Stress and anxiety: structural plasticity and epigenetic regulation as a consequence of stress

Physical Exercise Counteracts Stress-induced Upregulation of Melanin-concentrating Hormone in the Brain and Stress-induced Persisting Anxiety-like Behaviors

Chronic stress induces anxiety disorders, whereas physical exercise is believed to help people with clinical anxiety. In the present study, we investigated the mechanisms underlying stress-induced anxiety and its counteraction by exercise using an established animal model of anxiety. Mice treated with restraint for 2 h daily for 14 days exhibited anxiety-like behaviors, including social and nonsocial behavioral symptoms, and these behavioral impairments lasted for more than 12 weeks after the stress treatment was removed. Despite these lasting behavioral changes, wheel-running exercise treatment for 1 h daily from post-stress days 1 - 21 counteracted anxiety-like behaviors, and these anxiolytic effects of exercise persisted for more than 2 months, suggesting that anxiolytic effects of exercise stably induced. Repeated restraint treatment up-regulated the expression of the neuropeptide, melanin-concentrating hormone (MCH), in the lateral hypothalamus, hippocampus, and basolateral amygdala, the brain regions important for emotional behaviors. In an in vitro study, treatment of HT22 hippocampal cells with glucocorticoid increased MCH expression, suggesting that MCH upregulation can be initially triggered by the stress hormone, corticosterone. In contrast, post-stress treatment with wheel-running exercise reduced the stress-induced increase in MCH expression to control levels in the lateral hypothalamus, hippocampus and basolateral amygdala. Administration of an MCH receptor antagonist (SNAP94847) to stress-treated mice was therapeutic against stress-induced anxiety-like behaviors. These results suggest that repeated stress produces long-lasting anxiety-like behaviors and upregulates MCH in the brain, while exercise counteracts stress-induced MCH expression and persisting anxiety-like behaviors.

Aerobic Exercise as a Tool to Improve Hippocampal Plasticity and Function in Humans: Practical Implications for Mental Health Treatment

Aerobic exercise (AE) has been widely praised for its potential benefits to cognition and overall brain and mental health. In particular, AE has a potent impact on promoting the function of the hippocampus and stimulating neuroplasticity. As the evidence-base rapidly builds, and given most of the supporting work can be readily translated from animal models to humans, the potential for AE to be applied as a therapeutic or adjunctive intervention for a range of human conditions appears ever more promising. Notably, many psychiatric and neurological disorders have been associated with hippocampal dysfunction, which may underlie the expression of certain symptoms common to these disorders, including (aspects of) cognitive dysfunction. Augmenting existing treatment approaches using AE based interventions may promote hippocampal function and alleviate cognitive deficits in various psychiatric disorders that currently remain untreated. Incorporating non-pharmacological interventions into clinical treatment may also have a number of other benefits to patient well being, such as limiting the risk of adverse side effects. This review incorporates both animal and human literature to comprehensively detail how AE is associated with cognitive enhancements and stimulates a cascade of neuroplastic mechanisms that support improvements in hippocampal functioning. Using the examples of schizophrenia and major depressive disorder, the utility and implementation of an AE intervention to the clinical domain will be proposed, aimed to reduce cognitive deficits in these, and related disorders.

Putative Epigenetic Involvement of the Endocannabinoid System in Anxiety- and Depression-Related Behaviors Caused by Nicotine as a Stressor

Like various stressors, the addictive use of nicotine (NC) is associated with emotional symptoms such as anxiety and depression, although the underlying mechanisms have not yet been fully elucidated due to the complicated involvement of target neurotransmitter systems. In the elicitation of these emotional symptoms, the fundamental involvement of epigenetic mechanisms such as histone acetylation has recently been suggested. Furthermore, among the interacting neurotransmitter systems implicated in the effects of NC and stressors, the endocannabinoid (ECB) system is considered to contribute indispensably to anxiety and depression. In the present study, the epigenetic involvement of histone acetylation induced by histone deacetylase (HDAC) inhibitors was investigated in anxiety- and depression-related behavioral alterations caused by NC and/or immobilization stress (IM). Moreover, based on the contributing roles of the ECB system, the interacting influence of ECB ligands on the effects of HDAC inhibitors was evaluated in order to examine epigenetic therapeutic interventions. Anxiety-like (elevated plus-maze test) and depression-like (forced swimming test) behaviors, which were observed in mice treated with repeated (4 days) NC (subcutaneous 0.8 mg/kg) and/or IM (10 min), were blocked by the HDAC inhibitors sodium butyrate (SB) and valproic acid (VA). The cannabinoid type 1 (CB1) agonist ACPA (arachidonylcyclopropylamide; AC) also antagonized these behaviors. Conversely, the CB1 antagonist SR 141716A (SR), which counteracted the effects of AC, attenuated the anxiolytic-like effects of the HDAC inhibitors commonly in the NC and/or IM groups. SR also attenuated the antidepressant-like effects of the HDAC inhibitors, most notably in the IM group. From these results, the combined involvement of histone acetylation and ECB system was shown in anxiety- and depression-related behaviors. In the NC treatment groups, the limited influence of SR against the HDAC inhibitor-induced antidepressant-like effects may reflect the characteristic involvement of histone acetylation within the NC-related neurotransmitter systems other than the ECB system.

Psychiatric outcomes of bullying victimization: a study of discordant monozygotic twins

BACKGROUND

Bullying victimization in childhood is associated with a broad array of serious mental health disturbances, including anxiety, depression, and suicidal ideation and behavior. The key goal of this study was to evaluate whether bullying victimization is a true environmental risk factor for psychiatric disturbance using data from 145 bully-discordant monozygotic (MZ) juvenile twin pairs from the Virginia Twin Study of Adolescent Behavioral Development (VTSABD) and their follow-up into young adulthood.

METHOD

Since MZ twins share an identical genotype and familial environment, a higher rate of psychiatric disturbance in a bullied MZ twin compared to their non-bullied MZ co-twin would be evidence of an environmental impact of bullying victimization. Environmental correlations between being bullied and the different psychiatric traits were estimated by fitting structural equation models to the full sample of MZ and DZ twins (N = 2824). Environmental associations were further explored using the longitudinal data on the bullying-discordant MZ twins.

RESULTS

Being bullied was associated with a wide range of psychiatric disorders in both children and young adults. The analysis of data on the MZ-discordant twins supports a genuine environmental impact of bullying victimization on childhood social anxiety [odds ratio (OR) 1.7], separation anxiety (OR 1.9), and young adult suicidal ideation (OR 1.3). There was a shared genetic influence on social anxiety and bullying victimization, consistent with social anxiety being both an antecedent and consequence of being bullied.

CONCLUSION

Bullying victimization in childhood is a significant environmental trauma and should be included in any mental health assessment of children and young adults.

Adverse maternal exposures, methylation of glucocorticoid-related genes and perinatal outcomes: a systematic review

Aim: Maternal environmental exposures affect perinatal outcomes through epigenetic placental changes. We examine the literature addressing associations between adverse maternal exposures, perinatal outcomes and methylation of key genes regulating placental cortisol metabolism. Methods: We searched three databases for studies that examined NR3C1 and HSD11β1/HSD11 β 2 methylation with maternal exposures or perinatal outcomes. Nineteen studies remained after screening. We followed Cochrane's PRISMA reporting guidelines (2009). Results: NR3C1 and HSD11 β methylation were associated with adverse infant neurobehavior, stress response, blood pressure and physical development. In utero exposure to maternal stress, nutrition, preeclampsia, smoking and diabetes were associated with altered NR3C1 and HSD11 β methylation. Conclusion: NR3C1 and HSD11 β methylation are useful biomarkers of specific environmental stressors associated with important perinatal outcomes that determine pediatric and adult disease risk.

Enhanced anxiety in the male offspring of sires that self-administered cocaine

We previously showed that paternal cocaine exposure reduced the reinforcing efficacy of cocaine in male offspring. Here, we sought to determine whether paternal cocaine experience could also influence anxiety levels in offspring. Male rats were allowed to self-administer cocaine (controls received saline passively) for 60 days and then were bred with naïve females. Measures of anxiety and cocaine-induced anxiogenic effects were assessed in the adult offspring. Cocaine-sired male offspring exhibited increased anxiety-like behaviors, as measured using the novelty-induced hypophagia and defensive burying tasks, relative to saline-sired males. In contrast, sire cocaine experience had no effect on anxiety-like behaviors in female offspring. When challenged with an anxiogenic (but not anorectic) dose of cocaine (2.5 mg/kg, i.p.), anxiety-like behavior was enhanced in all animals to an equal degree regardless of sire drug experience. Since anxiety and depression are often co-morbid, we also assessed measures of depressive-like behavior. Sire cocaine experience had no effect on depression-like behaviors, as measured by the forced swim task, among male offspring. In a separate group of naïve littermates, select neuronal correlates of anxiety were measured. Male offspring of cocaine-experienced sires showed increased mRNA and protein expression of corticotropin-releasing factor receptor 2 in the hippocampus. Together, these results indicate that cocaine-experienced sires produce male progeny that have increased baseline anxiety, which is unaltered by subsequent cocaine exposure.

DBI/ACBP loss-of-function does not affect anxiety-like behaviour but reduces anxiolytic responses to diazepam in mice

Diazepam is well known for its anxiolytic properties, which are mediated via activation of the GABAA receptor. Diazepam Binding Inhibitor (DBI), also called acyl-CoA binding protein (ACBP), is a ubiquitously expressed protein originally identified based on its ability to displace diazepam from its binding site on the GABAA receptor. Central administration of ACBP or its cleaved fragment, commonly referred to as endozepines, induces proconflict and anxiety-like behaviour in rodents. For this reason, ACBP is known as an anxiogenic peptide. However, the role of endogenous ACBP in anxiety-like behaviour and anxiolytic responses to diazepam has not been investigated. To address this question, we assessed anxiety behaviour and anxiolytic responses to diazepam in two complementary loss-of-function mouse models including astrocyte-specific ACBP KO (ACBP(GFAP) KO) and whole-body KO (ACBP KO) mice. Male and female ACBP(GFAP) KO and ACBP KO mice do not show significant changes in anxiety-like behaviour compared to control littermates during elevated plus maze (EPM) and open field (OF) tests. Surprisingly, ACBP(GFAP) KO and ACBP KO mice were unresponsive to the anxiolytic effect of a low dose of diazepam during EPM tests. In conclusion, our experiments using genetic ACBP loss-of-function models suggest that endozepines deficiency does not affect anxiety-like behaviour in mice and impairs the anxiolytic action of diazepam.

Aging Well: Observations From the Women's Health Initiative Study

BACKGROUND

As the proportion of the population aged 80 and over accelerates, so does the value of understanding the processes of aging well. The purposes of this article are to: (a) review contemporary theoretical and conceptual perspectives on aging well, (b) describe indicators of aging well that reflect key concepts and perspectives as assessed in the Women's Health Initiative (WHI) and (c) characterize the status of aging among women aged 80 and older using data obtained from WHI participants at the WHI Extension 2 follow-up.

METHODS

Data from the Lifestyle Questionnaire, which was administered from 2011 to 2012 during the WHI Follow-up Study (Extension 2), were analyzed to provide a profile of the WHI cohort with respect to aging well.

RESULTS

Data revealed substantial diversity in the cohort with respect to the various measures of aging well. Although many reported physical functioning levels consistent with disability, most rated their health as good or better. Most reported moderately high levels of resilience, self-control, and self-mastery but lower levels of environmental mastery. Finally, the cohort reported high levels of optimal aging as reflected by their high levels of emotional well-being and moderately high levels of life satisfaction and social support, but more modest levels of personal growth and purpose in life.

CONCLUSIONS

The wide range of some dimensions of aging well suggest that further examination of predictors of positive coping and resilience in the face of aging-related disability could identify opportunities to support and facilitate aging well among U.S. women.

Integrated metabolomic and transcriptome analyses reveal finishing forage affects metabolic pathways related to beef quality and animal welfare

Beef represents a major dietary component and source of protein in many countries. With an increasing demand for beef, the industry is currently undergoing changes towards naturally produced beef. However, the true differences between the feeding systems, especially the biochemical and nutritional aspects, are still unclear. Using transcriptome and metabolome profiles, we identified biological pathways related to the differences between grass- and grain-fed Angus steers. In the latissimus dorsi muscle, we have recognized 241 differentially expressed genes (FDR < 0.1). The metabolome examinations of muscle and blood revealed 163 and 179 altered compounds in each tissue (P < 0.05), respectively. Accordingly, alterations in glucose metabolism, divergences in free fatty acids and carnitine conjugated lipid levels, and altered β-oxidation have been observed. The anti-inflammatory n3 polyunsaturated fatty acids are enriched in grass finished beef, while higher levels of n6 PUFAs in grain finished animals may promote inflammation and oxidative stress. Furthermore, grass-fed animals produce tender beef with lower total fat and a higher omega3/omega6 ratio than grain-fed ones, which could potentially benefit consumer health. Most importantly, blood cortisol levels strongly indicate that grass-fed animals may experience less stress than the grain-fed individuals. These results will provide deeper insights into the merits and mechanisms of muscle development.

Integrated metabolomic and transcriptome analyses reveal finishing forage affects metabolic pathways related to beef quality and animal welfare

Beef represents a major dietary component and source of protein in many countries. With an increasing demand for beef, the industry is currently undergoing changes towards naturally produced beef. However, the true differences between the feeding systems, especially the biochemical and nutritional aspects, are still unclear. Using transcriptome and metabolome profiles, we identified biological pathways related to the differences between grass- and grain-fed Angus steers. In the latissimus dorsi muscle, we have recognized 241 differentially expressed genes (FDR < 0.1). The metabolome examinations of muscle and blood revealed 163 and 179 altered compounds in each tissue (P < 0.05), respectively. Accordingly, alterations in glucose metabolism, divergences in free fatty acids and carnitine conjugated lipid levels, and altered β-oxidation have been observed. The anti-inflammatory n3 polyunsaturated fatty acids are enriched in grass finished beef, while higher levels of n6 PUFAs in grain finished animals may promote inflammation and oxidative stress. Furthermore, grass-fed animals produce tender beef with lower total fat and a higher omega3/omega6 ratio than grain-fed ones, which could potentially benefit consumer health. Most importantly, blood cortisol levels strongly indicate that grass-fed animals may experience less stress than the grain-fed individuals. These results will provide deeper insights into the merits and mechanisms of muscle development.

Paper or Plastic? Exploring the Effects of Natural Enrichment on Behavioural and Neuroendocrine Responses in Long-Evans Rats

Enriched environments are beneficial to neurobiological development; specifically, rodents exposed to complex, rather than standard laboratory, environments exhibit evidence of neuroplasticity and enhanced cognitive performance. In the present study, the nature of elements placed in the complex environment was investigated. Accordingly, rats (n = 8 per group) were housed either in a natural environment characterised by stimuli such as dirt and rocks, an artificial environment characterised by plastic toys and synthetic nesting materials, a natural/artificial environment characterised by a combination of artificial and natural stimuli or a laboratory standard environment characterised by no enrichment stimuli. Following exposure to emotional and cognitive behavioural tasks, including a cricket hunting task, a novel object preference task and a forced swim task, brains were processed for glial fibrillary acidic protein (GFAP)-, neuronal nuclei (NeuN)- and brain-derived neurotrophic factor (BDNF) immunoreactivity. Baseline and stress foecal samples were collected to assess corticosterone (CORT) and dehydroepiandrosterone (DHEA). Natural environment animals exhibited shorter diving latencies and increased diving frequencies in the second forced swimming task, along with higher DHEA/CORT ratios, and higher GFAP immunoreactivity in the hippocampus. The type of environmental enrichment did not influence levels of BDNF immunoreactivity in the CA1, CA3 and dentate gyrus of the hippocampus; however, natural environment animals exhibited higher levels of NeuN immunoreactivity in the retrosplenial cortex, an area involved in spatial memory and other cognitive functions. These results suggest that, in addition to enhancing behavioural and endocrinological variables associated with resilience, exposure to natural stimuli might alter plasticity in brain areas associated with cortical processing and learning.

The role of the hypothalamus-pituitary-adrenal/interrenal axis in mediating predator-avoidance trade-offs

Maintaining energy balance and reproducing are important for fitness, yet animals have evolved mechanisms by which the hypothalamus-pituitary-adrenal/interrenal (HPA/HPI) axis can shut these activities off. While HPA/HPI axis inhibition of feeding and reproduction may have evolved as a predator defense, to date there has been no review across taxa of the causal evidence for such a relationship. Here we review the literature on this topic by addressing evidence for three predictions: that exposure to predators decreases reproduction and feeding, that exposure to predators activates the HPA/HPI axis, and that predator-induced activation of the HPA/HPI axis inhibits foraging and reproduction. Weight of evidence indicates that exposure to predator cues inhibits several aspects of foraging and reproduction. While the evidence from fish and mammals supports the hypothesis that predator cues activate the HPA/HPI axis, the existing data in other vertebrate taxa are equivocal. A causal role for the HPA axis in predator-induced suppression of feeding and reproduction has not been demonstrated to date, although many studies report correlative relationships between HPA activity and reproduction and/or feeding. Manipulation of HPA/HPI axis signaling will be required in future studies to demonstrate direct mediation of predator-induced inhibition of feeding and reproduction. Understanding the circuitry linking sensory pathways to their control of the HPA/HPI axis also is needed. Finally, the role that fear and anxiety pathways play in the response of the HPA axis to predator cues is needed to better understand the role that predators have played in shaping anxiety related behaviors in all species, including humans.

Child Poverty and the Promise of Human Capacity: Childhood as a Foundation for Healthy Aging

The effect of child poverty and related early life experiences on adult health outcomes and patterns of aging has become a central focus of child health research and advocacy. In this article a critical review of this proliferating literature and its relevance to child health programs and policy are presented. This literature review focused on evidence of the influence of child poverty on the major contributors to adult morbidity and mortality in the United States, the mechanisms by which these associations operate, and the implications for reforming child health programs and policies. Strong and varied evidence base documents the effect of child poverty and related early life experiences and exposures on the major threats to adult health and healthy aging. Studies using a variety of methodologies, including longitudinal and cross-sectional strategies, have reported significant findings regarding cardiovascular disorders, obesity and diabetes, certain cancers, mental health conditions, osteoporosis and fractures, and possibly dementia. These relationships can operate through alterations in fetal and infant development, stress reactivity and inflammation, the development of adverse health behaviors, the conveyance of child chronic illness into adulthood, and inadequate access to effective interventions in childhood. Although the reviewed studies document meaningful relationships between child poverty and adult outcomes, they also reveal that poverty, experiences, and behaviors in adulthood make important contributions to adult health and aging. There is strong evidence that poverty in childhood contributes significantly to adult health. Changes in the content, financing, and advocacy of current child health programs will be required to address the childhood influences on adult health and disease. Policy reforms that reduce child poverty and mitigate its developmental effects must be integrated into broader initiatives and advocacy that also attend to the health and well-being of adults.

Chronic stress induces persistent changes in global DNA methylation and gene expression in the medial prefrontal cortex, orbitofrontal cortex, and hippocampus

Chronic stress is associated with a plethora of cognitive symptoms such as emotional dysregulation and impaired executive function that have been attributed to modifications in neuroanatomy in the orbitofrontal cortex (OFC), medial prefrontal cortex (mPFC), and hippocampus (HPC). While many studies have examined stress-induced changes in neuronal morphology, synaptic plasticity, and cellular function, there has been little investigation into persistent changes in gene expression that may be responsible for the maintenance of these changes. This study exposed adult rats to a chronic stressor and then examined changes in mRNA gene expression in the OFC, mPFC and HPC following a two-week withdrawal period. mRNA bio-sequencing results revealed sex- and region-dependent changes. Surprisingly the greatest changes in gene expression were found in the OFC, and similar to anatomical studies, analysis of gene changes with Ingenuity Pathway Analysis software demonstrated that the mPFC and OFC exhibited contrasting activation of canonical pathways and functional networks. The HPC demonstrated the largest degree of sex-dependent change in gene expression. In general, chronic stress induced persistent changes in gene expression in the three brain regions we examined and these changes could be associated with the commonly reported cognitive symptoms. The current study highlights the region- and sex-dependent nature of the brain's response to chronic stress and the difficulty we face when attempting to develop treatment options.

Synaptic plasticity and depression: new insights from stress and rapid-acting antidepressants

Depression is a common, devastating illness. Current pharmacotherapies help many patients, but high rates of a partial response or no response, and the delayed onset of the effects of antidepressant therapies, leave many patients inadequately treated. However, new insights into the neurobiology of stress and human mood disorders have shed light on mechanisms underlying the vulnerability of individuals to depression and have pointed to novel antidepressants. Environmental events and other risk factors contribute to depression through converging molecular and cellular mechanisms that disrupt neuronal function and morphology, resulting in dysfunction of the circuitry that is essential for mood regulation and cognitive function. Although current antidepressants, such as serotonin-reuptake inhibitors, produce subtle changes that take effect in weeks or months, it has recently been shown that treatment with new agents results in an improvement in mood ratings within hours of dosing patients who are resistant to typical antidepressants. Within a similar time scale, these new agents have also been shown to reverse the synaptic deficits caused by stress.

Lifelong Nutritional Omega-3 Deficiency Evokes Depressive-Like State Through Soluble Beta Amyloid

Recent evidence pointed out that the prevalence of depression has reached epidemic proportions in last decades. This increase has been linked to many environmental factors, among these the influence of dietary factors has gained great attention. In particular, it has been reported that low n-3 polyunsaturated fatty acid (n-3 PUFA) intake in diet is correlated to the development of depressive and anxiety-like symptoms. Furthermore, maternal malnutrition is a widely accepted risk factor for developing mental illness in later adulthood; among others, depression has been strongly associated to this event. On the other hand, we have previously found that acute intracerebral injection of the soluble beta amyloid 1–42 (Aβ_1–42) peptide induces a depressive-like behavior in rats, associated to altered hypothalamic–pituitary-adrenal (HPA) axis activation and reduced cortical serotonin and neurotrophin levels. The aim of the present work was to study the effect of pre- and post-natal (5 weeks post-weaning) exposure to diets differently enriched in n-3, n-6, as well as n-6/n-3 PUFA balanced, on immobility time displayed on the forced swimming test (FST), along with neuroendocrine quantification in offspring rats. Results showed that n-6 PUFA-enriched diet increased depressive- and anxiety-like behaviors, as shown by the elevation in the immobility time in the FST test and self-grooming in the open field test. Those effects were accompanied by reduced cortical serotonin, high plasmatic corticosterone and hypothalamic corticotropin-releasing factor levels. Finally, enhanced plasmatic Aβ_1–42 levels after n-6 PUFA diet and reduced plasmatic Aβ_1–42 levels after n-3 PUFA were found. Taken together, our data indicate that Aβ_1–42 might be crucially involved in behavioral alterations found after n-6 rich PUFA diet and strongly endorse the protective role of n-3 and the detrimental effect of improper n-6 PUFA diet consumption.

Emerging treatment mechanisms for depression: focus on glutamate and synaptic plasticity

Major depression is a chronic and debilitating illness that effects approximately 1 in 5 people, but currently available treatments are limited by low rates of efficacy, therapeutic time lag, and undesirable side effects. Recent efforts have been directed towards investigating rapid-acting agents that reverse the behavioral and neuronal deficits of chronic stress and depression, notably the glutamate NMDA receptor antagonist ketamine. The cellular mechanisms underlying the rapid antidepressant actions of ketamine and related agents are discussed, as well as novel, selective glutamatergic receptor targets that are safer and have fewer side effects.

Alcohol-induced dysregulation of stress-related circuitry: The search for novel targets and implications for interventions across the sexes

While the ability to process fermented fruits and alcohols was once an adaptive trait that improved nutrition and quality of life, the availability and prevalence of high potency alcoholic drinks has contributed to alcohol abuse disorders in a vulnerable portion of the population. Although the neural reward systems take part in the initial response to alcohol, negative reinforcement and stress, which are normally adaptive responses, can intersect to promote continued alcohol use at all stages of the addiction cycle. Eventually a point is reached where these once adaptive responses become dysregulated resulting in uncontrolled intake that constitutes a clinically important condition termed alcohol use disorder (AUD). Current research is targeted at both the behavioral and molecular adaptations in AUDs in an effort to better develop novel approaches to intervention. In this review, historical context is provided demonstrating the societal burden of alcohol use and abuse disorders. The importance of gender in the mechanism of action of alcohol is discussed. Finally, the impact of alcohol on stress-related circuitry, uncovered by preclinical research, is outlined to provide insight into potential novel pharmacological approaches to the treatment of AUD.

Depression as a Glial-Based Synaptic Dysfunction

Recent studies combining pharmacological, behavioral, electrophysiological and molecular approaches indicate that depression results from maladaptive neuroplastic processes occurring in defined frontolimbic circuits responsible for emotional processing such as the prefrontal cortex, hippocampus, amygdala and ventral striatum. However, the exact mechanisms controlling synaptic plasticity that are disrupted to trigger depressive conditions have not been elucidated. Since glial cells (astrocytes and microglia) tightly and dynamically interact with synapses, engaging a bi-directional communication critical for the processing of synaptic information, we now revisit the role of glial cells in the etiology of depression focusing on a dysfunction of the “quad-partite” synapse. This interest is supported by the observations that depressive-like conditions are associated with a decreased density and hypofunction of astrocytes and with an increased microglia “activation” in frontolimbic regions, which is expected to contribute for the synaptic dysfunction present in depression. Furthermore, the traditional culprits of depression (glucocorticoids, biogenic amines, brain-derived neurotrophic factor, BDNF) affect glia functioning, whereas antidepressant treatments (serotonin-selective reuptake inhibitors, SSRIs, electroshocks, deep brain stimulation) recover glia functioning. In this context of a quad-partite synapse, systems modulating glia-synapse bidirectional communication—such as the purinergic neuromodulation system operated by adenosine 5′-triphosphate (ATP) and adenosine—emerge as promising candidates to “re-normalize” synaptic function by combining direct synaptic effects with an ability to also control astrocyte and microglia function. This proposed triple action of purines to control aberrant synaptic function illustrates the rationale to consider the interference with glia dysfunction as a mechanism of action driving the design of future pharmacological tools to manage depression.

Corticosterone exposure augments sensitivity to the behavioral and neuroplastic effects of fluoxetine in C57BL/6 mice

Both genetic background and pre-existing stress play critical roles in the effects of antidepressant drugs. The current studies showed this principal by demonstrating that exposure to the stress hormone corticosterone (CORT) allowed behavioral and neurogenic effects to emerge following chronic treatment with fluoxetine of C57BL/6 mice, a strain ordinarily resistant to these effects. Adult male mice were implanted subcutaneously with 21-day slow-release CORT pellets (10 mg) or placebo and then co-treated with 5 mg/kg fluoxetine (b.i.d., i.p.) or saline for 14 days. Animals were then assessed for approach behavior in the novelty-induced hypophagia (NIH) test, hippocampal cell proliferation, corticosteroid receptor expression, and CORT plasma levels. Co-treatment of CORT with fluoxetine significantly reduced approach behavior in the novel environment of the NIH test and increased hippocampal cell proliferation whereas fluoxetine given alone was ineffective. CORT given alone did not alter approach behavior in the novel environment and caused a smaller increase of cell proliferation. The CORT effect was blocked by adrenalectomy and was likely due to increased adrenal feedback. Cell proliferation in CORT-treated animals was associated with reduced mineralocorticoid, but not glucocorticoid, receptor mRNA expression. Although the pellets were advertised to release CORT for 21 days, plasma CORT levels were increased at 1 day after implantation but were not sustained when measured at 7 days or longer intervals. Nevertheless, the transient CORT increase was sufficient to induce long-lasting behavioral and molecular changes when followed by fluoxetine treatment. These studies warrant further investigation into the role of glucocorticoids and environmental stress as adjunctive facilitators of the response to antidepressants, especially for treatment-resistant patients.

•

C57BL/6J mice are not responsive to behavioral and neurogenic effects of chronic fluoxetine.

•

CORT reduced anxiogenic behavior, increased hippocampal neurogenesis in response to fluoxetine.

•

CORT pellets are not effective in sustaining elevated plasma CORT levels.

Common Polymorphisms in the Age of Research Domain Criteria (RDoC): Integration and Translation

The value of common polymorphisms in guiding clinical psychiatry is limited by the complex polygenic architecture of psychiatric disorders. Common polymorphisms have too small an effect on risk for psychiatric disorders as defined by clinical phenomenology to guide clinical practice. To identify polymorphic effects that are large and reliable enough to serve as biomarkers requires detailed analysis of a polymorphism's biology across levels of complexity from molecule to cell to circuit and behavior. Emphasis on behavioral domains rather than clinical diagnosis, as proposed in the Research Domain Criteria framework, facilitates the use of mouse models that recapitulate human polymorphisms because effects on equivalent phenotypes can be translated across species and integrated across levels of analysis. A knockin mouse model of a common polymorphism in the brain-derived neurotrophic factor gene (BDNF) provides examples of how such a vertically integrated translational approach can identify robust genotype-phenotype relationships that have relevance to psychiatric practice.

Adult Hippocampal Neurogenesis, Fear Generalization, and Stress

The generalization of fear is an adaptive, behavioral, and physiological response to the likelihood of threat in the environment. In contrast, the overgeneralization of fear, a cardinal feature of posttraumatic stress disorder (PTSD), manifests as inappropriate, uncontrollable expression of fear in neutral and safe environments. Overgeneralization of fear stems from impaired discrimination of safe from aversive environments or discernment of unlikely threats from those that are highly probable. In addition, the time-dependent erosion of episodic details of traumatic memories might contribute to their generalization. Understanding the neural mechanisms underlying the overgeneralization of fear will guide development of novel therapeutic strategies to combat PTSD. Here, we conceptualize generalization of fear in terms of resolution of interference between similar memories. We propose a role for a fundamental encoding mechanism, pattern separation, in the dentate gyrus (DG)-CA3 circuit in resolving interference between ambiguous or uncertain threats and in preserving episodic content of remote aversive memories in hippocampal-cortical networks. We invoke cellular-, circuit-, and systems-based mechanisms by which adult-born dentate granule cells (DGCs) modulate pattern separation to influence resolution of interference and maintain precision of remote aversive memories. We discuss evidence for how these mechanisms are affected by stress, a risk factor for PTSD, to increase memory interference and decrease precision. Using this scaffold we ideate strategies to curb overgeneralization of fear in PTSD.

Neighborhood and Family Environment of Expectant Mothers May Influence Prenatal Programming of Adult Cancer Risk: Discussion and an Illustrative DNA Methylation Example

Childhood stressors including physical abuse predict adult cancer risk. Prior research portrays this finding as an indirect mechanism that operates through coping behaviors, including adult smoking, or through increased toxic exposures during childhood. Little is known about potential direct causal mechanisms between early-life stressors and adult cancer. Because prenatal conditions can affect gene expression by altering DNA methylation, with implications for adult health, we hypothesize that maternal stress may program methylation of cancer-linked genes during gametogenesis. To illustrate this hypothesis, we related maternal social resources to methylation at the imprinted MEG3 differentially methylated regulatory region, which has been linked to multiple cancer types. Mothers (n = 489) from a diverse birth cohort (Durham, North Carolina) provided newborns' cord blood and completed a questionnaire. Newborns of currently married mothers showed lower (-0.321 SD, p < .05) methylation compared to newborns of never-married mothers, who did not differ from newborns whose mothers were cohabiting and others (adjusted for demographics). MEG3 DNA methylation levels were also lower when maternal grandmothers co-resided before pregnancy (-0.314 SD, p < .05). A 1-SD increase in prenatal neighborhood disadvantage also predicted higher methylation (-0.137 SD, p < .05). In conclusion, we found that maternal social resources may result in differential methylation of MEG3, which demonstrates a potential partial mechanism priming socially disadvantaged newborns for later risk of some cancers.

Association of Epidemiologic Factors and Genetic Variants Influencing Hypothalamic-Pituitary-Adrenocortical Axis Function With Postconcussive Symptoms After Minor Motor Vehicle Collision

OBJECTIVES

To determine the influence of epidemiologic factors and the influence of genetic variants affecting FKBP5, a protein known to modulate hypothalamic-pituitary-adrenocortical axis function, on the severity of somatic symptoms commonly termed "postconcussive" 6 and 12 months after motor vehicle collision (MVC).

METHODS

European Americans 18 to 65 years of age who presented to one of eight emergency departments (EDs) after MVC were enrolled. Exclusion criteria included hospital admission. Blood samples were collected in the ED for genotyping. Participants completed evaluations including an adapted Rivermead Post-Concussive Symptoms Questionnaire in the ED and at 6 weeks, 6 months, and 1 year. Repeated-measures analysis of covariance was used to evaluate the association between epidemiologic factors (sociodemographic, pre-MVC health, collision characteristics, head injury, peritraumatic pain, and stress), FKBP5 genetic variants, and postconcussive symptom severity.

RESULTS

Among 943 patients recruited in the ED, follow-up was completed on 835 (88%) at 6 months and 857 (90%) at 1 year. Self-reported head impact during collision was not associated with chronic postconcussive symptom severity. After correction for multiple testing, three FKBP5 single-nucleotide polymorphisms (rs3800373, rs7753746, and rs9380526) predicted chronic postconcussive symptom severity, with an average symptom severity of 1.10 (95% confidence interval = 0.96-1.24), 1.36 (1.21-1.51), and 1.55 (1.23-1.88) for one, two, or three copies of minor allele at rs3800373 (p = .001). Similar effect sizes were observed for the minor alleles of rs7753746 and rs9380526.

CONCLUSIONS

Postconcussive symptoms after minor MVC are not generally related to the severity of mild brain injury. This study shows that neurobiologic stress systems may play a role in the pathogenesis of postconcussive symptoms.

Epigenetics/Programming in the HPA Axis

The hypothalamic-pituitary-adrenal axis provides physiological adaptations to various environmental stimuli in mammals. These stimuli including maternal care, diet, immune challenge, stress, and others have the potential to stably modify or program the functioning of the HPA axis when experienced early in life or at later critical stages of development. Epigenetic mechanisms mediate the biological embedding of environmental stimuli or conditions. These changes are influenced by the genotype and both, environment and genotype contribute to the development of a specific phenotype with regard to the stress response that might be more susceptible or resilient to the development of mental conditions. The effects of stress might be a result of cumulative stress or a mismatch between the environments experienced early in life versus the conditions much later. These effects including the associated epigenetic modifications are potentially reversible.

Exposure to Chronic Mild Stress Differentially Alters Corticotropin-Releasing Hormone and Arginine Vasopressin mRNA Expression in the Stress-Responsive Neurocircuitry of Male and Female Rats Prenatally Exposed to Alcohol

BACKGROUND

Prenatal alcohol exposure (PAE) results in dysregulation of the offspring hypothalamic-pituitary-adrenal (HPA) axis, increasing sensitivity to stressors and vulnerability to stress-related disorders. We have previously shown that exposure to chronic mild stress (CMS) in adulthood significantly increases anxiety-like behaviors (elevated plus maze) in PAE males and females compared to controls. To explore neurobiological mechanisms linking HPA dysregulation and altered anxiety-like behavior, we investigated neuropeptide (corticotropin-releasing hormone [CRH] and arginine vasopressin [AVP]) expression in brain areas involved in the stress neurocircuitry of animals from this previous behavioral study.

METHODS

Adult PAE, pair-fed (PF), and ad libitum fed control (C) male and female offspring exposed to CMS or remaining undisturbed (non-CMS) were terminated 30 minutes following behavioral testing.

RESULTS

In the paraventricular nucleus, CMS increased CRH mRNA levels in PAE compared to PF and C males and increased AVP mRNA levels in PAE compared to C males, with no differential effects for CRH or AVP in females. In the central nucleus of the amygdala, there was an increase in CRH mRNA expression overall, regardless of CMS condition or sex, in PAE compared to C animals. Moreover, in PF males, CMS increased AVP mRNA levels in the paraventricular nucleus, resulting in a decreased CRH/AVP ratio compared to PAE males, and decreased amygdala CRH mRNA compared to that in the non-CMS condition.

CONCLUSIONS

CMS differentially altered central HPA peptide expression in PAE and PF animals compared to their control counterparts, with a possible shift toward greater CRH mediation of HPA regulation in PAE males, and greater AVP mediation of HPA regulation in PF males. However, changes in CRH and AVP expression do not align fully with the anxiogenic profile observed in our previous behavior study, suggesting that other neuronal substrates and limbic forebrain regions also contribute to increased anxiety-like behavior following CMS.

Hippocampal and cerebellar atrophy in patients with Cushing’s disease

OBJECT

Cushing’s disease (CD) may cause atrophy of different regions of the human brain, mostly affecting the hippocampus and the cerebellum. This study evaluates the use of 3-T MRI of newly diagnosed patients with CD to detect atrophic degeneration with voxel-based volumetry.

METHODS

Subjects with newly diagnosed, untreated CD were included and underwent 3-T MRI. Images were analyzed using a voxelwise statistical test to detect reduction of brain parenchyma. In addition, an atlas-based volumetric study for regions likely to be affected by CD was performed.

RESULTS

Nineteen patients with a mean disease duration of 24 months were included. Tumor markers included adre-nocorticotropic hormone (median 17.5 pmol/L), cortisol (949.4 nmol/L), and dehydroepiandrosterone sulfate (5.4 μmol/L). The following values are expressed as the mean ± SD. The voxelwise statistical test revealed clusters of significantly reduced gray matter in the hippocampus and cerebellum, with volumes of 2.90 ± 0.26 ml (right hippocampus), 2.89 ± 0.28 ml (left hippocampus), 41.95 ± 4.67 ml (right cerebellar hemisphere), and 42.11 ± 4.59 ml (left cerebellar hemisphere). Healthy control volunteers showed volumes of 3.22 ± 0.25 ml for the right hippocampus, 3.23 ± 0.25 ml for the left hippocampus, 50.87 ± 4.23 ml for the right cerebellar hemisphere, and 50.42 ± 3.97 ml for the left cerebellar hemisphere.

CONCLUSIONS

Patients with untreated CD show significant reduction of gray matter in the cerebellum and hippocampus. These changes can be analyzed and objectified with the quantitative voxel-based method described in this study.

Chronic stress and brain plasticity: Mechanisms underlying adaptive and maladaptive changes and implications for stress-related CNS disorders

Stress responses entail neuroendocrine, autonomic, and behavioral changes to promote effective coping with real or perceived threats to one's safety. While these responses are critical for the survival of the individual, adverse effects of repeated exposure to stress are widely known to have deleterious effects on health. Thus, a considerable effort in the search for treatments to stress-related CNS disorders necessitates unraveling the brain mechanisms responsible for adaptation under acute conditions and their perturbations following chronic stress exposure. This paper is based upon a symposium from the 2014 International Behavioral Neuroscience Meeting, summarizing some recent advances in understanding the effects of stress on adaptive and maladaptive responses subserved by limbic forebrain networks. An important theme highlighted in this review is that the same networks mediating neuroendocrine, autonomic, and behavioral processes during adaptive coping also comprise targets of the effects of repeated stress exposure in the development of maladaptive states. Where possible, reference is made to the similarity of neurobiological substrates and effects observed following repeated exposure to stress in laboratory animals and the clinical features of stress-related disorders in humans.

Altered Trust Learning Mechanisms Among Female Adolescent Victims of Interpersonal Violence

Early-life interpersonal violence (IV) is a significant risk factor for a broad range of mental health disorders, increased rates of re-victimization, and psychosocial dysfunction. However, the cognitive mechanisms by which these risks are conferred are largely unknown. The current study attempted to address this empirical gap. Thirty-two adolescent girls, aged 12 to 16 (15 victims of IV), completed a social learning task. A computational learning model was fit to the behavioral data (ratings of trustworthiness during the learning task) to test for group differences in the cognitive mechanisms by which adolescent girls learn to differentially trust others. Specifically, we tested for differences in task performance and subject-level learning parameters: learning rate (the extent to which preferences are updated with new information) and preference stochasticity (the extent to which preferences seem random). Adolescent girls who were victims of IV demonstrated significantly worse performance than their control counterparts. Among IV victims, we observed a relationship between higher learning rates and greater preference stochasticity. Theoretical and clinical implications are discussed.

Quantitative Proteomic Analysis Reveals Molecular Adaptations in the Hippocampal Synaptic Active Zone of Chronic Mild Stress-Unsusceptible Rats

BACKGROUND

While stressful events are recognized as an important cause of major depressive disorder, some individuals exposed to life stressors maintain normal psychological functioning. The molecular mechanism(s) underlying this phenomenon remain unclear. Abnormal transmission and plasticity of hippocampal synapses have been implied to play a key role in the pathoetiology of major depressive disorder.

METHODS

A chronic mild stress protocol was applied to separate susceptible and unsusceptible rat subpopulations. Proteomic analysis using an isobaric tag for relative and absolute quantitation coupled with tandem mass spectrometry was performed to identify differential proteins in enriched hippocampal synaptic junction preparations.

RESULTS

A total of 4318 proteins were quantified, and 89 membrane proteins were present in differential amounts. Of these, SynaptomeDB identified 81 (91%) having a synapse-specific localization. The unbiased profiles identified several candidate proteins within the synaptic junction that may be associated with stress vulnerability or insusceptibility. Subsequent functional categorization revealed that protein systems particularly involved in membrane trafficking at the synaptic active zone exhibited a positive strain as potential molecular adaptations in the unsusceptible rats. Moreover, through STRING and immunoblotting analysis, membrane-associated GTP-bound Rab3a and Munc18-1 appear to coregulate syntaxin-1/SNAP25/VAMP2 assembly at the hippocampal presynaptic active zone of unsusceptible rats, facilitating SNARE-mediated membrane fusion and neurotransmitter release, and may be part of a stress-protection mechanism in actively maintaining an emotional homeostasis.

CONCLUSIONS

The present results support the concept that there is a range of potential protein adaptations in the hippocampal synaptic active zone of unsusceptible rats, revealing new investigative targets that may contribute to a better understanding of stress insusceptibility.

Stress effects on the hippocampus: a critical review

Uncontrollable stress has been recognized to influence the hippocampus at various levels of analysis. Behaviorally, human and animal studies have found that stress generally impairs various hippocampal-dependent memory tasks. Neurally, animal studies have revealed that stress alters ensuing synaptic plasticity and firing properties of hippocampal neurons. Structurally, human and animal studies have shown that stress changes neuronal morphology, suppresses neuronal proliferation, and reduces hippocampal volume. Since the inception of stress research nearly 80 years ago, much focus has been on the varying levels of hypothalamic-pituitary-adrenal (HPA) axis neuroendocrine hormones, namely glucocorticoids, as mediators of the myriad stress effects on the hippocampus and as contributing factors to stress-associated psychopathologies such as post-traumatic stress disorder (PTSD). However, reports of glucocorticoid-produced alterations in hippocampal functioning vary widely across studies. This review provides a brief history of stress research, examines how the glucocorticoid hypothesis emerged and guides contemporary stress research, and considers alternative approaches to understanding the mechanisms underlying stress effects on hippocampal functioning.

Psychological Coercion in Human Trafficking: An Application of Biderman's Framework

This study examined coercive conditions experienced by trafficked persons in the context of Biderman's theory of coercion. We conducted semi-structured interviews with 12 adult women trafficked into Los Angeles County, from 10 countries, for domestic work and/or sex work. Participants described health problems they experienced in relation to their trafficking experience and their perceptions of conditions that caused health problems. Utilizing a framework analysis approach, we analyzed themes using Biderman's framework. Participants reported experiencing the range of nonphysical coercive tactics outlined by Biderman, including isolation, monopolization of perception, induced debility or exhaustion, threats, occasional indulgences, demonstration of omnipotence, degradation, and enforcement of trivial demands. Our analysis demonstrates how these coercion tactics reinforced the submission of trafficked persons to their traffickers even in the absence of physical force or restraints. Such psychological abuse creates extreme stress that can lead to acute and chronic, physical and mental health problems.

Early weaning influences short-term synaptic plasticity in the medial prefrontal-anterior basolateral amygdala pathway

Early weaning in rodents reportedly influences behavioral and emotional traits and triggers precocious myelin formation in the anterior basolateral amygdala (aBLA; Ono et al., 2008), where prefrontal efferents terminate. We studied the correlation between behavior and the synaptic properties of the prefrontal-aBLA pathway. Open-field behaviors of adult male rats weaned at either 16 days or 30 days were measured on two consecutive days. On the first day, the rats received a slight footshock that was reportedly insufficient for fear conditioning. Electrophysiological recordings in the prefrontal-aBLA were then performed under urethane anesthesia. Without group differences in the stimulus intensity or the first evoked response, the overall paired-pulse facilitation was significantly lower in the early-weaned group from 25 to 100 ms. At the 25-ms interval, regression values between paired-pulse facilitation and locomotion on the second day were positive/insignificant and negative/significant in early- and control-weaned groups, respectively, and were statistically different between the groups.

Astroglial Plasticity Is Implicated in Hippocampal Remodelling in Adult Rats Exposed to Antenatal Dexamethasone

The long-term effects of antenatal dexamethasone treatment on brain remodelling in 3-month-old male Sprague Dawley rats whose mothers had been treated with dexamethasone were investigated in the present study. Dorsal hippocampus, basolateral amygdala and nucleus accumbens volume, cell numbers, and GFAP-immunoreactive astroglial cell morphology were analysed using stereology. Total brain volume as assessed by micro-CT was not affected by the treatment. The relative volume of the dorsal hippocampus (% of total brain volume) showed a moderate, by 8%, but significant reduction in dexamethasone-treated versus control animals. Dexamethasone had no effect on the total and GFAP-positive cell numbers in the hippocampal subregions, basolateral amygdala, and nucleus accumbens. Morphological analysis indicated that numbers of astroglial primary processes were not affected in any of the hippocampal subregions analysed but significant reductions in the total primary process length were observed in CA1 by 32%, CA3 by 50%, and DG by 25%. Mean primary process length values were also significantly decreased in CA1 by 25%, CA3 by 45%, and DG by 25%. No significant astroglial morphological changes were found in basolateral amygdala and nucleus accumbens. We propose that the dexamethasone-dependent impoverishment of hippocampal astroglial morphology is the case of maladaptive glial plasticity induced prenatally.

Astrocyte and microglial control of glutamatergic signalling: a primer on understanding the disruptive role of chronic stress

It is now well established that chronic stress can induce significant structural remodelling of astrocytes and microglia. Until recently, however, the full significance of these morphological disturbances has remained unclear. Clues to the significance of astroglial re-organisation following stress are beginning to emerge from a compelling literature describing how astrocytes contribute to glutamatergic neurotransmission. The present review briefly summarises these two fields of research, identifies points of overlap and, in doing so, pin-points future research directions for stress neurobiology. Ultimately, understanding how chronic stress can disrupt the interactions of astrocytes and microglia with neurones has the potential in the future to improve the development of therapeutics designed to treat stress-related illnesses such as depression.

Global and gene-specific DNA methylation alterations in the adolescent amygdala and hippocampus in an animal model of caregiver maltreatment

Epigenetic mechanisms such as DNA methylation are part of an emerging story on how early-life experiences can alter behavioral trajectories and lead to the development of disease and psychological disorders. Previous work from our laboratory has demonstrated alterations in methylation of DNA associated with the brain-derived neurotrophic factor (bdnf) gene within the amygdala and hippocampus of infant and adult rats that were repeatedly exposed to caregiver maltreatment outside the home cage during their first week of life. In the current study we examine changes in global levels of DNA methylation (5-mC) and hydroxymethylation (5-hmC), as well as gene-specific changes in methylation patterns of the candidate gene bdnf (at exons I and IV) within the adolescent amygdala and hippocampus resulting from exposure to maltreatment. While adolescent females exposed to maltreatment showed no significant alterations in global 5-mC or 5-hmC levels, examination of bdnf DNA methylation revealed that maltreated females had greater methylation of exon IV DNA in the amygdala and ventral hippocampus. While adolescent males exposed to maltreatment showed no significant alterations in bdnf DNA methylation, maltreated males had significantly higher 5-mC levels in the dorsal hippocampus and lower 5-hmC levels in the amygdala. These findings demonstrate that the effects of the early caregiving environment are detectable in the adolescent brain at the level of the epigenome, with brain-region specific and sexually-dimorphic epigenetic consequences that could have relevance to adolescent mental health and behavior.

Exploring hope and healing in patients living with advanced non-small cell lung cancer

PURPOSE/OBJECTIVES

To explore the experience and meaning of hope in relation to the healing process of patients living with stage IIIb or IV non-small cell lung cancer.

RESEARCH APPROACH

Interpretative qualitative study design.

SETTING

Peter Brojde Lung Cancer Centre in the Jewish General Hospital in Montreal, Quebec, Canada.

PARTICIPANTS

12 English- and French-speaking patients, aged 36-78 years.

METHODOLOGIC APPROACH

One 60-90-minute semistructured interview per participant was conducted. An inductive approach to data analysis was taken, involving immersion in the data, coding, classifying, and creating linkages.

FINDINGS

Four main themes emerged: (a) the morass of shattered hope, (b) tentative steps toward a new hope paradigm, (c) reframing hope within the context of a life-threatening illness, and (d) strengthening the link between hope and wellness.

CONCLUSIONS

Patients described a process where hope was diminished or lost entirely, regained, and reshaped as they learned to live and grow following their diagnosis.

INTERPRETATION

This study adds to the literature by describing the dynamic nature of hope as well as factors facilitating or hindering the hope process. It demonstrates how finding meaning, a structural component of healing, can be used to envision a new hopeful future. This study suggests hope and healing cannot exist in isolation, and highlights the importance of understanding the fluctuating nature of hope in patients with advanced lung cancer to foster it, therefore promoting healing.

Behavioral stress reduces RIP140 expression in astrocyte and increases brain lipid accumulation

Receptor-interacting protein 140 (RIP140) is highly expressed in the brain, and acts in neurons and microglia to affect emotional responses. The present study reveals an additional function of RIP140 in the brain, which is to regulate brain lipid homeostasis via its action in astrocytes. We found forced swim stress (FSS) significantly reduces the expression level of RIP140 and elevates cholesterol content in the brain. Mechanistically, FSS elevates endoplasmic reticulum stress, which suppresses RIP140 expression by increasing microRNA 33 (miR33) that targets RIP140 mRNA's 3'-untranslated region. Consequentially, cholesterol biosynthesis and export are dramatically increased in astrocyte, the major source of brain cholesterol. These results demonstrate that RIP140 plays an important role in maintaining brain cholesterol homeostasis through, partially, regulating cholesterol metabolism in, and mobilization from, astrocyte. Altering RIP140 levels can disrupt brain cholesterol homeostasis, which may contribute to behavioral stress-induced neurological disorders.

Monoamine Oxidase A is Required for Rapid Dendritic Remodeling in Response to Stress

BACKGROUND

Acute stress triggers transient alterations in the synaptic release and metabolism of brain monoamine neurotransmitters. These rapid changes are essential to activate neuroplastic processes aimed at the appraisal of the stressor and enactment of commensurate defensive behaviors. Threat evaluation has been recently associated with the dendritic morphology of pyramidal cells in the orbitofrontal cortex (OFC) and basolateral amygdala (BLA); thus, we examined the rapid effects of restraint stress on anxiety-like behavior and dendritic morphology in the BLA and OFC of mice. Furthermore, we tested whether these processes may be affected by deficiency of monoamine oxidase A (MAO-A), the primary enzyme catalyzing monoamine metabolism.

METHODS

Following a short-term (1-4h) restraint schedule, MAO-A knockout (KO) and wild-type (WT) mice were sacrificed, and histological analyses of dendrites in pyramidal neurons of the BLA and OFC of the animals were performed. Anxiety-like behaviors were examined in a separate cohort of animals subjected to the same experimental conditions.

RESULTS

In WT mice, short-term restraint stress significantly enhanced anxiety-like responses, as well as a time-dependent proliferation of apical (but not basilar) dendrites of the OFC neurons; conversely, a retraction in BLA dendrites was observed. None of these behavioral and morphological changes were observed in MAO-A KO mice.

CONCLUSIONS

These findings suggest that acute stress induces anxiety-like responses by affecting rapid dendritic remodeling in the pyramidal cells of OFC and BLA; furthermore, our data show that MAO-A and monoamine metabolism are required for these phenomena.

Inflammation and neuronal plasticity: a link between childhood trauma and depression pathogenesis

During the past two decades, there has been increasing interest in understanding and characterizing the role of inflammation in major depressive disorder (MDD). Indeed, several are the evidences linking alterations in the inflammatory system to Major Depression, including the presence of elevated levels of pro-inflammatory cytokines, together with other mediators of inflammation. However, it is still not clear whether inflammation represents a cause or whether other factors related to depression result in these immunological effects. Regardless, exposure to early life stressful events, which represent a vulnerability factor for the development of psychiatric disorders, act through the modulation of inflammatory responses, but also of neuroplastic mechanisms over the entire life span. Indeed, early life stressful events can cause, possibly through epigenetic changes that persist over time, up to adulthood. Such alterations may concur to increase the vulnerability to develop psychopathologies. In this review we will discuss the role of inflammation and neuronal plasticity as relevant processes underlying depression development. Moreover, we will discuss the role of epigenetics in inducing alterations in inflammation-immune systems as well as dysfunction in neuronal plasticity, thus contributing to the long-lasting negative effects of stressful life events early in life and the consequent enhanced risk for depression. Finally we will provide an overview on the potential role of inflammatory system to aid diagnosis, predict treatment response, enhance treatment matching, and prevent the onset or relapse of Major Depression.

Tempol treatment reduces anxiety-like behaviors induced by multiple anxiogenic drugs in rats

We have published that pharmacological induction of oxidative stress (OS) causes anxiety-like behavior in rats. Using animal models, we also have established that psychological stress induces OS and leads to anxiety-like behaviors. All evidence points towards the causal role of OS in anxiety-like behaviors. To fully ascertain the role of OS in anxiety-like behaviors, it is reasonable to test whether the pro-anxiety effects of anxiogenic drugs caffeine or N-methyl-beta-carboline-3-carboxamide (FG-7142) can be mitigated using agents that minimize OS. In this study, osmotic pumps were either filled with antioxidant tempol or saline. The pumps were attached to the catheter leading to the brain cannula and inserted into the subcutaneous pocket in the back pocket of the rat. Continuous i.c.v. infusion of saline or tempol in the lateral ventricle of the brain (4.3 mmol/day) was maintained for 1 week. Rats were intraperitoneally injected either with saline or an anxiogenic drug one at a time. Two hours later all groups were subjected to behavioral assessments. Anxiety-like behavior tests (open-field, light-dark and elevated plus maze) suggested that tempol prevented anxiogenic drug-induced anxiety-like behavior in rats. Furthermore, anxiogenic drug-induced increase in stress examined via plasma corticosterone and increased oxidative stress levels assessed via plasma 8-isoprostane were prevented with tempol treatment. Protein carbonylation assay also suggested preventive effect of tempol in the prefrontal cortex brain region of rats. Antioxidant protein expression and pro-inflammatory cytokine levels indicate compromised antioxidant defense as well as an imbalance of inflammatory response.

Adolescent and adult male rats habituate to repeated isolation, but only adolescents sensitize to partner unfamiliarity

We investigated whether adolescent male rats show less habituation of corticosterone release than adult male rats to acute vs repeated (16) daily one hour episodes of isolation stress, as well as the role of partner familiarity during recovery on social behavior, plasma corticosterone, and Zif268 expression in brain regions. Adolescents spent more time in social contact than did adults during the initial days of the repeated stress procedures, but both adolescents and adults that returned to an unfamiliar peer after isolation had higher social activity than rats returned to a familiar peer (p=0.002) or undisturbed control rats (p<0.001). Both ages showed evidence of habituation, with reduced corticosterone response to repeated than acute isolation (p=0.01). Adolescents, however, showed sensitized corticosterone release to repeated compared with an acute pairing with an unfamiliar peer during recovery (p=0.03), a difference not found in adults. Consistent with habituation of corticosterone release, the repeated isolation groups had lower Zif268 immunoreactive cell counts in the paraventricular nucleus (p<0.001) and in the arcuate nucleus (p=0.002) than did the acute groups, and adolescents had higher Zif268 immunoreactive cell counts in the paraventricular nucleus than did adults during the recovery period (p<0.001), irrespective of stress history and partner familiarity. Partner familiarity had only modest effects on Zif268 immunoreactivity, and experimental effects on plasma testosterone concentrations were only in adults. The results highlight social and endocrine factors that may underlie the greater vulnerability of the adolescent period of development.

The GABAB receptor associates with regulators of G-protein signaling 4 protein in the mouse prefrontal cortex and hypothalamus

Regulators of G-protein signaling (RGS) proteins regulate certain G-protein-coupled receptor (GPCR)-mediated signaling pathways. The GABA_B receptor (GABA_BR) is a GPCR that plays a role in the stress response. Previous studies indicate that acute immobilization stress (AIS) decreases RGS4 in the prefrontal cortex (PFC) and hypothalamus (HY) and suggest the possibility of a signal complex composed of RGS4 and GABA_BR. Therefore, in the present study, we tested whether RGS4 associates with GABA_BR in these brain regions. We found the co-localization of RGS4 and GABA_BR subtypes in the PFC and HY using double immunohistochemistry and confirmed a direct association between GABA_B2R and RGS4 proteins using co-immunoprecipitation. Furthermore, we found that AIS decreased the amount of RGS4 bound to GABA_B2R and the number of double-positive cells. These results indicate that GABA_BR forms a signal complex with RGS4 and suggests that RGS4 is a regulator of GABA_BR. [BMB Reports 2014; 47(6): 324-329]

Anticipation of smoking sufficiently dampens stress reactivity in nicotine-deprived smokers

Most smokers attempting to quit will relapse, even when using evidence-based cessation treatment. This illustrates the need for better understanding of the relapse process to thereby improve cessation treatments. Although the impact of stress sensitivity on relapse is clear, little research has precisely examined stress reactivity in addicted individuals. Further, most research on relapse focuses on affect surrounding self-administration, and does not address potentially important preconsumption processes such as anticipation of use. We examined the effects of anticipation and actual smoking on stress reactivity in 34 deprived smokers withdrawn for 24 hr and 37 nondeprived smokers, with 37 nonsmoker controls. Using a cued shock stressor task, we measured stress reactivity via startle potentiation and self-reported anxiety. After completing the task once, smokers anticipated smoking a cigarette resting in front of them while they completed the task a second time. Smokers then smoked before completing the task a third and final time. Nonsmokers anticipated and drank water as a control. Anticipation of smoking significantly attenuated both startle potentiation and self-reported anxiety to shock cues for deprived smokers relative to nondeprived smokers. Smokers' stress reactivity was not reduced by smoking beyond the prior effect of anticipation. These results suggest that anticipation, rather than actual drug consumption, may drive the primary reinforcing effect of reduced stress reactivity in smoking. Future research is needed to understand this effect of anticipation on drug use and to determine whether anticipation would make an effective intervention target for addiction and other psychopathology that exhibits increased stress sensitivity.