Anhedonic and anxiogenic effects of cytokine exposure

Involvement of Anti-Inflammatory and Stress Oxidative Markers in the Antidepressant-like Activity of Aloysia citriodora and Verbascoside on Mice with Bacterial Lipopolysaccharide- (LPS-) Induced Depression

Aloysia citriodora Palau is popularly used to treat nervous disorders. Experimental evidence has indicated that verbascoside (VBS) isolated from A. citriodora has pharmacological potential. In this study, we evaluated the antidepressant-like effects of a hydroalcoholic extract of A. citriodora (HEAc) and VBS against lipopolysaccharide- (LPS-) induced depressive-like behavior in mice. In the pretreatment protocol (performed to evaluate the preventive potential), mice were pretreated with HEAc (3, 30, or 300 mg/kg) or VBS (30 mg/kg) before the administration of LPS. In the posttreatment protocol (performed to evaluate the therapeutic potential), mice were initially administered LPS and were subsequently given HEAc (3, 30, or 300 mg/kg) or VBS (30 mg/kg). In both treatments, the mice were submitted to an open-field test and tail suspension test (TST) at 6 and 24 h after LPS administration. The posttreatment evaluation revealed that HEAc (30 or 300 mg/kg) and VBS produced an antidepressant-like effect, as indicated by a reduction in the time spent with no movement in the TST. Moreover, HEAc (30 or 300 mg/kg) was found to reduce interleukin-6 (IL-6) levels and N-acetyl-glycosaminidase activity in the hippocampus, increase glutathione (GSH) levels in the hippocampus and cortex, and enhance IL-10 in the cortex and, at a dose of 300 mg/kg, reduced myeloperoxidase activity in the cortex. Contrastingly, no comparable effects were detected in mice subjected to the pretreatment protocol. Administration of VBS similarly reduced the levels of IL-6 in the hippocampus and increased GSH levels in the cortex. Our observations indicate that both HEAc and VBS show promising antidepressant-like potential, which could be attributed to their beneficial effects in reducing neuroinflammatory processes and antioxidant effects in the central nervous system.

Antidepressant- and anxiolytic-like activities of Rosmarinus officinalis extract in rodent models: Involvement of oxytocinergic system

BACKGROUND

Oxytocin (OXT), a neuropeptide involved in mammal reproductive and prosocial behaviors, has been reported to interact with various stressor-provoked neurobiological changes, including neuroendocrine, neurotransmitter, and inflammatory processes. In view of disturbances in psychosocial relationships due to social isolation and physical distancing measures amid the COVID-19 pandemic, being one of the triggering factors for the recent rise in depression and anxiety, OXT is a potential candidate for a new antidepressant.

METHODS

In this present study, we have aimed to investigate the effects of oral administration of Rosmarinus officinalis extract (RE), extracted from distillation residue of rosemary essential oil, on central OXT level in the context of other stress biomarkers and neurotransmitter levels in mice models. Tail suspension test (TST) and elevated plus maze test (EPMT) following LPS injection were employed to assess depressive- and anxiety-like behavior in mice, respectively.

FINDINGS

Pretreatment with RE for seven days significantly improved behavior in TST and EPMT. Whole-genome microarray analysis reveals that RE significantly reversed TST stress-induced alterations in gene expressions related to oxytocinergic and neurotransmitter pathways and inflammatory processes. In both models, RE significantly increased central Oxt and Oxtr expressions, as well as OXT protein levels. RE also significantly attenuated stress-induced changes in serum corticosterone, brain and serum BDNF levels, and brain neurotransmitters levels in both models.

INTERPRETATION

Altogether, our study is the first to report antidepressant- and anxiolytic-like activities of RE through modulating oxytocinergic system in mice brain and thus highlights the prospects of RE in the treatment of depressive disorders of psychosocial nature.

The Differential Role of Cytokines on Stress Responses in a Menopause Rat Model

Menopause is a risk factor of anxiety and depression. Also, psychoneurological symptoms are shown in almost all women in the perimenopausal period. The present study investigated if repeated stress modulates behavioral changes or the balance of pro- and anti-inflammatory cytokines in ovariectomized (OVX) rats. Albino SD female rats were randomly divided into four groups: the naïve normal group (NOR), a surgically ovariectomized group (OVX), the only stressed group (ST), and the OVX and stressed groups (OVX + ST). We performed a battery of tests such as the forced swimming test (FST), the sucrose intake, and social exploration. In the same animals, corticosterone (CORT) was assessed in the serum, and also, two representative cytokines (IL-1β and IL-4) were examined in different brain regions after all the behavior sessions for all the experimental groups. The OVX + ST group showed more immobility time in FST than the OVX group or the ST group. Also, the OVX + ST group tended to have a decreased active social exploration and sucrose solution intake compared to the OVX group or ST group. The serum concentration of CORT of the OVX + ST group was higher than the OVX group or ST group and also the level of CORT in OVX + ST was markedly increased compared to the NOR group. In the brain, the number of IL-1β immunoreactive neurons of the OVX + ST group was increased compared to the NOR group. The OVX + ST group tended to have an increase in IL-1β-positive neurons compared to the OVX or ST group. However, the number of IL-4 immunoreactive neurons of the OVX + ST group was markedly decreased compared with the NOR group. Also, the IL-4-positive neurons in the OVX + ST group was significantly decreased when compared to the ST group. These results indicate that ovariectomy and stress combine to increase the depressive-like behaviors and neuroinflammatory responses. Together, these data show neuroinflammation as a potential contributor to depressive-like symptoms during menopausal transition.

The Fatigue Assessment Scale as a simple and reliable tool in systemic lupus erythematosus: a cross-sectional study

Background

The vast majority of patients with systemic lupus erythematosus (SLE) complain about fatigue. They also report fatigue as one of their most debilitating symptoms. Yet, in clinical practice, fatigue is only rarely assessed and remains poorly understood. The purpose of this study is to validate the Fatigue Assessment Scale (FAS) and assess the impact of disease activity on fatigue in SLE.

Methods

A cross-sectional single-center study of patients was included in the Swiss SLE Cohort Study. The FAS and the Short Form 36 (SF-36) were administered to SLE patients and controls with primary Sjogren’s syndrome (pSS) and healthy volunteers (HV) attending our clinic. Disease activity in SLE was captured at the same time as patient-reported outcomes using the SLE Disease Activity Index score with the Safety of Estrogens in SLE National Assessment modification (SELENA-SLEDAI) and the physician’s global assessment. We explored the internal consistency, reproducibility, construct validity, and convergence of the FAS, in comparison to the vitality subscale (VT) of the SF-36. We examined the association of FAS with demographics, disease type, SLE disease activity, and clinical features.

Results

Of the 73 SLE subjects, 89% were women and 77% were Caucasians. The median age was 43 years, and 23 (32%) patients had active SLE. Demographics in pSS and HV were similar. Within the SLE group, FAS displayed good internal consistency (Cronbach’s alpha = 0.93), unidimensionality, and test-retest reliability (ICC = 0.90). FAS and VT correlated well. The total FAS was highest in active SLE and pSS and higher in non-active SLE compared to HV.

Conclusion

The FAS is a promising tool to measure fatigue in SLE. Patients with SLE display a significantly higher level of fatigue than HV, which is even more pronounced in active disease and comparable to fatigue levels measured in pSS.

Low-Grade Inflammation as a Predictor of Antidepressant and Anti-Inflammatory Therapy Response in MDD Patients: A Systematic Review of the Literature in Combination With an Analysis of Experimental Data Collected in the EU-MOODINFLAME Consortium

Low-grade inflammation plays a role not only in the pathogenesis of major depressive disorder (MDD) but probably also in the poor responsiveness to regular antidepressants. There are also indications that anti-inflammatory agents improve the outcomes of antidepressants. Aim: To study whether the presence of low-grade inflammation predicts the outcome of antidepressants, anti-inflammatory agents, or combinations thereof. Methods: We carried out a systematic review of the literature on the prediction capability of the serum levels of inflammatory compounds and/or the inflammatory state of circulating leukocytes for the outcome of antidepressant/anti-inflammatory treatment in MDD. We compared outcomes of the review with original data (collected in two limited trials carried out in the EU project MOODINFLAME) on the prediction capability of the inflammatory state of monocytes (as measured by inflammatory gene expression) for the outcome of venlafaxine, imipramine, or sertraline treatment, the latter with and without celecoxib added. Results: Collectively, the literature and original data showed that: 1) raised serum levels of pro-inflammatory compounds (in particular of CRP/IL-6) characterize an inflammatory form of MDD with poor responsiveness to predominately serotonergic agents, but a better responsiveness to antidepressant regimens with a) (add-on) noradrenergic, dopaminergic, or glutamatergic action or b) (add-on) anti-inflammatory agents such as infliximab, minocycline, or eicosapentaenoic acid, showing-next to anti-inflammatory-dopaminergic or lipid corrective action; 2) these successful anti-inflammatory (add-on) agents, when used in patients with low serum levels of CRP/IL-6, decreased response rates in comparison to placebo. Add-on aspirin, in contrast, improved responsiveness in such "non-inflammatory" patients; 3) patients with increased inflammatory gene expression in circulating leukocytes had a poor responsiveness to serotonergic/noradrenergic agents. Conclusions: The presence of inflammation in patients with MDD heralds a poor outcome of first-line antidepressant therapies. Immediate step-ups to dopaminergic or glutamatergic regimens or to (add-on) anti-inflammatory agents are most likely indicated. However, at present, insufficient data exist to design protocols with reliable inflammation parameter cutoff points to guide such therapies, the more since detrimental outcomes are possible of anti-inflammatory agents in "non-inflamed" patients.

The protective role of Ocimum basilicum L. (Basil) against aspirin-induced gastric ulcer in mice: Impact on oxidative stress, inflammation, motor deficits and anxiety-like behavior

The gastroprotective effect of Ocimum basilicum L. (Basil) hexane extract (OBHE) in aspirin-induced gastric ulcers in mice and its ameliorative effect on behavioral alterations were determined. Pretreatment with OBHE (100 or 200 mg kg-1) or misoprostol (50 μg kg-1) alleviated the aspirin-induced oxidative stress by significantly decreasing (p < 0.001) gastric ulcer index scores (57, 76 and 79%), gastric TBARS (by 49, 51 and 52%), NO (21, 28 and 29%), H2O2 (24, 42 and 45%), and the serum pro-inflammatory mediator TNF-α (21, 53 and 53%) and IL-6 (29, 30 and 31%), as well as by markedly increasing gastric GSH (41, 61 and 70%), GSH-Px (21, 32 and 34%), GST (33, 63 and 70%), GR (90, 99 and 112%), CAT (167, 211 and 267%) and serum PGE-2 levels (22, 135 and 200%) and IL-4 (64, 81 and 104%), respectively, compared with the aspirin-treated group. Meanwhile, OBHE and misoprostol induced a significant decrease (p < 0.001) in the freezing time (53, 56 and 64%), and the grooming time (by 25, 43 and 44%), respectively, compared to the aspirin treated group. This study provides evidence that OBHE confers anxiolytic, antioxidant and anti-inflammatory prophylactic effects on aspirin-induced gastric ulcers. GC/MS was used for the characterization of OBHE components. Based on the findings of this study, basil may be used as a nutritional supplement or therapeutic drug to protect against aspirin-induced gastric ulcers, a common problem resulting from the use of aspirin.

Anorexia-cachexia syndrome-like hypothalamic neuroendocrine dysfunction in a patient with a papillary craniopharyngioma

The craniopharyngiomas are solid cystic suprasellar tumors that can present extension to adjacent structures, conditioning pituitary and hypothalamic dysfunction. Within hypothalamic neuroendocrine dysfunction, we can find obesity, behavioral changes, disturbed circadian rhythm and sleep irregularities, imbalances in the regulation of body temperature, thirst, heart rate and/or blood pressure and alterations in dietary intake (like anorexia). We present a rare case of anorexia–cachexia syndrome like a manifestation of neuroendocrine dysfunction in a patient with a papillary craniopharyngioma. Anorexia–cachexia syndrome is a complex metabolic process associated with underlying illness and characterized by loss of muscle with or without loss of fat mass and can occur in a number of diseases like cancer neoplasm, non-cancer neoplasm, chronic disease or immunodeficiency states like HIV/AIDS. The role of cytokines and anorexigenic and orexigenic peptides are important in the etiology. The anorexia–cachexia syndrome is a clinical entity rarely described in the literature and it leads to important function limitation, comorbidities and worsening prognosis.

Behavioural changes in dogs treated with corticosteroids

In human medicine, psychiatric side effects among patients on corticosteroid therapy are widely reported, but this appears to have been largely overlooked in the animal literature despite glucocorticoids being widely used in veterinary medicine. Therefore the aim of the current study was to identify possible psycho-behavioural changes in dogs treated with corticosteroids. Two different methodologies were used. Firstly, dog owners were asked to fill a 12 item questionnaire aimed at further validating the initial results of a previous survey relating to changes seen when their dog was receiving corticosteroid treatment. In a second study, a population of dogs undertook behavioural tests aimed at objectively identifying changes when receiving corticosteroid therapy. In the first study, a sample of owners whose dogs were receiving treatment for dermatological, orthopaedic or other conditions evaluated their dogs' behaviour on and off therapy, using a seven point scale. The survey was completed by 44 dog owners with dogs receiving treatment with a range of corticosteroid preparations (mainly prednisolone and methylprednisolone) and 54 dog owners with dogs receiving treatment with other drugs, mainly antibiotics and non-steroidal anti-inflammatory drugs. Dogs under corticosteroid treatment were reported to be significantly less playful, more nervous/restless, more fearful/less confident, more aggressive in the presence of food, more prone to barking, more prone to startle, more prone to reacting aggressively when disturbed, and more prone to avoiding people or unusual situations. In the second study, eleven “treatment” dogs were tested both before and during corticosteroid treatment with either methyl-prednisolone or prednisolone to assess their sensitivity to a potentially aversive sound stimulus. Eleven control dogs were also tested at the same time intervals in the same environment. Dogs were exposed to a brief dog growl while they explored bowls containing food and their behaviour was video recorded. Treatment dogs were found to investigate the area in the vicinity of the bowls for significantly less time and to eat significantly fewer pieces of food when on corticosteroids, compared to control dogs, after hearing the growl. These results provide the first empirical evidence of possible adverse psycho-behavioural side effects in a veterinary clinical setting following the use of corticosteroids, and suggest the need for concomitant behavioural advice when these drugs are used in general veterinary practise to avoid the risks associated with these changes.

IL-4 Inhibits IL-1β-Induced Depressive-Like Behavior and Central Neurotransmitter Alterations

It has been known that activation of the central innate immune system or exposure to stress can disrupt balance of anti-/proinflammatory cytokines. The aim of the present study was to investigate the role of pro- and anti-inflammatory cytokines in the modulation of depressive-like behaviors, the hormonal and neurotransmitter systems in rats. We investigated whether centrally administered IL-1β is associated with activation of CNS inflammatory pathways and behavioral changes and whether treatment with IL-4 could modulate IL-1β-induced depressive-like behaviors and central neurotransmitter systems. Infusion of IL-4 significantly decreased IL-1β-induced anhedonic responses and increased social exploration and total activity. Treatment with IL-4 markedly blocked IL-1β-induced increase in PGE₂ and CORT levels. Also, IL-4 reduced IL-1β-induced 5-HT levels by inhibiting tryptophan hydroxylase (TPH) mRNA and activating serotonin transporter (SERT) in the hippocampus, and levels of NE were increased by activating tyrosine hydroxylase (TH) mRNA expression. These results demonstrate that IL-4 may locally contribute to the regulation of noradrenergic and serotonergic neurotransmission and may inhibit IL-1β-induced behavioral and immunological changes. The present results suggest that IL-4 modulates IL-1β-induced depressive behavior by inhibiting IL-1β-induced central glial activation and neurotransmitter alterations. IL-4 reduced central and systemic mediatory inflammatory activation, as well as reversing the IL-1β-induced alterations in neurotransmitter levels. The present findings contribute a biochemical pathway regulated by IL-4 that may have therapeutic utility for treatment of IL-1β-induced depressive behavior and neuroinflammation which warrants further study.

Repeated exposure of male mice to low doses of lipopolysaccharide: dose and time dependent development of behavioral sensitization and tolerance in an automated light-dark anxiety test

Although lipopolysaccharide (LPS) is widely used to examine immune behavior relationships there has been little consideration of the effects of low doses and the roles of sensitization and, or tolerance. Here low doses of LPS (1.0, 5.0 and 25.0 μg/kg) were peripherally administered to male mice on Days 1, 4, 28 and 32 after a baseline recording of anxiety-like behaviors in an automated light-dark apparatus (total time in the light chamber, number of light-dark transitions, nose pokes into the light chamber). LPS at 1.0 μg/kg, while having no significant effects on anxiety-like behaviors in the light-dark test on Days 1 and 4, displayed sensitization with the mice exhibiting significantly enhanced anxiety-like responses on Days 28 and 32. LPS at 5.0 μg/kg had no consistent significant effects on anxiety-like behavior on Days 1 and 4, with sensitization and enhanced anxiety-like behaviors on Day 28 followed by tolerance on Day 32. LPS at 25 μg/kg significantly enhanced anxiety-like behaviors on Day 1, followed by tolerance on Day 4, which was not evident by Day 28 and re-emerged on Day 32. There was a similar overall pattern of sensitization and tolerance for LPS-induced decreases in locomotor activity in the safe dark chamber, without, however, any significant effects on activity in the riskier light chamber. This shows that low doses of LPS induce anxiety-like behavior and these effects are subject to sensitization and tolerance in a dose, context, and time related manner.

The Neuro-Immune Pathophysiology of Central and Peripheral Fatigue in Systemic Immune-Inflammatory and Neuro-Immune Diseases

Many patients with systemic immune-inflammatory and neuro-inflammatory disorders, including depression, rheumatoid arthritis, systemic lupus erythematosus, Sjögren's disease, cancer, cardiovascular disorder, Parkinson's disease, multiple sclerosis, stroke, and chronic fatigue syndrome/myalgic encephalomyelitis, endure pathological levels of fatigue. The aim of this narrative review is to delineate the wide array of pathways that may underpin the incapacitating fatigue occurring in systemic and neuro-inflammatory disorders. A wide array of immune, inflammatory, oxidative and nitrosative stress (O&NS), bioenergetic, and neurophysiological abnormalities are involved in the etiopathology of these disease states and may underpin the incapacitating fatigue that accompanies these disorders. This range of abnormalities comprises: increased levels of pro-inflammatory cytokines, e.g., interleukin-1 (IL-1), IL-6, tumor necrosis factor (TNF) α and interferon (IFN) α; O&NS-induced muscle fatigue; activation of the Toll-Like Receptor Cycle through pathogen-associated (PAMPs) and damage-associated (DAMPs) molecular patterns, including heat shock proteins; altered glutaminergic and dopaminergic neurotransmission; mitochondrial dysfunctions; and O&NS-induced defects in the sodium-potassium pump. Fatigue is also associated with altered activities in specific brain regions and muscle pathology, such as reductions in maximum voluntary muscle force, downregulation of the mitochondrial biogenesis master gene peroxisome proliferator-activated receptor gamma coactivator 1-alpha, a shift to glycolysis and buildup of toxic metabolites within myocytes. As such, both mental and physical fatigue, which frequently accompany immune-inflammatory and neuro-inflammatory disorders, are the consequence of interactions between multiple systemic and central pathways.

Soluble urokinase plasminogen activator receptor as a marker for use of antidepressants

Objectives

Inflammation is involved in the pathogenesis of depression. A few cross-sectional population-based studies have found that depression is associated with increased levels of inflammatory markers. Soluble urokinase plasminogen activation receptor (suPAR) is known to be a stable marker for inflammation. We investigated the bidirectional association between suPAR levels and use of antidepressants.

Methods

suPAR level was measured in 9305 blood donors and analysed in relation to 5-years follow-up data on purchase of antidepressants and hospital diagnoses of depression from a nationwide Danish register.

Results

For men and women without prior use of antidepressants we found a significantly higher risk for incident use of antidepressants with higher suPAR values. For men, the risk of first use of antidepressants increased by 72% from the 1^st to the 4^th quartile (HR = 1.72, 95% CI: 1.11–2.69). For women, it increased by 108% from the 1^st to the 4^th quartile (HR = 2.08, 95% CI: 1.45–2.98). Previous use of antidepressants was also significantly associated with higher suPAR levels (p = 0.002).

Conclusions

High suPAR levels are associated with an increased risk for both previous and future use of antidepressants in healthy men and women. High suPAR are also associated with increased risk for a hospital diagnosis of depression.

Quantifying serotonin transporters by PET with [11C]-DASB before and after interferon-α treatment

BACKGROUND

Interferon-α (IFN-α) therapy is frequently associated with disabling depression, fatigue, and related neuropsychiatric effects. Although depression in major depressive disorder is associated with low serotonin transporter binding, animal models suggest that IFN-associated mood effects are linked to increased presynaptic serotonin transporter binding. This study tested the hypotheses that IFN administration to human subjects increases presynaptic serotonin binding activity, and that this effect correlates with incident depression symptoms.

METHODS

Positron emission tomography (PET) scans using [11C]-DASB were obtained for nine hepatitis C patients before and after IFN-α treatment for 8 weeks. Serotonin transporter binding was estimated using the likelihood estimation in graphical analysis (LEGA) model and measured as the volume of distribution (VT) divided by the free fraction of ligand (fP). Depression was measured with the Structured Clinical Interview for DSM-IV Diagnosis (SCID) and the Hamilton Rating Scale for Depression (HAM-D).

RESULTS

Compared to pre-IFN treatment values, changes in serotonin transporter binding and depression symptoms were not significant. There was no correlation between changes in serotonin transporter binding and depression symptoms.

LIMITATIONS

The study is limited by small sample size, minimal effect on observed mood symptoms within the sample, and brief duration of follow-up.

CONCLUSION

These findings do not support the hypothesis of an IFN-induced change in serotonin transporter function as the cause of incident depressive symptoms in patients treated with IFN-α. Additional study of these possible relationships should be of longer duration and include more subjects with more pronounced changes in mood.

Faster, better, stronger: towards new antidepressant therapeutic strategies

Major depression is a highly prevalent disorder and is predicted to be the second leading cause of disease burden by 2020. Although many antidepressant drugs are currently available, they are far from optimal. Approximately 50% of patients do not respond to initial first line antidepressant treatment, while approximately one third fail to achieve remission following several pharmacological interventions. Furthermore, several weeks or months of treatment are often required before clinical improvement, if any, is reported. Moreover, most of the commonly used antidepressants have been primarily designed to increase synaptic availability of serotonin and/or noradrenaline and although they are of therapeutic benefit to many patients, it is clear that other therapeutic targets are required if we are going to improve the response and remission rates. It is clear that more effective, rapid-acting antidepressants with novel mechanisms of action are required. The purpose of this review is to outline the current strategies that are being taken in both preclinical and clinical settings for identifying superior antidepressant drugs. The realisation that ketamine has rapid antidepressant-like effects in treatment resistant patients has reenergised the field. Further, developing an understanding of the mechanisms underlying the rapid antidepressant effects in treatment-resistant patients by drugs such as ketamine may uncover novel therapeutic targets that can be exploited to meet the Olympian challenge of developing faster, better and stronger antidepressant drugs.

Inflammatory cytokine-associated depression

Inflammatory cytokines can sometimes trigger depression in humans, are often associated with depression, and can elicit some behaviors in animals that are homologous to major depression. Moreover, these cytokines can affect monoaminergic and glutamatergic systems, supporting an overlapping pathoetiology with major depression. This suggests that there could be a specific major depression subtype, inflammatory cytokine-associated depression (ICAD), which may require different therapeutic approaches. However, most people do not develop depression, even when exposed to sustained elevations in inflammatory cytokines. Thus several vulnerabilities and sources of resilience to inflammation-associated depression have been identified. These range from genetic differences in neurotrophic and serotonergic systems to sleep quality and omega-3 fatty acid levels. Replicating these sources of resilience as treatments could be one approach for preventing "ICAD". This article is part of a Special Issue entitled SI: Neuroimmunology in Health And Disease.

Assessment of depression in a rodent model of spinal cord injury

Despite an increased incidence of depression in patients after spinal cord injury (SCI), there is no animal model of depression after SCI. To address this, we used a battery of established tests to assess depression after a rodent contusion injury. Subjects were acclimated to the tasks, and baseline scores were collected before SCI. Testing was conducted on days 9-10 (acute) and 19-20 (chronic) postinjury. To categorize depression, subjects' scores on each behavioral measure were averaged across the acute and chronic stages of injury and subjected to a principal component analysis. This analysis revealed a two-component structure, which explained 72.2% of between-subjects variance. The data were then analyzed with a hierarchical cluster analysis, identifying two clusters that differed significantly on the sucrose preference, open field, social exploration, and burrowing tasks. One cluster (9 of 26 subjects) displayed characteristics of depression. Using these data, a discriminant function analysis was conducted to derive an equation that could classify subjects as "depressed" on days 9-10. The discriminant function was used in a second experiment examining whether the depression-like symptoms could be reversed with the antidepressant, fluoxetine. Fluoxetine significantly decreased immobility in the forced swim test (FST) in depressed subjects identified with the equation. Subjects that were depressed and treated with saline displayed significantly increased immobility on the FST, relative to not depressed, saline-treated controls. These initial experiments validate our tests of depression, generating a powerful model system for further understanding the relationships between molecular changes induced by SCI and the development of depression.

Role of brain transmigrating neutrophils in depression-like behavior during systemic infection

Peripheral inflammation induces transmigration of interleukin (IL)-1β-expressing neutrophils to the brain. We investigated the possibility that this presents a new route of immune-to-brain communication by assessing their role in sickness behaviors relevant for mood disorders. Mice treated with lipopolysaccharide (LPS) developed despair-like behavior, and administration of an anti-polymorphonuclear antibody abolished LPS-induced despair-like and asocial behaviors, which correlated with the levels of IL-1β expression in the brain. These behavioral changes were directly mediated by the energy-regulating hormone, leptin. Increasing the concentration of endogenous leptin during obesity exacerbated, whereas its neutralization using a specific antiserum attenuated sickness behaviors and importantly the neutrophil transmigrating process. Our results indicate a role for peripheral neutrophils in conveying inflammatory signals to the brain, which appears to be dependent on the energy status of the organism. This constitutes a novel mechanism of immune-to-brain communication relevant to mood disorders.

Soyo-san reduces depressive-like behavior and proinflammatory cytokines in ovariectomized female rats

Background

Soyo-san is a traditional oriental medicinal formula, a mixture of 9 crude drugs, and it has been clinically used for treating mild depressive disorders. The role of pro- and anti-inflammatory cytokines in psychiatric disorders has been the focus of great research attention in recent years. In the present study, we detected the antidepressant effect of soyo-san in the ovariectomized and repeated stressed female rats.

Methods

This study was designed to evaluate the antidepressant-like effect of soyo-san on the forced swimming test (FST). The rats were randomly divided into the following groups: the nonoperated and nonstressed group (non-op), the nonoperated and stressed group (non-op + ST), the ovariectomized and stress group (OVX) and sham operated and stressed group (sham), the ovariectomized and stressed group (OVX + ST), the ovariectomized, stressed and soyo-san 100 mg/kg treated group (SOY100) and the ovariectomized, stressed and soyo-san 400 mg/kg treated group (SOY400). The rats were exposed to immobilization stress (IMO) for 14day (2 h/14day), and soyo-san (100 mg/kg and 400 mg/kg) was administrated during the same time. In the same animals, the levels of corticosterone and interleukin-1-beta (IL-1β) were examined in the serum. Also, the change of IL-1β expression in brain regions was examined after behavior test.

Results

In the FST, the lower dose (100 mg/kg) of extract was effective in reducing immobility, along with an increase in swimming time. The serum levels of corticosterone and IL-1β in the SOY groups were significantly lower than those in the control group. In the brain, the expression of IL-1β positive neurons in the control group were significantly increased in the paraventricular nucleus (PVN) and hippocampus compared to the non-op. However, soyo-san groups significantly reduced the IL-1β-ir neurons in the PVN and hippocampal regions compared to the control.

Conclusion

The present results demonstrated that soyo-san effectively reduced behavioral and patho-physiological depression-like responses. Trial registration: Our results suggest that soyo-san may be useful for immune regulator in repeated stress-induced ovariectomized female rats.

Immunology of major depression

High levels of several proinflammatory components of the immune system, such as interleukin-6, C-reactive protein, tumor necrosis factor (TNF)-α, or neopterin in patients suffering from major depression (MD) point to the involvement of an inflammatory process in the pathophysiology of MD. The direct and indirect effects of cytokines on neurotransmitter storage and release - mediated by microglia cells and astrocytes - are discussed. The tryptophan/kynurenine metabolism is one of the indirect mechanisms because the enzyme indoleamine 2,3-dioxygenase - a key enzyme of this metabolism in the central nervous system - is driven by pro- and anti-inflammatory cytokines and degrades serotonin. Moreover, neuroactive kynurenines such as kynurenic acid and quinolinic acid act on the glutamatergic neurotransmission as N-methyl-D-aspartate antagonists and agonists, respectively. Alterations of the serotonergic, noradrenergic and glutamatergic neurotransmission have been shown with low-level neuroinflammation and may be involved in symptom generation. Epidemiological and clinical studies show a role for inflammation as a risk factor for MD. A large-scale epidemiological study in MD clearly demonstrates that severe infections and autoimmune disorders are lifetime risk factors for MD. The vulnerability-stress-inflammation model matches with this view as stress may increase proinflammatory cytokines and even contribute to a lasting proinflammatory state. Further support comes from the therapeutic benefit of anti-inflammatory medications such as the cyclo-oxygenase-2 inhibitors, TNF-α antagonists and others, and the anti-inflammatory and immunomodulatory intrinsic effects of antidepressants.

p21Cip restrains hippocampal neurogenesis and protects neuronal progenitors from apoptosis during acute systemic inflammation

Altered neurogenesis in adult hippocampus is implicated in cognition impairment and depression. Inflammation is a potent inhibitor of neurogenesis. The cyclin-dependent kinase inhibitor p21(Cip1) (p21) restrains cell cycle progression and arrests the cell in the G1 phase. We recently showed that p21 is expressed in neuronal progenitors and regulates proliferation of these cells in the subgranular zone of the dentate gyrus of hippocampus where adult neurogenesis occurs. The current study suggests that p21 is induced in vivo in the hippocampus of WT mice in response to acute systemic inflammation caused by LPS injections, restrains neuronal progenitor proliferation and protects these cells from inflammation-induced apoptosis. In intact p21-/- hippocampus, neuronal progenitors proliferate more actively as assessed by BrdU incorporation, and give rise to increased number of DCX positive neuroblasts. However, when mice were treated with LPS, the number of neuroblasts decreased due to induced subgranular zone apoptosis. In vitro, differentiating Tuj-1 positive neuroblasts isolated from p21-/- hippocampus exhibited increased proliferation rate, measured by Ki-67 staining, as compared to WT cells (p<0.05). In WT neuronal progenitors treated with IL-6, the number of p21-positive cells was increased (p<0.05), and this led to Tuj-1(+) cell proliferation restraint, whereas the number of proliferating GFAP(+) astrocytes was increased ~ 2-fold. Thus, when p21 is intact, inflammation might divert neuronal progenitors towards astrogliogenesis by inducing p21. At the same time, when p21 is lacking, no effects of IL-6 on proliferation of Tuj-1(+) cells or GFAP(+) cells are detected in differentiating p21-/- neuronal progenitors. These results underscore the important role of p21 controlling hippocampal neuronal differentiation during inflammation.

The impact of escitalopram on IL-2-induced neuroendocrine, immune, and behavioral changes in patients with malignant melanoma: preliminary findings

Interleukin (IL)-2, a T-cell cytokine used to treat malignant melanoma, can induce profound depression. To determine whether pretreatment with the antidepressant escitalopram could reduce IL-2-induced neuroendocrine, immune, and neurobehavioral changes, 20 patients with Stage IV melanoma were randomized to either placebo or the serotonin reuptake inhibitor, escitalopram (ESC) 10-20 mg/day, 2 weeks before, and during IL-2 treatment (720 000 units/kg Q8 h × 5 days (1 cycle) every 3 weeks × 4 cycles). Generalized estimation equations were used to examine HPA axis activity (plasma ACTH and cortisol), immune activation (plasma IL-6), and depressive symptoms (Hamilton Depression Rating Scale (HDRS) score). Tolerance of IL-2 treatment (concomitant medications required) and adherence (number of IL-2 doses received) were also assessed. Both the groups (ESC (n=9), placebo (n=11)) exhibited significant IL-2-induced increases in plasma cortisol, IL-6, and depressive symptoms (p<0.05), as well as a temporal trend for increases in plasma ACTH (p=0.054); the effects of age and treatment were not significant. Higher plasma ACTH concentrations were associated with higher depressive symptoms during cycles 1-3 of IL-2 therapy (p<0.01). Although ESC had no significant effects on ACTH, cortisol, IL-6, tolerance of, or adherence to IL-2, ESC treatment was associated with lower depressive symptoms, ie, a maximal difference of ∼3 points on the HDRS, which, though not statistically significant (in part, due to small sample size), represents a clinically significant difference according to the National Institute for Health and Clinical Excellence guidelines. A larger sample size will establish whether antidepressant pretreatment can prevent IL-2-induced neurobehavioral changes.

The role of immune genes in the association between depression and inflammation: a review of recent clinical studies

The role for dysregulation of the immune system in the pathogenesis of depressive disorder is well established, and emerging research suggests the role of an underlying genetic vulnerability. The purpose of this review is to summarize the existing literature on the genetic variants involved in neurobiological pathways associated with both immune activation and depression. Using PubMed, Scopus, The Cochrane Library, Embase, Ovid of Medline, PsycINFO and ISI web of Knowledge, we selected 52 papers which are relevant for this literature review. Findings across the literature suggest that functional allelic variants of genes for interleukin-1beta (IL)-1β, tumor necrosis factor-alpha (TNF-α) and C-reactive protein (CRP), as well as genetic variations affecting T-cell function, may increase the risk for depression. Moreover, single nucleotide polymorphisms (SNPs) in the IL-1β, IL-6 and IL-11 genes, and in those regulating T-cell function may be associated with reduced responsiveness to antidepressant therapy. There is also some evidence indicative of a role of genetic variants of the enzymes, Cyclo-oxygenase2 (COX-2) and Phospholipase2 (PLA2), in the aetiology of depression. Finally, SNPs in genes related to the serotonin pathway may play a fundamental role in the shared genetic liability to both immune activation and depressive symptoms. Our review confirms that genetic variants influence the biological mechanisms by which the innate immune system contributes to the development of depression. However, future studies are necessary to identify the molecular mechanisms underlying these associations.

WITHDRAWN: Protective effect of IL-4 on IL-1ß-induced behavioral, biochemical and immunological alterations

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Cytokine effects on the basal ganglia and dopamine function: the subcortical source of inflammatory malaise

Data suggest that cytokines released during the inflammatory response target subcortical structures including the basal ganglia as well as dopamine function to acutely induce behavioral changes that support fighting infection and wound healing. However, chronic inflammation and exposure to inflammatory cytokines appears to lead to persisting alterations in the basal ganglia and dopamine function reflected by anhedonia, fatigue, and psychomotor slowing. Moreover, reduced neural responses to hedonic reward, decreased dopamine metabolites in the cerebrospinal fluid and increased presynaptic dopamine uptake and decreased turnover have been described. This multiplicity of changes in the basal ganglia and dopamine function suggest fundamental effects of inflammatory cytokines on dopamine synthesis, packaging, release and/or reuptake, which may sabotage and circumvent the efficacy of current treatment approaches. Thus, examination of the mechanisms by which cytokines alter the basal ganglia and dopamine function will yield novel insights into the treatment of cytokine-induced behavioral changes and inflammatory malaise.

Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways

It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers.

Immune system inflammation in cocaine dependent individuals: implications for medications development

OBJECTIVES

Cocaine dependence is a chronic stress state. Furthermore, both stress and substance abuse have robust and reciprocal effects on immune system cytokines, which are known to be powerful modulators of mood. We therefore examine basal and provoked changes in peripheral cytokines in cocaine dependent individuals to better understand their role in the negative reinforcing effects of cocaine.

METHODS

Twenty-eight (16 F/12 M) treatment-seeking cocaine dependent individuals and 27 (14 F/13 M) social drinkers were exposed to three 5-min guided imagery conditions (stress, drug cue, relaxing) presented randomly across consecutive days. Measures of salivary cortisol, tumor necrosis factor alpha (TNFα), interleukin-10 (IL-10), and interleukin-1 receptor antagonist (IL-1ra) were collected at baseline and various post-imagery time-points.

RESULTS

Cocaine abusers demonstrated decreased basal IL-10 compared with social drinkers. They also showed significant elevations in pro-inflammatory TNFα when exposed to stress compared with when they were exposed to relaxing imagery. This was not observed in the social drinkers. Conversely, social drinkers demonstrated increases in the anti-inflammatory markers, IL-10 and IL-1ra, following exposure to cue, which were not seen in the dependent individuals.

CONCLUSIONS

Cocaine dependent individuals demonstrate an elevated inflammatory state both at baseline and following exposure to the stress imagery condition. Cytokines may reflect potentially novel biomarkers in addicted populations for treatment development.

Interleukin-1β: a new regulator of the kynurenine pathway affecting human hippocampal neurogenesis

Increased inflammation and reduced neurogenesis have been associated with the pathophysiology of major depression. Here, we show for the first time how IL-1β, a pro-inflammatory cytokine shown to be increased in depressed patients, decreases neurogenesis in human hippocampal progenitor cells. IL-1β was detrimental to neurogenesis, as shown by a decrease in the number of doublecortin-positive neuroblasts (-28%), and mature, microtubule-associated protein-2-positive neurons (-36%). Analysis of the enzymes that regulate the kynurenine pathway showed that IL-1β induced an upregulation of transcripts for indolamine-2,3-dioxygenase (IDO), kynurenine 3-monooxygenase (KMO), and kynureninase (42-, 12- and 30-fold increase, respectively, under differentiating conditions), the enzymes involved in the neurotoxic arm of the kynurenine pathway. Moreover, treatment with IL-1β resulted in an increase in kynurenine, the catabolic product of IDO-induced tryptophan metabolism. Interestingly, co-treatment with the KMO inhibitor Ro 61-8048 reversed the detrimental effects of IL-1β on neurogenesis. These observations indicate that IL-1β has a critical role in regulating neurogenesis whereas affecting the availability of tryptophan and the production of enzymes conducive to toxic metabolites. Our results suggest that inhibition of the kynurenine pathway may provide a new therapy to revert inflammatory-induced reduction in neurogenesis.

Dengue-3 encephalitis promotes anxiety-like behavior in mice

Dengue virus is a human pathogen that may cause meningoencephalitis and other neurological syndromes. The current study investigated anxiety-like behavior and expression of proinflammatory cytokines and pro-apoptotic caspase-3 in the hippocampus of C57BL/6 mice infected with non-adapted Dengue virus 3 genotype I (DENV-3) inoculated intracranially with 4×10(3) (plaque-forming unit) PFU. Anxiety-like behavior was assessed in control and DENV-3 infected mice using the elevated plus maze. The open field test was performed to evaluate locomotor activity. Histopathological changes in CA regions of the hippocampus were assessed by haematoxylin and eosin staining. Immunoreactive and protein levels of cleaved caspase-3 were also analyzed in the hippocampus. The mRNA expression of IL-6 and TNF-α in the hippocampus were estimated by quantitative real time (polymerase chain reaction) PCR. All procedures were conducted on day 5 post-infection. We found that DENV-3 infected mice presented higher levels of anxiety in comparison with controls (p≤0.05). No difference in motor activity was found between groups (p=0.77). The infection was followed by a significant increase of TNF-α and IL-6 mRNA expression in the hippocampus (p≤0.05). Histological analysis demonstrated meningoencephalitis with formation of perivascular cuffs, infiltration of immune cells and loss of neurons at CA regions of hippocampus. Numerous caspase-3 positive neurons were visualized at CA areas in DENV-3 infected mice. Marked increase of cleaved caspase-3 levels were observed after infection. This study described anxiety-like behavior, hippocampal inflammation and neuronal apoptosis associated with DENV-3 infection in the central nervous system.

New drug targets in depression: inflammatory, cell-mediated immune, oxidative and nitrosative stress, mitochondrial, antioxidant, and neuroprogressive pathways. And new drug candidates--Nrf2 activators and GSK-3 inhibitors

This paper reviews new drug targets in the treatment of depression and new drug candidates to treat depression. Depression is characterized by aberrations in six intertwined pathways: (1) inflammatory pathways as indicated by increased levels of proinflammatory cytokines, e.g. interleukin-1 (IL-1), IL-6, and tumour necrosis factor α. (2) Activation of cell-mediated immune pathways as indicated by an increased production of interferon γ and neopterin. (3) Increased reactive oxygen and nitrogen species and damage by oxidative and nitrosative stress (O&NS), including lipid peroxidation, damage to DNA, proteins and mitochondria. (4) Lowered levels of key antioxidants, such as coenzyme Q10, zinc, vitamin E, glutathione, and glutathione peroxidase. (5) Damage to mitochondria and mitochondrial DNA and reduced activity of respiratory chain enzymes and adenosine triphosphate production. (6) Neuroprogression, which is the progressive process of neurodegeneration, apoptosis, and reduced neurogenesis and neuronal plasticity, phenomena that are probably caused by inflammation and O&NS. Antidepressants tend to normalize the above six pathways. Targeting these pathways has the potential to yield antidepressant effects, e.g. using cytokine antagonists, minocycline, Cox-2 inhibitors, statins, acetylsalicylic acid, ketamine, ω3 poly-unsaturated fatty acids, antioxidants, and neurotrophic factors. These six pathways offer new, pathophysiologically guided drug targets suggesting that novel therapies could be developed that target these six pathways simultaneously. Both nuclear factor (erythroid-derived 2)-like 2 (Nrf2) activators and glycogen synthase kinase-3 (GSK-3) inhibitors target the six above-mentioned pathways. GSK-3 inhibitors have antidepressant effects in animal models of depression. Nrf2 activators and GSK-3 inhibitors have the potential to be advanced to phase-2 clinical trials to examine whether they augment the efficacy of antidepressants or are useful as monotherapy.

No evidence for an anti-inflammatory effect of escitalopram intervention in healthy individuals with a family history of depression

Inflammation may contribute to the pathogenesis of depression and antidepressants are hypothesised to have an anti-inflammatory effect. In this randomised double-blinded trial we investigated the cytokine levels in supernatants of stimulated whole blood samples from first degree relatives to patients with depression randomised to a single daily dose of either 10mg escitalopram or placebo for four weeks. No significant differences were found in any of the cytokine levels between the participants treated with escitalopram (n=21) or placebo (n=23). Our data does thus not support the hypothesis of a global anti-inflammatory effect of escitalopram on cytokines in healthy subjects.

Mechanistic explanations how cell-mediated immune activation, inflammation and oxidative and nitrosative stress pathways and their sequels and concomitants play a role in the pathophysiology of unipolar depression

This paper reviews that cell-mediated-immune (CMI) activation and inflammation contribute to depressive symptoms, including anhedonia; anxiety-like behaviors; fatigue and somatic symptoms, e.g. illness behavior or malaise; and mild cognitive impairment (MCI). These effects are in part mediated by increased levels of pro-inflammatory cytokines (PICs), e.g. interleukin-1 (IL-1), IL-6 and tumor necrosis factor (TNF)α, and Th-1-derived cytokines, such as IL-2 and interferon (IFN)γ. Moreover, new pathways, i.e. concomitants and sequels of CMI activation and inflammation, were detected in depression: (1) Induction of indoleamine 2,3-dioxygenase (IDO) by IFNγ and some PICs is associated with depleted plasma tryptophan, which may interfere with brain 5-HT synthesis, and increased production of anxiogenic and depressogenic tryptophan catabolites. (2) Increased bacterial translocation may cause depression-like behaviors by activating the cytokine network, oxidative and nitrosative stress (O&NS) pathways and IDO. (3) Induction of O&NS causes damage to membrane ω3 PUFAs, functional proteins, DNA and mitochondria, and autoimmune responses directed against intracellular molecules that may cause dysfunctions in intracellular signaling. (4) Decreased levels of ω3 PUFAs and antioxidants, such as coenzyme Q10, glutathione peroxidase or zinc, are associated with an increased inflammatory potential; more oxidative damage; the onset of specific symptoms; and changes in the expression or functions of brain 5-HT and N-methyl-d-aspartate receptors. (5) All abovementioned factors cause neuroprogression, that is a combination of neurodegeneration, neuronal apoptosis, and lowered neurogenesis and neuroplasticity. It is concluded that depression may be the consequence of a complex interplay between CMI activation and inflammation and their sequels/concomitants which all together cause neuroprogression that further shapes the depression phenotype. Future research should employ high throughput technologies to collect genetic and gene expression and protein data from patients with depression and analyze these data by means of systems biology methods to define the dynamic interactions between the different cell signaling networks and O&NS pathways that cause depression.

The effects of MyD88 deficiency on exploratory activity, anxiety, motor coordination, and spatial learning in C57BL/6 and APPswe/PS1dE9 mice

Toll-like receptors (TLRs) are a family of pattern-recognition receptors in innate immunity and provide a first line defense against pathogens and tissue injuries. In addition to important roles in infection, inflammation, and immune diseases, recent studies show that TLR signaling is involved in modulation of learning, memory, mood, and neurogenesis. Because MyD88 is essential for the downstream signaling of all TLRs, except TLR3, we investigated the effects of MyD88 deficiency (MyD88-/-) on behavioral functions in mice. Additionally, we recently demonstrated that a mouse model of Alzheimer's disease (AD) deficient for MyD88 had decreases in Aβ deposits and soluble Aβ in the brain as compared with MyD88 sufficient AD mouse models. Because accumulation of Aβ in the brain is postulated to be a causal event leading to cognitive deficits in AD, we investigated the effects of MyD88 deficiency on behavioral functions in the AD mouse model at 10 months of age. MyD88 deficient mice showed more anxiety in the elevated plus-maze. In the motor coordination tests, MyD88 deficient mice remained on a beam and a bar for a longer time, but with slower initial movement on the bar. In the Morris water maze test, MyD88 deficiency appeared to improve spatial learning irrespective of the transgene. Our findings suggest that the MyD88-dependent pathway contributes to behavioral functions in an AD mouse model and its control group.

Effects of acute and repeated administration of Staphylococcal enterotoxin A on Morris water maze learning, corticosterone and hippocampal IL-1β and TNFα

Staphylococcal enterotoxin A (SEA) is a bacterial superantigen that induces pronounced T cell expansion and cytokine production. In addition, SEA activates the HPA axis and forebrain regions relevant to cognitive functions. Since learning-related cognitive changes have not been assessed in response to SEA, spatial learning in the Morris water maze (MWM) was determined in male C57BL/6J mice subjected to acute or repeated injections of 5μg SEA or Saline. Injections were given 2h prior to 4-5days of hidden platform sessions. Animals were then rested for 1month and given retraining without further injections. In addition, splenic IL-1β, IL-2 and TNFα, plasma corticosterone, and hippocampal IL-1β and TNFα were measured after the regimen of treatment used in the behavioral experiments. The results showed no learning impairment following acute or repeated SEA challenge. Moreover, when retested 1month later, and without further injections, the SEA group showed more rapid relearning of the MWM. This suggested that coincidental superantigenic T cell activation and training served to promote long-term improvement in recovery of learning. Furthermore, repeated SEA challenge continued to drive increases in plasma corticosterone, but with a compensatory reduction in hippocampal IL-1β. However, while hippocampal TNFα was reduced after acute and repeated SEA treatment, this was not statistically significant. In view of the importance of modest glucocorticoid elevations and hippocampal IL-1β in promoting contextual learning, the data point to the hypothesis that SEA promotes long-term plasticity by restraining disruptive increases in hippocampal IL-1β, and possibly TNFα, during learning.

Gene expression biomarkers of response to citalopram treatment in major depressive disorder

There is significant variability in antidepressant treatment outcome, with ∼30-40% of patients with major depressive disorder (MDD) not presenting with adequate response even following several trials. To identify potential biomarkers of response, we investigated peripheral gene expression patterns of response to antidepressant treatment in MDD. We did this using Affymetrix HG-U133 Plus2 microarrays in blood samples, from untreated individuals with MDD (N=63) ascertained at a community outpatient clinic, pre and post 8-week treatment with citalopram, and used a regression model to assess the impact of gene expression differences on antidepressant response. We carried out technical validation of significant probesets by quantitative reverse transcriptase PCR and conducted central nervous system follow-up of the most significant result in post-mortem brain samples from 15 subjects who died during a current MDD episode and 11 sudden-death controls. A total of 32 probesets were differentially expressed according to response to citalopram treatment following false discovery rate correction. Interferon regulatory factor 7 (IRF7) was the most significant differentially expressed gene and its expression was upregulated by citalopram treatment in individuals who responded to treatment. We found these results to be concordant with our observation of decreased expression of IRF7 in the prefrontal cortex of MDDs with negative toxicological evidence for antidepressant treatment at the time of death. These findings point to IRF7 as a gene of interest in studies investigating genomic factors associated with antidepressant response.

What can post-mortem studies tell us about the pathoetiology of suicide?

Suicide is a major public health concern; however, its neurobiology is unclear. Post-mortem brain tissue obtained from suicide victims and normal controls offers a useful method for studying the neurobiology of suicide. Despite several limitations, these studies have offered important leads in the neurobiology of suicide. In this article, we discuss some important findings resulting from these studies, focusing on serotonergic mechanisms, signal transduction systems, neuroendocrine studies and immune function abnormalities in suicide. These studies suggest that abnormalities of certain receptor subtypes, components of signaling systems such as protein kinase C and protein kinase A, transcription factors such as cyclic AMP response element-binding protein and neurotrophins may play an important role in the pathophysiology of suicide. These studies also suggest abnormalities of hypothalamic-pituitary-adrenal axis system components, feedback mechanisms and cytokines, which are chemical mediators of the immune functions. Post-mortem brain tissue offers an opportunity for future studies, such as genetic and epigenetic studies.

Socioeconomic status moderates associations between CNS serotonin and expression of beta2-integrins CD11b and CD11c

One of the first steps in the development of atherogenesis is adhesion of circulating monocytes to the vascular endothelium that is stimulated by beta(2)-integrins. Stress has been associated with enhanced expression of beta(2)-integrins on monocyte cell surface (Greeson et al., 2008). Central nervous system (CNS) serotonin regulates aspects of the stress response that can influence inflammatory processes that increase risk for atherosclerosis. This study examines effects of an environmental stressor (indexed by socioeconomic status (SES)) and CNS serotonin (indexed by CSF 5HIAA level), on the expression of beta(2)-integrins (CD11a, CD11b, and CD11c) on circulating monocytes in 131 volunteers. Participants completed a protocol consisting of a lumbar puncture for assessment of CSF 5HIAA levels (day 1) followed by an experimental protocol (day 2). Blood samples for the present analyses were obtained at baseline on day 2. The interaction of SES x 5HIAA was a significant predictor of levels of CD11b and CD11c expression (p=.02, and p=.05, respectively); the mean CD11b difference between Hi and Lo SES subjects was significant (p=.003) only in those with Lo levels of 5HIAA, while SES differences in CD11b among those with Mid and Hi levels of 5HIAA did not vary statistically. The pattern of findings was similar for CD11c. The present results suggest that the combination of high environmental stress and low CNS serotonin function could contribute to atherogenesis through processes that lead to increased expression of the beta(2)-integrins CD11b and CD11c on monocyte cell surfaces.

Hypothalamic mechanisms in cachexia

The role of nutrition and balanced metabolism in normal growth, development, and health maintenance is well known. Patients affected with either acute or chronic diseases often show disorders of nutrient balance. In some cases, a devastating state of malnutrition known as cachexia arises, brought about by a synergistic combination of a dramatic decrease in appetite and an increase in metabolism of fat and lean body mass. Other common features that are not required for the diagnosis include decreases in voluntary movement, insulin resistance, and anhedonia. This combination is found in a number of disorders including cancer, cystic fibrosis, AIDS, rheumatoid arthritis, renal failure, and Alzheimer's disease. The severity of cachexia in these illnesses is often the primary determining factor in both quality of life, and in eventual mortality. Indeed, body mass retention in AIDS patients has a stronger association with survival than any other current measure of the disease. This has led to intense investigation of cachexia and the proposal of numerous hypotheses regarding its etiology. Most authors suggest that cytokines released during inflammation and malignancy act on the central nervous system to alter the release and function of a number of neurotransmitters, thereby altering both appetite and metabolic rate. This review will discuss the salient features of cachexia in human diseases, and review the mechanisms whereby inflammation alters the function of key brain regions to produce stereotypical illness behavior. The paper represents an invited review by a symposium, award winner or keynote speaker at the Society for the Study of Ingestive Behavior [SSIB] Annual Meeting in Portland, July 2009.

HPA axis, respiration and the airways in stress--a review in search of intersections

Given clear connections between respiratory distress and subjective anxiety, it is not surprising that respiratory psychophysiologists have been interested in the psychobiology of anxiety. Given parallel links between anxiety and stress, it is not surprising that the hypothalamic-pituitary adrenal (HPA) stress system has also been a focus in anxiety research. However, despite extensive work in respiratory psychophysiology and stress neuroendocrinology--and evidence that these systems are jointly dysregulated in anxiety disorders--direct studies of their interactions are rare. This paper reviews evidence for scientific intersections, providing an overview of the HPA axis, its psychobiology, and shared neural substrates for HPA and respiratory control. We examine HPA hormone effects on respiration, immune/inflammatory mediators, and lung maturation. We also examine respiratory/dyspnea effects on HPA axis. There are clear points of intersection in the neuroscience of respiration and stress. Given the importance of both systems to an organism's ability to survive and adapt in challenging and changing environments, further study of their interactions is needed.

Neural substrates of psychostimulant withdrawal-induced anhedonia

Psychostimulant drugs have powerful reinforcing and hedonic properties and are frequently abused. Cessation of psychostimulant administration results in a withdrawal syndrome characterized by anhedonia (i.e., an inability to experience pleasure). In humans, psychostimulant withdrawal-induced anhedonia can be debilitating and has been hypothesized to play an important role in relapse to drug use. Hence, understanding the neural substrates involved in psychostimulant withdrawal-induced anhedonia is essential. In this review, we first summarize the theoretical perspectives of psychostimulant withdrawal-induced anhedonia. Experimental procedures and measures used to assess anhedonia in experimental animals are also discussed. The review then focuses on neural substrates hypothesized to play an important role in anhedonia experienced after termination of psychostimulant administration, such as with cocaine, amphetamine-like drugs, and nicotine. Both neural substrates that have been extensively investigated and some that need further evaluation with respect to psychostimulant withdrawal-induced anhedonia are reviewed. In the context of reviewing the various neurosubstrates of psychostimulant withdrawal, we also discuss pharmacological medications that have been used to treat psychostimulant withdrawal in humans. This literature review indicates that great progress has been made in understanding the neural substrates of anhedonia associated with psychostimulant withdrawal. These advances in our understanding of the neurobiology of anhedonia may also shed light on the neurobiology of nondrug-induced anhedonia, such as that seen as a core symptom of depression and a negative symptom of schizophrenia.

Interleukin-1 receptor null mutant mice show decreased anxiety-like behavior and enhanced fear memory

IL-1beta is a proinflammatory cytokine that contributes to psychological stress responses and has been implicated in various psychiatric disorders most notably depression. Preclinical studies also demonstrate that IL-1beta modulates anxiety- and fear-related behaviors, although these findings are difficult to assess because IL-1beta infusions influence locomotor activity and nociception. Here we demonstrate that IL-1RI null mice exhibit a behavioral phenotype consistent with a decrease in anxiety-related behaviors. This includes significant effects in the elevated plus maze, light-dark, and novelty-induced hypophagia tests compared to wild-type mice, with no differences in locomotor activity. With regard to fear conditioning, IL-1RI null mice showed more freezing in auditory and contextual fear conditioning tests, and there was no effect on pain sensitivity. Taken together, the results indicate that the IL-1beta/IL-1RI signaling pathway induces anxiety-related behaviors and impairs fear memory.

Influence of continuous infusion of interleukin-1beta on depression-related processes in mice: corticosterone, circulating cytokines, brain monoamines, and cytokine mRNA expression

RATIONALE

Activation of the immune system typically occurs on a subchronic or chronic basis (e.g., in response to bacterial or viral insults). However, analyses of the effects of cytokine treatments have typically involved acute treatments, and limited data are available concerning the behavioral and central neurochemical impact of subchronic interleukin-1beta (IL-1beta) administration.

OBJECTIVES

Several peripheral and central effects of IL-1beta treatment were assessed following single or repeated bolus injections or after infusion of the cytokine (through Alzet minipumps) over several days.

RESULTS

The impact of an acute bolus injection of IL-1beta (1.0 microg) on plasma corticosterone and on circulating IL-1beta, IL-6, and TNF-alpha were diminished following 5-day IL-1beta treatment, although high levels of sickness were still apparent. When IL-1beta (1.0 or 2.0 mug/day) was continuously infused over 3 days, plasma corticosterone and sickness were elevated, but these effects were attenuated after 7 days (subchronic) of treatment. As well, the effects of IL-1beta treatment on diurnal variations of motor activity diminished over days. Despite the diminution of the behavioral and neuroendocrine effects of the cytokine after treatment 7 days, subchronic IL-1beta infusion altered prefrontal cortical and hippocampal serotonin and norepinephrine utilization, and within these regions, the messenger RNA (mRNA) expression of IL-1beta, IL-6, TNF-alpha, and their receptors, as well as that of 5-HT(2C), 5-HT(1B) receptors, and p11, was increased.

DISCUSSION

The findings indicate that peripheral cytokine infusion markedly influences central cytokine mRNA expression and also influences 5-HT turnover, which might contribute to behavioral changes elicited by IL-1beta.

Synergistic and additive actions of a psychosocial stressor and endotoxin challenge: Circulating and brain cytokines, plasma corticosterone and behavioral changes in mice

Activation of the inflammatory immune response may provoke neuroendocrine and central neurochemical effects that are reminiscent of those elicited by traditional stressors, and when administered concurrently may have synergistic effects. The present investigation assessed whether a psychosocial stressor, comprising social disruption, would augment the effects of lipopolysaccharide in mice. It was indeed observed that the social disruption engendered by a period of 2-4 weeks of social isolation (but not 1-7 days of this treatment) followed by regrouping, enhanced the effects of lipopolysaccharide (LPS: 10mug) in the provocation of sickness behavior, as well as plasma corticosterone, IL-6, TNF-alpha and IL-10 levels. Similar effects were not apparent with respect to IL-1beta, IL-4, or IFN-gamma. Synergy between LPS and other stressors (restraint, tail pinch, and loud noise) was not apparent with respect to sickness or plasma corticosterone, provisionally suggesting that social stressors, such as regrouping, may be more powerful or may engage unique neural or neuroendocrine circuits that favour synergistic outcomes. Within the CNS, the LPS and the regrouping stressor synergistically enhanced NE utilization within the prefrontal cortex, and additively influenced hippocampal NE utilization. In contrast to the effects on circulating cytokines, the LPS-induced elevation of IL-1beta, IL-6 and TNF-alpha mRNA expression in the hippocampus, PFC and nucleus tractus solitarius was diminished in animals that had experienced the regrouping stressor. In view of the combined actions of LPS challenge and a social stressor, these data are interpreted as suggesting that models of depression based on immune activation ought to consider the stressor backdrop upon which immune challenges are imposed.