The effect of pyruvate on the development and progression of post-stroke depression: A new therapeutic approach

Exploring the Pathogenesis and Treatment of PSD from the Perspective of Gut Microbiota

Post-stroke depression (PSD) is a psychological disease that can occur following a stroke and is associated with serious consequences. Research on the pathogenesis and treatment of PSD is still in the infancy stage. Patients with PSD often exhibit gastrointestinal symptoms; therefore the role of gut microbiota in the pathophysiology and potential treatment effects of PSD has become a hot topic of research. In this review, describe the research on the pathogenesis and therapy of PSD. We also describe how the gut microbiota influences neurotransmitters, the endocrine system, energy metabolism, and the immune system. It was proposed that the gut microbiota is involved in the pathogenesis and treatment of PSD through the regulation of neurotransmitter levels, vagal signaling, hypothalamic-pituitary-adrenal axis activation and inhibition, hormone secretion and release, in addition to immunity and inflammation.

Excitotoxic Storms of Ischemic Stroke: A Non-neuronal Perspective

Numerous neurological disorders share a fatal pathologic process known as glutamate excitotoxicity. Among which, ischemic stroke is the major cause of mortality and disability worldwide. For a long time, the main idea of developing anti-excitotoxic neuroprotective agents was to block glutamate receptors. Despite this, there has been little successful clinical translation to date. After decades of "neuron-centered" views, a growing number of studies have recently revealed the importance of non-neuronal cells. Glial cells, cerebral microvascular endothelial cells, blood cells, and so forth are extensively engaged in glutamate synthesis, release, reuptake, and metabolism. They also express functional glutamate receptors and can listen and respond for fast synaptic transmission. This broadens the thoughts of developing excitotoxicity antagonists. In this review, the critical contribution of non-neuronal cells in glutamate excitotoxicity during ischemic stroke will be emphasized in detail, and the latest research progress as well as corresponding therapeutic strategies will be updated at length, aiming to reconceptualize glutamate excitotoxicity in a non-neuronal perspective.

Establishing a 3-Tesla Magnetic Resonance Imaging Method for Assessing Diffuse Axonal Brain Injury in Rats

Traumatic brain injury (TBI) significantly contributes to death and disability worldwide. However, treatment options remain limited. Here, we focus on a specific pathology of TBI, diffuse axonal brain injury (DABI), which describes the process of the tearing of nerve fibers in the brain after blunt injury. Most protocols to study DABI do not incorporate a specific model for that type of pathology, limiting their ability to identify mechanisms and comorbidities of DABI. In this study, we developed a magnetic resonance imaging (MRI) protocol for DABI in a rat model using a 3-T clinical scanner. We compared the neuroimaging outcomes with histologic and neurologic assessments. In a sample size of 10 rats in the sham group and 10 rats in the DABI group, we established neurological severity scores before the intervention and at 48 h following DABI induction. After the neurological evaluation after DABI, all rats underwent MRI scans and were subsequently euthanized for histological evaluation. As expected, the neurological assessment showed a high sensitivity for DABI lesions indicated using the β-APP marker. Surprisingly, however, we found that the MRI method had greater sensitivity in assessing DABI lesions compared to histological methods. Out of the five MRI parameters with pathological changes in the DABI model, we found significant changes compared to sham rats in three parameters, and, as shown using comparative tests with other models, MRI was the most sensitive parameter, being even more sensitive than histology. We anticipate that this DABI protocol will have a significant impact on future TBI and DABI studies, advancing research on treatments specifically targeted towards improving patient quality of life and long-term outcomes.

Research progress on post-stroke depression

Stroke is a highly prevalent and widely detrimental cardiovascular disease, frequently resulting in impairments of both motor function and neural psychological capabilities, such as post-stroke depression (PSD). PSD is the most prevalent neuropsychological disorder among stroke patients, characterized by persistent emotional lowness and diminished interest as its primary features. This article summarizes the mechanism research, animal models and related treatments of PSD. Further improvements are needed in the screening of research subjects and the construction of animal models in the study of PSD. At the same time, in the study of the mechanism of PSD, we need to consider the interaction between multiple systems. The treatment of PSD requires more careful consideration. This can help us to find something new in the study of the mechanism of complex PSD, which provides a new direction for us to develop new treatment delivery.

Neuroinflammation and Post-Stroke Depression: Focus on the Microglia and Astrocytes

Post-stroke depression (PSD), a frequent and disabling complication of stroke, has a strong impact on almost thirty percent of stroke survivors. The pathogenesis of PSD is not completely clear so far. Neuroinflammation following stroke is one of underlying mechanisms that involves in the pathophysiology of PSD and plays an important function in the development of depression and is regarded as a sign of depression. During the neuroinflammation after ischemic stroke onset, both astrocytes and microglia undergo a series of morphological and functional changes and play pro-inflammatory or anti-inflammatory effect in the pathological process of stroke. Importantly, astrocytes and microglia exert dual roles in the pathological process of PSD due to the phenotypic transformation. We summarize the latest evidence of neuroinflammation involving in PSD in this review, focus on the phenotypic transformation of microglia and astrocytes following ischemic stroke and reveal the dual roles of both microglia and astrocytes in the PSD via modulating the neuroinflammation.

Astrocytes in Post-Stroke Depression: Roles in Inflammation, Neurotransmission, and Neurotrophin Signaling

Post-stroke depression (PSD) is a frequent and disabling complication of stroke that affects up to one-third of stroke survivors. The pathophysiology of PSD involves multiple mechanisms, including neurochemical, neuroinflammatory, neurotrophic, and neuroplastic changes. Astrocytes are a type of glial cell that is plentiful and adaptable in the central nervous system. They play key roles in various mechanisms by modulating neurotransmission, inflammation, neurogenesis, and synaptic plasticity. This review summarizes the latest evidence of astrocyte involvement in PSD from human and animal studies, focusing on the alterations of astrocyte markers and functions in relation to monoamine neurotransmitters, inflammatory cytokines, brain-derived neurotrophic factor, and glutamate excitotoxicity. We also discuss the potential therapeutic implications of targeting astrocytes for PSD prevention and treatment. Astrocytes could be new candidates for antidepressant medications and other interventions that aim to restore astrocyte homeostasis and function in PSD. Astrocytes could be new candidates for antidepressant medications and other interventions that aim to restore astrocyte homeostasis and function in PSD.

Metabolic Alterations and Related Biological Functions of Post-Stroke Depression in Ischemic Stroke Patients

Background

Post-stroke depression (PSD) is one of the most common neuropsychiatric complications after stroke. However, the underlying mechanisms of PSD remain ambiguous, and no objective diagnosis tool is available to diagnose PSD. Previous metabolomic studies on PSD included patients with ischemic and hemorrhagic stroke indiscriminately, which is not conducive to elucidating and predicting the occurrence of PSD. The aim of this study is to elucidate the pathogenesis of PSD and provide potential diagnostic markers for PSD in ischemic stroke patients.

Methods

In total, 51 ischemic stroke patients at 2 weeks were included in this study. Those with depressive symptoms were assigned to the PSD group, while the others were assigned to the non-PSD group. Plasma metabolomics based on liquid chromatography-mass spectrometry (LC-MS) was performed to explore the differential plasma metabolites between the PSD and non-PSD groups.

Results

Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and orthogonal partial least-squares discriminant analysis (OPLS-DA) showed significant metabolic alterations between PSD patients and non-PSD patients. In total, 41 differential metabolites were screened out, mainly including phosphatidylcholines (PCs), L-carnitine and acyl carnitines, succinic acid, pyruvic acid and L-lactic acid. Metabolite-related pathway analysis revealed that alanine, aspartate and glutamate metabolism, glycerophospholipid metabolism and the citrate cycle (TCA cycle) may contribute to the pathogenesis of PSD. A panel of three signature metabolites [PC(22:5(7Z,10Z,13Z,16Z,19Z)/15:0), LysoPA(18:1(9Z)/0:0) and 1,5-anhydrosorbitol] was determined as potential biomarkers for PSD in ischemic stroke patients.

Conclusion

These findings are conducive to providing new insights into the pathogenesis of PSD and developing objective diagnostic tools for PSD in ischemic stroke patients.

Microbiota-derived short-chain fatty acids may participate in post-stroke depression by regulating host's lipid metabolism

BACKGROUND

Post-stroke depression (PSD) is a common mental disorder of stroke survivors, its pathogenesis remains elusive. Previous studies suggested a role of the microbiota-gut-brain (MGB) axis in stroke and depression. In this study, we characterized microbial composition and function, and gut-brain metabolic signatures, in PSD rats. We aim to explore how disordered gut microbes participate in the pathogenesis of PSD through the MGB axis.

MATERIALS AND METHODS

16S rRNA gene sequence and fecal metabolome analysis were performed to identify the gut microbiome and their functional metabolites in PSD rats. Then, the lipid metabolic signatures in the prefrontal cortex (PFC) of PSD were conducted by liquid chromatography mass spectrometry. Finally, the potential pathway between gut and brain in the onset of PSD were explored.

RESULTS

Compared to control and stroke rats, there were 10 genera (most of them belonged to phylum Firmicutes) significantly changed and 3 short chain fatty acids (SCFAs: butyric acid, acetic acid and pentanoic acid) significantly decreased in PSD rats. Meanwhile, altered gut microbial in PSD rats was significantly associated with these SCFAs. Compared with control and stroke rats, 57 lipid metabolites in the PFC of PSD rats were significantly changed. In addition, the altered SCFAs in PSD rats were also significantly correlated with most of disordered lipid metabolites in PFC.

CONCLUSIONS

Our findings suggest that the SCFAs may be a bridge of gut-brain communication. The Firmicutes-SCFAs-lipid metabolism might be a potential pathway to further investigate the MGB axis and pathogenesis of PSD.

The Integrity of the Blood-Brain Barrier as a Critical Factor for Regulating Glutamate Levels in Traumatic Brain Injury

A healthy blood-brain barrier (BBB) shields the brain from high concentrations of blood glutamate, which can cause neurotoxicity and neurodegeneration. It is believed that traumatic brain injury (TBI) causes long-term BBB disruption, subsequently increasing brain glutamate in the blood, in addition to increased glutamate resulting from the neuronal injury. Here, we investigate the relationship between blood and brain glutamate levels in the context of BBB permeability. Rats exposed to BBB disruption through an osmotic model or TBI and treated with intravenous glutamate or saline were compared to control rats with an intact BBB treated with intravenous glutamate or saline. After BBB disruption and glutamate administration, the concentrations of glutamate in the cerebrospinal fluid and blood and brain tissue were analyzed. The results showed a strong correlation between the brain and blood glutamate concentrations in the groups with BBB disruption. We conclude that a healthy BBB protects the brain from high levels of blood glutamate, and the permeability of the BBB is a vital component in regulating levels of glutamate in the brain. These findings bring a new approach to treating the consequences of TBI and other diseases where long-term disruption of the BBB is the central mechanism of their development.

Blood glutamate scavenging as a novel glutamate-based therapeutic approach for post-traumatic brain injury anxiety and social impairment

Traumatic brain injury (TBI) is a serious condition that is associated with an increased risk of severe, long-term psychiatric consequences. Drugs that target the glutamatergic system have proven successful in treating both TBI and many of its psychiatric sequelae. Blood glutamate scavengers (BGS) cause a decrease in blood glutamate levels, leading to a reduction in glutamate's concentration gradient from the brain to the blood and decreased levels of brain glutamate. This study evaluated the BGS pyruvate as a treatment for TBI-related neuropsychiatric conditions in a rat model. 213 rats were divided into four groups in a 2 × 2 design: Sham or TBI rats treated with pyruvate or control treatment. Magnetic resonance imaging, neurological status, brain glutamate and blood glutamate levels were assessed following the injury. Four weeks after the start of treatment, all rats underwent behavioral tests to assess anxious behavior and social impairment (aggressive and hierarchical behavior). Rats responded positively to pyruvate in several tasks, lowering brain glutamate levels and reducing anxiety and depression, as well as modulating TBI-related changes in social behavior. Glutamate scavenging with pyruvate may be an effective therapeutic option for post-TBI behavioral changes by reducing associated elevations in brain glutamate levels.

Effect of acupuncture combined with antidepressants on post-stroke depression: A network meta-analysis of nine acupuncture therapy

Background

Post-stroke depression (PSD) is a common psychiatric complication of mental disorders after stroke. Acupuncture for PSD is effective and has few adverse effects. As a classical complementary and alternative therapy, acupuncture is often used in combination with antidepressants for PSD. However, there is a wide variety of acupuncture therapies, and the efficacy of different acupuncture varies. In this study, a network meta-analysis (NMA) was used to assess the clinical efficacy of different acupuncture combined with antidepressants for the treatment of PSD.

Methods

A comprehensive search of PubMed, The Cochrane Library, EMbase, Web of Science, CNKI, CBM, VIP, and Wan-Fang databases for published randomized controlled trials of acupuncture combined with antidepressants for the treatment of PSD was conducted. The time frame for the literature search was from the date of database creation to April 30, 2022. The Cochrane risk of bias tool for randomized trials (RoB 2.0) was used to evaluate the bias risk of the included studies. Data analysis was performed by STATA 14.0 software.

Results

A total of 38 literatures with 2,898 patients involving nine acupuncture therapies were included. NMA results were as follows: moxibustion plus antidepressants had the best efficacy in terms of improving total effective rate. Conventional acupuncture plus antidepressants was the most effective in improving HAMD scores. In terms of improving SDS scores, acupressure plus antidepressants was the most effective. In terms of improving NIHSS scores, moxibustion plus antidepressants showed the best results.

Conclusion

A comparison of the efficacy indicators of the nine different acupuncture therapies combined showed that moxibustion plus antidepressants, conventional acupuncture plus antidepressants and acupressure plus antidepressants were superior in the treatment of PSD. Based on the shortcomings of the existing studies, this conclusion needs to be validated by additional high-quality randomized controlled trials.

Pathophysiology and Current Drug Treatments for Post-Stroke Depression: A Review

Post-stroke depression (PSD) is a biopsychosocial disorder that affects individuals who have suffered a stroke at any point. PSD has a 20 to 60 percent reported prevalence among stroke survivors. Its effects are usually adverse, can lead to disability, and may increase mortality if not managed or treated early. PSD is linked to several other medical conditions, including anxiety, hyper-locomotor activity, and poor functional recovery. Despite significant awareness of its adverse impacts, understanding the pathogenesis of PSD has proved challenging. The exact pathophysiology of PSD is unknown, yet its complexity has been definitively shown, involving mechanisms such as dysfunction of monoamine, the glutamatergic systems, the gut-brain axis, and neuroinflammation. The current effectiveness of PSD treatment is about 30-40 percent of all cases. In this review, we examined different pathophysiological mechanisms and current pharmacological and non-pharmacological approaches for the treatment of PSD.

Glutamate Neurotoxicity and Destruction of the Blood–Brain Barrier: Key Pathways for the Development of Neuropsychiatric Consequences of TBI and Their Potential Treatment Strategies

Traumatic brain injury (TBI) is associated with significant cognitive and psychiatric conditions. Neuropsychiatric symptoms can persist for years following brain injury, causing major disruptions in patients’ lives. In this review, we examine the role of glutamate as an aftereffect of TBI that contributes to the development of neuropsychiatric conditions. We hypothesize that TBI causes long-term blood–brain barrier (BBB) dysfunction lasting many years and even decades. We propose that dysfunction in the BBB is the central factor that modulates increased glutamate after TBI and ultimately leads to neurodegenerative processes and subsequent manifestation of neuropsychiatric conditions. Here, we have identified factors that determine the upper and lower levels of glutamate concentration in the brain after TBI. Furthermore, we consider treatments of disruptions to BBB integrity, including repairing the BBB and controlling excess glutamate, as potential therapeutic modalities for the treatment of acute and chronic neuropsychiatric conditions and symptoms. By specifically focusing on the BBB, we hypothesize that restoring BBB integrity will alleviate neurotoxicity and related neurological sequelae.

The role of damage associated molecular pattern molecules (DAMPs) and permeability of the blood-brain barrier in depression and neuroinflammation

Depression is a heterogeneous mental disorder characterized by feelings of sadness and loss of interest that render the subject unable to handle basic daily activities such as sleeping, eating, or working. Neurobiological traits leading to depression include genetic background, early life abuse, life stressors, and systemic and central inflammatory profiles. Several clinical and preclinical reports documented that depression shows an increase in pro-inflammatory markers such as interleukin (IL-)1β, IL-6, IL-12, tumor necrosis factor (TNF), and interferon (IFN)-γ; and a decrease in anti-inflammatory IL-4, IL-10, and transforming growth factor (TGF)-β species. Inflammatory activation may trigger and maintain depression. Dynamic crosstalk between the peripheral immune system and the central nervous system (CNS) such as activated endothelial cells, monocytes, monocyte-derived dendritic cells, macrophages, T cells, and microglia has been proposed as a leading cause of neuroinflammation. Notably, pro-inflammatory cytokines disrupt the hypothalamic-pituitary-adrenal (HPA) axis and serotonergic, noradrenergic, dopaminergic, and glutamatergic neurotransmission. While still under investigation, peripheral cytokines can engage brain pathways and affect the central synthesis of HPA hormones and neurotransmitters through several mechanisms such as activation of the vagus nerve, increasing the permeability of the blood-brain barrier (BBB), altered cytokines transport systems, and engaging toll-like receptors (TLRs) by pathogen-associated molecular patterns (PAMPs) or damage-associated molecular patterns (DAMPs). However, physiological mechanisms that favor time-dependent central inflammation before or during illness are not totally understood. This review will provide preclinical and clinical evidence of DAMPs and the BBB permeability as contributors to depression and neuroinflammation. We will also discuss pharmacologic approaches that could potentially modulate DAMPs and BBB permeability for future interventions against major depression.

CysLT2R Antagonist HAMI 3379 Ameliorates Post-Stroke Depression through NLRP3 Inflammasome/Pyroptosis Pathway in Gerbils

Post-stroke depression (PSD) is a kind of prevalent emotional disorder following stroke that usually results in slow functional recovery and even increased mortality. We had reported that the cysteinyl leukotriene receptor 2 (CysLT₂R) antagonist HAMI3379 (HM3379) contributes to the improvement of neurological injury. The present study was designed to investigate the role of HM3379 in PSD-induced chronic neuroinflammation and related mechanisms in gerbils. The gerbils were subjected to transient global cerebral ischemia (tGCI) and spatial restraint stress to induce the PSD model. They were randomized to receive the vehicle or HM3379 (0.1 mg/kg, i.p.) for a consecutive 14 days. In the PSD-treated gerbils, HM3379 had noteworthy efficacy in improving the modified neurological severity score (mNSS) and depression-like behaviors, including the sucrose preference test and the forced swim test. HM3379 administration significantly mitigated neuron loss, lessened TUNEL-positive neurons, and reduced the activation of microglia in the cerebral cortex. Importantly, HM3379 downregulated protein expressions of the NOD-like receptor pyrin domain containing 3 (NLRP3) inflammasome and pyroptosis including NLRP3, cleaved caspase-1, interleukin-1β (IL-1β), IL-18, cleaved gasdermin-N domain (GSDMD-N), and apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC). Mechanistically, HM3379 could repress pyroptosis via inhibiting NLRP3 inflammasome activation under oxygen-glucose deprivation (OGD) stimulation. Knockdown of CysLT₂R by short hairpin RNA (shRNA) or overexpression of CysLT₂R by lentivirus (LV)-CysLT₂R could abolish or restore the anti-depression effect of HM3379. Our results demonstrated that the selective CysLT₂R antagonist HM3379 has beneficial effects on PSD, partially by suppressing the NLRP3 inflammasome/pyroptosis pathway.

Traumatic brain injury-induced submissive behavior in rats: link to depression and anxiety

Traumatic brain injury (TBI) affects millions of people worldwide, many of whom are affected with post-TBI mood disorders or behavioral changes, including aggression or social withdrawal. Diminished functionality can persist for decades after TBI and delay rehabilitation and resumption of employment. It has been established that there is a relationship between these mental disorders and brain injury. However, the etiology and causal relationships behind these conditions are poorly understood. Rodent models provide a helpful tool for researching mood disorders and social impairment due to their natural tendencies to form social hierarchies. Here, we present a rat model of mental complications after TBI using a suite of behavioral tests to examine the causal relationships between changes in social behavior, including aggressive, hierarchical, depressive, and anxious behavior. For this purpose, we used multivariate analysis to identify causal relationships between the above post-TBI psychiatric sequelae. We performed statistical analysis using principal component analysis, discriminant analysis, and correlation analysis, and built a model to predict dominant-submissive behavior based on the behavioral tests. This model displayed a predictive accuracy of 93.3% for determining dominant-submissive behavior in experimental groups. Machine learning algorithms determined that in rats, aggression is not a principal prognostic factor for dominant-submissive behavior. Alternatively, dominant-submissive behavior is determined solely by the rats' depressive-anxious state and exploratory activity. We expect the causal approach used in this study will guide future studies into mood conditions and behavioral changes following TBI.

Peripheral blood and urine metabolites and biological functions in post-stroke depression

Post-stroke depression (PSD) is the most common and severe neuropsychiatric complication after stroke. However, the molecular mechanism of PSD is still unclear. Previous studies have identified peripheral blood and urine metabolites associated with PSD using metabolomics techniques. We searched and systematically summarized metabolites that may be involved in metabolic changes in peripheral blood and urine of patients with PSD from the Metabolite Network of Depression Database (MENDA) and other biomedical databases. MetaboAnalyst5.0 software was used for pathway analysis and enrichment analysis of differential metabolites, and subgroup analyses were performed according to tissue types and metabolomics techniques. We identified 47 metabolites that were differentially expressed between patients with and without PSD. Five differential metabolites were found in both plasma and urine, including L-glutamic acid, pyroglutamic acid, palmitic acid, L-phenylalanine, and L-tyrosine. We integrated these metabolites into metabolic pathways, and six pathways were significantly altered. These pathways could be roughly divided into three modules including amino acid metabolism, nucleotide metabolism, and glucose metabolism. Among them, the most significantly altered pathway was "phenylalanine metabolism" and the pathway containing the most associated metabolites was "aminoacyl-tRNA biosynthesis", which deserve further study to elucidate their role in the molecular mechanism of PSD. In summary, metabolic changes in peripheral blood and urine are associated with PSD, especially the disruption of "phenylalanine metabolism" and "aminoacyl-tRNA biosynthesis" pathways. This study provides clues to the metabolic characteristics of patients with PSD, which may help to elucidate the molecular pathogenesis of PSD.

The Development of Novel Drug Treatments for Stroke Patients: A Review

Acute ischemic stroke is a critical condition that can result in disability and death. The consequences of this medical condition depend on various factors, including the size of the stroke, affected brain region, treatment onset, and the type of treatment. The primary objective of stroke treatment is to restart ischemic penumbra tissue perfusion and reduce infarct volume by sustaining blood flow. Recent research on the condition’s pathological pathways and processes has significantly improved treatment options beyond restoring perfusion. Many studies have concentrated on limiting injury severity via the manipulation of molecular mechanisms of ischemia, particularly in animal research. This article reviews completed and ongoing research on the development of acute ischemic stroke drugs. This study focuses on three main categories of antithrombotic drugs, thrombolytic drugs, and neuroprotective agents. The paper outlines findings from animal and clinical trials and explores the working mechanisms of these drugs.

Glutamate Efflux across the Blood–Brain Barrier: New Perspectives on the Relationship between Depression and the Glutamatergic System

Depression is a significant cause of disability and affects millions worldwide; however, antidepressant therapies often fail or are inadequate. Current medications for treating major depressive disorder can take weeks or months to reach efficacy, have troubling side effects, and are limited in their long-term capabilities. Recent studies have identified a new set of glutamate-based approaches, such as blood glutamate scavengers, which have the potential to provide alternatives to traditional antidepressants. In this review, we hypothesize as to the involvement of the glutamate system in the development of depression. We identify the mechanisms underlying glutamate dysregulation, offering new perspectives on the therapeutic modalities of depression with a focus on its relationship to blood–brain barrier (BBB) permeability. Ultimately, we conclude that in diseases with impaired BBB permeability, such as depression following stroke or traumatic brain injury, or in neurogenerative diseases, the glutamate system should be considered as a pathway to treatment. We propose that drugs such as blood glutamate scavengers should be further studied for treatment of these conditions.

Blood Glutamate Scavenging With Pyruvate as a Novel Preventative and Therapeutic Approach for Depressive-Like Behavior Following Traumatic Brain Injury in a Rat Model

Depression is a common and serious complication following traumatic brain injury (TBI). Both depression and TBI have independently been associated with pathologically elevated extracellular brain glutamate levels. In the setting of TBI, blood glutamate scavenging with pyruvate has been widely shown as an effective method to provide neuroprotection by reducing blood glutamate and subsequent brain glutamate levels. Here we evaluate pyruvate as a novel approach in the treatment and prevention of post-TBI depression-like behavior in a rat model. Rats were divided into five groups: (1) sham-operated control with pyruvate, (2) sham-operated control with placebo, (3) post-TBI with placebo, (4) post-TBI given preventative pyruvate, and (5) post-TBI treated with pyruvate. These groups had an equal number of females and males. Rats were assessed for depressive-like behavior, neurological status, and glutamate levels in the blood and brain. Post-TBI neurological deficits with concurrent elevations in glutamate levels were demonstrated, with peak glutamate levels 24 h after TBI. Following TBI, the administration of either prophylactic or therapeutic pyruvate led to reduced glutamate levels, improved neurologic recovery, and improved depressive-like behavior. Glutamate scavenging with pyruvate may be an effective prophylactic and therapeutic option for post-TBI depression by reducing associated elevations in brain glutamate levels.

A New NF-κB Inhibitor, MEDS-23, Reduces the Severity of Adverse Post-Ischemic Stroke Outcomes in Rats

Aim: Nuclear factor kappa B (NF-κB) is known to play an important role in the inflammatory process which takes place after ischemic stroke. The major objective of the present study was to examine the effects of MEDS-23, a potent inhibitor of NF-κB, on clinical outcomes and brain inflammatory markers in post-ischemic stroke rats. Main methods: Initially, a Toxicity Experiment was performed to determine the appropriate dose of MEDS-23 for use in animals, as MEDS-23 was analyzed in vivo for the first time. We used the middle cerebral artery occlusion (MCAO) model for inducing ischemic stroke in rats. The effects of MEDS-23 (at 10 mg/kg, ip) on post-stroke outcomes (brain inflammation, fever, neurological deficits, mortality, and depression- and anxiety-like behaviours) was tested in several efficacy experiments. Key findings: MEDS-23 was found to be safe and significantly reduced the severity of some adverse post-stroke outcomes such as fever and neurological deficits. Moreover, MEDS-23 significantly decreased prostaglandin E2 levels in the hypothalamus and hippocampus of post-stroke rats, but did not prominently alter the levels of interleukin-6 and tumor necrosis factor-α. Significance: These results suggest that NF-κB inhibition is a potential therapeutic strategy for the treatment of ischemic stroke.

A Novel Histological Technique to Assess Severity of Traumatic Brain Injury in Rodents: Comparisons to Neuroimaging and Neurological Outcomes

Here we evaluate an alternative protocol to histologically examine blood-brain barrier (BBB) breakdown, brain edema, and lesion volume following traumatic brain injury (TBI) in the same set of rodent brain samples. We further compare this novel histological technique to measurements determined by magnetic resonance imaging (MRI) and a neurological severity score (NSS). Sixty-six rats were randomly assigned to a sham-operated, mild TBI, moderate TBI, or severe TBI group. 48 h after TBI, NSS, MRI and histological techniques were performed to measure TBI severity outcome. Both the histological and MRI techniques were able to detect measurements of severity outcome, but histologically determined outcomes were more sensitive. The two most sensitive techniques for determining the degree of injury following TBI were NSS and histologically determined BBB breakdown. Our results demonstrate that BBB breakdown, brain edema, and lesion volume following TBI can be accurately measured by histological evaluation of the same set of brain samples.

Skeletal Muscle Metabolomic Responses to Endurance and Resistance Training in Rats under Chronic Unpredictable Mild Stress

The objectives of this study were to compare the antidepressant effects between endurance and resistance exercise for optimizing interventions and examine the metabolomic changes in different types of skeletal muscles in response to the exercise, using a rat model of chronic unpredictable mild stress (CUMS)-induced depression. There were 32 male Sprague-Dawley rats randomly divided into a control group (C) and 3 experimental groups: CUMS control (D), endurance exercise (E), and resistance exercise (R). Group E underwent 30 min treadmill running, and group R performed 8 rounds of ladder climbing, 5 sessions per week for 4 weeks. Body weight, sucrose preference, and open field tests were performed pre and post the intervention period for changes in depressant symptoms, and the gastrocnemius and soleus muscles were sampled after the intervention for metabolomic analysis using the ¹H-NMR technique. The results showed that both types of exercise effectively improved the depression-like symptoms, and the endurance exercise appeared to have a better effect. The levels of 10 metabolites from the gastrocnemius and 13 metabolites from the soleus of group D were found to be significantly different from that of group C, and both types of exercise had a callback effect on these metabolites, indicating that a number of metabolic pathways were involved in the depression and responded to the exercise interventions.

The gut microbiota metabolite propionate ameliorates intestinal epithelial barrier dysfunction-mediated Parkinson's disease via the AKT signaling pathway

OBJECTIVE

Parkinson's disease is a common neurodegenerative disease. Here, we investigated the protective effect and potential mechanisms of propionate on the intestinal epithelial barrier in mice with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced Parkinson's disease.

METHODS

Gas chromatography was used to determine short-chain fatty acids (SCFA) concentrations in the fecal samples of Parkinson's disease patients and healthy controls. The stepping test was used to analyze forelimb akinesia, whisker test was used to analyze sensorimotor injury, cylinder test was used to analyze sensorimotor function, and Western blotting was used to analyze protein expression.

RESULTS

The concentrations of SCFAs, including acetate, butyrate and propionate, were significantly downregulated in the fecal samples of Parkinson's disease patients, and among the SCFAs, propionate decreased the most. Propionate administration improved the stepping test score, whisker test score and cylinder test score of MPTP-induced Parkinson's disease mice. Additionally, propionate administration increased the protein expression of zonula occludens-1 and occludin. Moreover, the effects of propionate on motor behavior and the intestinal epithelial barrier were dependent on the proteirrserinc-threonine kinases (AKT) signaling pathway. More importantly, treatment with SC79, a specific AKT agonist, abolished the effects of propionate on the intestinal epithelial barrier and motor behavior.

CONCLUSION

Our results demonstrated that propionate, which was decreased in the fecal samples of Parkinson's disease patients, exerted beneficial effects on intestinal epithelial barrier function and improved motor behavior in MPTP-induced Parkinson's disease mice through the AKT signaling pathway.

Post-stroke depression: Chaos to exposition

Cerebral ischemia contributes to significant disabilities worldwide, impairing cognitive function and motor coordination in affected individuals. Stroke has severe neuropsychological outcomes, the major one being a stroke. Stroke survivors begin to show symptoms of depression within a few months of the incidence that overtime progresses to become a long-term ailment. As the pathophysiology for the progression of the disease is multifactorial and complex, it limits the understanding of the disease mechanism completely. Meta-analyses and randomized clinical trials have shown that intervening early with tricyclic antidepressants and selective serotonin receptor inhibitors can be effective. However, these pharmacotherapies possess several limitations that have given rise to newer approaches such as brain stimulation, psychotherapy and rehabilitation therapy, which in today's time are gaining attention for their beneficial results in post-stroke depression (PSD). The present review highlights numerous factors like lesion location, inflammatory mediators and genetic abnormalities that play a crucial role in the development of depression in stroke patients. Further, we have also discussed various mechanisms involved in post-stroke depression (PSD) and strategies for early detection and diagnosis using biomarkers that may revolutionize treatment for the affected population. Towards the end, along with the preclinical scenario, we have also discussed the various treatment approaches like pharmacotherapy, traditional medicines, psychotherapy, electrical stimulation and microRNAs being utilized for effectively managing PSD.

Post-stroke depression: A 2020 updated review

BACKGROUND

Post-stroke depression (PSD) is common and associated with higher mortality, poorer recovery, more pronounced cognitive deficits, and lower quality of life than is stroke without depression. This manuscript will conduct an updated, comprehensive and clinically-useful review of the risk factors, pathophysiology, assessment, prevention, and treatment of PSD.

METHODS

This narrative review summarizes articles obtained on PubMed, Medline, EMBase, Google Scholar and the Cochrane Database. This review prioritized articles with a more robust level of evidence, such as original articles with longitudinal data and/or larger samples, randomized controlled trials, systematic reviews, and metaanalyses.

RESULTS

One hundred twenty-four articles were reviewed, of which 44 (35%) were published before 2016 and 80 (65%) that were published since 2016.

DISCUSSION

Rates of PSD range from 18 to 33%, yet it is vastly underdiagnosed and undertreated. Risk factors for PSD include female sex, history of psychiatric illness, large or multiple strokes, injuries in frontal/anterior areas or in the basal ganglia, stroke occurrence within the past year, poor social support, and pronounced disability. The pathophysiology of PSD is multifactorial and likely involves decreased levels of monoamines, abnormal neurotrophic response, increased inflammation with dysregulation of hypothalamic-pituitary-adrenal axis, and glutamate-mediated excitotoxicity. The evidence for preventive interventions for PSD is somewhat inconsistent and modest. The best treatment for PSD consists of the combination of pharmacological, psychosocial and stroke-focused interventions.

CONCLUSION

PSD is a common, treatable condition that is associated with several negative outcomes. Early detection and proper management are critical to obtain better outcomes in individuals with PSD.

Targeting the NF-κB pathway for therapy of ischemic stroke

Ischemic strokes occur when a major cerebral artery or its branches are occluded, resulting in activation of inflammatory processes that cause secondary tissue injury, breakdown of the blood–brain barrier, edema or hemorrhage. Treatments that inhibit inflammatory processes may thus be highly beneficial. A key regulator of the inflammatory process is the nuclear factor kappa B (NF-κB) pathway. In its active form, NF-κB regulates expression of proinflammatory and proapoptotic genes. The molecules that interact with NF-κB, and the subunits that compose NF-κB itself, represent therapeutic targets that can be modulated to decrease inflammation. This review focuses on our current understanding of the NF-κB pathway and the potential benefits of inhibiting NF-κB in ischemia-reperfusion injury of the brain.

Glutamate Systems in DSM-5 Anxiety Disorders: Their Role and a Review of Glutamate and GABA Psychopharmacology

Serotonin reuptake inhibitors and benzodiazepines are evidence-based pharmacological treatments for Anxiety Disorders targeting serotonin and GABAergic systems, respectively. Although clearly effective, these medications fail to improve anxiety symptoms in a significant proportion of patients. New insights into the glutamate system have directed attention toward drugs that modulate glutamate as potential alternative treatments for anxiety disorders. Here we summarize the current understanding of the potential role of glutamate neurotransmission in anxiety disorders and highlight specific glutamate receptors that are potential targets for novel anxiety disorder treatments. We also review clinical trials of medications targeting the glutamate system in DSM-5 anxiety disorders. Understanding the role of the glutamate system in the pathophysiology of anxiety disorder may aid in developing novel pharmacological agents that are effective in treating anxiety disorders.

Blood glutamate scavenging as a novel glutamate-based therapeutic approach for post-stroke depression

Post-stroke depression (PSD) is a major complication of stroke that significantly impacts functional recovery and quality of life. While the exact mechanism of PSD is unknown, recent attention has focused on the association of the glutamatergic system in its etiology and treatment. Minimizing secondary brain damage and neuropsychiatric consequences associated with excess glutamate concentrations is a vital part of stroke management. The blood glutamate scavengers, oxaloacetate and pyruvate, degrade glutamate in the blood to its inactive metabolite, 2-ketoglutarate, by the coenzymes glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT), respectively. This reduction in blood glutamate concentrations leads to a subsequent shift of glutamate down its concentration gradient from the blood to the brain, thereby decreasing brain glutamate levels. Although there are not yet any human trials that support blood glutamate scavengers for clinical use, there is increasing evidence from animal research of their efficacy as a promising new therapeutic approach for PSD. In this review, we present recent evidence in the literature of the potential therapeutic benefits of blood glutamate scavengers for reducing PSD and other related neuropsychiatric conditions. The evidence reviewed here should be useful in guiding future clinical trials.

A Novel Method for Assessing Cerebral Edema, Infarcted Zone and Blood-Brain Barrier Breakdown in a Single Post-stroke Rodent Brain

Stroke is a major cause of global morbidity and mortality. Middle cerebral artery occlusion (MCAO) has historically been the most common animal model of simulating ischemic stroke. The extent of neurological injury after MCAO is typically measured by cerebral edema, infarct zone, and blood-brain barrier (BBB) permeability. A significant limitation of these methods is that separate sets of brains must be used for each measurement. Here we examine an alternative method of measuring cerebral edema, infarct zone and BBB permeability following MCAO in the same set of brain samples. Ninety-six rats were randomly divided into three experimental groups. Group 1 (n = 27) was used for the evaluation of infarct zone and brain edema in rats post-MCAO (n = 17) vs. sham-operated controls (n = 10). Group 2 (n = 27) was used for the evaluation of BBB breakdown in rats post-MCAO (n = 15) vs. sham-operated controls (n = 10). In Group 3 (n = 42), all three parameters were measured in the same set of brain slices in rats post-MCAO (n = 26) vs. sham-operated controls (n = 16). The effect of Evans blue on the accuracy of measuring infarct zone by 2,3,5-triphenyltetrazolium chloride (TTC) staining was determined by measuring infarct zone with and without an applied blue filter. The effects of various concentrations of TTC (0, 0.05, 0.35, 0.5, 1, and 2%) on the accuracy of measuring BBB permeability was also assessed. There was an increase in infarct volume (p < 0.01), brain edema (p < 0.01) and BBB breakdown (p < 0.01) in rats following MCAO compared to sham-operated controls, whether measured separately or together in the same set of brain samples. Evans blue had an effect on measuring infarct volume that was minimized by the application of a blue filter on scanned brain slices. There was no difference in the Evans blue extravasation index for the brain tissue samples without TTC compared to brain tissue samples incubated in TTC. Our results demonstrate that measuring cerebral edema, infarct zone and BBB permeability following MCAO can accurately be measured in the same set of brain samples.