Cellular mechanisms in the vulnerability to depression and response to antidepressants

Stress and depression among male police officers in Taiwan: Severity, determinants, and coping strategies

BACKGROUND

Police work, known for its high stress, exhibits elevated depression rates.

OBJECTIVE

This study explores stress and depression in male officers, examining personality traits, coping strategies, family, and social support. Aligned with the diathesis-stress hypothesis and job demands-resources model, it aims to illuminate these factors in policing.

METHODS

Two hundred and sixty-four male police officers from Yunlin, Taiwan were enrolled in this study. Structured measurements of stress level, depression symptoms, personality traits, family functioning, and social support were made. We used multiple regression analysis to assess predictors of stress level and depression and identified coping strategies used by the police officers.

RESULTS

Of the 264 male police officers, 36.4% had clinically significant depression. Occupational stress was mostly related to organizational factors. Multivariate regression analyses showed that age, personality traits, officer's rank, and period of education obtained could predict police officers' occupational stress. Personality traits, social support, occupational stress, and period of education obtained could predict depression. The most frequently used coping strategies were drinking and smoking.

CONCLUSIONS

The results of our study support the diathesis-stress hypothesis and the job demands-resources model. Enhancing male police officers' mental well-being requires addressing key factors like social support and occupational stress. Strategic measures, such as mental health education, destigmatization, counseling, and community-building, are vital. Policymakers should collaborate with mental health professionals for tailored interventions, fostering a healthier work environment.

Molecular Basic of Pharmacotherapy of Cytokine Imbalance as a Component of Intervertebral Disc Degeneration Treatment

Intervertebral disc degeneration (IDD) and associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. With age, IDD progresses, leading to spondylosis, spondylarthrosis, herniated disc, spinal canal stenosis. One of the leading mechanisms in the development of IDD and chronic back pain is an imbalance between pro-inflammatory and anti-inflammatory cytokines. However, classical therapeutic strategies for correcting cytokine imbalance in IDD do not give the expected response in more than half of the cases. The purpose of this review is to update knowledge about new and promising therapeutic strategies based on the correction of the molecular mechanisms of cytokine imbalance in patients with IDD. This review demonstrates that knowledge of the molecular mechanisms of the imbalance between pro-inflammatory and anti-inflammatory cytokines may be a new key to finding more effective drugs for the treatment of IDD in the setting of acute and chronic inflammation.

Combinatorial Regimen of Carbamazepine and Imipramine Exhibits Synergism against Grandmal Epilepsy in Rats: Inhibition of Pro-Inflammatory Cytokines and PI3K/Akt/mTOR Signaling Pathway

Epilepsy is a neurodegenerative disorder that causes recurring seizures. Thirty-five percent of patients remain refractory, with a higher prevalence of depression. We investigated the anticonvulsant efficacy of carbamazepine (CBZ; 20 and 50 mg/kg), imipramine (IMI; 10 and 20 mg/kg) alone, and as a low dose combination. This preclinical investigation included dosing of rats for 14 days followed by elicitation of electroshock on the last day of treatment. Along with behavioral monitoring, the rat hippocampus was processed for quantification of mTOR, IL-1β, IL-6 and TNF-α levels. The histopathological analysis of rat hippocampus was performed to ascertain neuroprotection. In vitro studies and in silico studies were also conducted. We found that the low dose combinatorial therapy of CBZ (20 mg/kg) + IMI (10 mg/kg) exhibits synergism (p < 0.001) in abrogation of maximal electroshock (MES) induced convulsions/tonic hind limb extension (THLE), by reducing levels of pro-inflammatory cytokines, and weakening of the PI3K/Akt/mTOR signal. The combination also exhibits cooperative binding at the Akt. As far as neuroprotection is concerned, the said combination increased cell viability by 166.37% compared to Pentylenetetrazol (PTZ) treated HEK-293 cells. Thus, the combination of CBZ (20 mg/kg) + IMI (10 mg/kg) is a fruitful combination therapy to elevate seizure threshold and provide neuroprotection.

Effect of Co-Driver on Job Content and Depression of Truck Drivers

Background

Since the presence of a co-driver can be considered as a companion, partner, or friend for a driver through eliminating driver's loneliness, it plays a significant role in health and safety of drivers. The objective of this study was to investigate the effect of co-drivers on depression and occupational stress on male truck drivers.

Methods

This study was an interventional case-control study. Seventy truck drivers were selected and divided into two groups: case (33 truck drivers with co-drivers) and control (37 truck drivers without co-drivers). Two Goldberg depression inventories (for evaluating driver's depression) and the Karasek job content questionnaire (for evaluating driver's job stress) were used to collect data which were completed by interview.

Results

The results showed that job content values for the case group were higher in all dimensions except job nature. The comparison of the percentages showed significant difference between two groups. Depression rate in drivers with co-driver is truly less than depression rate in drivers without co-driver. There was significant positive relationship between dimensions of job content and depression rate.

Conclusion

According to the results of this study, it can be claimed that a co-driver decreases stress and loneliness of drivers, as well as increases work performance and job satisfaction, and, in turn, leads to a decrease in job-related depression.

Antidepressants and anti-inflammatory drugs differentially reduce the release of NGF and BDNF from rat platelets

INTRODUCTION

Platelets store serotonin and brain-derived neurotrophic factor (BDNF) as well as amyloid precursor protein and nerve growth factor (NGF), thus platelets are of special interest in depression and Alzheimer's disease, respectively. Both diseases are associated with inflammation and release of NGF or BDNF from platelets may play a potent role.

METHODS

Platelets were isolated from adult Sprague-Dawley rats and were incubated with anti-inflammatory drugs (ibuprofen and indomethacin) and antidepressants (citalopram, paroxetine and sertraline) (final concentration: 0.3 µM) with or without 2 mM calcium chloride. The release of NGF and BDNF was analyzed in comparison to serotonin release from rat platelets after 10 or 60 min.

RESULTS

Spontaneous release of serotonin and BDNF was approximately 10-15% of total serotonin or BDNF content in platelets, but nearly all NGF was released within 10 min. All antidepressants increased the serotonin release from rat platelets. NGF release was reduced by sertraline, paroxetine and ibuprofen, but only when calcium was present, except for sertraline after 10 min. BDNF release was only reduced by ibuprofen when calcium was added.

CONCLUSION

We conclude that antidepressants and anti-inflammatory drugs differentially influence the NGF and BDNF release, in a time-, dose- and calcium-specific pattern.

Aripiprazole altered plasma levels of brain-derived neurotrophic factor and catecholamine metabolites in first-episode untreated Japanese schizophrenia patients

OBJECTIVE

We investigated the effects of aripiprazole on plasma levels of brain-derived neurotrophic factor (BDNF) and catecholamine metabolites in first-episode untreated schizophrenia patients.

METHODS

The subjects were 50 Japanese first-episode untreated schizophrenia patients who met the Diagnostic and Statistical Manual of Mental Disorders Text Revision criteria and were treated with aripiprazole monotherapy. Twenty-nine were males, and 21 were females. The age ranged from 21 to 42 years (mean ± SD; 30.8 ± 5.3 years). Plasma BDNF and catecholamine metabolites were measured by ELISA and HPLC, respectively. Psychiatric symptoms were evaluated using by Positive and Negative Syndrome Scale.

RESULTS

Treatment with aripiprazole for 8 weeks significantly increased plasma BDNF levels. It also changed plasma levels of homovanillic acid and 3-methoxy-4-hydroxyphenylglycol. A negative correlation was also observed between duration of psychosis and plasma BDNF levels. No correlation was observed however between plasma BDNF levels and the dose of aripiprazole.

CONCLUSIONS

To the best of our knowledge, this is the first report showing that aripiprazole increases plasma BDNF levels in first-episode untreated schizophrenia patients. Furthermore, the BDNF Val66Met polymorphism was independent of the response to aripiprazole.

Relationships between stress, social adaptation, personality traits, brain-derived neurotrophic factor and 3-methoxy-4-hydroxyphenylglycol plasma concentrations in employees at a publishing company in Japan

There is growing evidence that blood levels of brain-derived neurotrophic factor (BDNF) and 3-methoxy-4-hydroxyphenylglycol (MHPG), a major metabolite of noradrenaline, are related to depression-associated personality traits as well as to depressive, suicidal and anxious states. Psychological job stress is well known to lead to symptoms of depression, anxiety and suicide. We have recently reported that psychological job stress among hospital employees altered blood levels of BDNF and MHPG (Mitoma et al., 2008). In the present study, we re-examined the effects of social adaptation and personality traits, as well as those of psychological job stress, on plasma levels of BDNF and MHPG in healthy employees (n=269, male/female=210/59, age=49 ± 10years) working in a publishing company in Japan. The values (mean ± SD) of scores on the Stress and Arousal Check Lists (s-SACL and a-SACL), Social Adaptation Self-evaluation Scale (SASS), plasma MHPG levels and plasma BDNF levels were 6.0 ± 3.4, 5.7 ± 2.3, 33.7 ± 6.8, 5.8 ± 4.3 and 4.6 ± 3.1ngml(-1), respectively. A positive correlation was found between plasma MHPG levels and scores on the s-SACL, but not the a-SACL. A positive correlation was also found between SASS scores and plasma MHPG levels and between SASS scores and plasma BDNF levels. A negative correlation was found between plasma BDNF levels and s-SACL scores. Furthermore, a positive correlation between NEO-Five factor Inventory (Openness) scores and plasma MHPG levels was observed, as well as between NEO-Five factor Inventory (Extroversion) scores and plasma BDNF levels. These results suggest that levels of plasma BDNF and plasma MHPG might be associated with psychological job stress and certain personality traits among employees in the publishing industry in Japan.

A prospective study of predictors of depression symptoms in police

Police work is one of the most stressful occupations. Previous research has indicated that work stress and trauma exposure may place individuals at heightened risk for the development of depression symptomatology. This prospective longitudinal study was designed to examine predictors of depression symptoms in police service. Participants comprised 119 healthy police recruits from an ongoing prospective study. They completed baseline measures of depression symptoms, childhood trauma exposure, neuroticism, and self-worth during academy training. Follow-up measures of depression symptoms, PTSD symptoms, critical incident exposure, negative life events, and routine work environment stress were assessed after 12 months of police service. Hierarchical linear regression analysis was conducted to examine predictors of current levels of depression symptoms, controlling for baseline depression symptoms and current PTSD symptoms. Greater childhood trauma exposure, lower self-worth during training, and greater perceived work stress in the first year of police service predicted greater depression symptoms at 12 months. Depression symptoms at 1 year of police service were partly independent from PTSD symptoms at 12 months. Greater childhood trauma exposure and lower self-worth during training may be important variables to screen as risk factors for duty-related depression. Strategies to reduce routine work environment stress have the potential to decrease duty-related depression in law enforcement.

Running exercise-induced up-regulation of hippocampal brain-derived neurotrophic factor is CREB-dependent

The past decade has witnessed burgeoning evidence that antidepressant medications and physical exercise increase the expression of hippocampal brain-derived neurotrophic factor (BDNF). This phenomenon has gained widespread appeal, because BDNF is one of the first macromolecules observed to play a central role not only in the treatment of mood disorders, but also in neuronal survival-, growth-, and plasticity-related signaling cascades. Thus, it has become critical to understand how BDNF synthesis is regulated. Much evidence exists that changes in BDNF expression result from the activation/phosphorylation of the transcription factor, cAMP-response-element binding protein (CREB) following the administration of antidepressant medications. Utilizing a mouse model genetically engineered with an inducible CREB repressor, our current study provides evidence that increases in BDNF expression and cellular survival signaling resulting from physical exercise are also dependent upon activation of this central transcription factor. The transcription and expression of hippocampal BDNF, as well as the activation of Akt, a key survival signaling molecule, were measured following acute exercise, and also following short-term treatment with the norepinephrine reuptake inhibitor, reboxetine. We found that both interventions led to a marked increase in hippocampal BDNF mRNA, BDNF protein, and Akt phosphorylation (as well as CREB phosphorylation) in wild-type mice. As expected, activation of the CREB repressor in mutant mice sharply decreased CREB phosphorylation. In addition, all measures noted above remained at baseline levels when mutant mice exercised or received reboxetine. Increases in BDNF and phospho-Akt were also prevented when mutant mice received a combination of exercise and antidepressant treatment. The results are discussed in the context of what is currently known about BDNF signaling.

Serum levels of brain-derived neurotrophic factor in comorbidity of depression and alcohol dependence

Alcohol dependence is often comorbid with depression. The purpose of the present study was to compare serum brain-derived neurotrophic factor (BDNF) levels between depressive patients with and without alcohol dependence. Our subjects were 16 inpatients (M/F: 13/3, age: 48 +/- 8 years) at our university hospital who met the DSM-IV-TR criteria for both major depressive disorder and alcohol dependence and whose Hamilton Rating Scale for Depression (HAM-D) scores were at least 15. Twenty sex- and age-matched depressive patients and 20 healthy subjects were also examined. Serum BDNF levels in the depressive patients with (9.0 +/- 4.3 ng/ml) and without (9.8 +/- 5.2 ng/ml) alcohol dependence were significantly lower than those in the healthy subjects (21.1 +/- 7.0 ng/ml); however, no significant difference was found in the serum BDNF levels of depressive patients with and without alcohol dependence. Eight of the 16 (50%) depressive patients suffering from both depression and alcohol dependence responded to 8 weeks of treatment with antidepressant drugs which significantly increased their serum BDNF levels. These results suggest that the serum BDNF level is a useful biological marker for depression in patients with alcohol dependence.

Higher plasma interleukin-6 (IL-6) level is associated with SSRI- or SNRI-refractory depression

In the present study, we compared plasma levels of interleukin-6 (IL-6), tumor necrosis factor-alpha(TNFalpha), and brain-derived neurotrophic factor (BDNF) among selective serotonin reuptake inhibitor (SSRI)- or serotonin noradrenaline reuptake inhibitor (SNRI)-responsive depressed patients (n=31), SSRI- or SNRI-refractory depressed patients (n=20), and healthy controls (n=30). The plasma levels of IL-6 and TNF-alpha were significantly higher in depressed patients than in healthy controls. Treatment with antidepressants significantly reduced plasma levels of IL-6 and TNF-alpha. In addition, the plasma IL-6 level, but not the plasma TNF-alpha level, was higher in SSRI-refractory than SSRI-responsive depressed patients, and higher in SNRI-refractory than SNRI-responsive depressed patients. On the other hand, the plasma BDNF level was significantly lower in depressed patients than in healthy controls, whereas no difference was found in plasma BDNF levels between SSRI-responsive and -refractory depressed patients or between SNRI-responsive and -refractory depressed patients. These results suggest that higher plasma IL-6 activity is associated with the refractoriness of depression, and plasma IL-6 levels might be a predictor for response to SSRIs or SNRI.

Changes in perceived job strain and the risk of major depression: results from a population-based longitudinal study

Major depression is a prevalent mental disorder in the working population. Improving the work environment may reduce the risk of major depression. The authors examined data from the longitudinal cohort of the Canadian National Population Health Survey from 1994-1995 to 2004-2005. Survey participants were classified into 4 groups by changes in job strain status from 1994-1995 to 2000-2001 (no change in low job strain, no change in high job strain, changing from high to low job strain, and changing from low to high job strain). The incidence proportion of major depressive episodes in each of the 4 groups was 4.0%, 8.0%, 4.4%, and 6.9%, respectively. Participants who reported a change from high to low job strain had a risk of major depression similar to those exposed to persistently low job strain. Among those exposed to persistent high job strain, only participants who reported good or excellent health at baseline had a higher risk of major depression, but those who reported fair or poor health did not. Reducing job strain may have positive impacts on the risk of depression. Self-rated health is a strong predictor of depression and plays an important role in the relation between job strain and depression.

Altered glial cell line-derived neurotrophic factor (GDNF) concentrations in the brain of patients with depressive disorder: a comparative post-mortem study

INTRODUCTION

A growing body of evidence suggests that the glial cell line-derived neurotrophic factor (GDNF) is involved in the aetiopathology of mood disorders. GDNF is a neurotrophic factor from the transforming growth factor-beta-family, playing a role in cell development and function in the limbic system. This is the first study to examine GDNF concentration in different brain regions of patients with depressive disorder (DD).

MATERIAL AND METHODS

We used sandwich-ELISA-technique to ascertain GDNF concentration and Lowry assay for overall protein levels in post-mortem brain tissue of 7 patients with recurrent depressive disorder and 14 individuals without any neurological or psychiatric diagnoses. We included cortical regions as well as limbic area's (hippocampus, entorhinal cortex) basal ganglia (putamen, caudate nucleus), thalamus and cingulated gyrus.

RESULTS

We found a significant increase in GDNF concentration in the parietal cortex of patients with DD compared to the control group. In other regions the trend of an increased GDNF concentration did not reach statistical difference.

DISCUSSION

This proof of concept study supports previous findings of an alteration of the GDNF in patients with depressive disorder. However, for the first time a significant increase of GDNF in a cortical brain area was found in DD.

Stress at work alters serum brain-derived neurotrophic factor (BDNF) levels and plasma 3-methoxy-4-hydroxyphenylglycol (MHPG) levels in healthy volunteers: BDNF and MHPG as possible biological markers of mental stress?

There is growing evidence that blood levels of brain-derived neurotrophic factor (BDNF) and catecholamine, and cytokines are related to not only to depressive, suicidal, and anxious states but also to depression-associated personality traits. Psychological job stress is well known to lead to symptoms of depression and anxiety. In the present study, we examined effects of psychological job stress on serum levels of BDNF and plasma levels of catecholamine metabolites, and cytokines in healthy volunteers (n=106, male/female=42/64, age=36+/-12 yr) working in a hospital setting. The values (mean+/-SD) of scores for stress items in the Stress and Arousal Check List (s-SACL), plasma MHPG levels, and, serum BDNF levels in all participants were 7.2+/-3.3, 5.2+/-3.4 ng/mL, and 23.3+/-14.7 ng/mL, respectively. A negative correlation was found between scores for s-SACL and serum BDNF levels (rho=-0.211, p=0.022). A positive correlation was also found between scores on the s-SACL and plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) (rho=0.416, p=0.01), but not homovanillic acid (HVA). No relationship was found between s-SACL scores and plasma levels of interleukin-6 (IL-6) or tumor necrosis factor alpha (TNFalpha). These results suggest that serum BDNF levels and plasma MHPG levels might be biological markers reflective of psychological job stress in hospital employees.

Social neuroscience of child and adolescent depression

The social neuroscience of child and adolescent depression is inherently multidisciplinary. Depressive disorders beginning early in life can have serious developmental and functional consequences. Psychopathology research has described depression's defining clinical and contextual features, and intervention research has characterized its response to treatment and prevention programs. Neuroendocrine, electrophysiological, and neuroimaging studies have identified core neurobiological aspects of early-onset mood disorders. These areas are reviewed using a developmental social neuroscience perspective for integrating disparate observations. The paper introduces a dynamic adaptive systems framework, and it discusses hedonic capacity, stress sensitivity, ruminative self-focus, and attentional impairments as fundamental components of mood disorders.

Treatment with risperidone for 4 weeks increased plasma 3-methoxy-4-hydroxypnenylglycol (MHPG) levels, but did not alter plasma brain-derived neurotrophic factor (BDNF) levels in schizophrenic patients

In the present study, we investigated the effects of risperidone treatment for 4 weeks on plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and brain-derived neurotrophic factor (BDNF) in 89 schizophrenic patients. We also compared the plasma levels of BDNF and MHPG between the schizophrenic group and 103 sex-and age-matched normal controls. In addition, we investigated the effects of two SNPs of the noradrenaline transporter (NAT) gene on plasma levels of MHPG, BDNF, and clinical improvement. The mean dose of risperidone was 3.8+/-1.4 mg/day. We demonstrated that treatment with risperidone increased plasma MHPG levels, and this increase was associated with an improvement of the negative symptoms of schizophrenia. In contrast, plasma BDNF did not change after 4 weeks of risperidone treatment, and the two SNPs in NAT did not influence the response to risperidone treatment or plasma MHPG and BDNF levels. These results suggest that the enhancement of noradrenergic neurons by risperidone, which occurs independently of the two SNPs of NAT, plays a role in the clinical efficacy of the drug.

Effects of paroxetine or milnacipran on serum brain-derived neurotrophic factor in depressed patients

Brain-derived neurotrophic factor (BDNF) is an important member of the neurotrophin family of growth factors, abundant in the brain and periphery. Researchers have reported that serum BDNF levels in drug-free depressed patients are lower than those of healthy controls, and have proposed that these low levels might reflect a failure of neuronal plasticity in depression. In the present study, we investigated the effects of paroxetine, an SSRI, and milnacipran, an SNRI, on serum BDNF levels in depressed patients. Serum levels of BDNF were measured by ELISA before, 4 weeks, and 8 weeks after the start of treatment with antidepressants. Forty-two patients were randomly administered paroxetine (21 cases) or milnacipran (21 cases). A negative correlation was found between serum BDNF levels and baseline Ham-D scores. The response and remission rates for each drug were not significantly different. Serum BDNF levels in responders were significantly increased 2.6- and 1.8-fold 8 weeks after treatment with paroxetine or milnacipran, respectively. These results suggest that both drugs improve the depressive state by increasing BDNF levels.

Cyclic AMP response element binding protein and brain-derived neurotrophic factor: molecules that modulate our mood?

Depression is the major psychiatric ailment of our times, afflicting approximately 20% of the population. Despite its prevalence, the pathophysiology of this complex disorder is not well understood. In addition, although antidepressants have been in existence for the past several decades, the mechanisms that underlie their therapeutic effects remain elusive. Building evidence implicates a role for the plasticity of specific neuro-circuitry in both the pathophysiology and treatment of depression. Damage to limbic regions is thought to contribute to the etiology of depression and antidepressants have been reported to reverse such damage and promote adaptive plasticity. The molecular pathways that contribute to the damage associated with depression and antidepressant-mediated plasticity are a major focus of scientific enquiry. The transcription factor cyclic AMP response element binding protein (CREB) and the neurotrophin brain-derived neurotrophic factor (BDNF) are targets of diverse classes of antidepressants and are known to be regulated in animal models and in patients suffering from depression. Given their role in neuronal plasticity, CREB and BDNF have emerged as molecules that may play an important role in modulating mood. The purpose of this review is to discuss the role of CREB and BDNF in depression and as targets/mediators of antidepressant action.

Effect of treatment on serum brain-derived neurotrophic factor levels in depressed patients

Researchers have reported that serum brain-derived neurotrophic factor (sBDNF) of drug-free depressed patients are lower than those of healthy controls and proposed that low sBDNF levels might reflect failure of neuronal plasticity in depression. In this study, we compared sBDNF levels of depressed patients (n = 28) before and after 8 weeks of antidepressant treatment, with those of healthy controls (n = 18) to test the hypothesis that initially low sBDNF levels of drug-free depressed patients will increase parallel with their clinical response to antidepressant treatment. The severity of depression and response to treatment were assessed with Hamilton Rating Scale for Depression (HAM-D). sBDNF was assayed with the sandwich ELISA method. Baseline sBDNF levels of patients (mean, 20.8 ng/ml; [S.D., 6.7]) were significantly lower than those of controls (mean, 26.8 ng/ml; [S.D., 9.3]; p = 0.015), and were negatively correlated with HAM-D scores (r = -0.49, p = 0.007). After 8 weeks of treatment, sBDNF levels of patients had increased significantly (mean, 33.3 ng/ml; [S.D., 9.9]; p < 0.001) and no longer differed from those of controls. These results support the hypothesis that BDNF might play a critical role in the pathophysiology of major depressive disorder and successful antidepressant treatment increases the attenuated BDNF levels in depressed patients.

Partial normalization of serum brain-derived neurotrophic factor in remitted patients after a major depressive episode

We had previously reported decreased serum brain-derived neurotrophic factor (BDNF) levels in depressed patients. In the present study, we tested the hypothesis that antidepressant treatment would normalize serum BDNF levels, at least in a subgroup of patients. Major depressed patients (15 females and 11 males) diagnosed according to DSM-IV criteria and healthy controls (13 females and 13 males) participated in this study. Serum BDNF was assayed with the ELISA method for depressed and remitted patients and the severity of depression was evaluated with the Montgomery-Asberg Depression Rating Scale. An analysis of variance showed that treatment had an effect [F(1, 24) = 4.46, p = 0.045] on the normalization of serum BDNF levels. We also found a correlation between the severity of depression (r = 0.51, p = 0.008), the pretreatment BDNF levels (r = 0.62, p = 0.001) and the difference in serum BDNF levels after antidepressant treatment. These results suggest that antidepressant treatment has a positive effect on serum BDNF levels and support the hypothesis of neurotrophic factor involvement in affective disorders.

Recent findings on the genetic basis of bipolar disorder

What began as a search for a specific gene for bipolar disorder has now become a search for multiple susceptibility genes as it has be-come clear that the genetic basis of bipolar disorder probably involves multiple genes interacting with each other and with environmental components in as-yet mysterious ways. This article reviews the most recent findings and the emerging picture in the genetics of bipolar disorder.

Exercise activates the phosphatidylinositol 3-kinase pathway

Physical exercise is known to enhance psychological well-being and coping capacity. Voluntary physical exercise in rats also robustly and rapidly up-regulates hippocampal brain-derived neurotrophic factor (BDNF) mRNA levels, which are potentiated following a regimen of chronic antidepressant treatment. Increased BDNF levels are associated with enhanced activity of cyclic AMP response element binding protein (CREB). So far, relatively little is known about the intracellular signaling mechanisms mediating this effect of exercise. We wished to explore the possibility that exercise and/or antidepressant treatment activate the hippocampal phosphatidylinositol-3 (PI-3) kinase pathway, which mediates cellular survival. In young male Sprague-Dawley rats, we examined the effects of 2 weeks of daily voluntary wheel-running activity and/or tranylcypromine (n = 7 per group) on the levels of the active forms of protein-dependent kinase-1 (PDK-1), PI-3 kinase, phospho-thr308-Akt, phospho-ser473-Akt, and phospho-glycogen synthase kinase-3beta (GSK3beta; inactive form), as well as BDNF, activated CREB, and the phospho-Trk receptor, in the rat hippocampus, and compared these with sedentary saline-treated controls. Immunoblotting analyses revealed that in exercising rats, there was a significant increase in PI-3 kinase expression (4.61 times that of controls, P = 0.0161) and phosphorylation of PDK-1 (2.73 times that of controls, P = 0.0454), thr308-Akt (2.857 times that of controls, P = 0.0082), CREB (60.27 times that of controls, P = 0.05), and Trk (35.3 times that of controls, P < 0.0001) in the hippocampi of exercising animals; BDNF was also increased (3.2 times that of controls), but this was not statistically significant. In rats receiving both exercise and tranylcypromine, BDNF (4.51 times that of controls, P = 0.0068) and PI-3 kinase (4.88 times that of controls, P = 0.0103), and the phospho- forms of Trk (13.67 times that of controls, P = 0.0278), thr308-Akt (3.644 times that of controls, P = 0.0004), GSK-3beta (2.93 times that of controls, P = 0.026), and CREB (88.97 times that of controls, P = 0.0053) were significantly increased. These results suggest that the exercise-induced expression of BDNF is associated with the increased expression of several key intermediates of the PI-3 kinase/Akt pathway, which is known for its role in enhancing neuronal survival.

Piracetam counteracts the effects of amitriptyline on inhibitory avoidance in CD1 mice

The purpose of the present work was to study the effects of amitriptyline on animal cognition in relation to some characteristics of its therapeutic effects. The modulation of acute and chronic effects of amitriptyline on inhibitory avoidance in male and female mice by piracetam was investigated. In Experiment 1, mice were subjected to the training phase of inhibitory avoidance conditioning 60 min after acute piracetam (100 mg/kg) or physiological saline administration. Immediately after the behavioural task, they received a single injection of the tricyclic antidepressant amitriptyline (30 mg/kg) or physiological saline. Twenty-four hours later, subjects were tested for avoidance. In Experiment 2, the same doses of amitriptyline and piracetam were chronically administered. Mice were subjected to the training phase of inhibitory avoidance on the 22nd day, and to the test phase 24 h later. Forty-five minutes after test, subjects explored the elevated plus-maze for 5 min in order to assess whether the effects of amitriptyline on avoidance performance may reflect general behavioural changes. Results obtained were that: (a) acute and chronic amitriptyline impaired inhibitory avoidance of male and female mice, (b) piracetam counteracted the effect of acutely administered amitriptyline on inhibitory avoidance, and (c) piracetam counteracted the effects of chronically administered amitriptyline in males but not females in the same learning task. These effects do not seem to be mediated by non-specific drug effects on spontaneous motor activity or anxiety.

Future antidepressants: what is in the pipeline and what is missing?

Monoamine reuptake inhibitors still reign in the treatment of major depression, but possibly not for long. While medicinal chemists have been able to reduce the side effects of these drugs, their delayed onset of action and considerable non-response rate remain problematic. Of late, serious questions have been raised regarding the efficacy of monoamine reuptake inhibitors. The present review presents an inventory of what is (and until recently was) in the antidepressant pipeline of pharmaceutical companies. Novel antidepressant compounds can be categorised into four groups depending on their target(s): (i) monoamine receptors; (ii) non-monoamine receptors; (iii) neuropeptide receptors; and (iv) hormone receptors. Other possible targets include components of post-receptor intracellular processes and elements of the immune system; to date, however, compounds specifically aimed at these targets have not been the subject of clinical trials. Development of several compounds targeted at monoamine receptors has recently been discontinued. At least five neurokinin-1 (NK(1)) receptor antagonists were until recently in phase II of clinical testing. However, the apparent interest in the NK(1) receptor should not be interpreted as representing a departure from the monoamine hypothesis since neurokinins also modulate monoaminergic systems. In the authors' view, development of future antidepressants will continue to rely on the serendipity-based monoamine hypothesis. However, an alternative approach, based on the hypothesis that chronic stress precipitates depressive symptoms, might be more productive. Unfortunately, clinical results using drugs targeted at components of the HPA axis have not been very encouraging to date. In the short run, the authors believe that augmentation strategies offer the best hope for improving the efficacy of antidepressant treatment. Several approaches to improve the efficacy of SSRIs are conceivable, such as concurrent blockade of monoamine autoreceptors and the addition of antipsychotics, neuromodulators or hormones (HPA axis and gender related). In the long-term, however, construction of a scientifically verified conceptual framework will be needed before more effective antidepressants can be developed. It can be argued that it is not depression itself that should be treated, but rather that its duration should be reduced by pharmacological means. Animal models that take this concept into consideration and identify mechanisms for acceleration of recovery from the effects of stress need to be developed.

New formulations of existing antidepressants: advantages in the management of depression

For nearly 50 years, antidepressant drugs have been the first-line treatment for various forms of depression. Despite their widespread use, these medications have significant shortcomings, in particular problems of patient compliance due to adverse effects. The introduction of new formulations of existing antidepressant medications may provide patients with benefits in terms of convenience of use. As a consequence, improvements in compliance may lead to better antidepressant efficiency.An orally disintegrating formulation of mirtazapine (mirtazapine SolTab), a once-weekly formulation of fluoxetine, an enantiomer-specific formulation of citalopram (escitalopram), an extended-release formulation of venlafaxine (venlafaxine XR), a controlled-release formulation of paroxetine (paroxetine CR) and intravenous formulations of some of the newer antidepressants have all been evaluated in limited clinical trials. In this article, a review of the pharmacokinetics and clinical evaluations of these formulations is presented. While there do not appear to be major clinical advantages for the new formulations in terms of antidepressant efficacy, none of them is less efficacious than their older counterpart. Indeed, some of the new formulations are more acceptable to patients (fluoxetine once-weekly, paroxetine CR), others have pharmacokinetic advantages (venlafaxine XR, paroxetine CR), while others may have a faster onset of effect (mirtazapine SolTab, intravenous formulations). Further evaluation of some formulations is still required (mirtazapine SolTab, fluoxetine once-weekly), while others (venlafaxine XR, escitalopram) are finding widespread acceptance in clinical practice.

The role of estrogen in mood disorders in women

Major depression is twice as common in women as men and depressive episodes appear to be more common in women with bipolar disorder. There is accumulating evidence that, in at least some women, reproductive-related hormonal changes may play a role in increasing the risk of depressive symptoms premenstrually, postpartum and in the perimenopausal period. In this review, the evidence for the role of hormonal fluctuations, specifically estrogen, in triggering depressive symptoms in a subgroup of women is summarized. In addition, the potential role of estrogen in triggering depressive symptoms via its effects on the serotonergic system, brain-derived neurotrophic factor and Protein Kinase C is reviewed.

Cognitive impairment in patients with chronic pain: the significance of stress

This review article examines the role of emotional distress and other aspects of suffering in the cognitive impairment that often is apparent in patients with chronic pain. Research suggests that pain-related negative emotions and stress potentially impact cognitive functioning independent of the effects of pain intensity. The anterior cingulate cortex is likely an integral component of the neural system that mediates the impact of pain-related distress on cognitive functions, such as the allocation of attentional resources. A maladaptive physiologic stress response is another plausible cause of cognitive impairment in patients with chronic pain, but a direct role for dysregulation of the hypothalamic-pituitary-adrenocortical axis has not been systematically investigated.

Decreased serum brain-derived neurotrophic factor levels in major depressed patients

Recent findings with animal models have suggested a possible role for brain-derived neurotrophic factor (BDNF) in depression. We have therefore hypothesized that depression could be characterized by low levels of serum BDNF. Major depressed patients (15F + 15M) diagnosed according to DSM-IV criteria and healthy controls (15F + 15M) participated in the study. Serum BDNF was assayed with the ELISA method and the severity of depression was evaluated with Montgomery-Asberg-Depression Rating Scale (MADRS). BDNF levels were significantly lower in patients than in controls: 22.6 +/- 3 and 26.5 +/- 7 ng/ml (t-test = 2.7; d.f. = 58; P < 0.01). They were negatively correlated to the MADRS scores (r = -0.55; P < 0.02). Female patients were more depressed and released less BDNF than men. Analysis of covariance (MADRS and gender as independent variable vs. BDNF as dependent variable) indicated that depression severity mainly accounted for the negative correlation. These results suggest that major depression is characterized by low serum BDNF levels and support the hypothesis of neurotrophic factor involvement in affective disorders.

Perceived work stress and major depression in the Canadian employed population, 20-49 years old

Data from the Canadian National Population Health Survey (1994-1995) were used to evaluate the associations between work stress and major depression (N = 7,344). Major depression was evaluated using the World Health Organization's Composite International Diagnostic Interview- Short Form. Work stress was measured by a 12-item scale in 6 dimensions. Significant associations between work stress and major depression were found. Gender may alter the type of work stress that is most strongly associated with major depression: psychological demands for men and physical demands for women. Some forms of work stress were more strongly associated with major depression in smokers than in nonsmokers.

Substance P: a new era, a new role

Substance P has been extensively studied and is considered the prototypic neuropeptide of the more than 50 known neuroactive molecules. The understanding of substance P has evolved beyond the original concept as the pain transmitter of the dorsal horn. Animal and genetic research, recent developments of nonpeptide substance P antagonists, and important changes in the understanding of neurotransmission have each contributed to the current understanding of substance P After 7 decades, the physiologic role of substance P is known as a modulator of nociception, involved in signaling the intensity of noxious or aversive stimuli. Genetic studies in mice and development of substance P antagonists provide more recent results that support the redefinition of the central role of substance P Evidence suggests that this neuropeptide is an integral part of central nervous system pathways involved in psychologic stress.

Protein kinase a in major depression: the link between hypothalamic-pituitary-adrenal axis hyperactivity and neurogenesis

The latest and most generative biological theories of major depression center on two major hypotheses. The first focuses on the concept that hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis leads to many of the pathological changes in the brain that accompany major depression. The second posits that neurogenesis leads to the repair of depression-related injuries. These two hypotheses are complementary: the former alludes to the etiology or consequences of depression, while the latter suggests mechanisms of antidepressant action. Significant crosstalk occurs between these two systems at many levels. Protein kinase A (PKA) may play an important role in this crosstalk at the intracellular level of signaling cascades. PKA is involved in the formation of long-term potentiation and fear conditioning in response to stress. Chronic stress leads to the suppression of hippocampal activity, which may cause the hyperactivity of the HPA axis during melancholic depression. PKA is also involved in the stimulation of hippocampal neurogenesis after antidepressant treatment. In theory, neurogenesis may lead to the restoration of hippocampal function, and this may be the mechanism that leads to antidepressant-mediated normalization of HPA hyperactivity. Thus, PKA is active during processes that potentially lead to depression and other processes that lead to the resolution of the illness. These opposing processes may be mediated by separate PKA isozymes that activate two distinct pathways. This review highlights the dual role of this enzyme in two biological hypotheses pertaining to depression and its treatment.