticoids. A number of psychiatric and psychological disturbances may be associated with the condition, regardless of its aetiology. Major depression is the most common comorbid disorder. Other psychopathological aspects of Cushing's syndrome in adults include mania, anxiety disorders and cognitive dysfunction. The presence of depression connotes a severe clinical presentation and, in patients with hypothalamic-pituitary forms of Cushing's syndrome, is prognostically useful. Inhibitors of corticosteroid production (e.g. ketoconazole, metyrapone, aminoglutethimide), rather than antidepressant drugs, are generally successful in relieving depressive symptoms, as well as other disabling symptoms. These drugs can be used to control symptoms prior to surgical treatment of Cushing's syndrome. Long-standing hypercortisolism may cause some degree of irreversible pathological damage and induce highly individualised affective responses based on each patient's psychological assets and liabilities. As a result, upon normalisation of cortisol levels, treatment may still be required, and should encompass both psychotherapeutic strategies (particularly cognitive-behavioural therapies that have been found to be effective in affective disorders) and psychotropic drug treatment [antidepressants such as tricyclic agents and selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitors]. In patients with severe anxiety, benzodiazepines (e.g. clonazepam in small doses) may also be helpful.

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.

Social regulation of the cortisol levels in early human development

Other papers in this special edition provide evidence to implicate activity of the limbic hypothalamic-pituitary-adrenocortical (L-HPA) system in the etiology of drug and alcohol abuse. Furthermore, studies in rodents and primates suggest that responsivity and regulation of this system later in life may be shaped by social experiences during early development. Cortisol is the major hormonal product of the L-HPA system in humans. Although it provides only a partial understanding of the activity of this neuroendocrine axis, its regulation may bear importantly on human growth and development. We review developmental studies of cortisol and behavior in human children, birth to approximately 5 years of age. We describe the development of social buffering of cortisol responses that produces a functional analogue of the rodent stress hyporesponsive period by the time children are about 12 months of age. We further describe the sensitivity of cortisol activity to variations in care quality among infants and toddlers, along with evidence that children with negative emotional temperaments may be most likely to exhibit elevations in cortisol under conditions of less than optimal care. Finally, the few studies of cortisol activity under conditions of neglectful and abusive care of young children are considered, noting that these often have yielded evidence of reduced rather than increased cortisol levels.

Novel expression of neuropeptide Y (NPY) mRNA in hypothalamic regions during development: region-specific effects of maternal deprivation on NPY and Agouti-related protein mRNA

During development there is novel expression of NPY mRNA in the dorsomedial hypothalamic nucleus (DMH) and perifornical region (PFR), in addition to the arcuate nucleus (ARH). Furthermore, NPY mRNA levels peak in all regions on postnatal d 16 (P16) and decrease to adult levels by P30. The purpose of the present study was to determine whether NPY and agouti-related protein (AGRP) mRNA expression in the different hypothalamic regions on P11 and P16 are similarly affected by fasting. An examination of the full rostral to caudal extent of the hypothalamus revealed two additional regions displaying novel NPY mRNA expression, the parvocellular division of the paraventricular nucleus (PVH) and lateral hypothalamus (LH). Maternal deprivation for 36 h, used to bring about a fast, similarly increased (23-29%) NPY and AGRP mRNA expression in the ARH on P11 and P16. In contrast, NPY expression in the DMH and PFR were significantly decreased (19-30% and 48-53%, respectively), whereas NPY mRNA levels in the PVH and LH were not altered by this treatment. The increase in NPY and AGRP mRNA expression in the ARH in response to maternal deprivation suggests that these neuronal populations respond to signals of energy balance. In contrast, NPY expression in the DMH, PFR, PVH, and LH is differentially regulated by maternal deprivation or other factors associated with maternal separation.

Non-genomic effects of glucocorticoids in the neural system. Evidence, mechanisms and implications

Complementing the classical concept of genomic steroid actions, here we (i) review evidence showing that important neural effects of glucocorticoids are exerted by non-genomic mechanisms; (ii) describe known mechanisms that may underlie such effects; (iii) summarize the functions and implications of non-genomic mechanisms and (iv) outline future directions of research. The role of non-genomic mechanisms is to shape the response of the organism to challenges that require a substantial reorganization of neural and somatic functions and involve massive behavioral shifts. Non-genomic effects may (i) prepare the cell for subsequent glucocorticoid-induced genomic changes, (ii) bridge the gap between the early need of change and the delay in the expression of genomic effects and (iii) may induce specific changes that in some instances are opposite to those induced by genomic mechanisms. The latter can be explained by the fact that challenging situations require different responses in early (acute) and later (chronic) phases. Data show that non-genomic mechanisms of glucocorticoid action play a role in both pathological phenomena and the expression of ameliorative pharmacological effects. Non-genomic mechanisms that underlie many glucocorticoid-induced neural changes constitute a for long overlooked controlling factor. Despite the multitude and the variety of accumulated data, important questions remain to be answered.

Postnatal maternal deprivation produces long-lasting modifications of the stress response, feeding and stress-related behaviour in the rat

The hypothalamo-pituitary-adrenal (HPA) axis plays a central role both in the regulation of the stress response, and in the control of feeding behaviour. Sensitivity of the HPA axis to respond to stress varies both during ontogeny and between individuals, and can be altered by neonatal events. The aim of our experiments was to determine whether early events that affect the HPA axis could also induce persistent modifications in food intake (quantitatively and qualitatively), as well as alterations of anxiety-related behaviour. Twenty-four-hour maternal deprivation was introduced at two different periods of HPA maturation, on day 5 (DEP5) or day 14 (DEP14) after birth. Sequential measurements of plasma levels of adrenocorticotropin hormone (ACTH) and corticosterone showed that this deprivation altered the HPA axis of adults; the response to restraint stress was prolonged in DEP5 and a higher ACTH peak appeared in DEP14. The neonatal stress also produced long-lasting modifications of rat behaviour, as DEP14 adults became more anxious. Standard food intake decreased in both groups of deprived rats. Diet preferences also changed, as carbohydrate intake decreased in DEP5 rats. Corticosteroid receptor binding did not vary in the hippocampus of the deprived rats. The modifications of the stress response and the behaviour parameters could be due to the alteration of corticosteroid receptors in the hypothalamic paraventricular nucleus and/or corticotropin-releasing hormone or vasopressin function, but these parameters have yet to be determined. This early stress paradigm altering feeding behaviour could become an interesting model for research into human eating disorders.

Rat strain differences in responses of plasma prolactin and PRL mRNA expression after acute amphetamine treatment or restraint stress

1. The aim of this study was to compare the effects of acute amphetamine (AMPH) treatment and restraint stress on plasma level of prolactin (PRL) and PRL mRNA expression in the adenohypophysis in Sprague-Dawley and Lewis male rats, the latter known to have a deficient hypothalamo-pituitary-adrenal (HPA) axis. 2. Both restraint stress and AMPH treatment (i.p. in a dose of 8 mg/kg of b.w.) were applied 15 or 30 min before termination of the experiment. Plasma PRL and corticosterone (CORT) were determined by radioimmunoassay. PRL mRNA expression was estimated by a dot-blot hybridization. 3. Restraint stress and AMPH treatment induced a significant increase in the CORT plasma level, as an indicator of stress response. Compared to Sprague-Dawley rats, the magnitude of CORT increase after both stimuli was significantly lower in Lewis rats. 4. Although restraint stress significantly increased the PRL plasma levels in both rat strains, AMPH treatment reduced the PRL levels in both rat strains. However, the changes of PRL plasma levels had another pattern in Lewis rats than in Sprague-Dawley rats. Control plasma PRL levels were significantly higher in Lewis rats, and in this rat strain AMPH treatment for 30 min increased the PRL levels as compared to the values obtained after AMPH treatment for 15 min. 5. Expression of PRL mRNA in adenohypophysis by restraint stress and AMPH treatment had a similar pattern. After a 15-min lasting restraint stress, the expression of PRL mRNA was decreased insignificantly in both rat strains. AMPH treatment induced in Sprague-Dawley rats a significant decrease of PRL mRNA after a 15-min interval while after 30 min there was a significant increase. However, in Lewis rats AMPH failed to significantly change PRL mRNA. 6. The results from the present study indicate that the mechanisms mediating the effects of acute restraint stress and acute AMPH treatment differ in PRL response in Sprague-Dawley and Lewis male rat strains. Differences in the observed responses in Lewis rats could be related to the deficient activity of HPA axis in this rat strain.

Chronicity, genes en behavior

Since 1863 psychiatry is dominated by the nosological conceptual paradigm that was further stimulated by the introduction of the DSM-III. This has resulted in an ignorance of the European psychiatric diagnostic tradition and a loss of the necessary critical observations and descriptions of psychopathology. This unfortunate process may be observed in the diagnosis of psychiatric disorders in mentally retarded patients where entities such as atypical psychoses, unstable mood disorder and motivational deficit syndrome are not recognized in general. The enormous increase of neuroscienti-fic knowledge, particularly the impact of genetic and intracellular mechanisms in the pathophysiology of psychiatric disorders, warrants the use of a more dimensional and functional psychiatric paradigm. It concerns the effect of gene transcription on the expression of neurotransmitters and receptors that may account for an increased vulnerability or a relapsing course. A so called anticipatory treatment approach is therefore advocated.

Corticosteroid receptor mRNA expression in the brains of patients with epilepsy

The effects of corticosteroids in the brain are mediated through the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR). We used a sensitive competitive RT-PCR assay to quantify the amounts of GR and MR mRNA in human brain tissue specimens from patients with focal epilepsies. GR and MR mRNAs were expressed at approximately the same levels in the temporal lobe, frontal lobe, and hippocampus as compared to tissues with high glucocorticoid/mineralocorticoid receptor expression (liver/kidney). GR and MR mRNA concentrations in the temporal lobe increased markedly during childhood and reached adult levels at puberty. GR and MR mRNA expression was significantly higher in the temporal lobe and frontal lobe cortex of women than in those of men. In women, MR and GR mRNA concentrations were markedly lower in hippocampal tissue than in frontal and temporal lobe cortex tissue. In conclusion, our data demonstrate sex- and site-dependent expression of corticosteroid receptor mRNA in the human brain.