The pathogenesis of clinical depression: stressor- and cytokine-induced alterations of neuroplasticity

A detailed examination of cytokine abnormalities in Major Depressive Disorder

Recent technological advances offer an opportunity to further elucidate the complex cytokine network in Major Depressive Disorder (MDD). Twenty cytokines were simultaneously assessed in 49 individuals with MDD and 49 age and gender matched controls. Multiple pro-inflammatory and two anti-inflammatory cytokines were significantly elevated in the MDD sample, including an antidepressant naïve subset. These data support a generalized chronic inflammatory state in MDD, and implicate additional cytokines and chemokines previously linked to cardiovascular disease.

Lipopolysaccharide modulation of thyrotropin-releasing hormone (TRH) and TRH-like peptide levels in rat brain and endocrine organs

Lipopolysaccharide (LPS) is a proinflammatory and depressogenic agent whereas thyrotropin-releasing hormone (TRH; pGlu-His-Pro-NH2) is an endogenous antidepressant and neuroprotective peptide. LPS and TRH also have opposing effects on K+ channel conductivity. We hypothesized that LPS can modulate the expression and release of not only TRH but also TRH-like peptides with the general structure pGlu-X-Pro-NH2, where "X" can be any amino acid residue. The response might be "homeostatic," that is, LPS might increase TRH and TRH-like peptide release, thereby moderating the cell damaging effects of this bacterial cell wall constituent. On the other hand, LPS might impair the synthesis and release of these neuropeptides, thus facilitating the induction of early response genes, cytokines, and other downstream biochemical changes that contribute to the "sickness syndrome." Sprague-Dawley rats (300 g) received a single intraperitoneal injection of 100 microg/kg LPS. Animals were then decapitated 0, 2, 4, 8, and 24 h later. Serum cytokines and corticosterone peaked 2 h after intraperitoneal LPS along with a transient decrease in serum T3. TRH and TRH-like peptides were measured by a combination of high-performance liquid chromatography and radioimmunoassay. TRH declined in the nucleus accumbens and amygdala in a manner consistent with LPS-accelerated release and degradation. Various TRH-like peptide levels increased at 2 h in the anterior cingulate, hippocampus, striatum, entorhinal cortex, posterior cingulate, and cerebellum, indicating decreased release and clearance of these peptides. These brain regions are part of a neuroimmunomodulatory system that coordinates the behavioral, endocrine, and immune responses to the stresses of sickness, injury, and danger. A sustained rise in TRH levels in pancreatic beta-cells accompanied LPS-impaired insulin secretion. TRH and Leu-TRH in prostate and TRH in epididymis remained elevated 2-24 h after intraperitoneal LPS. We conclude that these endogenous neuroprotective and antidepressant-like peptides both mediate and moderate some of the behavioral and toxic effects of LPS.

Neuroprotection by Imipramine against lipopolysaccharide-induced apoptosis in hippocampus-derived neural stem cells mediated by activation of BDNF and the MAPK pathway

Depression is accompanied by the activation of the inflammatory-response system, and increased production of proinflammatory cytokines may play a role in the pathophysiology of depressive disorders. Imipramine (IM), a tricyclic antidepressant drug, has recently been shown to promote neurogenesis and improve the survival rate of neurons in the hippocampus. However, whether IM elicits a neuroprotective or anti-inflammatory effect, or promotes the differentiation of neural stem cells (NSCs) remains to be elucidated. In this study, we cultured NSCs derived from the hippocampal tissues of adult rats as an in vitro model to evaluate the NSCs drug-modulation effects of IM. Our results showed that 3 microM IM treatment significantly increased the survival rate of NSCs, and up-regulated the mRNA and protein expression of brain-derived neurotrophic factor (BDNF) and Bcl-2 in Day-7 IM-treated NSCs. Similar to BDNF-treated effect, incubation of NSCs with 3 microM IM increased Bcl-2 protein levels and further prevented lipopolysaccharide (LPS)-induced apoptosis through the activation of the mitogen-activated protein kinase (MAPK)/extracellular-regulated kinase (ERK) pathway. Inhibition of BDNF expression with small interfering RNA (siRNA), or blocking the MAPK pathway with U0126 further significantly decreased Bcl-2 protein levels and abrogated the neuroprotective effects of IM against LPS-induced apoptosis in NSCs. In addition, the percentages of serotonin and MAP-2-positive neuronal cells in the Day 7 culture of IM-treated NSCs were significantly increased. By using microdialysis with high performance liquid chromatography-electrochemical detection, the functional release of serotonin in the process of serotoninergic differentiation of IM-treated NSCs was concomitantly increasing and mediated by the activation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades. In sum, the study results indicate that IM can increase the neuroprotective effects, suppress the LPS-induced inflammatory process, and promote serotoninergic differentiation in NSCs via the modulation of the BDNF/MAPK/ERK pathway/Bcl-2 cascades.

Association analysis between variants of the interleukin-1beta and the interleukin-1 receptor antagonist gene and antidepressant treatment response in major depression

This study investigated the possible association of the interleukin-1 beta (IL-1beta) C-511T promoter polymorphism and the interleukin-1 receptor antagonist (IL-1Ra) (86bp)(n) variable number of tandem repeats (VNTR) polymorphism with antidepressant response to paroxetine and mirtazapine treatment. The study group consisted of 101 patients suffering from DSM-IV major depression participating in a randomized double-blind controlled clinical trial. Patients homozygous for the IL-1beta-511T allele had a significantly faster and more pronounced response to paroxetine treatment than IL-1beta-511C allele carriers. No association was found for the IL-1beta C-511T polymorphism with mirtazapine treatment response. The IL-1Ra VNTR showed neither an association with paroxetine nor with mirtazapine treatment response. Our results provide further suggestive evidence that time course of response and antidepressant efficacy of paroxetine, but not of mirtazapine, is influenced in a clinically relevant manner by the IL-1beta C-511T gene variant. Our data do not support the hypothesis that the IL-1Ra (86bp)(n) VNTR affects antidepressant treatment response to paroxetine or mirtazapine. An independent replication of our finding is needed. If replicated, the IL-1beta C-511T promoter polymorphism could be considered useful for prospective confirmatory pharmacogenetic trials in patients with major depression.

Differential effect of environment enrichment and social isolation on depressive-like behavior, spontaneous activity and serotonin and norepinephrine concentration in prefrontal cortex and ventral striatum

In order to determine the effect of postnatal environments on some behavioral and neurochemical depressive-like parameters, male Sprague-Dawley rats were reared from weaning in either social isolation, standard laboratory conditions, or environmental enrichment. Open-field activity was assessed at postnatal days 37, 65, 93 and 107 and 1 h before the last open-field test, a forced-swimming test was carried out. After behavioral tests, the monoamines concentrations were analyzed in prefrontal cortex and ventral striatum. Relative to control and isolation rearing, the environmental enrichment reduced open-field activity, led to antidepressive-like effects and increased serotonin concentrations in the prefrontal cortex. Social isolation, on the other hand, did not affect open-field activity, but increased depressive-like behavior and reduced the amount of norepinephrine in the ventral striatum. Those neurochemical changes induced by rearing conditions correlated with the behavioral performance in the forced-swimming test. Also, immobility behavior could be predicted by locomotor activity even from the first week of housing. Overall, specific variations in physical and social environment during early rearing lead to some behavioral and neurochemical alterations which might be relevant for understanding the role that neurodevelopmental and experiential factors could have in human depression.

One year pre-post intervention follow-up of psychological, immune, endocrine and blood pressure outcomes of mindfulness-based stress reduction (MBSR) in breast and prostate cancer outpatients

OBJECTIVES

This study investigated the ongoing effects of participation in a mindfulness-based stress reduction (MBSR) program on quality of life (QL), symptoms of stress, mood and endocrine, immune and autonomic parameters in early stage breast and prostate cancer patients.

METHODS

Forty-nine patients with breast cancer and 10 with prostate cancer enrolled in an eight-week MBSR program that incorporated relaxation, meditation, gentle yoga and daily home practice. Demographic and health behaviors, QL, mood, stress symptoms, salivary cortisol levels, immune cell counts, intracellular cytokine production, blood pressure (BP) and heart rate (HR) were assessed pre- and post-intervention, and at 6- and 12-month follow-up.

RESULTS

Fifty-nine, 51, 47 and 41 patients were assessed pre- and post-intervention and at 6- and 12-month follow-up, respectively, although not all participants provided data on all outcomes at each time point. Linear mixed modeling showed significant improvements in overall symptoms of stress which were maintained over the follow-up period. Cortisol levels decreased systematically over the course of the follow-up. Immune patterns over the year supported a continued reduction in Th1 (pro-inflammatory) cytokines. Systolic blood pressure (SBP) decreased from pre- to post-intervention and HR was positively associated with self-reported symptoms of stress.

CONCLUSIONS

MBSR program participation was associated with enhanced quality of life and decreased stress symptoms, altered cortisol and immune patterns consistent with less stress and mood disturbance, and decreased blood pressure. These pilot data represent a preliminary investigation of the longer-term relationships between MBSR program participation and a range of potentially important biomarkers.

Neuropsychiatric manifestations of depression in multiple sclerosis: neuroinflammatory, neuroendocrine, and neurotrophic mechanisms in the pathogenesis of immune-mediated depression

Evidence suggests that depression in multiple sclerosis (MS) is largely biologically mediated by some of the same processes involved in the immunopathogenesis of this neurologic disease. In particular, the increase in proinflammatory cytokines, activation of the hypothalamic-pituitary-adrenal (HPA) axis, and reduction in neurotrophic factors that occur in MS may each account for the increased rate of depression seen in MS. The possible contributions of these neuroinflammatory, neuroendocrine, and neurotrophic mechanisms suggest a diverse array of novel treatment strategies for depression, both in the context of inflammatory conditions as well as in idiopathic depression. Furthermore, if such processes in MS play a causative role in the pathogenesis of depression, and depression in turn has affects on neurophysiological processes related to immune function, then treatment of depression might have a positive effect on MS disease progression. This makes treating MS depression a neuropsychiatric imperative.

A final common pathway for depression? Progress toward a general conceptual framework

Functional neuroimaging studies of depressed patients have converged with functional brain mapping studies of depressed animals in showing that depression is accompanied by a hypoactivity of brain regions involved in positively motivated behavior together with a hyperactivity in regions involved in stress responses. Both sets of changes are reversed by diverse antidepressant treatments. It has been proposed that this neural pattern underlies the symptoms common to most forms of the depression, which are the loss of positively motivated behavior and increased stress. The paper discusses how this framework can organize diverse findings ranging from effects of monoamine neurotransmitters, cytokines, corticosteroids and neurotrophins on depression. The hypothesis leads to new insights concerning the relationship between the prolonged inactivity of the positive motivational network during a depressive episode and the loss of neurotrophic support, the potential antidepressant action of corticosteroid treatment, and to the key question of whether antidepressants act by inhibiting the activity of the stress network or by enhancing the activity of the positive motivational system.

Thiazolidinediones: novel treatments for cognitive deficits in mood disorders?

The aim of this review is to provide a rationale for evaluating thiazolidinediones (TZDs) as putative treatments for cognitive deficits in individuals with mood disorders. A MedLine search of all English-language articles published between January 1966 and August 2006 was conducted. The search terms were: the non-proprietary names of TZDs (e.g., rosiglitazone and pioglitazone), peroxisome proliferator-activated receptor, cognition, neuroprotection, inflammation, oxidative stress, cellular metabolism and excitotoxicity cross-referenced with the individual names of mood (e.g., major depressive disorder and bipolar disorder) and dementing disorders (e.g., Alzheimer's disease) as defined in the Diagnostic and Statistical Manual of Mental Disorders third edition, revised/fourth edition, text revision (DSM-III-R/IV-TR). The search was augmented with a manual review of article reference lists. Articles selected for review were based on adequacy of sample size, the use of standardized experimental procedures, validated assessment measures and overall manuscript quality. Contemporary pathophysiologic models of mood disorders emphasize alterations in neuronal plasticity, metabolism and cytoarchitecture with associated regional abnormalities in neuronal (and glial) density and morphology. These abnormalities are hypothesized to subserve cognitive deficits and other clinical features of mood disorders. TZDs may attenuate, abrogate and/or reverse the neurotoxic effects of depressive illness by means of disparate mechanisms, notably insulin signaling, anti-inflammation, glucocorticoid activity and cellular metabolism. Extant data provide the basis for formulating a hypothesis that TZDs may be salutary for cognitive deficits and several aspects of somatic health (e.g., cardiovascular disease) associated with mood disorders.

Heat-shock protein-70 genes and response to antidepressants in major depression

In the search of predictors of antidepressant efficacy, much interest has recently focused on pro-inflammatory proteins, as they were found to be elevated during major depressives states and decreased by antidepressant drugs. In the present paper we investigated the role of the genes coding for heat-shock-70 family proteins, recently hypothesized to be activated by antidepressants and thus mediate the reduction of pro-inflammatory cytosines. One hundred and forty two hospitalised patients, affected by major depression and treated with antidepressants drugs for a major depressive episode were evaluated for depressive severity at the baseline and at the discharge and genotyped for five SNPs within the genes HSPA1L, HSPA1A and HSPA1B. Markers were not individually associated with symptom severity after treatment. Instead, we found a three markers haplotype, including SNPs within HSPA1L and HSPA1A, associated with a poorer response to antidepressant treatment (p=0.005). Single markers as well as haplotypes were not associated with other clinical features. In conclusion, genetic variants within the genes coding for HSP-70 family proteins may affect the action of antidepressants and thus their therapeutic efficacy.

Marked improvement of psychiatric symptoms after parathyroidectomy in elderly primary hyperparathyroidism

Psychosomatic symptoms in primary hyperparathyroidism (PHPT) are various and include such conditions as obsessive-compulsive disorder, depression, anxiety, and paranoia. In the elderly the clinical features of the disease are often non-specific and difficult to diagnose. To quantify subjective symptoms of patients with hyperparathyroidism in the elderly, we determined whether these clinical manifestations resolved after surgical parathyroidectomy (PTX) in three PHPT patients over eighty years old. They were diagnosed with hypercalcemia, hypophosphatemia, high PTH concentrations, and osteoporosis. A single parathyroid adenoma was confirmed in each patient by Tc-MIBI scintigram, neck ultrasonography and computed tomographic scanning. PTX was performed in these three patients. Assessments of psychologic symptoms, using the Hamilton Rating Scale for Depression (HAM-D), serum calcium, and intact PTH were obtained before and after PTX. Mean weight of the resected adenomas was 438 +/- 138 mg (mean +/- SD). After PTX, serum calcium decreased from 11.1 +/- 0.5 to 9.2 +/- 0.5 mg/dl and intact PTH from 160.0 +/- 25.2 to 45.3 +/- 22.2 pg/ml. Total HAM-D scores in each patient decreased from 45 to 9, 17 to 1 and 15 to 5, respectively. Especially, there were marked improvements in depressive mood, psychomotor inhibition, anxiety and somatic symptoms after PTX. The quality of life in those patients was also improved by PTX. We propose here that PTX in elderly PHPT patients with psychiatric symptoms should be considered instead of oral administration, such as anti-depressants or bisphosphonates.

Serotonergic vulnerability and depression: assumptions, experimental evidence and implications

In recent years, the term serotonergic vulnerability (SV) has been used in scientific literature, but so far it has not been explicitly defined. This review article attempts to elucidate the SV concept. SV can be defined as increased sensitivity to natural or experimental alterations of the serotonergic (5-HTergic) system. Several factors that may disrupt the 5-HTergic system and hence contribute to SV are discussed, including genetic factors, female gender, personality characteristics, several types of stress and drug use. It is explained that SV can be demonstrated by means of manipulations of the 5-HTergic system, such as 5-HT challenges or acute tryptophan depletion (ATD). Results of 5-HT challenge studies and ATD studies are discussed in terms of their implications for the concept of SV. A model is proposed in which a combination of various factors that may compromise 5-HT functioning in one person can result in depression or other 5-HT-related pathology. By manipulating 5-HT levels, in particular with ATD, vulnerable subjects may be identified before pathology initiates, providing the opportunity to take preventive action. Although it is not likely that this model applies to all cases of depression, or is able to identify all vulnerable subjects, the strength of the model is that it may enable identification of vulnerable subjects before the 5-HT related pathology occurs.

Diversity of GABA(A) receptor synaptic currents on individual pyramidal cortical neurons

Miniature GABA(A) receptor-mediated inhibitory postsynaptic currents (mIPSCs) in cortical pyramidal neurons have previously been categorized into two types: small amplitude mIPSCs with a mono-exponential deactivation (mono-mIPSCs) and relatively larger mIPSCs with bi-exponential deactivation (bi-mIPSCs). The aim of this study was to determine if the GABA(A) channels that underlie these mIPSCSs are molecularly distinct. We found, using non-stationary noise analysis, that the difference in their amplitude could be not accounted for by their single channel conductance (both were 40 pS). Next, using alpha subunit selective GABA(A) receptor modulators, we examined the identity of the alpha subunits that may be expressed in the synapses that give rise to these mIPSCs. Zolpidem (100 and 500 nM, alpha1 selective) affected the deactivation of a subset of the mono-mIPSCs, indicating that alpha1 subunits are not highly expressed in these synapses. However, zolpidem (100 nM) prolonged the deactivation of all bi-mIPSCs, indicating a high abundance of alpha1 subunits in these synapses. SB-205384 (alpha3 selective) had no effect on the mono-mIPSCs but the bi-mIPSCs were prolonged. Furosemide (alpha4 selective) reduced the amplitude of only the mono-mIPSCs. L655,708 (alpha5 selective) reduced the amplitude of both populations and shortened the duration of the mono-mIPSCs. Finally, we found that the neuroactive steroid pregesterone sulphate reduced the amplitude of both mIPSC types. These results provide pharmacological evidence that synapses on cortical pyramidal neurons are molecularly distinct. The purpose of these different types of synapses may be to provide different inhibitory timing patterns on these cells.

Influence of poly I:C on sickness behaviors, plasma cytokines, corticosterone and central monoamine activity: moderation by social stressors

Stressor and cytokine challenges provoke several common effects, and may synergistically influence behavioral and neurochemical functioning. In the present investigation, we assessed whether the effects of poly I:C would be influenced when administered on a backdrop of a psychosocial stressor. In naïve mice, poly I:C (2mg/kg) modestly increased sickness behaviors, plasma IL-6, TNF-alpha and IL-10 levels, but did not affect IL-1, IL-4, or IFN-gamma. The viral analogue also increased plasma corticosterone levels and norepinephrine (NE) utilization within the paraventricular hypothalamus (PVN) and hippocampus. However, among mice that had experienced social disruption (comprising 14 days of isolation followed by regrouping), the behavioral, IL-6, IL-10, and corticoid alterations provoked by poly I:C were markedly augmented. Moreover, following social disruption the effect of poly I:C on NE utilization was increased within the PVN, prefrontal cortex and central amygdala, as was serotonin utilization within the hippocampus. The effects of poly I:C were likewise augmented following social disruption engendered by introducing mice to strangers.. However, among mice that had previously been exposed to a chronic, variable psychosocial stressor regimen, the augmented behavioral, neuroendocrine and monoamine effects of poly I:C were absent, and IL-6 and IL-10 levels were reduced relative to mice that had not been chronically stressed. In contrast, levels of IL-1 beta and IFN-gamma were increased. Mechanisms that might be responsible for the interactive effects of social disruption and immune activation are presented, and the data were related to depressive symptoms associated with stressor and cytokine treatments.

Interferon-α effects are exaggerated when administered on a psychosocial stressor backdrop: Cytokine, corticosterone and brain monoamine variations

Immunotherapy involving interferon-alpha (IFN-alpha) treatment is often accompanied by symptoms of depressive illness. These effects may stem from the direct actions of the cytokine, or may be unique to individuals undergoing considerable strain. In two experiments using CD-1 mice, we demonstrate that intraperitoneal administration of IFN-alpha dose dependently influences plasma corticosterone and sickness behaviors, and modestly influences norepinephrine turnover in brain. However, when mice are exposed to a psychosocial stressor (social disruption by transferring mice from isolated to grouped conditions, and to a moderate extent a transfer from grouped housing to isolation), the effects of IFN-alpha on sickness, plasma corticosterone and hippocampal norepinephrine, as well as on the levels of circulating IL-6, TNF-alpha and IL-10 (but not IL-1beta or IFN-gamma) are greatly augmented. It is suggested that the depressive effects of immunotherapy in humans likewise reflects the synergistic actions of the cytokine and the ongoing distress experienced by patients.

Life-Long Hippocampal Neurogenesis: Environmental, Pharmacological and Neurochemical Modulations

It is now well documented that active neurogenesis does exist throughout the life span in the brain of various species including human. Two discrete brain regions contain progenitor cells that are capable of differentiating into neurons or glia, the subventricular zone and the dentate gyrus of the hippocampal formation. Recent studies have shown that neurogenesis can be modulated by a variety of factors, including stress and neurohormones, growth factors, neurotransmitters, drugs of abuse, and also strokes and traumatic brain injuries. In particular, the hippocampal neurogenesis may play a role in neuroadaptation associated with pathologies, such as cognitive disorders and depression. The increased neurogenesis at sites of injury may represent an attempt by the central nervous system to regenerate after damage. We herein review the most significant data on hippocampal neurogenesis in brain under various pathological conditions, with a special attention to mood disorders including depression and addiction.

Persistent generalized anxiety after brief exposure to the dopamine antagonist metoclopramide

The authors describe a 31-year-old woman who developed persistent generalized anxiety after brief exposure to the dopamine antagonist metoclopramide. Independently of that, she had experienced a panic attack followed by dystonias, shortly after a single dose of that drug, 17 years before. Both temporal association and recurrence of anxiety symptoms after re-challenge with metoclopramide suggest a causal relationship. The case might provide an initial piece of evidence that dopaminergic neurotransmission can be involved in the pathogenesis of generalized anxiety disorder.

Evaluation of anti-Fas ligand-induced apoptosis and neural differentiation of PC12 cells treated with nerve growth factor using small interfering RNA method and sampling by microdialysis

The small interfering RNA (siRNA) method is an effective technique for silencing gene expression and is a useful tool for screening the gene functions in drug discovery. Our study found that nerve growth factor (NGF) can increase the cell viability of PC12 cells and that NGF induction up-regulates the expression of Bcl-2 detected by real-time reverse transcription-polymerase chain reaction (RT-PCR). To further investigate the role of Bcl-2 expression in NGF-treated PC12 cells, the plasmid of Bcl-2 siRNA was then transfected into PC12 cells. Moreover, to investigate and continuously monitor the real-time dynamic neurotransmitter release, and to compare with the time course of Bcl-2 expression, a liquid chromatography coupled with electrochemical detection (LC-ED) and with a microdialysis device was used. After 6h of NGF being added to the PC12 cell culture medium, the dopamine (DA) concentrations were significantly increased (P<0.05). This result is simultaneously compatible with the up-regulated messenger RNA (mRNA) expressions of tyrosine hydroxylase (TH), aromatic acid decarboxylase (AADC), and Bcl-2 by RT-PCR. Using the Bcl-2 siRNA method, our data revealed that NGF can inhibit Fas ligand (FasL)-induced apoptosis in PC12 cells through the activation of Bcl-2. The in vitro observation further demonstrated that NGF can stimulate the neurite development in PC12 cells through the activation of Bcl-2. Moreover, the DA concentrations of NGF induction were decreased specifically by Bcl-2 siRNA (P<0.05). In sum, our data support that NGF prevents Fas-induced apoptosis, facilitates neural differentiation, promotes dendritic formation, and increases DA release in PC12 cells through activation of Bcl-2.

Serotonin-1A receptor gene HTR1A variation predicts interferon-induced depression in chronic hepatitis C

BACKGROUND & AIMS

Interferon-induced depression is a major complication in antiviral therapy of chronic hepatitis C. Little is known about underlying mechanisms and reliable predictive factors associated with cytokine-induced depressive symptoms.

METHODS

In a cohort of 139 hepatitis C-infected outpatients treated with interferon alfa-2b, we investigated the impact of functional gene variants of the cerebral serotonin (5-HT) signalling pathway previously implicated in depression risk. Depression was monitored using the Hospital Anxiety and Depression Scale (HADS). All patients were genotyped for functional variations in the 5-HT(1A) receptor (HTR1A), 5-HT transporter (SLC6A4, 5-HTT), and tryptophan hydoxylase-2 (TPH2).

RESULTS

Homozygosity for the HTR1A-1019G variant significantly increased both incidence and severity of interferon-induced depression. Maximum increases in HADS depression scores during antiviral therapy correlated with HTR1A variation (P = .011). Clinically relevant depression was significantly associated with the HTR1A-1019G genotype (P = .017; OR, 2.95). 5-HTT and TPH2 variations did not contribute significantly to the prediction of interferon-induced depression by HTR1A (sensitivity, 35.9%; specificity, 84.0%).

CONCLUSIONS

Our findings suggest an impact of allelic variation in 5-HT(1A) receptor expression on the development of interferon alfa-induced depression during antiviral treatment of chronic hepatitis C. Prediction models of interferon-induced depressive symptoms based on HTR1A variation offer a perspective for an antidepressant selective serotonin reuptake inhibitor prophylaxis in patients genetically at risk for interferon-induced depression.

Glycogen synthase kinase-3 (GSK3): inflammation, diseases, and therapeutics

Deciphering what governs inflammation and its effects on tissues is vital for understanding many pathologies. The recent discovery that glycogen synthase kinase-3 (GSK3) promotes inflammation reveals a new component of its well-documented actions in several prevalent diseases which involve inflammation, including mood disorders, Alzheimer's disease, diabetes, and cancer. Involvement in such disparate conditions stems from the widespread influences of GSK3 on many cellular functions, with this review focusing on its regulation of inflammatory processes. GSK3 promotes the production of inflammatory molecules and cell migration, which together make GSK3 a powerful regulator of inflammation, while GSK3 inhibition provides protection from inflammatory conditions in animal models. The involvement of GSK3 and inflammation in these diseases are highlighted. Thus, GSK3 may contribute not only to primary pathologies in these diseases, but also to the associated inflammation, suggesting that GSK3 inhibitors may have multiple effects influencing these conditions.

The molecular neurobiology of depression

Depression is a condition with a complex biologic pattern in etiology. Environmental stressors modulate subsequent vulnerability to depression. In particular, early adversity seems to induce heightened reactivity to stress through several possible mechanisms, both biologic and psychologic. This increased reactivity results in an enhancement of biologic stress-response mechanisms, especially the HPA axis. Regulators of this system, particularly signal transduction pathways involving PKA and PKC, may be important in the regulation of key genes in this system including genes for GR, BDNF, and trk-b. This system potentially is vulnerable to ROS and therefore, indirectly, to the effects of cytokines. Finally, some of these effects may be controlled by chemical modification of DNA, specifically, methylation of promoters or other gene regions. This modification is a mechanism by which long-term biologic change can be induced by environmental stressors. The brain is homeostatic, and it is possible that alterations at multiple points in this system may induce dysregulation and, as a result, vulnerability to stress. Therefore, a person may be vulnerable to depression, which may be a final common "pathway" for this family of conditions. Individuals may very considerably with regard to the locus of the problem, however. For example, functional variants in a set of genes might predispose some people to depression; others may have epigenetic imprinting; and yet different causes may be at work in others. Although this mix is complicated, it can be unraveled. Doing so could lead to the development of novel interventions that could target specific points of vulnerability, allowing an improved matching of patient to treatment based on differential abnormalities at the cellular level.

Desipramine Activated Bcl-2 Expression and Inhibited Lipopolysaccharide-Induced Apoptosis in Hippocampus-Derived Adult Neural Stem Cells

Desipramine (DP) is a tricyclic antidepressant used for treating depression and numerous other psychiatric disorders. Recent studies have shown that DP can promote neurogenesis and improve the survival rate of hippocampal neurons. However, whether DP induces neuroprotection or promotes the differentiation of neural stem cells (NSCs) needs to be elucidated. In this study, we cultured NSCs derived from the hippocampal tissues of adult rats as an in vitro model to evaluate the modulation effect of DP on NSCs. First, we demonstrated that the expression of Bcl-2 mRNA and nestin in 2 microM DP-treated NSCs were up-regulated and detected by real-time reverse transcriptase polymerase chain reaction (RT-PCR). The results of Western blotting and immunofluorescent study confirmed that Bcl-2 protein expression was significantly increased in Day 3 DP-treated NSCs. Using the Bcl-2 small interfering RNA (siRNA) method, our results further showed that DP protects the lipopolysaccharide (LPS)-induced apoptosis in NSCs, in part by activating the expression of Bcl-2. Furthermore, DP treatment significantly inhibited the induction of proinflammatory factor interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha in the culture medium of LPS-treated NSCs mediated by Bcl-2 modulation. The results of high performance liquid chromatography coupled to electrochemical detection further confirmed that DP significantly increased the functional production of serotonin (26+/-3.5 microM, DP-treated 96 h) and noradrenaline (50+/-8.9 microM, DP-treated 96 h) in NSCs through activation of the MAPK/ERK pathway and partially mediated by Bcl-2. In conclusion, the present results indicate that DP can increase neuroprotection ability by inhibiting the LPS-induced inflammatory process in NSCs via the modulation of Bcl-2 expression, as confirmed by the siRNA method.

Behavioral genomics of honeybee foraging and nest defense

The honeybee has been the most important insect species for study of social behavior. The recently released draft genomic sequence for the bee will accelerate honeybee behavioral genetics. Although we lack sufficient tools to manipulate this genome easily, quantitative trait loci (QTLs) that influence natural variation in behavior have been identified and tested for their effects on correlated behavioral traits. We review what is known about the genetics and physiology of two behavioral traits in honeybees, foraging specialization (pollen versus nectar), and defensive behavior, and present evidence that map-based cloning of genes is more feasible in the bee than in other metazoans. We also present bioinformatic analyses of candidate genes within QTL confidence intervals (CIs). The high recombination rate of the bee made it possible to narrow the search to regions containing only 17–61 predicted peptides for each QTL, although CIs covered large genetic distances. Knowledge of correlated behavioral traits, comparative bioinformatics, and expression assays facilitated evaluation of candidate genes. An overrepresentation of genes involved in ovarian development and insulin-like signaling components within pollen foraging QTL regions suggests that an ancestral reproductive gene network was co-opted during the evolution of foraging specialization. The major QTL influencing defensive/aggressive behavior contains orthologs of genes involved in central nervous system activity and neurogenesis. Candidates at the other two defensive-behavior QTLs include modulators of sensory signaling (Am5HT₇ serotonin receptor, AmArr4 arrestin, and GABA-B-R1 receptor). These studies are the first step in linking natural variation in honeybee social behavior to the identification of underlying genes.

The role of gastrin-releasing peptide on conditioned fear: differential cortical and amygdaloid responses in the rat

RATIONALE

Bombesin (BB), an amphibian peptide, was shown to affect the expression of the stress response. However, the physiological role of the mammalian counterparts of BB in mediating anxiety and fear responses remain to be characterized.

OBJECTIVE

This study examined the effects of gastrin-releasing peptide (GRP), a mammalian analogue of BB, and its receptor antagonist, BW2258U89, on conditioned emotional response (CER), using fear conditioning.

MATERIALS AND METHODS

The effects of these compounds on contextual and cued fear conditioning were assessed after direct bilateral infusions into the prelimbic (PrL) cortex, infralimbic (IL) cortex or central nucleus of the amygdala (CeA).

RESULTS

GRP (300 ng) microinjected into each of the three target nuclei significantly reduced freezing to contextual cues. Similarly, in the cued portion of CER, GRP administered to the IL cortex significantly reduced freezing. Administration of BW2258U89 resulted in dose-dependent and site-specific effects. At the IL cortex, the 50 ng dose decreased freezing to both contextual and cued fear conditioning. At the CeA, the 300 ng dose also decreased freezing, but at the 50 ng dose, it increased contextual freezing. At the PrL cortex, BW2258U89 did not affect freezing.

CONCLUSIONS

These results illustrate that (1) GRP system(s) can significantly affect the expression of learned fear, (2) some of the relevant brain sites mediating these effects include the PrL, IL and the CeA, and (3) such effects may be dependent upon whether responses were evoked by environmental contextual fear cues or by specific auditory cues that were explicitly paired with an aversive stimulus.

Nogo A, B and C expression in schizophrenia, depression and bipolar frontal cortex, and correlation of Nogo expression with CAA/TATC polymorphism in 3′-UTR

Schizophrenia may result from altered gene expression leading to abnormal neurodevelopment. In a search for genes with altered expression in schizophrenia, our previous work on human frontal cerebral cortex found the mRNA of Nogo, a myelin-associated protein which inhibits the outgrowth of neurites and nerve terminals, to be overexpressed in schizophrenia. Because those earlier results did not examine tissues for the separate Nogo A, B and C isoforms from age- and sex-matched individuals, we repeated the study for all three isoforms, using a new set of tissues from matched individuals, and using the more accurate method of quantitative real-time PCR (polymerase chain reaction). We found Nogo C to be overexpressed by 26% in the schizophrenia tissues, which is in accordance with our earlier results. The expression of Nogo B was statistically significantly reduced by 17% in the frontal cortices from individuals who had been diagnosed as having had severe depression. Furthermore, we show that there is a direct correlation between the expression of Nogo A and C and the presence of alleles with a CAA insert, irrespective of disease status. While upregulation of Nogo C expression may play a role in schizophrenia, altered Nogo B may contribute to the clinical condition of depression. Nogo A showed a statistically non-significant increase in expression in schizophrenia.

Elevation of plasma concentration of adhesion molecules in late-life depression

OBJECTIVES

Late-life depression may be associated with vascular disease. The purpose of the study was to investigate this association by determining the levels of soluble adhesion molecules (sICAM-1 and sVCAM-1) which represent markers of ischemia-induced inflammation in elderly individuals with depression.

METHODS

Blood samples were obtained from 33 subjects with depression selected from a community-dwelling population after screening with the Geriatric Depression Scale, and 33 matched controls. Serum concentrations of sICAM-1 (ng/mL) and sVCAM-1 (ng/mL) were measured in both groups.

RESULTS

Depressed patients (Group A) possessed significantly higher sICAM-1 levels compared to healthy controls (Group B) (674.94 +/- 166.90 ng/ml vs 467.05 +/- 231.26 ng/ml, respectively, p < 0.01). Similarly the same groups demonstrated elevated sVCAM-1 levels compared to controls (572.14 +/- 182.20 ng/ml vs 449.04 +/- 285.27 ng/ml, p < 0.05); a difference that in both cases remained significant after adjustment for potential confounders (gender, smoking, presence of metabolic syndrome).

CONCLUSION

These findings indicate an association between high serum levels of VCAM-1, and ICAM-1 and depression in the elderly and further support the vascular depression hypothesis, which has important implications for the understanding and management of late-life depression.

Changes in the immune system in depression and dementia: causal or coincidental effects?

Epidemiological studies show that there is a correlation between chronic depression and the likelihood of demential in later life. There is evidence that inflammatory changes in the brain are pathological features of both depression and dementia. This suggests that an increase in inflammation-induced apoptosis, together with a reductin in the synthesis of neurotrophic factors caused by a rise in brain glucocorticoids, may play a role in the pathology of these disorders. A reduction in the neuroprotective components of the kynurenine pathway, such as kynurenic acid, and an increase in the neurodegenerative components, 3-hydroxykynurenine and quinolinic acid, contribute to the pathological changes. Such changes are postulated t cause neuronal damage, and thereby predispose chronically depressed patients to demential.

Acetylsalicylic acid accelerates the antidepressant effect of fluoxetine in the chronic escape deficit model of depression

Evidence has accumulated suggesting that major depression is associated with dysfunction of inflammatory mediators. Moreover, antidepressants show an anti-inflammatory action possibly related to their clinical efficacy. An improvement in psychiatric symptoms has been recently reported in patients treated with anti-inflammatory drugs for other indications. These data imply that inflammation may be involved in the pathogenesis of depression and that anti-inflammatory drugs may be used as an adjunctive therapy. The aim of the present study was to evaluate the behavioural effect of the co-administration of acetylsalicylic acid (ASA, 45 mg/kg or 22.5 mg/kg) and fluoxetine (FLX, 5 mg/kg) in the chronic escape deficit model of depression. The chronic escape deficit model is based on the modified reactivity of rats to external stimuli induced by exposure to unavoidable stress and allows evaluation of the capacity of a treatment to revert the condition of escape deficit. In this model, FLX alone needs to be administered for at least 3 weeks to revert this condition. Our results show that combined treatment of fluoxetine and ASA completely reverted the condition of escape deficit by as early as 7 days, the effect being already partially present after 4 days. The effect was maintained after 14 and 21 days of treatment. ASA alone was ineffective at any time tested and the effect of fluoxetine was significant only at 21 days. These results, together with clinical data from preliminary results, suggest that ASA might accelerate the onset of action of selective serotonin reuptake inhibitor antidepressants.

Moclobemide upregulated Bcl-2 expression and induced neural stem cell differentiation into serotoninergic neuron via extracellular-regulated kinase pathway

1. Moclobemide (MB) is an antidepressant drug that selectively and reversibly inhibits monoamine oxidase-A. Recent studies have revealed that antidepressant drugs possess the characters of potent growth-promoting factors for the development of neurogenesis and improve the survival rate of serotonin (5-hydroxytrytamine; 5-HT) neurons. However, whether MB comprises neuroprotection effects or modulates the proliferation of neural stem cells (NSCs) needs to be elucidated. 2. In this study, firstly, we used the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay to demonstrate that 50 microM MB can increase the cell viability of NSCs. The result of real-time reverse transcription-polymerase chain reaction (RT-PCR) showed that the induction of MB can upregulate the gene expressions of Bcl-2 and Bcl-xL. By using caspases 8 and 3, ELISA and terminal dUTP nick-end labeling (TUNEL) assay, our data further confirmed that 50 microM MB-treated NSCs can prevent FasL-induced apoptosis. 3. The morphological findings also supported the evidence that MB can facilitate the dendritic development and increase the neurite expansion of NSCs. Moreover, we found that MB treatment increased the expression of Bcl-2 in NSCs through activating the extracellular-regulated kinase (ERK) phosphorylation. 4. By using the triple-staining immunofluorescent study, the percentages of serotonin- and MAP-2-positive cells in the day 7 culture of MB-treated NSCs were significantly increased (P<0.01). Furthermore, our data supported that MB treatment increased functional production of serotonin in NSCs via the modulation of ERK1/2. In sum, the study results support that MB can upregulate Bcl-2 expression and induce the differentiation of NSCs into serotoninergic neuron via ERK pathway.