Escitalopram reduces circulating pro-inflammatory cytokines and improves depressive behavior without affecting sleep in a rat model of post-cardiac infarct depression

Characterization of Sleep, Emotional, and Cognitive Functions in a New Rat Model of Concomitant Spinal Cord and Traumatic Brain Injuries

Traumatic injuries to the spinal cord or the brain have serious medical consequences and lead to long-term disability. The epidemiology, medical complications, and prognosis of isolated spinal cord injury (SCI) and traumatic brain injury (TBI) have been well described. However, there are limited data on patients suffering from concurrent SCI and TBI, even if a large proportion of SCI patients have concomitant TBI. The complications associated with this "dual-diagnosis" such as cognitive or behavioral dysfunction are well known in the rehabilitation setting, but evidence-based and standardized approaches for diagnosis and treatment are lacking. Our goal was to develop and characterize a pre-clinical animal model of concurrent SCI and TBI to help identifying "dual-diagnosis" tools. Female rats received a unilateral contusive SCI at the thoracic level alone (SCI group) or combined with a TBI centered on the contralateral sensorimotor cortex (SCI-TBI group). We first validated that the SCI extent was comparable between SCI-TBI and SCI groups, and that hindlimb function was impaired. We characterized various neurological outcomes, including locomotion, sleep architecture, brain activity during sleep, depressive- and anxiety-like behaviors, and working memory. We report that SCI-TBI and SCI groups show similar impairments in global locomotor function. While wake/sleep amount and distribution and anxiety- and depression-like symptoms were not affected in SCI-TBI and SCI groups in comparison to the control group (laminectomy and craniotomy only), working memory was impaired only in SCI-TBI rats. This pre-clinical model of concomitant SCI and TBI, including more severe variations of it, shows a translational value for the identification of biomarkers to refine the "dual-diagnosis" of neurotrauma in humans.

Whole-body vibration as a passive alternative to exercise after myocardial damage in middle-aged female rats: Effects on the heart, the brain, and behavior

Background

Females with cardiovascular disease seem more vulnerable to develop concomitant mental problems, such as depression and cognitive decline. Although exercise is shown beneficial in cardiovascular disease as well as in mental functions, these patients may be incapable or unmotivated to perform exercise. Whole body vibration (WBV) could provide a passive alternative to exercise. Aim of the present study was to compare WBV to exercise after isoproterenol (ISO)-induced myocardial damage in female rats, regarding effects on heart, brain and behavior.

Methods

One week after ISO (70 mg/kg s.c., on 2 consecutive days) or saline injections, 12 months old female rats were assigned to WBV (10 minutes daily), treadmill running (30 minutes daily) or pseudo intervention for 5 weeks. During the last 10 days, behavioral tests were performed regarding depressive-like behavior, cognitive function, and motor performance. Rats were sacrificed, brains and hearts were dissected for (immuno)histochemistry.

Results

Significant ISO-induced cardiac collagen deposition (0.67 ± 0.10 vs 0.18 ± 0.03%) was absent after running (0.45 ± 0.26 vs 0.46 ± 0.08%), but not after WBV (0.83 ± 0.12 vs 0.41 ± 0.05%). However, WBV as well as running significantly reduced hippocampal (CA3) collagen content in ISO-treated rats. Significant regional differences in hippocampal microglia activity and brain derived neurotrophic factor (BDNF) expression were observed. Significant ISO-induced CA1 microglia activation was reduced after WBV as well as running, while opposite effects were observed in the CA3; significant reduction after ISO that was restored by WBV and running. Both WBV and running reversed the ISO-induced increased BDNF expression in the CA1, Dentate gyrus and Hilus, but not in the CA3 area. Whereas running had no significant effect on behavior in the ISO-treated rats, WBV may be associated with short-term spatial memory in the novel location recognition test.

Conclusion

Although the female rats did not show the anticipated depressive-like behavior or cognitive decline after ISO, our data indicated regional effects on neuroinflammation and BDNF expression in the hippocampus, that were merely normalized by both WBV and exercise. Therefore, apart from the potential concern about the lack of cardiac collagen reduction, WBV may provide a relevant alternative for physical exercise.

The protective effects of escitalopram on synaptic plasticity in the CA1 region of chronically stressed and non-stressed male rats

INTRODUCTION

Stress impairs cognitive processes and escitalopram affects them in various ways. The present study has compared the protective effects of two escitalopram doses on neural excitability and synaptic plasticity in the CA1 region of chronically stressed and non-stressed male rats.

METHODS

Forty-nine rats were randomly allocated into seven groups: control (Co), stress (St), sham (Sh), escitalopram 10 and 20 mg/kg (Esc10 & Esc20), stress-escitalopram 10 and 20 mg/kg (St-Esc10 & St-Esc20). Induction of restraint stress (6 h/day) and escitalopram injections were performed for 14 days. The fEPSP slope and amplitude were measured according to input-output functions and after the LTP induction in the hippocampal CA1 region. Also, serum corticosterone levels were evaluated in all experimental groups.

RESULTS

The fEPSP slope and amplitude decreased significantly in the St group and increased significantly in the Esc10 group compared to the Co group. In non-stressed states, significant increases in slope and amplitude occurred in the Esc10 group compared to the Esc20 group. Notably, these values were also significantly enhanced by both escitalopram doses under stressed conditions. Moreover, serum corticosterone levels significantly elevated in the St group although its levels decreased in both St-Esc groups compared to the St.

CONCLUSION

Stress significantly attenuated neural excitability and long-term plasticity in the CA1 area. Only escitalopram 10 mg/kg improved synaptic excitability, as well as LTP induction and maintenance in non-stressed subjects even more than normal levels. However, under stress conditions, both escitalopram doses enhanced neural excitability and memory probably due to reduced serum corticosterone levels.

Shuangxinfang Prevents S100A9-Induced Macrophage/Microglial Inflammation to Improve Cardiac Function and Depression-Like Behavior in Rats After Acute Myocardial Infarction

Background: Depression is a common complication of cardiovascular disease, which deteriorates cardiac function. Shuangxinfang (psycho-cardiology formula, PCF) was reported to alleviate myocardial ischemia injury and improve depression-like behavior. Interestingly, our previous proteomics study predicted that the protein S100A9 appeared as an important target, and macrophage/microglial inflammation might be involved in the process of PCF improving depression induced by acute myocardial infarction (AMI). This study aims to validate the proteomics results.

Methods: AMI rat models were established in vivo, followed by the administration of PCF or ABR-215757 (also named paquinimod, inhibiting S100A9 binding to TLR4) for 5 days. Forced swimming test (FST) and open field test (OFT) were applied to record depression-like behavior, and echocardiography was employed to evaluate cardiac function. Morphological changes of cardiomyocytes were assessed by HE staining and TUNEL staining on day 7 after cardiac surgery, as well as Masson trichrome staining on day 21. Hippocampal neurogenesis was determined by Nissl staining, while 5-hydroxytryptamine (5-HT), tryptophan/kynurenine ratio, and brain-derived neurotrophic factor (BDNF) in the hippocampus were analyzed as biochemical indicators of depression. We employed RT-qPCR, western blotting, and immunofluorescence to detect the expression of pathway-related genes and proteins. Myocardial and hippocampal expression of inflammatory factors were performed by ELISA. The activation of macrophage and microglia was assessed via immunoreaction using CD68 and Iba1, respectively. For in vitro confirmation, BV2 cells were primed with recombinant protein S100A9 and then treated with PCF serum or ferulic acid to determine alterations in microglial inflammation.

Results: Rats in the AMI group showed heart function deterioration and depression-like behavior. Coronary ligation not only brought about myocardial inflammation, cell apoptosis, and fibrosis but also reduced the neurogenesis, elevated the tryptophan/kynurenine ratio, and decreased the content of 5-HT. PCF could ameliorate the pathological and phenotypic changes in the heart and brain and inhibit the expression of the S100A9 protein, the activation of the microglial cell, and the secretion of IL-1β and TNF-α raised by AMI. ABR-215757 showed therapeutic effect and molecular biological mechanisms similar to PCF. Treatment with PCF serum or ferulic acid in vitro was proved to efficiently block the hyperactivation of BV2 cells and increment of cytokine contents induced by recombinant protein S100A9.

Conclusion: We identify S100A9 as a novel and potent regulator of inflammation in both the heart and brain. Macrophage/microglia inflammation mediated by S100A9 is considered a pivotal pathogenic in depression after AMI and a major pathway for the treatment of PCF, suggesting that PCF is a promising therapeutic candidate for psycho-cardiology disease.

The effects of exercise training on heart, brain and behavior, in the isoproterenol-induced cardiac infarct model in middle-aged female rats

Women with cardiovascular disease may be more susceptible to concomitant mental health problems, such as depression and cognitive decline. Exercise training has beneficial effects on the cardiovascular system as well as on mental functions. Aim of the present study was to study the effects of exercise training on heart, brain and behavior in the isoproterenol (ISO) model in middle-aged female rats. Twelve months old female Wistar rats were submitted to ISO injections (70 mg/kg s.c., on two consecutive days) or received saline. One week later, rats were assigned to either exercise training (treadmill running) or control handling for five weeks. During the last 7 days, tests were performed regarding depressive-like behavior and cognitive function. Then, rats were sacrificed and heart and brains were dissected for (immuno)histochemistry. ISO-induced cardiac effects were eminent from cardiac fibrosis and declined cardiac function. Exercise training reversed cardiac damage and partly restored ISO-induced cardiac dysfunction. However, ISO treatment could not be associated with neuroinflammation, nor impaired hippocampal neurogenesis or neuronal function. Accordingly, no cognitive impairment or depressive-like behavior were observed. Actually, hippocampal microglia hyper-ramification was observed after ISO. Exercise left neuroinflammation and behavior merely unaltered, and even reduced neuronal function. Our data indicated that the cardiac damage after ISO in middle-aged female rats, and the subsequent beneficial effects of five weeks exercise training on the heart, were not reflected in changes in the brain nor in altered behavior.

Combination of electroconvulsive stimulation with ketamine or escitalopram protects the brain against inflammation and oxidative stress induced by maternal deprivation and is critical for associated behaviors in male and female rats

This study aimed at evaluating the treatment effects with ketamine, electroconvulsive stimulation (ECS), escitalopram, alone or in combination in adult rats of both sexes, subjected to the animal model of maternal deprivation (MD). All groups were subjected to the forced swimming test (FST), splash and open field tests. The prefrontal cortex (PFC), hippocampus and serum were collected to analyze oxidative stress and inflammatory parameters. MD induced depressive-like behavior in the FST test in males and reduced grooming time in male and female rats. The treatments alone or combined reversed depressive and anhedonic behavior in females. In males, all treatments increased grooming time, except for ECS + escitalopram + ketamine. MD increased lipid peroxidation and protein carbonylation, nitrite/nitrate concentration and myeloperoxidase activity in the PFC and hippocampus of males and females. However, the treatment's response was sex dependent. Catalase activity decreased in the PFC of males and the PFC and hippocampus of females, and most treatments were not able to reverse it. MD increased the inflammation biomarkers levels in the PFC and hippocampus of males and females, and most treatments were able to reverse this increase. In all groups, a reduction in the interleukin-10 levels in the PFC and hippocampus of female and male rats was observed. Our study shows different responses between the sexes in the patterns evaluated and reinforces the use of the gender variable as a biological factor in MDD related to early stress and in the response of the therapeutic strategies used.

Psycho-cardiology therapeutic effects of Shuangxinfang in rats with depression-behavior post acute myocardial infarction: Focus on protein S100A9 from proteomics

BACKGROUND

Depressive disorders induced by acute myocardial infarction (AMI) play a pivotal role in the deterioration of cardiac function, and Shuangxinfang (Psycho-cardiology Formula, PCF) was reported to alleviate heart function damage and improve depression-like behavior, but the complex mechanism in such process has not been clarified.

METHODS

AMI models were established and PCF was administered in rats. Subjects were then assessed in open field test (OFT) and forced swimming test (FST) recapitulating symptoms of depressive disorder. Afterward, pharmacoproteomic profiling of the hippocampus and peri-infarct border zone (BZ) was performed using a label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) technique, to identify contributing proteins and pathways responsible for myocardial ischemia and behavioral allostasis. Bioinformatics analysis was processed for further investigation, while western blotting was employed for testing dominating proteins to validate proteomic results.

RESULTS

Rats in the AMI group showed depression-like behavior in OFT and FST, which was improved by PCF. There were 131 differentially expressed proteins (DEPs) in BZ and 64 proteins in the hippocampus being detected and quantified shared by the sham group, the AMI group, and the PCF group. Subsequently, pertinent pathways and molecular functions were further identified. Altered molecules were discovered to be enriched in the apoptotic process, innate immune response, and NF-κB transcription factor activity in BZ, as well as chemical synaptic transmission, axon, collagen binding, cell adhesion, response to carbohydrate, laminin binding, and cellular response to nitric oxide in the hippocampus. Groups of signal transducers were also able to select multiple pathways, including innate immunity and arginine biosynthesis in the heart, also integrin signaling in the brain. DEPs were intersected from the myocardium and hippocampus to screen out the protein S100A9, which was up-regulated in the AMI group compared with the sham, and showed a down-regulation trend after treatment with PCF.

CONCLUSION

Taken together, we present a comprehensive proteomics analysis of rat models with depression post-AMI. Reviewing the literatures concerned, it's hypothesized that macrophage/microglia inflammation mediated by S100A9 might be the pivotal pathogenic process of psycho-cardiology disease, as well as potential mechanisms for the treatment of PCF.

Cognitive impairment in myocardial infarction and heart failure

Myocardial infarction (MI) occurs when coronary blood flow is decreased due to an obstruction/occlusion of the vessels, leading to myocardial death and progression to heart failure (HF). Cognitive impairment, anxiety, depression and memory loss are the most frequent mental health problems among patients with HF. The most common cause of cognitive decline is cardiac systolic dysfunction, which leads to reduced cerebral perfusion. Several in vivo and clinical studies provide information regarding the underlying mechanisms of HF in brain pathology. Neurohormonal activation, oxidative stress, inflammation, glial activation, dendritic spine loss and brain programmed cell death are all proposed as contributors of cognitive impairment in HF. Furthermore, several investigations into the effects of various medications on brain pathology utilizing MI models have been reported. In this review, potential mechanisms involving HF-associated cognitive impairment, as well as neuroprotective interventions in HF models, are discussed and summarized. In addition, gaps in the surrounding knowledge, including the types of brain cell death and the effects of cell death inhibitors in HF, are presented and discussed. This review provides valuable information that will suggest the potential therapeutic strategies for cognitive impairment in patients with HF.

Escitalopram Ameliorates Cardiomyopathy in Type 2 Diabetic Rats via Modulation of Receptor for Advanced Glycation End Products and Its Downstream Signaling Cascades

Type 2 diabetes mellitus (T2DM) has been recognized as a known risk factor for cardiovascular diseases. Additionally, studies have shown the prevalence of depression among people with diabetes. Thus, the current study aimed to investigate the possible beneficial effects of escitalopram, a selective serotonin reuptake inhibitor, on metabolic changes and cardiac complications in type 2 diabetic rats. Diabetes was induced by feeding the rats high fat-high fructose diet (HFFD) for 8 weeks followed by a subdiabetogenic dose of streptozotocin (STZ) (35 mg/kg, i. p.). Treatment with escitalopram (10 mg/kg/day; p. o.) was then initiated for 4 weeks. At the end of the experiment, electrocardiography was performed and blood samples were collected for determination of glycemic and lipid profiles. Animals were then euthanized and heart samples were collected for biochemical and histopathological examinations. Escitalopram alleviated the HFFD/STZ-induced metabolic and cardiac derangements as evident by improvement of oxidative stress, inflammatory, fibrogenic and apoptotic markers in addition to hypertrophy and impaired conduction. These results could be secondary to its beneficial effects on the glycemic control and hence the reduction of receptor for advanced glycation end products content as revealed in the present study. In conclusion, escitalopram could be considered a favorable antidepressant medication in diabetic patients as it seems to positively impact the glycemic control in diabetes in addition to prevention of its associated cardiovascular complications.

The anti-inflammatory role of SSRI and SNRI in the treatment of depression: a review of human and rodent research studies

RATIONALE

Depression has the topmost prevalence of all psychiatric diseases. It is characterized by a high recurrence rate, disability, and numerous and mostly unclear pathogenic mechanisms. Besides the monoamine or the neurotrophic hypothesis of depression, the inflammatory mechanism has begun to be supported by more and more evidence. At the same time, the current knowledge about the standard treatment of choice, the selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs), is expanding rapidly, adding more features to the initial ones.

OBJECTIVES

This review summarizes the in vivo anti-inflammatory effects of SSRIs and SNRIs in the treatment of depression and outlines the particular mechanisms of these effects for each drug separately. In addition, we provide an overview of the inflammation-related theory of depression and the underlying mechanisms.

RESULTS

SSRIs and SNRIs decrease the neuroinflammation through multiple mechanisms including the reduction of blood or tissue cytokines or regulating complex inflammatory pathways: nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inflammasomes, Toll-like receptor 4 (TLR4), peroxisome proliferator-activated receptor gamma (PPARγ). Also, SSRIs and SNRIs show these effects in association with an antidepressant action.

CONCLUSIONS

SSRIs and SNRIs have an anti-neuroinflammatory role which might contribute the antidepressant effect.

The Antidiabetic Metformin as an Adjunct to Antidepressants in Patients with Major Depressive Disorder: A Proof-of-Concept, Randomized, Double-Blind, Placebo-Controlled Trial

Metformin (MET) has been reported to have antidepressant effects in animal models and in diabetic patients with depression, owing to its anti-inflammatory, antioxidant, and neuroprotective activity. Accordingly, we proposed that MET would show antidepressant effects in patients with major depressive disorder (MDD) without other comorbidities. In this double-blind placebo-controlled study, 80 adult outpatients with MDD (DSM-IV criteria) and a Hamilton Depression Rating Scale (HAM-D) score >18 were randomized to receive fluoxetine 20 mg once daily plus placebo (n = 40) or fluoxetine 20 mg once daily plus MET 1000 mg once daily for 12 weeks. Patients were assessed by HAM-D score (weeks 0, 4, 8, and 12). The serum levels of TNF-α, IL-1β, IL-6, IGF-1, MDA, CRP, BDNF, and serotonin were measured before and after therapy. Mixed-effects model repeated-measures analysis of covariance was used to compare the HAM-D scores and the biological markers between the two groups. After 4, 8 and 12 weeks, patients in the MET group showed a statistically significant decline in HAM-D score relative to the placebo group (least squares mean difference [LSMD] -2.347, p = 0.000, LSMD -3.369, p = 0.000, and LSMD -3.454, p = 0.000, respectively). Response and remission rates were significantly higher in the MET group (89% and 81%, respectively) than in the placebo group (59% and 46%, respectively). Moreover, the MET group was superior in conserving the measured biological markers compared with the placebo group. Our findings suggest MET as a promising, effective, and safe short-term adjunctive approach in nondiabetic MDD patients. Trial registration ID: NCT04088448.

Potential Anti-Inflammatory Effect of Escitalopram in Iodoacetamide-Induced Colitis in Depressed Ovariectomized Rats: Role of α7-nAChR

Escitalopram, a drug of choice in the treatment of depression, was recently shown to possess an anti-inflammatory activity. The aim of the present study was to elucidate the effect of escitalopram on peripheral inflammatory cascades in iodoacetamide-induced colitis associated with depressive behavior in ovariectomized rats. Moreover, the role of α-7 nicotinic acetylcholine receptor in mediating the anti-colitic effect of escitalopram was examined using a nicotinic receptor antagonist methyllycaconitine citrate. Colitis was induced by intracolonic injection of 4% iodoacetamide in ovariectomized rats. Escitalopram (10 mg/kg/day, i.p.) was then injected for 1 week and several parameters including macroscopic (colon mass index and ulcerative area), microscopic (histopathology and scoring), and biochemical (myeloperoxidase and tumor necrosis factor-α) were determined. Colitis induction in ovariectomized rats resulted in a marked increase in colon mass index, ulcerative area, histopathological scoring, myeloperoxidase activity and tumor necrosis factor-α levels. These effects were ameliorated by escitalopram, even in the presence of methyllycaconitine indicating that α-7 nicotinic acetylcholine receptor does not mediate the anti-inflammatory effect of escitalopram. The present study revealed the beneficial effect of escitalopram in iodoacetamide induced colitis in ovariectomized rats and suggests that it may represent a new therapeutic agent for the treatment of inflammatory bowel disease, especially in patients with or at high risk of depressive behavior.

A joint study of whole exome sequencing and structural MRI analysis in major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a leading cause of disability worldwide and influenced by both environmental and genetic factors. Genetic studies of MDD have focused on common variants and have been constrained by the heterogeneity of clinical symptoms.

METHODS

We sequenced the exome of 77 cases and 245 controls of Han Chinese ancestry and scanned their brain. Burden tests of rare variants were performed first to explore the association between genes/pathways and MDD. Secondly, parallel Independent Component Analysis was conducted to investigate genetic underpinnings of gray matter volume (GMV) changes of MDD.

RESULTS

Two genes (CSMD1, p = 5.32×10-6; CNTNAP5, p = 1.32×10-6) and one pathway (Neuroactive Ligand Receptor Interactive, p = 1.29×10-5) achieved significance in burden test. In addition, we identified one pair of imaging-genetic components of significant correlation (r = 0.38, p = 9.92×10-6). The imaging component reflected decreased GMV in cases and correlated with intelligence quotient (IQ). IQ mediated the effects of GMV on MDD. The genetic component enriched in two gene sets, namely Singling by G-protein coupled receptors [false discovery rate (FDR) q = 3.23×10-4) and Alzheimer Disease Up (FDR q = 6.12×10-4).

CONCLUSIONS

Both rare variants analysis and imaging-genetic analysis found evidence corresponding with the neuroinflammation and synaptic plasticity hypotheses of MDD. The mediation of IQ indicates that genetic component may act on MDD through GMV alteration and cognitive impairment.

Preventive Effects of Escitalopram Against Anxiety-Like Depressive Behaviors in Monosodium Glutamate-Teated Rats Subjected to Partial Hepatectomy

The reasons for the relationship between depression and chronic liver disease (CLD) are complex and multifactorial. Further research is needed to decipher the etiology and establish an optimal management approach for depression in patients, including the potential role of non-pharmacological treatments. monosodium glutamate (MSG)-treated rats are more likely to develop anxiogenic- and depressive-like behaviors, which could be related to the dysfunction of serotonergic system. In this study, partial hepatectomy (PH) was performed in MSG-treated rats and the histopathological changes were observed in orbitofrontal cortex (OFC) and liver. The effect of escitalopram, a widely used antidepressant, on neural and liver injury in this model was also examined. The MSG + PH-treated rats displayed decreased distances traveled in total, in center arena, and in the left side of arena in inner open field test (OFT), as compared to saline, saline + PH, and MSG-treated animals. The present study established that PH aggravated anxiety-like depressive behaviors in MSG-treated rats, concordant with damaged Nissl bodies (and neurites), decreased IBA-1 and Sox-2 expression in OFC and neurotransmitter disorder. Escitalopram treatment could alleviate these pathological changes as well as reduce hepatic steatosis and lipid metabolism.

Learned helplessness reveals a population at risk for depressive-like behaviour after myocardial infarction in mice

Aims

Myocardial infarction (MI) and heart failure (HF) are risk factors for the development of depression, additionally worsening the quality of life and patient outcome. How HF causes depression and how depression promotes HF remain mechanistically unclear, which is at least partly caused by the difficulty of in vivo modelling of psychosomatic co‐morbidity. We aimed to study the potential sequence of events with respect to different depression aspects upon HF.

Methods and results

Male C57BL6 mice underwent MI, followed by behavioural and echocardiographic characterization. Motility, exploration, and anxiety‐like behaviour were unaffected in mice after MI. We did not observe increased depressive‐like behaviour in the sucrose preference, tail suspension, or Porsolt forced swim test. Mice did not display signs of learned helplessness (LH) when compared to sham. Accordingly, cluster analysis revealed only a slightly higher quota of LH in HF (38%) vs. sham mice (32%). But strikingly, three‐group cluster analysis revealed an additional intermediate subpopulation at risk for LH after HF (29%). Interestingly, this population featured elevated cardiac expression of nr4a1.

Conclusions

The LH paradigm uncovered a subtle predisposition to depressive‐like behaviour after MI, whereas testing for anhedonia and despair was insufficient to show a behavioural shift in mice. Therefore, we suggest an accumulating risk profile and a multiple‐hits hypothesis regarding the pathogenesis of co‐morbid depression after MI. Symptoms of LH may present a marker of subclinical depression after MI, the impact of which remains to be investigated. The proposed sequence of behavioural testing enables the mechanistic dissection of cardio‐psychogenic signalling in the future.

Cognitive Deficits Following a Post-Myocardial Infarct in the Rat Are Blocked by the Serotonin-Norepinephrine Reuptake Inhibitor Desvenlafaxine

Myocardial infarction (MI) in animal models induces cognitive deficits as well as the activation of caspase in the limbic system; both can be blocked by 2 weeks of treatment following MI using tricyclic antidepressants or selective serotonin uptake blockers. Here we used three different treatment schedules to test the short- and long-term effects of the combined serotonin-norepinephrine reuptake inhibitor desvenlafaxine on post-MI-associated cognitive deficits and caspase activation. MI was induced in 39 young adult rats, and 39 rats served as sham-operated controls. Desvenlafaxine (3 mg/kg/day, i.p.) or saline was administered according to one of three schedules: (1) for 2 weeks, starting right after surgery; (2) for 16 weeks, starting 2 weeks after surgery; (3) for 16 weeks, starting right after surgery. Behavior was tested 2 weeks (social interaction, passive avoidance) and 16 weeks (forced swimming, Morris water maze) after surgery. Caspase-3 and caspase-6 activities were measured 16 weeks after surgery. At 2 and 16 weeks post-surgery, saline-treated MI rats displayed performance deficits compared to desvenlafaxine-treated rats, regardless of the treatment schedule. Caspase-3 activity was higher in the amygdala (medial and lateral) and hippocampal CA3 region in untreated MI rats, whereas caspase-6 activity was higher in the CA1 region. Caspase-6 activity correlated positively with deficits in the Morris water maze. These results indicate that, independently of treatment schedules, various treatment schedules with desvenlafaxine can prevent MI-associated cognitive deficits and decrease caspase activities in the limbic system.

Sex differences in depression-like behavior and neuroinflammation in rats post-MI: role of estrogens

Patients with heart failure (HF) have a high prevalence of depression associated with a worse prognosis, particularly in older women. The present study evaluated whether sex and estrogens affect depression-like behavior and associated neuroinflammation induced by myocardial infarction (MI) in rats. MI was induced by occlusion of the left anterior descending artery in young adult male and female Wistar rats or in ovariectomized (OVX) female rats without and with estrogen [17β-estradiol (E₂)] replacement. MI groups showed a comparable degree of cardiac dysfunction. Eight weeks post-MI, male rats with HF exhibited depression-like behaviors, including anhedonia and higher immobility in the sucrose preference and forced swim tests, which were not observed in female rats with HF. In the cued fear conditioning test, male but not female rats with HF froze more than sham rats. After OVX, female sham rats developed mild depression-like behaviors that were pronounced in OVX female rats post-MI and were largely prevented by E₂ replacement. Cytokine levels in the plasma and paraventricular nucleus increased in both sexes with HF, but only male rats with HF showed an increase in cytokine levels in the prefrontal cortex. OVX alone did not affect cytokine levels, but OVX-MI caused significant increases in the prefrontal cortex, which were shifted to an anti-inflammatory pattern by E₂ replacement. These results suggest that estrogens prevent depression-like behavior induced by HF post-MI in young adult female rats by inhibiting proinflammatory cytokine production and actions in the prefrontal cortex. NEW & NOTEWORTHY In contrast to male rats, female rats with heart failure after myocardial infarction do not develop depression-like behavior or increases in prefrontal cortex cytokines. However, after ovariectomy, female rats exhibit similar changes, which are prevented by 17β-estradiol replacement. Neuroinflammation in the prefrontal cortex in male subjects may contribute to depression-like behavior, whereas its estrogen-dependent absence in female subjects may protect against depression.

Anti-inflammatory treatment for major depressive disorder: implications for patients with an elevated immune profile and non-responders to standard antidepressant therapy

Major depressive disorder (MDD) is a prevalent and disabling psychiatric disease with rates of non-responsiveness to antidepressants ranging from 30-50%. Historically, the monoamine depletion hypothesis has dominated the view on the pathophysiology of depression. However, the lack of responsiveness to antidepressants and treatment resistance suggests that additional mechanisms might play a role. Evidence has shown that a subgroup of depressive patients may have an underlying immune deregulation that could explain the lack of therapeutic benefit from antidepressants. Stimuli like inflammation and infection can trigger the activation of microglia to release pro-inflammatory cytokines, acting on two main pathways: (1) activation of the hypothalamic-pituitary adrenal axis, generating an imbalance in the serotonergic and noradrenergic circuits; (2) increased activity of the enzyme indoleamine-2,3-dioxygenase, resulting in depletion of serotonin levels and the production of quinolinic acid. If this hypothesis is proven true, the subgroup of MDD patients with increased levels of pro-inflammatory cytokines, mainly IL-6, TNF-α and IL-1β, might benefit from an anti-inflammatory intervention. Here, we discuss the pre-clinical and clinical studies that have provided support for treatment with non-steroidal anti-inflammatory drugs in depressed patients with inflammatory comorbidities or an elevated immune profile, as well as evidences for anti-inflammatory properties of standard antidepressants.

Relationship between interleukin-1β and depressive disorder after acute coronary syndrome

This study was aimed to investigate the effect of serum interleukin (IL)-1β in the depression trajectory after acute coronary syndrome (ACS) considering two IL-1β polymorphisms: -511C/T or +3953C/T. A total of 969 patients were evaluated within 2weeks after ACS and of these, 711 were followed-up 1year later. Depressive disorders were evaluated at baseline and 1year after ACS, using the Mini-International Neuropsychiatric Interview. Serum IL-1β levels and IL-1β genotypes were investigated at baseline. Covariates on socio-demographic and clinical characteristics including depressive symptoms, cardiovascular risk factors, and current cardiac status were assessed. Depression during the acute ACS was significantly associated with the IL-1β levels and the -511T allele. The interaction of the IL-1β level with depression at baseline in the presence of the -511T allele was also significant. No associations were found with depression during the chronic ACS. For the +3953C/T genotype, there was no association with depression in either the acute or chronic phase. The IL-1β level and -511C/T genotype, separately or interactively, could be a biomarker for depressive disorder in the acute phase of ACS. Focused interventions for those with higher IL-1β level and -511T allele might reduce the risk of depressive disorder.

Early citalopram treatment increases mortality due to left ventricular rupture in mice after myocardial infarction

AIMS

Both anxiety and depression are common and independent outcome predictors in patients after myocardial infarction (MI). However, it is unclear whether and how anti-depressants influence remodeling after MI. Thus, we studied cardiac remodeling in mice after experimental MI under treatment with citalopram, a selective serotonin reuptake inhibitor widely used as antidepressant.

METHODS AND RESULTS

Treatment with citalopram versus saline was applied via osmotic pump after coronary artery ligation. Two different groups were studied: early treatment during the healing phase (starting immediately after surgery), or late treatment in the remodeling phase (starting 7days after surgery). Late treatment did not change mortality or left ventricular remodeling after MI over the period of 6weeks. However, in the early treatment group mortality was increased in citalopram-treated mice predominantly due to left ventricle rupture without differences in infarct size. Remodeling 4weeks after MI was not altered by the treatment. Neither infiltration of inflammatory cells, as determined by FACS analysis of myocardial tissue, nor mRNA-expression of inflammatory cytokines changed 3days after MI in the early treatment group. However, extracellular matrix functioning was altered: There was a significant increase of MMP13 in citalopram treated animals after MI. Pretreatment with the MMP inhibitor PD 166793 prevented left ventricular ruptures and demonstrated a tendency to improved survival after citalopram treatment.

CONCLUSIONS

Treatment with antidepressant citalopram in the acute but not in the late phase after MI significantly increased mortality in mice by disturbing early healing. Pharmacological MMP inhibition partially reversed the deleterious effects of citalopram.

Caspase-3 Activity in the Rat Amygdala Measured by Spectrofluorometry After Myocardial Infarction

Myocardial infarction (MI) has dramatic mid- and long-term consequences at the physiological and behavioral levels, but the mechanisms involved are still unclear. Our laboratory has developed a rat model of post-MI syndrome that displays impaired cardiac functions, neuronal loss in the limbic system, cognitive deficits and behavioral signs of depression. At the neuronal level, caspase-3 activation mediates post-MI apoptosis in different limbic regions, such as the amygdala – peaking at 3 days post-MI. Cognitive and behavioral impairments appear 2-3 weeks post-MI and these correlate statistically with measures of caspase-3 activity. The protocol described here is used to induce MI, collect amygdala tissue and measure caspase-3 activity using spectrofluorometry. To induce MI, the descending coronary artery is occluded for 40 min. The protocol for evaluation of caspase-3 activation starts 3 days after MI: the rats are sacrificed and the amygdala isolated rapidly from the brain. Samples are quickly frozen in liquid nitrogen and kept at -80 °C until actual analysis. The technique performed to assess caspase-3 activation is based on cleavage of a substrate (DEVD-AMC) by caspase-3, which releases a fluorogenic compound that can be measured by spectrofluorometry. The methodology is quantitative and reproducible but the equipment required is expensive and the procedure for quantifying the samples is time-consuming. This technique can be applied to other tissues, such as the heart and kidneys. DEVD-AMC can be replaced by other substrates to measure the activity of other caspases.

Vagotomy prevents the effect of probiotics on caspase activity in a model of postmyocardial infarction depression

BACKGROUND

Myocardial infarction (MI) is associated with apoptosis in the amygdala and, ultimately, with clinical signs of depression. Different treatments have proven to be beneficial in preventing depression, including combination of the probiotics Lactobacillus helveticus and Bifidobacterium longum for prophylaxis. We have speculated previously that the benefit of these probiotics is due to their anti-inflammatory properties, and evidence suggests that an intact vagus nerve is important for this effect to occur. This study was designed to ascertain vagus nerve involvement in the beneficial influence of probiotics on caspase activities in our post-MI animal model of depression.

METHODS

Probiotics and/or vehicle were administered daily to male adult rats, 14 days before MI and until euthanasia. Vagotomy was performed in subgroups of rats 40 min before MI. They were sacrificed after 3 days of reperfusion, and MI size was assessed along with caspase-3 and -8 activities in the amygdala.

KEY RESULTS

Probiotics had no effect on infarct size but vagotomy increased it. Caspase-3 and caspase-8 activities in the amygdala were higher in MI than in sham-operated rats, and this outcome was reversed by probiotics. The beneficial influence of probiotics was abolished by vagotomy.

CONCLUSIONS & INFERENCES

Our data indicate that the effect of probiotics on caspase activities in the amygdala after MI depends on an intact vagus nerve.

The effects of escitalopram on myocardial apoptosis and the expression of Bax and Bcl-2 during myocardial ischemia/reperfusion in a model of rats with depression

BACKGROUND

Major depressive disorder (MDD) is an independent risk factor for coronary heart disease (CHD), and influences the occurrence and prognosis of cardiovascular events. Although there is evidence that antidepressants may be cardioprotective after acute myocardial infarction (AMI) comorbid with MDD, the operative pathophysiological mechanisms remain unclear. Our aim was therefore to explore the molecular mechanisms of escitalopram on myocardial apoptosis and the expression of Bax and Bcl-2 in a rat model of depression during myocardial ischemia/reperfusion (I/R).

METHODS

Rats were divided randomly into 3 groups (n = 8): D group (depression), DI/R group (depression with myocardial I/R) and escitalopram + DI/R group. The rats in all three groups underwent the same chronic mild stress and separation for 21 days, at the same time, in the escitalopram + DI/R group, rats were administered escitalopram by gavage (10 mg/kg/day). Ligation of the rat's left anterior descending branch was done in the myocardial I/R model. Following which behavioral tests were done. The size of the myocardial infarction was detected using 1.5% TTC dye. The Tunel method was used to detect apoptotic myocardial cells, and both the Rt-PCR method and immunohistochemical techniques were used to detect the expression of Bcl-2 and Bax.

RESULTS

Compared with the D and DI/R groups, rats in Escitalopram + DI/R group showed significantly increased movements and sucrose consumption (P < .01). Compared with the DI/R group, the myocardial infarct size in the escitalopram + DI/R group was significantly decreased (P < .01). Compared with the D group, there were significantly increased apoptotic myocardial cells in the DI/R and escitalopram + DI/R groups (P < .01); however compared with the DI/R group, apoptotic myocardial cell numbers in the escitalopram + DI/R group were significantly decreased (P < .01). Compared with the DI/R group, there was a down-regulated Bax:Bcl-2 ratio in the escitalopram + DI/R group (P < .01).

CONCLUSIONS

These results suggest that in patients with AMI comorbid with MDD, there is an increase in pro-apoptotic pathways that is reversed by escitalopram. This suggests that clinically escitalopram may have a direct cardioprotective after acute myocardial infarction.

Resolvin D1, a metabolite of omega-3 polyunsaturated fatty acid, decreases post-myocardial infarct depression

We hypothesized that inflammation induced by myocardial ischemia plays a central role in depression-like behavior after myocardial infarction (MI). Several experimental approaches that reduce inflammation also result in attenuation of depressive symptoms. We have demonstrated that Resolvin D1 (RvD1), a metabolite of omega-3 polyunsaturated fatty acids (PUFA) derived from docosahexaenoic acid, diminishes infarct size and neutrophil accumulation in the ischemic myocardium. The aim of this study is to determine if a single RvD1 injection could alleviate depressive symptoms in a rat model of MI. MI was induced in rats by occlusion of the left anterior descending coronary artery for 40 min. Five minutes before ischemia or after reperfusion, 0.1 μg of RvD1 or vehicle was injected in the left ventricle cavity. Fourteen days after MI, behavioral tests (forced swim test and socialization) were conducted to evaluate depression-like symptoms. RvD1 reduced infarct size in the treated vs. the vehicle group. Animals receiving RvD1 also showed better performance in the forced swim and social interaction tests vs. vehicle controls. These results indicate that a single RvD1 dose, given 5 min before occlusion or 5 min after the onset of reperfusion, decreases infarct size and attenuates depression-like symptoms.

Escitalopram alters gene expression and HPA axis reactivity in rats following chronic overexpression of corticotropin-releasing factor from the central amygdala

We have previously demonstrated that viral-mediated overexpression of corticotropin-releasing factor (CRF) within the central nucleus of the amygdala (CeA) reproduces many of the behavioral and endocrine consequences of chronic stress. The present experiment sought to determine whether administration of the selective serotonin reuptake inhibitor (SSRI) escitalopram reverses the adverse effects of CeA CRF overexpression. In a 2×2 design, adult male rats received bilateral infusions of a control lentivirus or a lentivirus in which a portion of the CRF promoter is used to drive increased expression of CRF peptide. Four weeks later, rats were then implanted with an Alzet minipump to deliver vehicle or 10mg/kg/day escitalopram for a 4-week period of time. The defensive withdrawal (DW) test of anxiety and the sucrose-preference test (SPT) of anhedonia were performed both before and after pump implantation. Additional post-implant behavioral tests included the elevated plus maze (EPM) and social interaction (SI) test. Following completion of behavioral testing, the dexamethasone/CRF test was performed to assess HPA axis reactivity. Brains were collected and expression of HPA axis-relevant transcripts were measured using in situ hybridization. Amygdalar CRF overexpression increased anxiety-like behavior in the DW test at week eight, which was only partially prevented by escitalopram. In both CRF-overexpressing and control groups, escitalopram decreased hippocampal CRF expression while increasing hypothalamic and hippocampal expression of the glucocorticoid receptor (GR). These gene expression changes were associated with a significant decrease in HPA axis reactivity in rats treated with escitalopram. Interestingly, escitalopram increased the rate of weight gain only in rats overexpressing CRF. Overall these data support our hypothesis that amygdalar CRF is critical in anxiety-like behavior; because the antidepressant was unable to reverse behavioral manifestations of CeA CRF-OE. This may be a potential animal model to study treatment-resistant psychopathologies.

ATP-binding cassette sub-family F member 1 (ABCF1) is identified as a putative therapeutic target of escitalopram in the inflammatory cytokine pathway

The inflammatory cytokine pathway may be a potential therapeutic target for major depressive disorder (MDD). Previous reports suggest that antidepressants have anti-inflammatory properties and can cause a reduction in proinflammatory cytokines. Recent evidence suggests this might be mediated at the level of the transcriptome. The current study investigated the transcription of 86 genes in the inflammatory cytokine pathway both at baseline and after eight weeks of escitalopram treatment in MDD patients who were either clinical responders (n=25) or non-responders (n=21), using a subset of samples in the Genome-Based Therapeutic Drugs for Depression project (GENDEP). Changes in expression between baseline and eight weeks of treatment were assessed using two-tailed t-tests. To establish if any significant expression changes related to clinical response, the magnitude of the relative expression change between baseline and eight weeks of treatment was established and binary logistic regressions were used to compare differences between responders and non-responders. ATP-binding cassette sub-family F member 1 (ABCF1), a translational regulator of the inflammatory cytokine pathway showed a significant increase in expression after escitalopram treatment which was significantly greater in responders compared to non-responders, suggesting that ABCF1 may play a role in mediating antidepressant response.

Evidence for a dysregulated immune system in the etiology of psychiatric disorders

There is extensive bi-directional communication between the brain and the immune system in both health and disease. In recent years, the role of an altered immune system in the etiology of major psychiatric disorders has become more apparent. Studies have demonstrated that some patients with major psychiatric disorders exhibit characteristic signs of immune dysregulation and that this may be a common pathophysiological mechanism that underlies the development and progression of these disorders. Furthermore, many psychiatric disorders are also often accompanied by chronic medical conditions related to immune dysfunction such as autoimmune diseases, diabetes and atherosclerosis. One of the major psychiatric disorders that has been associated with an altered immune system is schizophrenia, with approximately one third of patients with this disorder showing immunological abnormalities such as an altered cytokine profile in serum and cerebrospinal fluid. An altered cytokine profile is also found in a proportion of patients with major depressive disorder and is thought to be potentially related to the pathophysiology of this disorder. Emerging evidence suggests that altered immune parameters may also be implicated in the neurobiological etiology of autism spectrum disorders. Further support for a role of immune dysregulation in the pathophysiology of these psychiatric disorders comes from studies showing the immunomodulating effects of antipsychotics and antidepressants, and the mood altering effects of anti-inflammatory therapies. This review will not attempt to discuss all of the psychiatric disorders that have been associated with an augmented immune system, but will instead focus on several key disorders where dysregulation of this system has been implicated in their pathophysiology including depression, schizophrenia and autism spectrum disorder.

Combination of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 reduces post-myocardial infarction depression symptoms and restores intestinal permeability in a rat model

Myocardial infarction (MI) in rats is accompanied by apoptosis in the limbic system and a behavioural syndrome similar to models of depression. We have already shown that probiotics can reduce post-MI apoptosis and designed the present study to determine if probiotics can also prevent post-MI depressive behaviour. We also tested the hypothesis that probiotics achieve their central effects through changes in the intestinal barrier. MI was induced in anaesthetised rats via 40-min transient occlusion of the left anterior coronary artery. Sham rats underwent the same surgical procedure without actual coronary occlusion. For 7 d before MI and between the seventh post-MI day and euthanasia, half the MI and sham rats were given one billion live bacterial cells of Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 per d dissolved in water, while the remaining animals received only the vehicle (maltodextrin). Depressive behaviour was evaluated 2 weeks post-MI in social interaction, forced swimming and passive avoidance step-down tests. Intestinal permeability was evaluated by oral administration with fluorescein isothiocyanate-dextran, 4 h before euthanasia. MI rats displayed less social interaction and impaired performance in the forced swimming and passive avoidance step-down tests compared to the sham controls (P < 0·05). Probiotics reversed the behavioural effects of MI (P < 0·05), but did not alter the behaviour of sham rats. Intestinal permeability was increased in MI rats and reversed by probiotics. In conclusion, L. helveticus R0052 and B. longum R0175 combination interferes with the development of post-MI depressive behaviour and restores intestinal barrier integrity in MI rats.