Can stress cause depression?

The gut microbiome regulates the increases in depressive-type behaviors and in inflammatory processes in the ventral hippocampus of stress vulnerable rats

Chronic exposure to stress is associated with increased incidence of depression, generalized anxiety, and PTSD. However, stress induces vulnerability to such disorders only in a sub-population of individuals, as others remain resilient. Inflammation has emerged as a putative mechanism for promoting stress vulnerability. Using a rodent model of social defeat, we have previously shown that rats with short-defeat latencies (SL/vulnerable rats) show increased anxiety- and depression-like behaviors, and these behaviors are mediated by inflammation in the ventral hippocampus. The other half of socially defeated rats show long-latencies to defeat (LL/resilient) and are similar to controls. Because gut microbiota are important activators of inflammatory substances, we assessed the role of the gut microbiome in mediating vulnerability to repeated social defeat stress. We analyzed the fecal microbiome of control, SL/vulnerable, and LL/resilient rats using shotgun metagenome sequencing and observed increased expression of immune-modulating microbiota, such as Clostridia, in SL/vulnerable rats. We then tested the importance of gut microbiota to the SL/vulnerable phenotype. In otherwise naive rats treated with microbiota from SL/vulnerable rats, there was higher microglial density and IL-1β expression in the vHPC, and higher depression-like behaviors relative to rats that received microbiota from LL/resilient rats, non-stressed control rats, or vehicle-treated rats. However, anxiety-like behavior during social interaction was not altered by transplant of the microbiome of SL/vulnerable rats into non-stressed rats. Taken together, the results suggest the gut microbiome contributes to the depression-like behavior and inflammatory processes in the vHPC of stress vulnerable individuals.

A systematic review of the effect of L-tryptophan supplementation on mood and emotional functioning

L-tryptophan (TRP), one of the essential amino acids in humans, is a precursor of serotonin, and hence its intake is closely related to the suppression of depressed and anxious moods. We did a systematic review of RCTs to examine the effects of tryptophan intake on the mood of healthy adults by searching PubMed, the Cochrane Library, and Ichu-shi according to PRISMA guidelines. As a result, 11 RCTs met the criteria and were accepted. Four RCTs showed the effects of tryptophan intake on negative feelings and happy feelings in healthy individuals, with significant differences between the treatment and the control groups. This suggests that TRP intake may be an effective approach to decrease anxiety and increase positive mood in healthy individuals. On the other hand, the effectiveness of TRP for aggressive feelings was not recognized. Reviewing these 11 RCTs, we concluded that taking 0.14-3 g of TRP per day in addition to the usual meal can be expected to improve the mood of healthy individuals. In order to estimate the optimum amount of TRP intake more accurately, further studies need to be conducted with more appropriate settings of intake period, intake frequency, and intake method.

EEG based Classification of Long-term Stress Using Psychological Labeling

Stress research is a rapidly emerging area in the field of electroencephalography (EEG) signal processing. The use of EEG as an objective measure for cost effective and personalized stress management becomes important in situations like the nonavailability of mental health facilities. In this study, long-term stress was classified with machine learning algorithms using resting state EEG signal recordings. The labeling for the stress and control groups was performed using two currently accepted clinical practices: (i) the perceived stress scale score and (ii) expert evaluation. The frequency domain features were extracted from five-channel EEG recordings in addition to the frontal and temporal alpha and beta asymmetries. The alpha asymmetry was computed from four channels and used as a feature. Feature selection was also performed to identify statistically significant features for both stress and control groups (via t-test). We found that support vector machine was best suited to classify long-term human stress when used with alpha asymmetry as a feature. It was observed that the expert evaluation-based labeling method had improved the classification accuracy by up to 85.20%. Based on these results, it is concluded that alpha asymmetry may be used as a potential bio-marker for stress classification, when labels are assigned using expert evaluation.

Sleep therapeutics and neuropsychiatric illness

Alterations in sleep are extremely common in patients with neuropsychiatric illness. In addition, sleep disorders such as insomnia, obstructive sleep apnea, rapid eye movement sleep behavior disorder, and circadian rhythm disorders commonly occur at a rate greater than the general population in neuropsychiatric conditions. Historically, sleep problems have been viewed as symptoms of associated neuropsychiatric disorders. However, there is increasing evidence suggesting a complex inter-relationship with possible bidirectional causality. The inter-relatedness of these conditions represents an opportunity for understanding mechanisms and improving clinical treatment. To the extent that sleep problems affect neuropsychiatric conditions, it may be possible to address sleep problems and have a positive impact on the course of neuropsychiatric illnesses. Further, some treatments for sleep disorders have direct effects on neuropsychiatric illnesses that may be unrelated to their effects on sleep disorders. Similarly, neuropsychiatric conditions and their treatments can affect sleep and sleep disorders. This article reviews available evidence on the effects of therapies for sleep disorders on neuropsychiatric conditions and also secondarily considers the impacts of therapies for neuropsychiatric conditions on sleep. Primary goals of this review are to identify gaps in current research, to determine the extent to which the cross-therapeutic effects of these treatments help to elucidate therapeutic or pathological mechanisms, and to assist clinicians in optimizing therapeutic choice in patients with sleep disorders and neuropsychiatric conditions.

Hydrogen sulfide-mediated resistance against water avoidance stress-induced gastritis by maintenance of gastric microbial homeostasis

Chronic persistent stress is an important cause of gastritis, but the underlying mechanism remains to be further researched, especially the role of the gastric microbiota in this process. Here, we used the water avoidance stress (WAS) test in mouse models for chronic stress‐induced gastritis to investigate the underlying mechanisms of this disease. The effect of stress on the gastric microbiota was analyzed based on 16S rRNA sequencing; the changes in hydrogen sulfide (H₂S) and inflammatory cytokine levels in gastric tissues were detected by Western blotting, ELISA, immunofluorescence, and qRT‐PCR. Hematoxylin and eosin staining was used as an indicator of the gastritis histological score. This finding is consistent with previous studies showing that gastric H₂S is negatively associated with the inflammatory index and might protect the gastrointestinal tract from inflammation. WAS‐induced gastritis was associated with a reduction in H₂S release, which appeared to affect the homeostasis of the gastric microbiota of mice. Inflammation and microbial dysbiosis were partially reversed by sodium hydrosulfide (NaHS) and vitamin B6 (VB6) supplementation, suggesting the therapeutic potential of VB6 supplementation for the treatment of stress‐induced gastritis. Gastritis has a serious impact on health and quality of life. An increasing number of people are suffering from chronic gastritis linked to a high‐stress lifestyle, and our research provides clues for the prevention and treatment of stress‐induced gastritis.

Chronic stress, depression and personality type in patients with myasthenia gravis

BACKGROUND AND PURPOSE

Stress is a known risk factor for the onset and modulation of disease activity in autoimmune disorders. The aim of this cross-sectional study was to determine any associations between myasthenia gravis (MG) severity and chronic stress, depression and personality type.

METHODS

In all, 179 consecutive adult patients with confirmed MG attending the Neuromuscular Clinic between March 2017 and December 2017 were included. At baseline, patients were assessed clinically and they completed self-administered scales for disease severity, perceived stress, depression and personality type.

RESULTS

Higher disease severity [Myasthenia Gravis Impairment Index (MGII)] showed a moderate correlation with depression score (Beck's Depression Inventory, Second Edition, r = 0.52, P < 0.001) and a lower correlation with chronic stress (Trier Inventory for Assessment of Chronic Stress, r = 0.28, P = 0.001). Chronic stress scores were different according to personality types (anova, P = 0.02). The linear regression model with MGII score as the dependent variable showed R² = 0.34, likelihood ratio chi-squared 74.55, with P < 0.0001. The only variables that predicted disease severity were depression scores (P < 0.0001) and female sex (P = 0.003).

CONCLUSIONS

A significant association of MG severity with depression and chronic stress was found, as well as with female gender. These findings should raise awareness that the long-term management of MG should address depression and potential stress and consider behavioural management to prevent stress-related immune imbalance.

The involvement of sleep in the relationship between the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and depression: A systematic review

BACKGROUND

Recent meta-analyses stimulate an ongoing debate whether 5-HTTLPR modulates the risk for depression including a more pronounced association between stress and depression in the short (S) allele relative to the long (L) allele. Elucidating the pathways by which 5-HTTLPR contributes to depression could resolve this controversy. Insomnia independently contributes to the onset and course of negative affective symptoms and, hence, represents one of the primary risk factors for depression. To evaluate the relevance of this relationship for the interaction between 5-HTTLPR and stress in depression, the present review investigated the moderating influence of 5-HTTLPR on the relationship between stress and sleep quality as well as on the relationship between sleep and affective symptomatology.

METHODS

A systematic search was performed in the PubMed and PsycINFO databases to include a complete outline of studies investigating the relationships of interest.

RESULTS

Results of the included articles reveal that the 5-HTTLPR S-allele relative to the L-allele increases the risk for stress-related sleep quality reductions and promotes the negative affective consequences of inadequate sleep.

LIMITATIONS

The apparent involvement of sleep in the association between 5-HTTLPR and depression remains to be more directly (empirically) examined and studies exploring the influence of 5-HTTLPR on sleep quality produced inconsistent results.

CONCLUSIONS

The reviewed findings support the involvement of sleep in the interaction between 5-HTTLPR and stress in depression. This could have important implications for the inconsistent findings characterizing this field of research and may provide valuable insight into the pathophysiological mechanisms underlying genetic contributions to depression.

The role of NMDA receptor in neurobiology and treatment of major depressive disorder: Evidence from translational research

There is accumulating evidence demonstrating that dysfunction of glutamatergic neurotransmission, particularly via N-methyl-d-aspartate (NMDA) receptors, is involved in the pathophysiology of major depressive disorder (MDD). Several studies have revealed an altered expression of NMDA receptor subtypes and impaired NMDA receptor-mediated intracellular signaling pathways in brain circuits of patients with MDD. Clinical studies have demonstrated that NMDA receptor antagonists, particularly ketamine, have rapid antidepressant effects in treatment-resistant depression, however, neurobiological mechanisms are not completely understood. Growing body of evidence suggest that signal transduction pathways involved in synaptic plasticity play critical role in molecular mechanisms underlying rapidly acting antidepressant properties of ketamine and other NMDAR antagonists in MDD. Discovering the molecular mechanisms underlying the unique antidepressant actions of ketamine will facilitate the development of novel fast acting antidepressants which lack undesirable effects of ketamine. This review provides a critical examination of the NMDA receptor involvement in the neurobiology of MDD including analyses of alterations in NMDA receptor subtypes and their interactive signaling cascades revealed by postmortem studies. Furthermore, to elucidate mechanisms underlying rapid-acting antidepressant properties of NMDA receptor antagonists we discussed their effects on the neuroplasticity, mostly based on signaling systems involved in synaptic plasticity of mood-related neurocircuitries.

Tryptophan hydroxylase 2 as a therapeutic target for psychiatric disorders: focus on animal models

Introduction: Tryptophan hydroxylase 2 (TPH2) is the key, rate-limiting enzyme of serotonin (5-HT) synthesis in the brain. Some polymorphic variants of the human Tph2 gene are associated with psychiatric disorders. Area covered: This review focuses on the mechanisms underlying the association between the TPH2 activity and behavioral disturbances in models of psychiatric disorders. Specifically, it discusses: 1) genetic and posttranslational mechanisms defining the TPH2 activity, 2) behavioral effects of knockout and loss-of-function mutations in the mouse Tph2 gene, 3) pharmacological inhibition and the activation of the TPH2 activity and 4) alterations in the brain TPH2 activity in animal models of psychiatric disorders. We show the dual role of the TPH2 activity: both deficit and excess of the TPH2 activity cause significant behavioral disturbances in animal models of depression, anxiety, aggression, obsessive-compulsive disorders, schizophrenia, and catalepsy. Expert opinion: Pharmacological chaperones correcting the structure of the TPH2 molecule are promising tools for treatment of some hereditary psychiatric disorders caused by loss-of-function mutations in the human Tph2 gene; while some stress-induced affective disorders, associated with the elevated TPH2 activity, may be effectively treated by TPH2 inhibitors. This dual role of TPH2 should be taken into consideration during therapy of psychiatric disorders.

Nitrergic neurotransmission in the paraventricular nucleus of the hypothalamus modulates autonomic, neuroendocrine and behavioral responses to acute restraint stress in rats

We investigated the involvement of nitrergic neurotransmission within the paraventricular nucleus of the hypothalamus (PVN) in modulation of local neuronal activation, autonomic and neuroendocrine responses and behavioral consequences of acute restraint stress in rats. Bilateral microinjections of the selective neuronal nitric oxide (NO) synthase (nNOS) inhibitor Nw-Propyl-L-arginine (NPLA) or the NO scavenger carboxy-PTIO into the PVN reduced arterial pressure and heart rate increases, as well as the fall in cutaneous tail temperature induced by restraint stress. PVN injection of either NPLA or carboxy-PTIO also inhibited restraint-induced increases in anxiety-related behaviors in the elevated plus-maze 24 h later. Local microinjection of NPLA or carboxy-PTIO into the PVN reduced the number of c-fos-immunoreactive neurons in the dorsal parvocellular, ventromedial, medial parvocellular and lateral magnocelllular portions of the PVN in animals subjected to restraint stress. However, neither NPLA nor carboxy-PTIO into the PVN affected restraint-induced increases in plasma corticosterone concentration. The present results indicate that PVN nitrergic neurotransmission acting via nNOS activation has a facilitatory influence on autonomic responses to acute restraint and the delayed emotional consequences of restraint stress. Our results also provide evidence of a prominent role of local nitrergic neurotransmission in PVN neuronal activation during stress.

Impact of space allowance on performance traits, brain neurotransmitters and blood antioxidant activity of New Zealand White rabbits

The objective of this trial was to investigate the effect of space allowance on performance, welfare-related parameters and the levels of brain neurotransmitters in growing male rabbits. In a cage housing system, a total of 96 weaned rabbits were accommodated on three space allowance conditions (S₁ = 1425 cm²/rabbit; S₂ = 850 cm²/rabbit; S₃ = 625 cm²/rabbit), with 8 replicate cages per each group. Rabbits in the S₁ and S₂ groups showed better daily feed intake and feed conversion ratio compared with the high stocking density group (p = 0.004 and 0.018, respectively). Compared to the highest stocking density group (S₃), rabbits in the S₁ and S₂ groups showed significantly lower serum cortisol, MDA and GSSH level (p = 0.026, 0.018 and 0.009, respectively). The concentration of dopamine in brain tissues was significantly decreased in the S₃ group compared with other experimental groups (P = 0.001). However, there was no significant effect of space allowance on the brain AChE level (P = 0.277). Brain serotonin and GABA levels showed a significant decrease in rabbits reared with a limited space allowance (S₃) compared with S₁ and S₂ groups (P = 0.001 and 0.038, respectively). The level of brain MDA was significantly increased in the S₃ group compared with the S₁ group (P = 0.006). However, there were no detectable differences in the brain ATP level in rabbits reared with different space allowance (P = 0.693). In conclusion, the current study indicates that the 850 cm²/rabbit stocking density has resulted in a better feed intake, and welfare-related conditions compared with the 625 cm²/rabbit. Furthermore, the limited space allowance may impair the most important brain neurotransmitters in male rabbits.

Increased sensitivity to sad faces in depressive symptomatology: A longitudinal study

BACKGROUND

Negative bias to sad emotional stimuli has repeatedly been identified as a cognitive feature of major depressive disorder, particularly in facial expression recognition. However, it is unknown how negative bias applies to facial expression recognition in individuals with depressive symptoms.

METHODS

A total of 58 university students' facial expression recognition and depression scores were measured using facial stimuli displaying the whole face, with 39 participants completing a 3-month follow-up assessment of depressive symptoms. We used an index that differentiates sensitivity to sadness from sensitivity to general facial expressions. Participants gave written informed consent after a complete description of the study.

RESULTS

The group with higher depressive symptoms showed a higher sensitivity to sadness than those with lower depressive symptoms, indicating a relationship between negative bias in facial expression recognition and nonclinical depressive symptoms. From a longitudinal point of view, negative bias to sad expressions at one time point was found to predict the change in depression scores at the 3-month follow-up.

LIMITATIONS

Since the participants included only college students, the generalizability of our results to other populations is limited. The three-month interval may not be sufficient to determine the prognosis of depression, suggesting the need for further replications.

DISCUSSION

This study was the first to report the negative bias of facial expression recognition in individuals with nonclinical depressive symptoms. Given that negative bias predicts present and future depression, facial expression recognition has the potential to be used as a screening tool for early detection of depression.

The serotonin transporter polymorphism (5-HTTLPR) and cortisol stress responsiveness: preliminary evidence for a modulating role for sleep quality

The short (S) allele of a functional polymorphism (5-HTTLPR) within the promoter region of the serotonin transporter gene (SLC6A4) is found to predispose the risk for stress-related affective disorders relative to the long (L) allele. Evidence suggests that elevated stress reactivity of the hypothalamic-pituitary-adrenal (HPA) axis might underlie this association although there is little understanding about the origin of inconsistent findings. Since inadequate sleep is commonly known to promote HPA stress reactivity, it might well play an important modulating role. The present study tested this hypothesis by investigating whether sleep quality moderates the relationship between 5-HTTLPR and cortisol stress responsiveness. From a large 5-HTTLPR database (n = 771), a sample of healthy male and female participants homozygous for either the 5-HTTLPR S-allele (n = 25) or L-allele (n = 25) were assessed for sleep quality and salivary cortisol secretion during acute laboratory stress. Diminished sleep quality was found to exclusively potentiate cortisol stress reactivity in the homozygous L-allele genotype. Accounting for this 5-HTTLPR-dependent influence enhanced the predictive value of 5-HTTLPR on cortisol stress responsiveness, revealing greater HPA reactivity in S-allele relative to L-allele carriers. Current findings suggest that variations in sleep quality may serve as a confounding factor in the search for genetic differences in stress sensitivity and related affective disorders.

Development of a Self Report Stress Scale Using Item Response Theory-I: Item Selection, Formation of Factor Structure and Examination of Its Psychometric Properties

INTRODUCTION

Due to the absence of Turkish psychometric devices assessing stress, in the present study it was aimed to develop a stress scale, and examine its basic psychometric properties.

METHODS

Current study included two processes, formation of item pool and examination of psychometric properties of the selected items through three studies. In the first study, 611 individuals aged between 18 and 77 responded to 130 selected items. In the second study, 2223 individuals aged between 18 and 68 responded to 80 items. In the third study, 1969 individuals aged between 18 and 79 responded to the final form of 36 items. Further, in study 3 for criterion related validity 163 individuals completed the Coopersmith Self-Esteem Inventory, 113 individuals completed the Beck Anxiety Inventory, 104 individuals completed the Hospital Anxiety and Depression Scale, 107 individuals completed the Beck Depression Inventory, and 265 individuals completed the Perceived Stress Scale. Moreover, in the investigation of test-retest reliability, 119 individuals took the final form of the test after 2 weeks, and 111 individuals took the final form of the test after 3 weeks.

RESULTS

In the first study, out of 130 items, 54 that showed item-total score correlations below 0.30 were excluded from the scale. Fifty-seven items were preserved exactly, and 19 items' sentence structures were changed. Furthermore, by adding 4 new items, 80 were prepared for the second study. In the second study, two factors structure namely "Physiological Reactions/Strain" and "Psychological/Cognitive Appraisals" sub-dimensions were identified, and 36 items were selected via Item Response Theory representing these sub-dimensions. In study 3, exploratory factor analysis provided strong support for our hypothesized two factors structure. Confirmatory factor analysis indicated hypothesized model had a better fit to the data. Internal consistency coefficients were 0.94 for the entire scale, 0.90 for Physiological Reactions/Strain sub-dimension, and 0.91 for Psychological/Cognitive Appraisals sub-dimension. Correlation coefficients between the entire scale and other criterion scales ranged from 0.22 to 0.63. Test-retest correlation coefficients between the first administration of the scale, and the administrations at two and three week intervals were 0.88.

CONCLUSION

Results showed that the scale has basic psychometric requirements provided that the scale will be supported by validity studies.

Does stress influence sleep patterns, food intake, weight gain, abdominal obesity and weight loss interventions and vice versa?

Decades of research have reported only weak associations between the intakes of specific foods or drinks and weight gain and obesity. Randomized controlled dietary intervention trials have only shown very modest effects of changes in nutrient intake and diet composition on body weight in obese subjects. This review summarizes the scientific evidence on the role mental stress (either in or not in association with impaired sleep) may play in poor sleep, enhanced appetite, cravings and decreased motivation for physical activity. All these factors contribute to weight gain and obesity, possibly via decreasing the efficacy of weight loss interventions. We also review evidence for the role that lifestyle and stress management may play in achieving weight loss in stress-vulnerable individuals with overweight.

Pharmacological challenge studies with acute psychosocial stress

Chronic stress is known to affect many psychiatric disorders, and studies of responses to acute stress may reveal processes that ultimately lead to maladaptive responses to chronic stress. Many studies have used simulated public speaking tasks to induce stress in the laboratory and, of interest to this review, the tasks have been used to assess the effects of both therapeutic and nonmedical drugs on stress reactivity. Here we review 38 studies that examined effects of single doses of drugs on subjective, cardiovascular and hormonal responses to an acute social stressor in healthy volunteers. Most studies have used the Trier Social Stress Test (TSST), or variations on it involving public speaking or mental arithmetic. Pharmacological studies with the TSST (ph-TSST) have been conducted for three main reasons: i) to determine the clinical effectiveness of psychiatric medications to reduce stress responses, ii) to investigate the neurochemical mechanisms involved in the stress response, and iii) to determine whether drugs of abuse relieve, or occasionally worsen, responses to acute stress. The review indicates that standard anxiolytic medications consistently reduce subjective responses to the TSST, whereas single doses of antidepressants produce mixed effects. Mechanistic studies indicate that several neurotransmitter systems are involved in the stress response, including serotonin, norepinephrine, GABA, glutamate, opioids, and endocannabinoids. Among drugs of abuse, alcohol and cannabinoids exert some stress-dampening effects, whereas caffeine, nicotine, and amphetamines tend to increase stress responses. Comparing outcome measures of the responses to stress, subjective ratings of anxiety are among the most sensitive indices of the stress response, with cortisol levels second and cardiovascular responses least sensitive. We conclude that the TSST is a valuable tool to study the clinical effectiveness of medications for stress-related disorders, and that it is important to use standardized procedures to enable comparisons across studies.

The interaction between 5-HTTLPR genotype and ruminative thinking on BMI

Negative affect or stress is often found to increase energy intake for high palatable energy-rich foods and hence weight gain. Reduced brain serotonin (5-HT) function is known to increase stress vulnerability and the risk for eating-related disturbances. A short (S) allele polymorphism in the serotonin transporter gene (5-HTTLPR) is associated with a less efficient functioning brain serotonin system and therefore higher stress vulnerability. It has been suggested that this genotype may be directly linked to an increased risk for weight gain and/or obesity. However, a high amount of variability has been apparent in replicating such a direct gene on weight gain relationship. A most recent suggestion is that this gene by weight relationship might be moderated by an additional (cognitive) vulnerability factor involving repetitive negative thinking (rumination). Our objective was to investigate whether the S-allele of 5-HTTLPR contributes to weight gain particularly in high cognitive ruminating individuals. A total of 827 healthy young male and female college students (aged 21·3 (sd 3·0) years; BMI 16–41·7 kg/m2) were genotyped for the 5-HTTLPR polymorphism and assessed for rumination (Event Related Ruminative Index) and body weight. In line with the hypothesis, a hierarchical regression model showed that higher BMI scores were observed in specifically high ruminating S'-carriers (P=0·031, f²=0·022). These results suggest that cognitive rumination may be a critical moderator of the association between 5-HTTLPR and body mass.

A Randomized Controlled Trial on Functional Relaxation as an Adjunct to Psychoeducation for Stress

This randomized controlled trial investigated whether adding the psychodynamically based body-oriented psychotherapy “Functional Relaxation” (FR) to psychoeducation (PE) is more effective than PE alone to reduce stress and stress-associated complaints. Eighty-one participants with elevated stress-levels, ≥50 points on the global scale of the Perceived Stress Questionnaire (PSQ), received either 10 sessions of manualized FR + PE (n = 42) or two sessions of manualized PE alone (n = 39) in a group setting. Six FR trainers took part in this study. Stress-level (PSQ) was the primary outcome and secondary outcomes were depression (PHQ-9) and somatization (PHQ-15). Multilevel models for discontinuous change revealed that FR + PE was more helpful to reduce stress-levels than PE from pre-treatment to post-treatment (t0 → t1) as well as from pre-treatment to 6-month follow-up (t0 → t2) (both p < 0.05) with effect sizes (d) being medium for PE (d_{t0 → t1} = 0.57; d_{t0 → t2} = 0.67) and large for FR + PE (d_{t0 → t1} = 1.57; d_{t0 → t2} = 1.39). Moreover, FR + PE affected depression and somatization more positively than did PE from t0 to t1 as well as from t0 to t2 (all p < 0.05). Effect sizes for depression were small to medium for PE (d_{t0 → t1} = 0.52; d_{t0 → t2} = 0.37) and large for FR + PE (d_{t0 → t1} = 1.04; d_{t0 → t2} = 0.95). Effect sizes for somatization were small for PE (d_{t0 → t1} = 0.18; d_{t0 → t2} = 0.19) and medium to large for FR + PE (d_{t0 → t1} = 0.73; d_{t0 → t2} = 0.93). In summary, the combination of FR and PE was more effective than PE alone. The results of the present trial provide first evidence of FR as a potent component of stress interventions. Adding FR to such interventions might better help prevent clinically relevant disorders such as depression or somatization.

Medical school predictors of later perceived mastery of clinical work among Norwegian doctors: a cohort study with 10-year and 20-year follow-up

OBJECTIVE

Doctors' self-perceived mastery of clinical work might have an impact on their career and patient care, in addition to their own health and well-being. The aim of this study is to identify predictors at medical school of perceived mastery later in doctors' careers.

DESIGN

A cohort of medical students (n=631) was surveyed in the final year of medical school in 1993/1994 (T1), and 10 (T2) and 20 (T3) years later.

SETTING

Nationwide healthcare institutions.

PARTICIPANTS

Medical students from all universities in Norway.

MAIN OUTCOME MEASURES

Perceived mastery of clinical work was measured at T2 and T3. The studied predictors measured at T1 included personality traits, medical school stress, perceived medical recording skills, identification with the role of doctor, hazardous drinking and drinking to cope, in addition to age and gender. Effects were studied using multiple linear regression models.

RESULTS

Response rates: T1, 522/631 (83%); T2, 390/522 (75%); and T3, 303/522 (58%). Mean scores at T2 and T3 were 22.3 (SD=4.2) and 24.5 (3.0) (t=8.2, p<0.001), with no gender difference. Adjusted associations at T2 were: role identification (β=0.16; p=0.006; 95% CI 0.05 to 0.28), perceived medical recording skills (β=0.13; p=0.02; 95% CI 0.02 to 0.24) and drinking to cope (β=-2.45; p=0.001; 95% CI -3.88 to -1.03). Adjusted association at T3 was perceived medical recording skills (β=0.11; p=0.015; 95% CI 0.02 to 0.21).

CONCLUSIONS

Perceived medical recording skills and role identification were associated with higher perceived mastery. Medical schools should provide experiences, teaching and assessment to enhance students' physician role identification and confidence in their own skills. Drinking to cope was associated with lower perceived mastery, which indicates the importance of acquiring healthier coping strategies in medical school.

Comparison of two approaches to prevention of mental health problems in college students: Enhancing coping and executive function skills

OBJECTIVE

College students face a significant number of stressors, increasing risk for internalizing and externalizing psychopathology. The current study examines two promising avenues of intervention aimed to reduce stress and prevent psychopathology in this population: a coping skills group and a cognitive training program.

PARTICIPANTS

62 undergraduate students from two universities were recruited from 2013 to 2015.

METHODS

Students were randomized to a 6-week coping skills group or cognitive training program and completed measures of stress, coping, executive function, and symptoms of anxiety, depression and Attention-Deficit Hyperactivity Disorder (ADHD) at pre- and post-intervention.

RESULTS

Participants in both conditions reported significant decreases in social stress, executive function difficulties, and anxiety symptoms post-intervention. Students in the cognitive program improved significantly more on measures of behavior regulation and ADHD symptoms compared to the coping group at post-intervention.

CONCLUSIONS

Brief stress management interventions targeting coping and executive function may benefit college students at risk for psychopathology.

Inflammation and vascular remodeling in the ventral hippocampus contributes to vulnerability to stress

During exposure to chronic stress, some individuals engage in active coping behaviors that promote resiliency to stress. Other individuals engage in passive coping that is associated with vulnerability to stress and with anxiety and depression. In an effort to identify novel molecular mechanisms that underlie vulnerability or resilience to stress, we used nonbiased analyses of microRNAs in the ventral hippocampus (vHPC) to identify those miRNAs differentially expressed in active (long-latency (LL)/resilient) or passive (short-latency (SL)/vulnerable) rats following chronic social defeat. In the vHPC of active coping rats, miR-455-3p level was increased, while miR-30e-3p level was increased in the vHPC of passive coping rats. Pathway analyses identified inflammatory and vascular remodeling pathways as enriched by genes targeted by these microRNAs. Utilizing several independent markers for blood vessels, inflammatory processes and neural activity in the vHPC, we found that SL/vulnerable rats exhibit increased neural activity, vascular remodeling and inflammatory processes that include both increased blood-brain barrier permeability and increased number of microglia in the vHPC relative to control and resilient rats. To test the relevance of these changes for the development of the vulnerable phenotype, we used pharmacological approaches to determine the contribution of inflammatory processes in mediating vulnerability and resiliency. Administration of the pro-inflammatory cytokine vascular endothelial growth factor-164 increased vulnerability to stress, while the non-steroidal anti-inflammatory drug meloxicam attenuated vulnerability. Collectively, these results show that vulnerability to stress is determined by a re-designed neurovascular unit characterized by increased neural activity, vascular remodeling and pro-inflammatory mechanisms in the vHPC. These results suggest that dampening inflammatory processes by administering anti-inflammatory agents reduces vulnerability to stress. These results have translational relevance as they suggest that administration of anti-inflammatory agents may reduce the impact of stress or trauma in vulnerable individuals.

A translational approach to clinical practice via stress-responsive glucocorticoid receptor signaling

A recent article by Kwan and colleagues could elegantly demonstrate the necessary interaction between neuronal serotonin (5-HT) systems and the hypothalamic-pituitary-adrenal (HPA) axis through glucocorticoid receptors (GR), producing an adequate stress response, in this case, responding to hypoxia with an increase in hematopoietic stem and progenitor cells (HSPC). There is an intricate system connecting brain, body and mind and this exchange is only possible when all these systems-nervous, endocrine, and immune-have receptors on critical cells to receive information (via messenger molecules) from each of the other systems. There is evidence that the expression and function of GR in the hippocampus, mainly MR, is regulated by the stimulation of 5-HT receptors. Stressful stimuli increase 5-HT release and turnover in the hippocampus, and it seems reasonable to suggest that some of the changes in mineralocorticoid and GR expression may be mediated, in part at least, by the increase in 5-HT. Also serotonin and HPA axis dysfunctions have already been implicated in a variety of psychiatric disorders, especially depression. Early life stress (ELS) can have profound impact on these systems and can predispose subjects to a variety of adult metabolic and psychiatric conditions. It is important to analyze the mechanisms of this complex interaction and its subsequent programming effects on the stress systems, so that we can find new ways and targets for treatment of psychiatric disorders. Different areas of research on basic biological sciences are now being integrated and this approach will hopefully provide several new insights, new pharmacological targets and improve our global understanding of these highly debilitating chronic conditions, that we now call mental disorders.

Traditional herbal formula Sini Powder extract produces antidepressant-like effects through stress-related mechanisms in rats

Sini Powder (SP), a traditional Chinese herbal formula, has long been used to treat depression in patients, although the underlying mechanisms remain to be elucidated. In the present study, we found that rats treated with SP extract for 7 days showed a significant increase in swimming time and reduction in immobility time in forced swimming test in a dose-dependent manner, without changes in locomotion. These effects could be attributed to SP's modulation of the hypothalamus-pituitary-adrenal axis, because a single pretreatment of SP extract could rescue increased serum corticosterone and plasma adrenocorticotropin levels induced by acute elevated platform stress. A single pretreatment of SP extract could also elevate the mRNA expression of hippocampal glucocorticoid receptors. In conclusion, our results suggest that SP extract may act as an anti-stress medication to produce antidepressant-like effects.

Depressive vulnerability, stressful life events and episode onset of major depression: a longitudinal model

BACKGROUND

The nature of the relationship between depressive vulnerability (DV) and acute adversity in the etiology of major depression (MD) remains poorly understood.

METHOD

Stressful life events (SLEs) and MD onsets in the last year were assessed at four waves in cohort 1 (females) and at two waves in cohort 2 (males and females) from the Virginia Adult Twin Study. Structural equation modeling was conducted in Mplus.

RESULTS

In cohort 1, DV was strongly indexed by depressive episodes over the four waves (paths from +0.72 to 0.79) and predicted by SLEs in the month of their occurrence (+0.31 to 0.36). Wave-specific DV was associated both with stable DV (+0.29 to 0.33) and by forward transmission of DV from the preceding wave (+0.33 to 0.36). SLEs were predicted by stable DV (+0.29) and from SLEs in the preceding month (+0.06). As the cohort aged, MD onsets were better indexed by DV and more poorly predicted by SLEs. Parameter estimates were similar in males and females from cohort 2. In individuals with prior depressive episodes, the association between MD onset and SLEs was weakened while the prediction of SLEs from DV was substantially strengthened. We found no evidence for 'reverse causation' from MD episodes to SLEs.

CONCLUSION

The interrelationship between DV and acute adversity in the etiology of MD is complex and temporally dynamic. DV impacts on MD risk both directly and indirectly through selection into high stress environments. Over time, depressive episodes become more autonomous. Both DV and SLEs transmit forward over time and therefore form clear targets for intervention.

Concordance and incongruence in preclinical anxiety models: Systematic review and meta-analyses

Rodent defense behavior assays have been widely used as preclinical models of anxiety to study possibly therapeutic anxiety-reducing interventions. However, some proposed anxiety-modulating factors - genes, drugs and stressors - have had discordant effects across different studies. To reconcile the effect sizes of purported anxiety factors, we conducted systematic review and meta-analyses of the literature on ten anxiety-linked interventions, as examined in the elevated plus maze, open field and light-dark box assays. Diazepam, 5-HT1A receptor gene knockout and overexpression, SERT gene knockout and overexpression, pain, restraint, social isolation, corticotropin-releasing hormone and Crhr1 were selected for review. Eight interventions had statistically significant effects on rodent anxiety, while Htr1a overexpression and Crh knockout did not. Evidence for publication bias was found in the diazepam, Htt knockout, and social isolation literatures. The Htr1a and Crhr1 results indicate a disconnect between preclinical science and clinical research. Furthermore, the meta-analytic data confirmed that genetic SERT anxiety effects were paradoxical in the context of the clinical use of SERT inhibitors to reduce anxiety.

Adolescence and the ontogeny of the hormonal stress response in male and female rats and mice

Adolescent development is marked by many changes in neuroendocrine function, resulting in both immediate and long-term influences on an individual's physiology and behavior. Stress-induced hormonal responses are one such change, with adolescent animals often showing different patterns of hormonal reactivity following a stressor compared with adults. This review will describe the unique ways in which adolescent animals respond to a variety of stressors and how these adolescent-related changes in hormonal responsiveness can be further modified by the sex and previous experience of the individual. Potential central and peripheral mechanisms that contribute to these developmental shifts in stress reactivity are also discussed. Finally, the short- and long-term programming effects of chronic stress exposure during adolescence on later adult hormonal responsiveness are also examined. Though far from a clear understanding of the neurobehavioral consequences of these adolescent-related shifts in stress reactivity, continued study of developmental changes in stress-induced hormonal responses may shed light on the increased vulnerability to physical and psychological dysfunctions that often accompany a stressful adolescence.

Current Models and Future Directions for Understanding the Neural Circuitries of Maternal Behaviors in Rodents

Maternal behaviors in rodents include a number of subcomponents, such as nursing, nest building, licking and grooming of pups, pup retrieval, and maternal aggression. Because each behavior involves a unique motor pattern, a unique ensemble neural circuitry must underlie each behavior. To what extent there is overlap in terms of brain regions and specific neurons for each circuit is being actively investigated. This review will first examine overlapping and separate components of pup retrieval and maternal aggression circuitries while examining a central role for medial preoptic area (MPA) in both behaviors. With an emphasis on experimental approaches, the review will then highlight recent findings and propose future directions for understanding maternal behavior regulation. Finally, examples for why studying the neural basis of maternal behaviors can bring insights to other areas of neuroscience, such as feeding, addiction, and anxiety and aggression regulation will be provided.

Alterations in pharmacological and behavioural responses in recombinant mouse line with an increased predisposition to catalepsy: role of the 5-HT1A receptor

BACKGROUND AND PURPOSE

One important syndrome of psychiatric disorders in humans is catalepsy. Here, we created mice with different predispositions to catalepsy and analysed their pharmacological and behavioural properties.

EXPERIMENTAL APPROACH

Two mouse lines, B6-M76C and B6-M76B, were created by transfer of the main locus of catalepsy containing the 5-HT1A receptor gene to the C57BL/6 genetic background. Behaviour, brain morphology, expression of key components of the serotoninergic system, and pharmacological responses to acute and chronic stimulation of the 5-HT1A receptor were compared.

KEY RESULTS

B6-M76B mice were not cataleptic, whereas 14% of B6-M76C mice demonstrated catalepsy and decreased depressive-like behaviour. Acute administration of the 5-HT1A receptor agonist 8-OH-DPAT resulted in dose-dependent hypothermia and in decreased locomotion in both lines. Chronic 8-OH-DPAT administration abolished the 5-HT1A receptor-mediated hypothermic response in B6-M76C mice and increased locomotor activity in B6-M76B mice. In addition, 5-HT metabolism was significantly reduced in the hippocampus of B6-M76C mice, and this effect was accompanied by an increased expression of the 5-HT1A receptor.

CONCLUSIONS AND IMPLICATIONS

Our findings indicate that transfer of the main locus of hereditary catalepsy containing the 5-HT1A receptor from CBA mice to the C57BL/6 genetic background led to increased postsynaptic and decreased presynaptic functional responses of the 5-HT1A receptor. This characteristic establishes the B6-M76C line as an attractive model for the pharmacological screening of 5-HT1A receptor-related drugs specifically acting on either pre- or postsynaptic receptors.

LINKED ARTICLES

This article is part of a themed section on Updating Neuropathology and Neuropharmacology of Monoaminergic Systems. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v173.13/issuetoc.

Behavioral and self-reported sensitivity to reward are linked to stress-related differences in positive affect

Despite the high prevalence of stress exposure healthy adaptation or resilience is a common response. Theoretical work and recent empirical evidence suggest that a robust reward system, in part, supports healthy adaptation by preserving positive emotions even under exceptionally stressful circumstances. We tested this prediction by examining empirical relations among behavioral and self-reported measures of sensitivity to reward, trait resilience, and measures of affect in the context of experimentally induced stress. Using a quasi-experimental design we obtained measures of sensitivity to reward (self-report and behavioral), as well as affective and physiological responses to experimental psychosocial stress in a sample of 140 healthy college-age participants. We used regression-based moderation and mediational models to assess associations among sensitivity to reward, affect in the context of stress, and trait resilience and found that an interaction between exposure to experimental stress and self-reported sensitivity to reward predicted positive affect following experimental procedure. Participants with high sensitivity to reward reported higher positive affect following stress. Moreover, positive affect during or after stress mediated the relation between sensitivity to reward and trait resilience. Consistent with the prediction that a robust reward system serves as a protective factor against stress-related negative outcomes, our results found predictive associations among sensitivity to reward, positive affect, and resilience.

Ancient Anxiety Pathways Influence Drosophila Defense Behaviors

Anxiety helps us anticipate and assess potential danger in ambiguous situations [1, 2, 3]; however, the anxiety disorders are the most prevalent class of psychiatric illness [4, 5, 6]. Emotional states are shared between humans and other animals [7], as observed by behavioral manifestations [8], physiological responses [9], and gene conservation [10]. Anxiety research makes wide use of three rodent behavioral assays—elevated plus maze, open field, and light/dark box—that present a choice between sheltered and exposed regions [11]. Exposure avoidance in anxiety-related defense behaviors was confirmed to be a correlate of rodent anxiety by treatment with known anxiety-altering agents [12, 13, 14] and is now used to characterize anxiety systems. Modeling anxiety with a small neurogenetic animal would further aid the elucidation of its neuronal and molecular bases. Drosophila neurogenetics research has elucidated the mechanisms of fundamental behaviors and implicated genes that are often orthologous across species. In an enclosed arena, flies stay close to the walls during spontaneous locomotion [15, 16], a behavior proposed to be related to anxiety [17]. We tested this hypothesis with manipulations of the GABA receptor, serotonin signaling, and stress. The effects of these interventions were strikingly concordant with rodent anxiety, verifying that these behaviors report on an anxiety-like state. Application of this method was able to identify several new fly anxiety genes. The presence of conserved neurogenetic pathways in the insect brain identifies Drosophila as an attractive genetic model for the study of anxiety and anxiety-related disorders, complementing existing rodent systems.

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Drosophila orthologs of anxiety genes affect fly wall following

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Conserved anxiety genes influence fly defense behaviors similarly to mouse anxiety

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New candidate anxiety genes are identified from fly defense behavior screen

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Drosophila identified as a new neurogenetic tool for anxiety research

Effects of a Web-Based Intervention for Stress Reduction in Primary Care: A Cluster Randomized Controlled Trial

BACKGROUND

Preliminary findings suggest that Web-based interventions may be effective in achieving significant stress reduction. To date, there are no findings available for primary care patients. This is the first study that investigates a Web-based intervention for stress reduction in primary care.

OBJECTIVE

The aim was to examine the short-term effectiveness of a fully automated Web-based coaching program regarding stress reduction in a primary care setting.

METHODS

The study was an unblinded cluster randomized trial with an observation period of 12 weeks. Individuals recruited by general practitioners randomized to the intervention group participated in a Web-based coaching program based on education, motivation, exercise guidance, daily text message reminders, and weekly feedback through the Internet. All components of the program were fully automated. Participants in the control group received usual care and advice from their practitioner without the Web-based coaching program. The main outcome was change in the Perceived Stress Questionnaire (PSQ) over 12 weeks.

RESULTS

A total of 93 participants (40 in intervention group, 53 in control group) were recruited into the study. For 25 participants from the intervention group and 49 participants from the control group, PSQ scores at baseline and 12 weeks were available. In the intention-to-treat analysis, the PSQ score decreased by mean 8.2 (SD 12.7) in the intervention group and by mean 12.6 (SD 14.7) in the control group. There was no significant difference identified between the groups (mean difference -4.5, 95% CI -10.2 to 1.3, P=.13).

CONCLUSIONS

This trial could not show that the tested Web-based intervention was effective for reducing stress compared to usual care. The limited statistical power and the high dropout rate may have reduced the study's ability to detect significant differences between the groups. Further randomized controlled trials are needed with larger populations to investigate the long-term outcome as well as the contents of usual primary care.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00003067; http://drks-neu.uniklinik-freiburg.de/drks_web/navigate.do?=DRKS00003067 (Archived by WebCite at http://www.webcitation.org/6eXk0PXmO).

The association between maternal psychological stress and inflammatory cytokines in allergic young children

Background. Previous studies have shown that psychological stress is linked to asthma prevalence. Parental psychological stress may potentially influence inflammatory responses in their allergic children. The purpose of this study is to clarify the association between maternal psychological status and inflammatory response of allergic young children.

Methods. The study subjects were 152 young allergic children (median age: 13 months) who had not shown any allergic symptoms in the past one month. mRNA expression levels of the inflammatory response genes IL-6, IL-8, IL-10 and IL-22 were quantified by qRT-PCR. Maternal psychological status was assessed by standardized questionnaires: the Centre for Epidemiological Studies Depression Scale (CES-D) for depression and the Japanese Perceived Stress Scale (JPSS) for perceived stress.

Results. A significant positive association was observed between maternal CES-D scores and IL-6 mRNA expression in the children with asthma. The JPSS scores were also positively associated with IL-8 mRNA expression in asthmatic children and IL-6 mRNA expression in children with allergic rhinitis. Similar trends were observed among children positive for house dust mite-specific IgE, but these associations were not significant.

Conclusion. This study supports the hypothesis that maternal psychological stress affects the inflammatory response in their allergic children.

IS OXYTOCIN RELEVANT FOR THE AFFECTIVE DISORDERS?

Oxytocin is a complex molecule involved in a variety of biological processes at both the central and the peripheral level. Although its role was initially associated almost exclusively with birth and breastfeeding, recent studies are suggesting that in fact oxytocin could be involved in many other physiological and pathological processes. In this way, lately there is a growing interest towards a possible involvement of oxytocin in many etiopathogenic and psychopathological processes, as for example in the affective disorders, where the roles of oxytocin are not yet clearly understood. In this paper we shortly describe the main aspects regarding the relevance of oxytocin administration or its mechanisms in the affective disorders, as well as its relations with the hypothalamic-pituitary-adrenal axis and cortisol secretion. It seems that although the researches on the importance of oxytocin in the affective disorders are rather at the beginning, an increasing number of evidence is supporting the involvement of oxytocin in the pathogenic processes of these psychiatric disorders. Still, the studies covering this topic are still in their early days, and the results that are trying to understand if there is a major role of oxytocin in affective disorders are not consistent enough to draw definitive conclusions and establish with certainty where the place of oxytocin in the affective disorders pathology is.

Analysis of structural relationship among the occupational dysfunction on the psychological problem in healthcare workers: a study using structural equation modeling

Purpose. The purpose of this study is to demonstrate the hypothetical model based on structural relationship with the occupational dysfunction on psychological problems (stress response, burnout syndrome, and depression) in healthcare workers.

Method. Three cross sectional studies were conducted to assess the following relations: (1) occupational dysfunction on stress response (n = 468), (2) occupational dysfunction on burnout syndrome (n = 1,142), and (3) occupational dysfunction on depression (n = 687). Personal characteristics were collected through a questionnaire (such as age, gender, and job category, opportunities for refreshment, time spent on leisure activities, and work relationships) as well as the Classification and Assessment of Occupational Dysfunction (CAOD). Furthermore, study 1 included the Stress Response Scale-18 (SRS-18), study 2 used the Japanese Burnout Scale (JBS), and study 3 employed the Center for Epidemiological Studies Depression Scale (CES-D). The Kolmogorov–Smirnov test, confirmatory factor analysis (CFA), exploratory factor analysis (EFA), and path analysis of structural equation modeling (SEM) analysis were used in all of the studies. EFA and CFA were used to measure structural validity of four assessments; CAOD, SRS-18, JBS, and CES-D. For examination of a potential covariate, we assessed the correlation of the total and factor score of CAOD and personal factors in all studies. Moreover, direct and indirect effects of occupational dysfunction on stress response (Study 1), burnout syndrome (Study 2), and depression (Study 3) were also analyzed.

Results. In study 1, CAOD had 16 items and 4 factors. In Study 2 and 3, CAOD had 16 items and 5 factors. SRS-18 had 18 items and 3 factors, JBS had 17 items and 3 factors, and CES-D had 20 items and 4 factors. All studies found that there were significant correlations between the CAOD total score and the personal factor that included opportunities for refreshment, time spent on leisure activities, and work relationships (p < 0.01). The hypothesis model results suggest that the classification of occupational dysfunction had good fit on the stress response (RMSEA = 0.061, CFI = 0.947, and TLI = 0.943), burnout syndrome (RMSEA = 0.076, CFI = 0.919, and TLI = 0.913), and depression (RMSEA = 0.060, CFI = 0.922, TLI = 0.917). Moreover, the detected covariates include opportunities for refreshment, time spent on leisure activities, and work relationships on occupational dysfunction.

Conclusion. Our findings indicate that psychological problems are associated with occupational dysfunction in healthcare workers. Reduction of occupational dysfunction might be a strategy of better preventive occupational therapies for healthcare workers with psychological problems. However, longitudinal studies will be needed to determine a causal relationship.

The Cortisol Awakening Response in Patients with Poststroke Depression Is Blunted and Negatively Correlated with Depressive Mood

It is important to reduce poststroke depression (PSD) to improve the stroke outcomes and quality of life in stroke patients, but the underlying mechanisms of PSD are not completely understood. As many studies implicate dysregulation of hypothalamic-pituitary-adrenal axis in the etiology of major depression and stroke, we compared the cortisol awakening response (CAR) of 28 admitted PSD patients with that of 23 age-matched caregiver controls. Saliva samples for cortisol measurement were collected immediately, 15, 30, and 45 min after awakening for two consecutive days. Depressive mood status in PSD patients was determined with Beck Depression Inventory and Hamilton Depression Rating Scale. Salivary cortisol levels of PSD patients did not rise significantly at any sampling time, showing a somewhat flat curve. Caregiver controls showed significantly higher CAR at 15 and 30 min after awakening compared to PSD patients even though the two groups did not differ at awakening or 45 min after awakening. Area-under-the-curve analysis revealed a significant negative correlation between the CAR and the degree of depression in PSD patients. Thus, our findings suggest that poststroke depression is closely related with dysfunctional HPA axis indicated by blunted CAR.

Exercise copes with prolonged stress-induced impairment of spatial memory performance by endoplasmic reticulum stress

The present study demonstrates that prolonged restraint administration for 21 days caused memory impairment and induced hippocampal endoplasmic reticulum (ER) stress-mediated apoptosis. On the contrary, this change was revered by treadmill running for 8 weeks. Repeated psychological stress caused an increase in escape latency time in the water maze test, accompanied by the induction of glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), and cleaved/active caspase-12 protein in the hippocampus. The expression pattern of ER stress response-related proteins were counter-regulated by chronic exercise, as indicated by a reduction in GRP78, CHOP, and cleaved caspase-12, along with a decrease in escape latency time. In addition, the hippocampal expression pattern of phospho-cAMP response element-binding protein (CREB) and brain-derived neurotrophic factor (BDNF) opposed that of ER stress response components. Accordingly, chronic exercise may attenuate prolonged stress-induced hippocampal ER stress and memory deficit, likely through CREB/BDNF signaling.

What's wrong with my mouse cage? Methodological considerations for modeling lifestyle factors and gene-environment interactions in mice

The mechanistic understanding of lifestyle contributions to disease has been largely driven by work in laboratory rodent models using environmental interventions. These interventions show an array of methodologies and sometimes unclear collective conclusions, hampering clinical interpretations. Here we discuss environmental enrichment, exercise and stress interventions to illustrate how different protocols can affect the interpretations of environmental factors in disease. We use Huntington's disease (HD) as an example because its mouse models exhibit excellent validity and HD was the first genetic animal model in which environmental stimulation was found to be beneficial. We make a number of observations and recommendations. Firstly, environmental enrichment and voluntary exercise generally show benefits across laboratories and mouse models. However, the extent to which these environmental interventions have beneficial effects depends on parameters such as the structural complexity of the cage in the case of enrichment, the timing of the intervention and the nature of the control conditions. In particular, clinical interpretations should consider deprived control living conditions and the ethological relevance of the enrichment. Secondly, stress can have negative effects on the phenotype in mouse models of HD and other brain disorders. When modeling stress, the effects of more than one type of experimental stressor should be investigated due to the heterogeneity and complexity of stress responses. With stress in particular, but ideally in all studies, both sexes should be used and the randomized group sizes need to be sufficiently powered to detect any sex effects. Opportunities for clinical translation will be guided by the 'environmental construct validity' of the preclinical data, including the culmination of complementary protocols across multiple animal models. Environmental interventions in mouse models of HD provide illustrative examples of how valid preclinical studies can lead to conclusions relevant to clinical populations.

The role of the dynorphin/κ opioid receptor system in anxiety

Anxiety disorders are the most common and prevalent forms of psychiatric disease, although the biological basis of anxiety is not well understood. The dynorphin/κ opioid receptor system is widely distributed in the central nervous system and has been shown to play a critical role in modulating mood and emotional behaviors. In the present review, we summarize current literature relating to the role played by the dynorphin/κ opioid receptor system in anxiety and κ opioid receptor antagonists as potential therapeutic agents for the treatment of anxiety disorders.

Effects of tryptophan supplementation on growth performance, antioxidative activity, and meat quality of ducks under high stocking density

High stocking density (STD) could affect duck welfare and production. The objective of our study was to investigate whether dietary tryptophan (TRP) supplementation could alleviate the detrimental effects of high STD on ducks. White Pekin ducks at 4 to 6 wk of age were raised at 11 birds/m(2) and fed diets containing 0.18, 0.48, 0.78, or 1.08% TRP for 21 d. Growth performance, concentrations of TRP and metabolites in the blood and hypothalamus, antioxidative activities in serum and tissue, meat quality, serum uric acid, and urea nitrogen were measured. Weight gain and feed efficiency were significantly improved by TRP supplementation at ≥ 0.48 and ≥ 0.78% (P < 0.05 and P < 0.001, respectively). Serum TRP, hypothalamic TRP, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacitic acid (5-HIAA), and 5-HIAA/5-HT were also increased significantly (P < 0.01). These increases plateaued at 0.48% TRP, and no further improvement was obtained by adding more TRP to the diet. Dietary TRP supplementation significantly increased levels of total antioxidant capacity, glutathione peroxidase (GSH-Px), and catalase (CAT) in serum; GSH-Px in liver; and GSH-Px and CAT in breast muscle (P < 0.05). Malondialdehyde levels in breast muscle decreased (P < 0.001). Drip loss of breast muscle and pH decline at 45 min postmortem were reduced by TRP supplementation (P < 0.01 and P < 0.05, respectively). Meat color was similar among different treatments (P > 0.05). Breast muscle shear force was increased significantly when dietary TRP level increased to 1.08% (P < 0.01). For ducks raised at 11 birds/m², dietary TRP supplementation could alleviate stress and improve growth performance, antioxidative activity, and meat quality.

Gene × cognition interaction on stress-induced eating: effect of rumination

People often crave for high-caloric sweet foods when facing stress and this 'emotional eating' is a most important cause for weight gain and obesity. Eating under stress contrasts with the normally expected response of a loss of appetite, yet in spite of intensive research from neurobiological and cognitive disciplines we still do not know why stress or negative affect triggers overeating in so many of us. Since the prevalence of overweight and obesity still rises, the discovery of crucial risk factors is a most desirable goal of today's research on sub-optimal eating habits. This paper summarizes the most relevant current knowledge from the (human) literature regarding cognitive and biological vulnerabilities for stress-induced emotional eating. A (non-systematic) review of the most relevant studies reveals that most studies contemplate a rather one-directional way of focusing on either cognitive or biological factors, showing inconsistent results. The current paper elaborates and/or integrates these findings into a biological-cognitive interaction model in which a specific combination of genetic and cognitive vulnerabilities are thought to increase our bio-behavioral response to stress, critically increasing the rewarding value of pleasant foods and, hence, emotional eating.