Cyclooxygenase-2 inhibition protects cultured cerebellar granule neurons from glutamate-mediated cell death

Agmatine inhibits NMDA receptor-mediated calcium transients in mouse spinal cord dorsal horn via intact PSD95-nNOS signaling

Intrathecal administration of agmatine, an NMDA receptor (NMDAr) antagonist and nitric oxide synthase inhibitor, prevents neuropathic pain behavior in a dose-dependent manner by acting at the GluN2B subunit of the NMDAr. The present study investigated the pharmacological mechanism of agmatine's inhibitory effect using calcium imaging and an in vivo assay of nociceptive responses induced by NMDA. The application of NMDA-evoked calcium transients in the mouse spinal cord dorsal horn slice was inhibited by the NMDAr antagonist, 2-amino-5-phosphonovalerate. Agmatine also concentration-dependently inhibited NMDA-evoked calcium responses. To evaluate the role of the GluN2B subunit of the NMDAr in the agmatine response, we conditionally knocked-down Grin2B, the gene encoding GluN2B, in spinal cord dorsal horn neurons (GluN2B knockdown [GluN2B-KD]). In control spinal cord slices, ifenprodil inhibited NMDAr-mediated calcium transients, but it was not effective in GluN2B-KD. Surprisingly, agmatine was equally effective in reducing calcium transients in control and GluN2B-KD mouse spinal cord slices. To determine whether the effect of agmatine could be attributed to an action downstream of the NMDAr (eg, neuronal nitric oxide synthase [nNOS]), we used the PSD95-nNOS tethering inhibitor, IC87201, to disrupt the link between NMDAr and nNOS. In the presence of IC87201, agmatine's attenuation of NMDA-evoked calcium transients in ex vivo spinal cord dorsal horn was significantly reversed as was agmatine's antihyperalgesic effect in the intrathecal NMDA-evoked thermal hyperalgesia in vivo model. These results indicated that agmatine requires an intact NMDAr-PSD95-nNOS pathway to attenuate NMDAr-mediated calcium transients and thermal hyperalgesia induced by intrathecal NMDA. SIGNIFICANCE STATEMENT: Chronic pain is an urgent public health concern, and effective long-term treatments are still needed. Agmatine reduces pain in preclinical models without the side effects of motor dysfunction or addiction. Clarifying the pharmacological mechanism of agmatine's analgesic effect in spinal neurotransmission may facilitate the development of novel pain-alleviating therapeutics.

Early Celecoxib Use in Spontaneous Intracerebral Hemorrhage is Associated with Reduced Mortality

BACKGROUND

Hemorrhagic strokes constitute 10-15% of all strokes and have the worst mortality and morbidity of all subtypes. Mortality and morbidity of spontaneous intracerebral hemorrhage (sICH) are often secondary to the effects of inflammation, brain edema, and swelling. Studies have shown that celecoxib, a selective cyclooxygenase 2 (COX-2) inhibitor, reduces perihematomal edema formation and inflammation. This study aimed to examine the impact of celecoxib on sICH outcomes.

METHODS

TriNetX, a multi-institutional research database, was retrospectively queried to identify patients with sICH. Outcomes in patients who received celecoxib within 5 days (cohort 1) were analyzed and compared to those in patients who did not receive celecoxib (cohort 2). The primary end point was mortality within 1 year of sICH. Secondary end points included ventilator dependence, tracheostomy, percutaneous endoscopic gastrostomy tube placement, craniotomy, deep venous thrombosis, pulmonary embolism, ischemic stroke, transient ischemia attack, myocardial infarction, and seizures. Further analysis was performed to assess these outcomes for patients treated with ibuprofen, a nonselective COX inhibitor.

RESULTS

After propensity score matching, 833 patients were identified in each cohort based on celecoxib use. Mortality at 1 year was significantly reduced in patients with sICH receiving celecoxib compared to those who did not (13.33% vs. 17.77%; p = 0.0124). Risks of ventilator dependence, tracheostomy, percutaneous endoscopic gastrostomy tube placement, craniotomy, deep venous thrombosis, pulmonary embolism, ischemic stroke, transient ischemia attack, myocardial infarction, and seizures were not significantly increased in patients who received celecoxib within 5 days of sICH compared to those who did not receive celecoxib. There was no significant difference in mortality between patients based on ibuprofen administration.

CONCLUSIONS

There exists a growing interest in using COX-2 as a potential target strategy for neuroprotection in patients with sICH, with some evidence of a mortality benefit in small cohort studies. This study shows that early celecoxib use is associated with decreased mortality in patients with sICH.

Indian Hedgehog (IHh) Protein and COX-2 as Biomarkers to Define the Mechanism of Epilepsy and Gastrointestinal Problems as Comorbid Medical Illnesses in Autism Spectrum Disorder: Combining ROC Curves to Improve Diagnostic Values

Background/Objectives: Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is increasing throughout the world. Nevertheless, no specific diagnostic or even risk assessment marker is available. Combining more than one marker can improve the diagnostic value of each marker alone and maximize the AUC for ROC curve. Hedgehog (Hh) signaling modulates both intestinal inflammation and immunity. Cyclooxygenase-2 (COX-2) is required for inflammation, and it has been related to epileptic seizures. COX-2 generates prostaglandins-EP2 (PGE2) in the brain, which plays a major role in neuropathology and epilepsy. This study aims to understand the pathophysiology of ASD by investigating the diagnostic value of COX-2 and IHh using independent and combined ROC curves. Methods: COX-2 and IHh were measured in 40 children with ASD and 41 age and sex-matched controls using ELISA. Statistical analyses were performed using ROC curves, odds ratios, and multiple logistic regression models. Results: Higher levels of COX-2 and IHh were observed in the plasma of patients with autism than in controls. The ROC curve of HIh and COX-2 independently showed poor and fair AUCs of 0.662 and 0.776, respectively, while the combined ROC for both variables in relation to the control group increased the AUC = 0.831 significantly (p < 0.001). Conclusions: Thus, combining these variables could be a useful diagnostic marker for ASD.

Early alterations in the MCH system link aberrant neuronal activity and sleep disturbances in a mouse model of Alzheimer's disease

Early Alzheimer's disease (AD) is associated with hippocampal hyperactivity and decreased sleep quality. Here we show that homeostatic mechanisms transiently counteract the increased excitatory drive to CA1 neurons in App^NL-G-F mice, but that this mechanism fails in older mice. Spatial transcriptomics analysis identifies Pmch as part of the adaptive response in App^NL-G-F mice. Pmch encodes melanin-concentrating hormone (MCH), which is produced in sleep-active lateral hypothalamic neurons that project to CA1 and modulate memory. We show that MCH downregulates synaptic transmission, modulates firing rate homeostasis in hippocampal neurons and reverses the increased excitatory drive to CA1 neurons in App^NL-G-F mice. App^NL-G-F mice spend less time in rapid eye movement (REM) sleep. App^NL-G-F mice and individuals with AD show progressive changes in morphology of CA1-projecting MCH axons. Our findings identify the MCH system as vulnerable in early AD and suggest that impaired MCH-system function contributes to aberrant excitatory drive and sleep defects, which can compromise hippocampus-dependent functions.

Effects of Pregnant Fatigue on the Development of Offspring in Rats

AIM

To explore the correlation between pregnant fatigue and intrauterine physical and neural development of offspring in rats.

METHODS

Sprague-Dawley pregnant rats were randomly divided into a normal control group, a mild fatigue group (stand in water for 6 hours/day), and a severe fatigue group (stand in water for 15 h/day). The levels of lactic acid, 5-Hydroxytryptamine and Interleukin-6 in cardiac serum of rats were used to evaluate the fatigue. The expression of S100β in the telencephalon, Insulin-like growth factor-1 (IGF-1) in the liver and Cyclooxygenage-2 (COX-2) in the small intestine tissues of fetal rats were examined. Frozen sections were taken from the telencephalon of rat pups to observe morphological changes in the hippocampal primordium.

RESULTS

Pregnant fatigue led to a decrease in food intake (F = 37.586, p = 0.000) and water intake (F = 23.608, p = 0.000) in rats. The IGF-1 mRNA expression of fetal rats in the severe fatigue group was lower than that in the control group (p = 0.0003). The expression of S100β mRNA (p = 0.000) and COX-2 mRNA (p = 0.0002) of fetal rats were higher in the severe fatigue group than in the control group. HE staining of the telencephalon of fetal rats in the pregnant fatigue group revealed sparse and irregular cell arrangement and increased gaps in the hippocampal primordial site.

CONCLUSION

Pregnant fatigue rats had both physical fatigue and mental fatigue. Fatigue during pregnancy affects physical development and neurodevelopment of offspring. Further research should elucidate the mechanisms of pregnant fatigue and its effects on offspring.

LC-MS/MS-based arachidonic acid metabolomics in acute spinal cord injury reveals the upregulation of 5-LOX and COX-2 products

Arachidonic acid (AA) plays a critical role in inflammatory regulation and secondary injury after spinal cord injury (SCI). However, the overall AA metabolism profile in the acute phase of SCI remains elusive. Here we quantified AA metabolomics by High Performance Liquid Chromatography-Tandem Mass Spectrometry-Based Method (LC-MS/MS) using spinal cord tissue collected at 4 h, 24 h and 48 h after contusive SCI in rats. Remarkably, Prostaglandin E2 (PGE2) and Leukotriene B4 (LTB4) were significantly increased throughout the acute SCI. Cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX), the key enzymes involved in the production of PGE2 and LTB4, were elevated in the lesioned spinal cord tissue, validated by both western blot and immunofluorecnce. The spatial-temporal changes of COX-2 and 5-LOX mainly occurs in neurons both in epicenter and rostral and caudal spinal cord segments after SCI. Our study sheds light on the dynamic microenvironment changes in acute SCI by characterizing the profile of AA metabolism. The COX-2 and 5-LOX may be promising therapeutic target for SCI.

A multiomics and network pharmacological study reveals the neuroprotective efficacy of Fu-Fang-Dan-Zhi tablets against glutamate-induced oxidative cell death

Neuroprotective therapy after ischemic stroke remains a significant need, but current measures are still insufficient. The Fu-Fang-Dan-Zhi tablet (FFDZT) is a proprietary Chinese medicine clinically employed to treat ischemic stroke in the recovery period. This work aims to systematically investigate the neuroprotective mechanism of FFDZT. A systems strategy that integrated metabolomics, transcriptomics, network pharmacology, and in vivo and in vitro experiments was used. First, middle cerebral artery occlusion (MCAO) model rats were treated with FFDZT. FFDZT treatment significantly reduced the infarct volume in the brains of middle cerebral artery occlusion (MCAO) model rats. Then, samples of serum and brain tissue were taken for metabolomics and transcriptomics studies, respectively; gene expression profiles of MCF7 cells treated with FFDZT and its 4 active compounds (senkyunolide I, formononetin, drilodefensin, and tanshinone IIA) were produced for CMAP analysis. Computational analysis of metabolomics and transcriptomics results suggested that FFDZT regulated glutamate and oxidative stress-related metabolites (2-hydroxybutanoic acid and 2-hydroxyglutaric acid), glutamate receptors (NMDAR, KA, and AMPA), glutamate involved pathways (glutamatergic synapse pathway; d-glutamine and d-glutamate metabolism; alanine, aspartate and glutamate metabolism), as well as the reactive oxygen species metabolic process. CMAP analysis indicated that two active ingredients of FFDZT (tanshinone ⅡA and senkyunolide I) could act as glutamate receptor antagonists. Next, putative therapeutic targets of FFDZT's active ingredients identified in the brain were collected from multiple resources and filtered by statistical criteria and tissue expression information. Network pharmacological analysis revealed extensive interactions between FFDZT's putative targets, anti-IS drug targets, and glutamate-related enzymes, while the resulting PPI network exhibited modular topology. The targets in two of the modules were significantly enriched in the glutamatergic synapse pathway. The interactions between FFDZT's ingredients and important targets were verified by molecular docking. Finally, in vitro experiments validated the effects of FFDZT and its ingredients in suppressing glutamate-induced PC12 cell injury and reducing the generation of reactive oxygen species. All of our findings indicated that FFDZT's efficacy for treating ischemic stroke could be due to its neuroprotection against glutamate-induced oxidative cell death.

P-glycoprotein: new insights into structure, physiological function, regulation and alterations in disease

The multidrug resistance phenomenon presents a major threat to the pharmaceutical industry. This resistance is a common occurrence in several diseases and is mediated by multidrug transporters that actively pump substances out of the cell and away from their target regions. The most well-known multidrug transporter is the P-glycoprotein transporter. The binding sites within P-glycoprotein can accommodate a variety of compounds with diverse structures. Hence, numerous drugs are P-glycoprotein substrates, with new ones being identified every day. For many years, the mechanisms of action of P-glycoprotein have been shrouded in mystery, and scientists have only recently been able to elucidate certain structural and functional aspects of this protein. Although P-glycoprotein is highly implicated in multidrug resistant diseases, this transporter also performs various physiological roles in the human body and is expressed in several tissues, including the brain, kidneys, liver, gastrointestinal tract, testis, and placenta. The expression levels of P-glycoprotein are regulated by different enzymes, inflammatory mediators and transcription factors; alterations in which can result in the generation of a disease phenotype. This review details the discovery, the recently proposed structure and the regulatory functions of P-glycoprotein, as well as the crucial role it plays in health and disease.

Application potential of modulation of cyclooxygenase-2 activity: a cognitive approach

Cognitive functions of the brain depend largely on the condition of the cell membranes and the proportion of fatty acids. It is known and accepted that arachidonic acid (AA) is one of the main ω-6 fatty acids (phospholipids) in brain cells. Metabolism of that fatty acid depends on the functionality and presence of cyclooxygenase (COX). COX is a primary enzyme in the cycle of transformation of AA to prostanoids, which may mediate response of immune cells, contributing to brain function and cognition. Two COX isoforms (COX-1 and COX-2), as well as a splice variant (COX-3), have been detected in the brain. Findings released in the last decade showed that COX-2 may play an important role in cognition. There are many preclinical and clinical reports showing its engagement in Alzheimer disease, spatial learning, and plasticity. This manuscript focuses on summarizing the above-mentioned discoveries.

Arbutin attenuates monosodium L-glutamate induced neurotoxicity and cognitive dysfunction in rats

Excitotoxicity, oxidative stress, and neuro-inflammation underlie the pathogenesis of neurodegenerative brain disorders. Although L-glutamate is the prime excitatory neurotransmitter involved in diverse brain functions, however, overabundance at synapse can activate cell death mechanisms. Previous studies indicate that arbutin affords relief in metabolic, cardiovascular, and gastrointestinal disorders. Recently, arbutin showed benefits in animal models of epilepsy, Parkinson's disease, and Alzheimer's disease that further expanded its therapeutic potential against brain disorders. In the present study, we aimed to evaluate the potential of arbutin against monosodium L-glutamate (MSG) neurotoxicity in rats. Wistar rats (male, 180-200 g) were administered MSG (4 mg/kg) and arbutin (50 and 100 mg/kg) intraperitoneally for 21 days. Cognitive functions were assessed using elevated plus maze and novel object recognition task. Biochemical parameters of oxidative stress, tumour necrosis factor-α (TNF-α), γ-amino butyric acid (GABA), acetylcholinesterase (AChE) activity, lactate dehydrogenase (LDH), and intracellular cation-levels (Na+, Ca2+, K+) were determined using whole brain. Administration of MSG augmented cation-levels, oxidative stress, inflammation, AChE, and LDH activities, and decreased GABA levels in the brain. Arbutin (50 and 100 mg/kg, i.p.) significantly decreased these biochemical disturbances in the brain of MSG administered rats. Behavioural results showed that MSG triggered cognitive deficits in rats that were significantly attenuated by arbutin. Histopathological findings in hippocampus and cortex revealed neuroprotective outcome of arbutin treatments against MSG. MK-801 and N(G)-nitro-L-arginine methyl ester (L-NAME) enhanced memory and neuroprotective effects in rats treated with arbutin and MSG. Arbutin may afford therapeutic advantages in neurodegenerative brain disorders by suppressing the excitotoxic pathways.

Deciphering the mechanisms of regulation of an excitatory synapse via cyclooxygenase-2. A review

Cyclooxygenase (COX) is a heme-containing enzyme that produces prostaglandins (PGs) via a pathway known as the arachidonic acid (AA) cascade. Two isoforms of COX enzyme (COX-1 and COX-2) and splice variant (COX-3) have been described so far. COX-2 is a neuronal enzyme that is intensively produced during activation of the synapse and glutamate (Glu) release. The end product of COX-2 action, prostaglandin E2 (PGE2), regulates Glu level in a retrograde manner. At the same time, the level of Glu, the primary excitatory neurotransmitter, is regulated in the excitatory synapse via Glu receptors, both ionotropic and metabotropic ones. Glu receptors are known modulators of behavior, engaged in cognition and mood. So far, the interaction between ionotropic N-methyl-D-aspartate (NMDA) receptors or metabotropic glutamate (mGluRs) receptors and COX-2 was found. Here, based on literature data and own research, a new mechanism of action of COX-2 in an excitatory synapse will be presented.

Tyrosine phosphatase STEP is a key regulator of glutamate-induced prostaglandin E2 release from neurons

The neuron-specific tyrosine phosphatase striatal-enriched phosphatase (STEP) is emerging as a key regulator of excitotoxicity, which is involved in the pathogenesis of both acute and chronic neurological diseases. However, the intracellular mechanisms that are regulated by STEP to confer neuroprotection against excitotoxic insults are not well understood. The present study investigates the role of STEP in regulating neuronal release of the proinflammatory prostanoid prostaglandin E2 (PGE2), which is associated with a wide range of pathological conditions. The findings show that glutamate-mediated activation of the N-methyl-D-aspartic acid receptor in STEP-deficient neurons leads to rapid and sustained increase in the phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), a signaling molecule involved in the production of inflammatory mediators. Such sustained p38 MAPK activation increases the activity of cytosolic phospholipase A2, which catalyzes the release of arachidonic acid, the initial substrate for PGE2 biosynthesis. Sustained p38 MAPK activation also induces nuclear factor-κB-mediated increase in expression of cyclooxygenase-2 that is involved in the conversion of arachidonic acid to prostanoids, resulting in enhanced biosynthesis and release of PGE2 from neurons. Restoration of STEP function with a STEP mimetic (TAT-STEP-myc peptide) significantly decreases the activation of p38 MAPK-mediated cytosolic phospholipase A2/cyclooxygenase-2/PGE2 signaling cascade. This study identifies an important mechanism involved in the neuronal release of the proinflammatory mediator PGE2 after excitotoxic insult and highlights for the first time the immunomodulatory ability of a neuronal tyrosine phosphatase.

D-dopachrome tautomerase activates COX2/PGE2 pathway of astrocytes to mediate inflammation following spinal cord injury

Background

Astrocytes are the predominant glial cell type in the central nervous system (CNS) that can secrete various cytokines and chemokines mediating neuropathology in response to danger signals. D-dopachrome tautomerase (D-DT), a newly described cytokine and a close homolog of macrophage migration inhibitory factor (MIF) protein, has been revealed to share an overlapping function with MIF in some ways. However, its cellular distribution pattern and mediated astrocyte neuropathological function in the CNS remain unclear.

Methods

A contusion model of the rat spinal cord was established. The protein levels of D-DT and PGE₂ synthesis-related proteinase were assayed by Western blot and immunohistochemistry. Primary astrocytes were stimulated by different concentrations of D-DT in the presence or absence of various inhibitors to examine relevant signal pathways. The post-injury locomotor functions were assessed using the Basso, Beattie, and Bresnahan (BBB) locomotor scale.

Results

D-DT was inducibly expressed within astrocytes and neurons, rather than in microglia following spinal cord contusion. D-DT was able to activate the COX2/PGE₂ signal pathway of astrocytes through CD74 receptor, and the intracellular activation of mitogen-activated protein kinases (MAPKs) was involved in the regulation of D-DT action. The selective inhibitor of D-DT was efficient in attenuating D-DT-induced astrocyte production of PGE₂ following spinal cord injury, which contributed to the improvement of locomotor functions.

Conclusion

Collectively, these data reveal a novel inflammatory activator of astrocytes following spinal cord injury, which might be beneficial for the development of anti-inflammation drug in neuropathological CNS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02186-z.

Investigational and Experimental Drugs to Treat Obsessive-Compulsive Disorder

Treatment-resistance is a frequent condition for obsessive-compulsive disorder (OCD). Over the past decades, a lot of effort has been made to address this issue, and several augmentation strategies of serotonergic drugs have been investigated. Antidopaminergic drugs are considered the first choice as augmentation strategy for treatment-resistant OCD patients, but they seem to work only for a subset of patients, and none of them have been officially approved for OCD. Recently, the role of glutamate and inflammation in OCD pathophysiology clearly emerged, and this has led to several investigations on glutamatergic and anti-inflammatory agents. Results seem promising but still inconclusive. Probiotic interventions (considered to modulate the immune systems and the brain activity) are gaining attention in several psychiatric fields but are still at their early stages in the OCD field. Research on new treatment approaches for OCD is moving forward, and more than one hundred interventional trials are ongoing around the world. While the vast majority of these trials involve neuromodulation and psychotherapeutic approaches, only a small proportion (around 20%) involve the investigation of new pharmacological approaches (tolcapone, nabilone, psilocybin, troriluzole, nitrous oxide, rituximab, naproxen, and immunoglobulins). Here, we provide a comprehensive review of investigational and experimental drugs to treat OCD.

Possible interplay between the theories of pharmacoresistant epilepsy

Epilepsy is one of the oldest known neurological disorders and is characterized by recurrent seizure activity. It has a high incidence rate, affecting a broad demographic in both developed and developing countries. Comorbid conditions are frequent in patients with epilepsy and have detrimental effects on their quality of life. Current management options for epilepsy include the use of anti-epileptic drugs, surgery, or a ketogenic diet. However, more than 30% of patients diagnosed with epilepsy exhibit drug resistance to anti-epileptic drugs. Further, surgery and ketogenic diets do little to alleviate the symptoms of patients with pharmacoresistant epilepsy. Thus, there is an urgent need to understand the underlying mechanisms of pharmacoresistant epilepsy to design newer and more effective anti-epileptic drugs. Several theories of pharmacoresistant epilepsy have been suggested over the years, the most common being the gene variant hypothesis, network hypothesis, multidrug transporter hypothesis, and target hypothesis. In our review, we discuss the main theories of pharmacoresistant epilepsy and highlight a possible interconnection between their mechanisms that could lead to the development of novel therapies for pharmacoresistant epilepsy.

NSAIDs-dependent adaption of the mitochondria-proteasome system in immortalized human cardiomyocytes

The progressive consumption growth of non-steroidal anti-inflammatory drugs (NSAIDs) has progressively raised the attention toward the gastrointestinal, renal, and cardiovascular toxicity. Increased risk of cardiovascular diseases was strictly associated with the usage of COX-2 selective NSAIDs. Other studies allowed to clarify that the cardiovascular risk is not limited to COX-2 selective but also extended to non-selective NSAIDs, such as Diclofenac and Ketoprofen. To date, although a less favorable cardiovascular risk profile for Diclofenac as compared to Ketoprofen is reported, the mechanisms through which NSAIDs cause adverse cardiovascular events are not entirely understood. The present study aimed to evaluate the effects of Ketoprofen in comparison with Diclofenac in immortalized human cardiomyocytes. The results obtained highlight the dose-dependent cardiotoxicity of Diclofenac compared to Ketoprofen. Despite both drugs induce the increase in ROS production, decrease of mitochondrial membrane potential, and proteasome activity modulation, only Diclofenac exposure shows a marked alteration of these intracellular parameters, leading to cell death. Noteworthy, Diclofenac decreases the proteasome 26S DC and this scenario may be dependent on the intracellular overload of oxidized proteins. The data support the hypothesis that immortalized human cardiomyocytes exposed to Ketoprofen are subjected to tolerable stress events, conversely Diclofenac exposition triggers cell death.

The evolution of the pilocarpine animal model of status epilepticus

The pilocarpine animal model of status epilepticus is a well-established, clinically translatable model that satisfies all of the criteria essential for an animal model of status epilepticus: a latency period followed by spontaneous recurrent seizures, replication of behavioural, electrographic, metabolic, and neuropathological changes, as well as, pharmacoresistance to anti-epileptic drugs similar to that observed in human status epilepticus. However, this model is also characterized by high mortality rates and studies in recent years have also seen difficulties in seizure induction due to pilocarpine resistant animals. This can be attributed to differences in rodent strains, species, gender, and the presence of the multi-transporter, P-glycoprotein at the blood brain barrier. The current paper highlights the various alterations made to the original pilocarpine model over the years to combat both the high mortality and low induction rates. These range from the initial lithium-pilocarpine model to the more recent Reduced Intensity Status Epilepticus (RISE) model, which finally brought the mortality rates down to 1%. These modifications are essential to improve animal welfare and future experimental outcomes.

Macrophage migration inhibitory factor facilitates prostaglandin E2 production of astrocytes to tune inflammatory milieu following spinal cord injury

Background

Astrocytes have been shown to produce several pro- and anti-inflammatory cytokines to maintain homeostasis of microenvironment in response to vast array of CNS insults. Some inflammation-related cytokines are responsible for regulating such cell events. Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that can be inducibly expressed in the lesioned spinal cord. Unknown is whether MIF can facilitate the production of immunosuppressive factors from astrocytes to tune milieu following spinal cord injury.

Methods

Following establishment of contusion SCI rat model, correlation of PGE₂ synthesis-related protein levels with that of MIF was assayed by Western blot. ELISA assay was used to detect production of PGE₂, TNF-α, IL-1β, and IL-6. Immunohistochemistry was performed to observe colocalization of COX2 with GFAP- and S100β-positive astrocytes. The primary astrocytes were treated by various inhibitors to validate relevant signal pathway.

Results

The protein levels of MIF and COX2, but not of COX1, synchronously increased following spinal cord injury. Treatment of MIF inhibitor 4-IPP to the lesion sites significantly reduced the expression of COX2, mPGES-1, and as a consequence, the production of PGE₂. Astrocytes responded robustly to the MIF interference, by which regulated MAPK/COX2/PGE₂ signal pathway through coupling with the CD74 membrane receptor. MIF-induced production of PGE₂ from astrocytes was able to suppress production of TNF-α, but boosted production of IL-1β and IL-6 in LPS-activated macrophages.

Conclusion

Collectively, these results reveal a novel function of MIF-mediated astrocytes, which fine-tune inflammatory microenvironment to maintain homeostasis. These suggest an alternative therapeutic strategy for CNS inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12974-019-1468-6) contains supplementary material, which is available to authorized users.

COX-2 Inhibitors, Aspirin, and Other Potential Anti-Inflammatory Treatments for Psychiatric Disorders

Inflammatory processes associated with persistent (chronic) infection have long been discussed as etiological factors in psychiatric disorders. Studies have found that people with major depression have higher levels of pro-inflammatory cytokines, for example, IL-1, IL-6, and tumor necrosis factor-alpha, and C-reactive protein. In schizophrenia, many reports have described raised levels of cytokines, for example, IL-6; and meta-analyses have confirmed these findings. Microglia cells are important in inflammatory processes, and positron emission tomography studies have shown microglia activation in both depression and schizophrenia.As a consequence of the above findings, immunomodulation is widely discussed as a potential treatment approach in both major depression and schizophrenia. The COX-2 inhibitor celecoxib was found to have a significant positive effect on major depression, not only in single studies but also in meta-analyses. Celecoxib has also been studied in schizophrenia and has shown efficacy, in particular, in early disease stages. The mixed COX inhibitor aspirin (acetylsalicylic acid) seems to have both protective and therapeutic effects on schizophrenia.This paper discusses the hypothesized role of inflammation in major depression and schizophrenia, including markers of inflammation; pertinent studies on celecoxib and aspirin; and additional immunomodulatory therapeutic strategies.

Edaravone acts as a potential therapeutic drug against pentylenetetrazole-induced epilepsy in male albino rats by downregulating cyclooxygenase-II

INTRODUCTION

The effects of edaravone against pentylenetetrazole (PTZ)-induced epilepsy in male albino rats were investigated. Edaravone is a well-known commercial drug used in the treatment of strokes and amyotrophic lateral sclerosis (ALS). Antioxidant and free radical scavenging activities of edaravone have been reported in patients with ALS.

METHODS

In this study, the experimental groups were as follows: sham, control, 5 mg/kg edaravone, and 10 mg/kg edaravone. Behavioral assessment, determination of biochemical markers, apoptosis, nitric oxide (NO), and mRNA and protein expression of cyclooxygenase-II (COX-II) were carried out. Seizure incidence, including generalized tonic-clonic seizure (GTCS) and minimal clonic seizure (MCS), was directly associated with PTZ administration in rats.

RESULTS

Edaravone supplementation substantially increased MCS and GTCS latency in rats, and biochemical markers were significantly altered in the brain tissue of PTZ-treated rats. Edaravone treatment normalized altered biochemical markers compared with the untreated control. Apoptosis and NO levels were significantly reduced by more than 50% compared to their respective controls. COX-II mRNA was increased by 130% in PTZ-treated rats, while edaravone supplementation reduced mRNA and protein expression of COX-II by more than 20% and 40%, respectively. Immunohistochemistry indicated that COX-II protein expression was reduced by 13.2% and 33.7% following supplementation with 5 and 10 mg/kg edaravone, respectively.

CONCLUSION

Taken together, our results suggest that edaravone functions by downregulating the levels of COX-II and NO and is a potential candidate for the treatment of PTZ-induced epilepsy.

Influence of Cyclooxygenase-2 Inhibitors on Kynurenic Acid Production in Rat Brain in Vitro

Significant body of evidence suggests that abnormal kynurenic acid (KYNA) level is involved in the pathophysiology of central nervous system disorders. In the brain, KYNA is synthesized from kynurenine (KYN) by kynurenine aminotransferases (KATs), predominantly by KAT II isoenzyme. Blockage of ionotropic glutamate (GLU) receptors is a main cellular effect of KYNA. High KYNA levels have been linked with psychotic symptoms and cognitive dysfunction in animals and humans. As immunological imbalance and impaired glutamatergic neurotransmission are one of the crucial processes in neurological pathologies, we aimed to analyze the effect of anti-inflammatory agents, inhibitors of cyclooxygenase-2 (COX-2): celecoxib, niflumic acid, and parecoxib, on KYNA synthesis and KAT II activity in rat brain in vitro. The influence of COX-2 inhibitors was examined in rat brain cortical slices and on isolated KAT II enzyme. Niflumic acid and parecoxib decreased in a dose-dependent manner KYNA production and KAT II activity in rat brain cortex in vitro, whereas celecoxib was ineffective. Molecular docking results suggested that niflumic acid and parecoxib interact with an active site of KAT II. In conclusion, niflumic acid and parecoxib are dual COX-2 and KAT II inhibitors.

Neurobiology and Therapeutic Potential of Cyclooxygenase-2 (COX-2) Inhibitors for Inflammation in Neuropsychiatric Disorders

Neuropsychiatric disorders, such as depression, bipolar disorder, schizophrenia, obsessive-compulsive disorder, and neurodevelopmental disorders such as autism spectrum disorder, are associated with significant illness burden. Accumulating evidence supports an association between these disorders and inflammation. Consequently, anti-inflammatory agents, such as the cyclooxygenase-2 inhibitors, represent a novel avenue to prevent and treat neuropsychiatric illness. In this paper, we first review the role of inflammation in psychiatric pathophysiology including inflammatory cytokines' influence on neurotransmitters, the hypothalamic-pituitary-adrenal axis, and microglial mechanisms. We then discuss how cyclooxygenase-2-inhibitors influence these pathways with potential therapeutic benefit, with a focus on celecoxib, due to its superior safety profile. A search was conducted in PubMed, Embase, and PsychINFO databases, in addition to Clinicaltrials.gov and the Stanley Medical Research Institute trial registries. The results were presented as a narrative review. Currently available outcomes for randomized controlled trials up to November 2017 are also discussed. The evidence reviewed here suggests cyclooxygenase-2 inhibitors, and in particular celecoxib, may indeed assist in treating the symptoms of neuropsychiatric disorders; however, further studies are required to assess appropriate illness stage-related indication.

Diagnostic Issues in Early-Onset Obsessive-Compulsive Disorder and their Treatment Implications

BACKGROUND

The lifespan approach and recent shift in the conceptualization of Obsessive- Compulsive Disorder (OCD) promoted by the Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM5) along with novel insights into the pathogenesis of this heterogeneous disorder are driving the development of new outcome measures and new treatments for a disease that, on the other hand, is characterized by high rates of refractoriness.

OBJECTIVE AND METHODS

The aim of this review is to provide a discussion of the translational evidence about Early Onset OCD (EO) in compliance with a neurodevelopmental and RdoC perspective.

RESULTS AND CONCLUSION

EO might be considered the neurodevelopmental subtype of OCD. Indeed there is evidence that different clusters of symptoms and dimensions at an early stage predict different trajectories in phenotype and that distinct neurocircuit pathways underpin the progression of the disorder. Despite the development of high refractoriness in the course of the disorder, evidence suggests that EO may be particularly treatment responsive in the early stages, thus showing the need for early recognition and additional recovery oriented studies in this subgroup. Consistent with the neurodevelopmental perspective, immunity and glutamate neurotransmission are emerging as novel pathways for parsing out the neurobiology of OCD, the EO form, in particular, supporting the implementation of new multisystemic models of the OCD phenotype. Brain connectivity patterns, immune and microbiome profiles are standing out as promising areas for biomarkers with the potential for targeted personalized therapies in EO.

Current and up-and-coming pharmacotherapy for obsessive-compulsive disorder in adults

INTRODUCTION

Only 40-60% of obsessive-compulsive patients respond to first line treatments, such as selective serotonin reuptake inhibitors (SSRIs) and cognitive-behavioral therapy. Several second-line treatments have been investigated in the last two decades, and most of them seem to work, at least in a subset of patients. However, since there is still a lack of treatment predictors, the treatment of obsessive-compulsive disorder (OCD) is still empirical and non-evidence based.

AREAS COVERED

In this paper, we review current and up-and-coming pharmacotherapy for OCD in adults, focusing on two emerging fields of research, inflammation and glutamate systems, since they have attracted the greatest attention in recent years in OCD pharmacological research.

EXPERT OPINION

Most of the investigated second-line agents seem to work at least in a subset of patients with OCD. These results raise an open question: what works for who? In our opinion, this question should be answered in a precision medicine perspective or, in other words, individualizing diagnostic processes and treatment approaches. In a precision medicine approach, OCD treatment should be sub-type specific, phase specific, multimodal and sequential, and, more importantly, dimensional.

Inflammation in Schizophrenia: Pathogenetic Aspects and Therapeutic Considerations

This paper discusses the current evidence from animal and human studies for a central role of inflammation in schizophrenia. In animal models, pre- or perinatal elicitation of the immune response may increase immune reactivity throughout life, and similar findings have been described in humans. Levels of pro-inflammatory markers, such as cytokines, have been found to be increased in the blood and cerebrospinal fluid of patients with schizophrenia. Numerous epidemiological and clinical studies have provided evidence that various infectious agents are risk factors for schizophrenia and other psychoses. For example, a large-scale epidemiological study performed in Denmark clearly showed that severe infections and autoimmune disorders are such risk factors. The vulnerability-stress-inflammation model may help to explain the role of inflammation in schizophrenia because stress can increase pro-inflammatory cytokines and may even contribute to a chronic pro-inflammatory state. Schizophrenia is characterized by risk genes that promote inflammation and by environmental stress factors and alterations of the immune system. Typical alterations of dopaminergic, serotonergic, noradrenergic, and glutamatergic neurotransmission described in schizophrenia have also been found in low-level neuroinflammation and consequently may be key factors in the generation of schizophrenia symptoms. Further support for the relevance of a low-level neuroinflammatory process in schizophrenia is provided by the loss of central nervous system volume and microglial activation demonstrated in neuroimaging studies. Last but not least, the benefit of anti-inflammatory medications found in some studies and the intrinsic anti-inflammatory and immunomodulatory effects of antipsychotics provide further support for the role of inflammation in this debilitating disease.

Eruca sativa seed extract: A novel natural product able to counteract neuroinflammation

Certain nutrients are able to exert health promoting effects. The consumption of Brassicaceae vegetables has increased given their reported beneficial effects on human health, due to their high content of nutraceutical compounds. The health benefits appear to be associated with the presence of glucosinolates and flavonoids. Certain nutraceutics have been revealed to have anti-inflammatory action. In the present study, the anti-inflammatory properties of Eruca sativa seed extract (ESE) were evaluated in NSC-34 motor neurons exposed to the cell culture medium of lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Treatment with LPS-stimulated RAW 264.7 medium induced apoptosis and the expression of Toll-like receptor 4 (TLR4) and cyclooxygenase 2 (COX2) in NSC-34 motor neurons. Additionally, the stimulation of NSC-34 motor neurons with the medium of LPS-treated macrophages triggered the expression of NLR family pyrin domain containing 3 (NLRP3) inflammasome proteins and the production of pro-inflammatory cytokines. Pre-treatment with ESE counteracted the apoptosis and production of pro-inflammatory cytokines in NSC-34 motor neurons treated with the medium of LPS-treated RAW 264.7. It also eliminated COX2 and TLR4/NLRP3 inflammasome expression. In addition, pre-treatment with ESE was able to restore interleukin 10 expression in NSC-34 cells. These results demonstrate the anti-inflammatory and neuroprotective effects of ESE.

Sevoflurane Postconditioning-Induced Anti-Inflammation via Inhibition of the Toll-Like Receptor-4/Nuclear Factor Kappa B Pathway Contributes to Neuroprotection against Transient Global Cerebral Ischemia in Rats

The anti-inflammatory actions of sevoflurane postconditioning are suggested as an important mechanism of sevoflurane postconditioning-induced neuroprotection against cerebral ischemia. Here, we determined whether the anti-inflammatory effects of sevoflurane postconditioning were mediated via inhibition of the toll-like receptor (TLR)-4/nuclear factor kappa B (NF-κB) pathway after global transient cerebral ischemia in rats. Forty-five rats were randomly assigned to five groups as follows: (1) control (10 min of ischemia, n = 10); (2) sevoflurane postconditioning (two periods of sevoflurane inhalation after ischemia for 10 min with a wash period of 10 min, n = 10); (3) resatorvid (intraperitoneal injection of a selective TLR-4 antagonist (3 mg/kg) 30 min before ischemia, n = 10); (4) sevoflurane postconditioning plus resatorvid (n = 10), and sham (n = 5). The numbers of necrotic and apoptotic cells in the hippocampal CA1 region, the expression levels of TLR-4, NF-κB, cleaved caspase-3, and tumor necrosis factor alpha (TNF-α) in the anterior part of each brain, and the serum levels of TNF-α, interleukin 6 (IL-6), and interleukin 1 beta (IL-1β) were assessed 1 day after ischemia. The necrotic cell counts and expression levels of TLR-4, NF-κB, caspase-3, and TNF-α in brain tissue as well as serum levels of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) were significantly higher in the control group than in the other groups. Our findings suggest that the anti-inflammatory actions of sevoflurane postconditioning via inactivation of the TLR-4/NF-κB pathway and subsequent reduction in pro-inflammatory cytokine production, in part, contribute to sevoflurane postconditioning-induced neuroprotection after global transient cerebral ischemia in rats.

Oroxylin A promotes retinal ganglion cell survival in a rat optic nerve crush model

Purpose

To investigate the effect of oroxylin A on the survival of retinal ganglion cells (RGC) and the activation of microglial cells in a rat optic nerve (ON) crush model.

Methods

Oroxylin A (15mg/Kg in 0.2ml phosphate-buffered saline) or phosphate-buffered saline (PBS control) was immediately administered after ON crush once by subcutaneous injection. Rats were euthanized at 2 weeks after the crush injury. The density of RGC was counted by retrograde labeling with FluoroGold and immunostaining of retina flat mounts for Brn3a. Electrophysiological visual function was assessed by flash visual evoked potentials (FVEP). TUNEL assay, immunoblotting analysis of glial fibrillary acidic protein (GFAP), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the retinas, and immunohistochemistry of GFAP in the retinas and ED1 in the ON were evaluated.

Results

Two weeks after the insult, the oroxylin A-treated group had significantly higher FG labeled cells and Brn3a+ cells suggesting preserved RGC density in the central and mid-peripheral retinas compared with those of the PBS-treated group. FVEP measurements showed a significantly better preserved latency of the P1 wave in the ON-crushed, oroxylin A-treated rats than the ON-crushed, PBS treated rats. TUNEL assays showed fewer TUNEL positive cells in the ON-crushed, oroxylin A-treated rats. The number of ED1 positive cells was reduced at the lesion site of the optic nerve in the ON-crushed, oroxylin A-treated group. Increased GFAP expression in the retina was reduced greatly in ON-crushed, oroxylin A-treated group. Furthermore, administration of oroxylin A significantly attenuated ON crush insult-induced iNOS and COX-2 expression in the retinas.

Conclusions

These results demonstrated that oroxylin A hasss neuroprotective effects on RGC survival with preserved visual function and a decrease in microglial infiltration in the ONs after ON crush injury.

Inhibition of cyclooxygenase-2 by NS398 attenuates noise-induced hearing loss in mice

Noise-induced hearing loss (NIHL) is an important occupational disorder. However, the molecular mechanisms underlying NIHL have not been fully clarified; therefore, the condition lacks effective therapeutic methods. Cyclooxygenase-2 (Cox-2) is an inducible enzyme involved in the synthesis of prostaglandins, and has been implicated in many pathophysiological events, such as oxidative stress and inflammation. In this study, we investigated the possible role of Cox-2 in the mechanisms of NIHL and the therapeutic effect of the Cox-2 inhibitor NS398 on NIHL using a mouse model. We demonstrated that Cox-2 is constitutively expressed in the mouse cochlea, and its expression could be dramatically up-regulated by high levels of noise exposure. Furthermore, we demonstrated that pre-treatment with the Cox-2 inhibitor NS398 could inhibit Cox-2 expression during noise overstimulation; and could attenuate noise-induced hearing loss and hair cell damage. Our results suggest that Cox-2 is involved in the pathogenesis of NIHL; and pharmacological inhibition of Cox-2 has considerable therapeutic potential in NIHL.

Neuroprotective effect of 4-(Phenylsulfanyl)butan-2-one on optic nerve crush model in rats

This study is to investigate the effect of coral-related compound, 4-(phenylsulfanyl)butan-2-one (4-PSB-2) on optic nerves (ON) and retinal ganglion cells (RGC) in a rat model subjected to ON crush. The ONs of adult male Wistar rat (150-180 g) were crushed by a standardized method. The control eyes received a sham operation. 4-PSB-2 (5 mg/kg in 0.2 mL phosphate-buffered saline) or phosphate-buffered saline (PBS control) was immediately administered after ON crush once by subcutaneous injection. Rats were euthanized at 2 weeks after the crush injury. RGC density was counted by retrograde labeling with FluoroGold (FG) application to the superior colliculus, and visual function was assessed by flash visual evoked potentials (FVEP). TUNEL assay, immunoblotting analysis of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX2) in the retinas, and immunohistochemistry of ED1 in the ON were evaluated. Two weeks after the insult, the RGC densities in the central and mid-peripheral retinas in ON-crushed, 4-PSB-2-treated rats were significantly higher than that of the corresponding ON-crushed, PBS-treated rats FVEP measurements showed a significantly better preserved latency of the P1 wave in the ON-crushed, 4-PSB-2-treated rats than the ON-crushed, PBS treated rats. TUNEL assays showed fewer TUNEL positive cells in the ON-crushed, 4-PSB-2-treated rats. The number of ED1 positive cells was reduced at the lesion site of the optic nerve in the ON-crushed, 4-PSB-2-treated group. Furthermore, administration of 4-PSB-2 significantly attenuated ON crush insult-stimulated iNOS and COX2 expression in the retinas. These results demonstrated that 4-PSB-2 protects RGCs and helps preserve the visual function in the rat model of optic nerve crush. 4-PSB-2 may work by being anti-apoptotic and by attenuation of the inflammatory responses involving less ED1 positive cells infiltration in ON as well as suppression of iNOS/COX-2 signaling pathway in the retinas to rescue RGCs after ON crush injury.

A single dose of PPARγ agonist pioglitazone reduces cortical oxidative damage and microglial reaction following lateral fluid percussion brain injury in rats

Neuroprotective actions of the peroxisome proliferator-activated receptor-γ (PPARγ) agonists have been observed in various animal models of the brain injuries. In this study we examined the effects of a single dose of pioglitazone on oxidative and inflammatory parameters as well as on neurodegeneration and the edema formation in the rat parietal cortex following traumatic brain injury (TBI) induced by the lateral fluid percussion injury (LFPI) method. Pioglitazone was administered in a dose of 1mg/kg at 10min after the brain trauma. The animals of the control group were sham-operated and injected by vehicle. The rats were decapitated 24h after LFPI and their parietal cortices were analyzed by biochemical and histological methods. Cortical edema was evaluated in rats sacrificed 48h following TBI. Brain trauma caused statistically significant oxidative damage of lipids and proteins, an increase of glutathione peroxidase (GSH-Px) activity, the cyclooxygenase-2 (COX-2) overexpression, reactive astrocytosis, the microglia activation, neurodegeneration, and edema, but it did not influence the superoxide dismutase activity and the expressions of interleukin-1 beta, interleukin-6 and tumor necrosis factor-alpha in the rat parietal cortex. Pioglitazone significantly decreased the cortical lipid and protein oxidative damage, increased the GSH-Px activity and reduced microglial reaction. Although a certain degree of the TBI-induced COX-2 overexpression, neurodegeneration and edema decrease was detected in pioglitazone treated rats, it was not significant. In the injured animals, cortical reactive astrocytosis was unchanged by the tested PPARγ agonist. These findings demonstrate that pioglitazone, administered only in a single dose, early following LFPI, reduced cortical oxidative damage, increased antioxidant defense and had limited anti-inflammatory effect, suggesting the need for further studies of this drug in the treatment of TBI.

Meloxicam inhibits fipronil-induced apoptosis via modulation of the oxidative stress and inflammatory response in SH-SY5Y cells

Oxidative stress and inflammatory responses have been identified as key elements of neuronal cell apoptosis. In this study, we investigated the mechanisms by which inflammatory responses contribute to apoptosis in human neuroblastoma SH-SY5Y cells treated with fipronil (FPN). Based on the cytotoxic mechanism of FPN, we examined the neuroprotective effects of meloxicam against FPN-induced neuronal cell death. Treatment of SH-SY5Y cells with FPN induced apoptosis via activation of caspase-9 and -3, leading to nuclear condensation. In addition, FPN induced oxidative stress and increased expression of cyclooxygenase-2 (COX-2) and tumor necrosis factor-α (TNF-α) via inflammatory stimulation. Pretreatment of cells with meloxicam enhanced the viability of FPN-exposed cells through attenuation of oxidative stress and inflammatory response. FPN activated mitogen activated protein kinase (MAPK) and inhibitors of MAPK abolished FPN-induced COX-2 expression. Meloxicam also attenuated FPN-induced cell death by reducing MAPK-mediated pro-inflammatory factors. Furthermore, we observed both nuclear accumulation of p53 and enhanced levels of cytosolic p53 in a concentration-dependent manner after FPN treatment. Pretreatment of cells with meloxicam blocked the translocation of p53 from the cytosol to the nucleus. Together, these data suggest that meloxicam may exert anti-apoptotic effects against FPN-induced cytotoxicity by both attenuating oxidative stress and inhibiting the inflammatory cascade via inactivation of MAPK and p53 signaling.

Telmisartan ameliorates glutamate-induced neurotoxicity: roles of AT(1) receptor blockade and PPARγ activation

Sartans (Angiotensin II AT(1) Receptor Blockers, ARBs) are powerful neuroprotective agents in vivo and protect against IL-1β neurotoxicity in vitro. The purpose of this research was to determine the extent of sartan neuroprotection against glutamate excitotoxicity, a common cause of neuronal injury and apoptosis. The results show that sartans are neuroprotective, significantly reducing glutamate-induced neuronal injury and apoptosis in cultured rat primary cerebellar granule cells (CGCs). Telmisartan was the most potent sartan studied, with an order of potency telmisartan > candesartan > losartan > valsartan. Mechanisms involved reduction of pro-apoptotic caspase-3 activation, protection of the survival PI3K/Akt/GSK-3β pathway and prevention of glutamate-induced ERK1/2 activation. NMDA receptor stimulation was essential for glutamate-induced cell injury and apoptosis. Participation of AT(1A) receptor was supported by glutamate-induced upregulation of AT(1A) gene expression and AT(1) receptor binding. Conversely, AT(1B) or AT(2) receptors played no role. Glutamate-induced neuronal injury and the neuroprotective effect of telmisartan were decreased, but not abolished, in CGCs obtained from AT(1A) knock-out mice. This indicates that although AT(1) receptors are necessary for glutamate to exert its full neurotoxic potential, part of the neuroprotective effect of telmisartan is independent of AT(1) receptor blockade. PPARγ activation was also involved in the neuroprotective effects of telmisartan, as telmisartan enhanced PPARγ nuclear translocation and the PPARγ antagonist GW9662 partially reversed the neuroprotective effects of telmisartan. The present results substantiate the therapeutic use of sartans, in particular telmisartan, in neurodegenerative diseases and traumatic brain disorders where glutamate neurotoxicity plays a significant role.

Neuroprotection by mefenamic acid against D-serine: involvement of oxidative stress, inflammation and apoptosis

Mefenamic acid, a non-steroidal antiinflammatory drug (NSAID), directly and dose-dependently exhibits neuroprotective activity. In our study, we investigated the effects of mefenamic acid against d-serine on oxidative stress in the hippocampus, cortex and cerebellum of rats. Furthermore, the potential inflammatory and apoptotic effects of d-serine and potential protective effect of mefenamic acid were determined at mRNA and protein levels of TNF-α, IL-1β, Bcl-2 and Bax. We found that d-serine significantly increased oxidative stress, levels of inflammation- and apoptosis-related molecules in a region specific manner. Mefenamic acid treatment provided significant protection against the elevation of lipid peroxidation, protein oxidation, levels of TNF-α, IL-1β and Bax. As a conclusion, we suggest that d-serine, as a potential neurodegenerative agent, may have a pivotal role in the regulation of oxidative stress, inflammation and apoptosis; and NSAIDs, such as mefenamic acid, may assist other therapeutics in treating disorders where d-serine-induced neurotoxic mechanisms are involved in.

Effects of enoxaparin in the rat hippocampus following traumatic brain injury

Purpose of this study was to investigate the effects of low molecular weight heparin, enoxaparin, on different parameters of the hippocampal damage following traumatic brain injury (TBI) in the rat. TBI of moderate severity was performed over the left parietal cortex using the lateral fluid percussion brain injury model. Animals were s.c. injected with either enoxaparin (1mg/kg) or vehicle 1, 7, 13, 19, 25, 31, 37, and 43 h after the TBI induction. Sham-operated, vehicle-treated animals were used as the control group. Rats were sacrificed 48h after the induction of TBI. Hippocampi were processed for spectrophotometric measurements of the products of oxidative lipid damage, thiobarbituric acid-reactive substances (TBARS) levels, as well as the activities of antioxidant enzymes, superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px). Moreover, the Western blotting analyses of the oxidized protein levels, expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), pro- and mature-interleukin-1β (pro-, and mature-IL-1β), and active caspase-3 were performed. COX-2 expressions were also explored by using immunohistochemistry. Glial fibrillary acidic protein immunochistochemistry was performed with the aim to assess the level of astrocytic activity. Fluoro-Jade B staining was used to identify the level and extent of hippocampal neuronal injury. TBI caused statistically significant increases of the hippocampal TBARS and oxidized protein levels as well as COX-2, pro-IL-1β, and active caspase-3 overexpressions, but it did not significantly affect the SOD and GSH-Px activities, the iNOS, and mature-IL-1β expression levels. TBI also induced hippocampal reactive astrocytosis and neurodegeneration. Enoxaparin significantly decreased the hippocampal TBARS and oxidized protein levels, COX-2 overexpression and reactive gliosis, but it did not influence the SOD and GSH-Px activities, pro-IL-1β and active caspase-3 overexpressions as well as neurodegeneration following TBI. These findings demonstrate that enoxaparin may reduce oxidative damage, inflammation and astrocytosis following TBI in the rat and could be a candidate drug for neuroprotective treatment of this injury.

Meloxicam exerts neuroprotection on spinal cord trauma in rats

Traumatic injury to the central nervous system results in the delayed dysfunction and neuronal death. Impaired mitochondrial function, generation of reactive oxygen species (ROS), and lipid peroxidation occur soon after traumatic spinal cord injury (SCI), while the activation of compensatory molecules that neutralize ROS occurs at later time points. The aim of the current study was to investigate the putative neuroprotective effect of the COX2 inhibitor meloxicam in a rat model of SCI. In order to induce SCI, a standard weight-drop method that induced a moderately severe injury (100 g/cm force) at T10, was used. Injured animals were given either 2 mg/kg meloxicam or saline 30 min postinjury by intraperitoneal injection. At seven days postinjury, neurological examination was performed and rats were decapitated. Spinal cord samples were taken for histological examination or determination of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity and DNA fragmentation. Formation of ROS in spinal cord tissue samples was monitored by using a chemiluminescence (CL) technique. SCI caused a significant decrease in spinal cord GSH content, which was accompanied with significant increases in CL, MDA levels, MPO activity, and DNA damage. On the other hand, meloxicam treatment reversed all these biochemical parameters as well as SCI-induced histopathological alterations. Furthermore, impairment of the neurological functions due to SCI was improved by meloxicam treatment. The present study suggests that meloxicam, reduces SCI-induced oxidative stress and exerts neuroprotection by inhibiting lipid peroxidation, GSH depletion, and DNA fragmentation.

TNF-α potentiates glutamate-induced spinal cord motoneuron death via NF-κB

Besides glutamate excitotoxicity, the neuroinflammatory response is emerging as a relevant contributor to motoneuron loss in amyotrophic lateral sclerosis (ALS). In this regard, high levels of circulating proinflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) have been shown both in human patients and in animal models of ALS. The aim of this work was to study the effects of TNF-α on glutamate-induced excitotoxicity in spinal cord motoneurons. In rat spinal cord organotypic cultures chronic glutamate excitotoxicity, induced by the glutamate-uptake inhibitor threohydroxyaspartate (THA), resulted in motoneuron loss that was associated with a neuroinflammatory response. In the presence of TNF-α, THA-induced excitotoxic motoneuron death was potentiated. Co-exposure to TNF-α and THA also resulted in down-regulation of the astroglial glutamate transporter 1 (GLT-1) and in increased extracellular glutamate levels, which were prevented by nuclear factor-kappaB (NF-κB) inhibition. Furthermore, TNF-α and THA also cooperated in the induction of oxidative stress in a mechanism involving the NF-κB signalling pathway as well. The inhibition of this pathway abrogated the exacerbation of glutamate-mediated motoneuron death induced by TNF-α. These data link two important pathogenic mechanisms, excitotoxicity and neuroinflammation, suggested to play a role in ALS and, to our knowledge, this is the first time that TNF-α-induced NF-κB activation has been reported to potentiate glutamate excitotoxicity on motononeurons.

Interaction of PGHS-2 and glutamatergic mechanisms controlling the ovine fetal hypothalamus-pituitary-adrenal axis

Prostaglandins, generated within the fetal brain, are integral components of the mechanism controlling the fetal hypothalamus-pituitary-adrenal (HPA) axis. Previous studies in this laboratory demonstrated that prostaglandin G/H synthase isozyme 2 (PGHS-2) inhibition reduces the fetal HPA axis response to cerebral hypoperfusion, blocks the preparturient rise in fetal plasma ACTH concentration, and delays parturition. We also discovered that blockade of N-methyl-d-aspartate (NMDA) receptors reduces the fetal ACTH response to cerebral hypoperfusion. The present study was designed to test the hypothesis that PGHS-2 action and the downstream effect of HPA axis stimulation are stimulated by NMDA-mediated glutamatergic neurotransmission. Chronically catheterized late-gestation fetal sheep (n = 8) were injected with NMDA (1 mg iv). All responded with increases in fetal plasma ACTH and cortisol concentrations. Pretreatment with resveratrol (100 mg iv, n = 5), a specific inhibitor of PGHS-1, did not alter the magnitude of the HPA axis response to NMDA. Pretreatment with nimesulide (10 mg iv, n = 6), a specific inhibitor of PGHS-2, significantly reduced the HPA axis response to NMDA. To further explore this interaction, we injected NMDA in six chronically catheterized fetal sheep that were chronically infused with nimesulide (n = 6) at a rate of 1 mg/day into the lateral cerebral ventricle for 5-7 days. In this group, there was no significant ACTH response to NMDA. Finally, we tested whether the HPA axis response to prostaglandin E(2) (PGE(2)) is mediated by NMDA receptors. Seven chronically catheterized late-gestation fetal sheep were injected with 100 ng of PGE(2), which significantly increased fetal plasma ACTH and cortisol concentrations. Pretreatment with ketamine (10 mg iv), an NMDA antagonist, did not alter the ACTH or cortisol response to PGE(2). We conclude that generation of prostanoids via the action of PGHS-2 in the fetal brain augments the fetal HPA axis response to NMDA-mediated glutamatergic stimulation.

Bradykinin protects against brain microvascular endothelial cell death induced by pathophysiological stimuli

The morphological and functional integrity of the microcirculation is compromised in many cardiovascular diseases such as hypertension, diabetes, stroke, and sepsis. Angiotensin converting enzyme inhibitors (ACEi), which are known to favor bradykinin (BK) bioactivity by reducing its metabolism, may have a positive impact on preventing the microvascular structural rarefaction that occurs in these diseases. Our study was designed to test the hypothesis that BK, via B2 receptors (B2R), protects the viability of the microvascular endothelium exposed to the necrotic and apoptotic cell death inducers H(2)O(2) and LPS independently of hemodynamics. Expression (RT-PCR and radioligand binding) and functional (calcium mobilization with fura-2AM, and p42/p44MAPK and Akt phosphorylation assays) experiments revealed the presence of functional B2R in pig cerebral microvascular endothelial cells (pCMVEC). In vitro results showed that the cytocidal effects of H(2)O(2) and LPS on pCMVEC were significantly decreased by a BK pretreatment (MTT and crystal violet tests, annexin-V staining/FACS analysis), which was countered by the B2R antagonist HOE 140. BK treatment coincided with enhanced expression of the cytoprotective proteins COX-2, Bcl-2, and (Cu/Zn)SOD. Ex vivo assays on rat brain explants showed that BK impeded (by approximately 40%) H(2)O(2)-induced microvascular degeneration (lectin-FITC staining). The present study proposes a novel role for BK in microvascular endothelial protection, which may be pertinent to the complex mechanism of action of ACEi explaining their long-term beneficial effects in maintaining vascular integrity.

Platelet kainate receptor signaling promotes thrombosis by stimulating cyclooxygenase activation

RATIONALE

Glutamate is a major signaling molecule that binds to glutamate receptors including the ionotropic glutamate receptors; kainate (KA) receptor (KAR), the N-methyl-d-aspartate receptor, and the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor. Each is well characterized in the central nervous system, but glutamate has important signaling roles in peripheral tissues as well, including a role in regulating platelet function.

OBJECTIVE

Our previous work has demonstrated that glutamate is released by platelets in high concentrations within a developing thrombus and increases platelet activation and thrombosis. We now show that platelets express a functional KAR that drives increased agonist induced platelet activation.

METHODS AND RESULTS

KAR induced increase in platelet activation is in part the result of activation of platelet cyclooxygenase in a mitogen-activated protein kinase-dependent manner. Platelets derived from KAR subunit knockout mice (GluR6(-/-)) are resistant to KA effects and have a prolonged time to thrombosis in vivo. Importantly, we have also identified polymorphisms in KAR subunits that are associated with phenotypic changes in platelet function in a large group of whites and blacks.

CONCLUSIONS

Our data demonstrate that glutamate regulation of platelet activation is in part cyclooxygenase-dependent and suggest that the KAR is a novel antithrombotic target.

S-nitrosylation/activation of COX-2 mediates NMDA neurotoxicity

Glutamate/N-methyl-d-aspartate (NMDA) receptor-mediated neurotoxicity involves cyclooxygenase (COX)-2. We demonstrate that this neurotoxicity reflects activation of COX-2 by S-nitrosylation after selective binding of neuronal nitric oxide synthase (nNOS) to COX-2. nNOS, via its PDZ domain, binds COX-2 with the generated NO S-nitrosylating and activating the enzyme. Selective disruption of nNOS-COX-2 binding prevents NMDA neurotoxicity.