COX-2, a synaptically induced enzyme, is expressed by excitatory neurons at postsynaptic sites in rat cerebral cortex

Neuroprotective efficiency of celecoxib vesicular bilosomes for the management of lipopolysaccharide-induced Alzheimer in mice employing 23 full factorial design

The aim of this study was to develop and evaluate bilosomes loaded with Celecoxib (CXB) for the efficient treatment of Alzheimer. The thin-film hydration approach was utilized in the formulation of CXB bilosomes (CXB-BLs). The study used a 23-factorial design to investigate the impact of several formulation variables. Three separate parameters were investigated: bile salt type (X1), medication amount (X2), and lipid-bile salt ratio (X3). The dependent responses included entrapment efficiency (Y1: EE %), particle size (Y2: PS), and zeta potential (Y3: ZP). The formulation factors were statistically optimized using the Design-Expert® program. The vesicles demonstrated remarkable CXB encapsulation efficiency, ranging from 94.16 ± 1.91 to 98.38 ± 0.85%. The vesicle sizes ranged from 241.8 ± 6.74 to 352 ± 2.34 nm. The produced formulations have high negative zeta potential values, indicating strong stability. Transmission electron microscopy (TEM) revealed that the optimized vesicles had a spherical form. CXB release from BLs was biphasic, with the release pattern following Higuchi's model. In vivo studies confirmed the efficiency of CXB-BLs in management of lipopolysaccharide-induced Alzheimer as CXB-BLs ameliorated cognitive dysfunction, decreased acetylcholinesterase (AChE), and inhibited neuro-inflammation and neuro-degeneration through reducing Toll-like receptor (TLR4), and Interleukin-1β (IL-1β) levels. The findings suggested that the created CXB-BLs could be a potential drug delivery strategy for Alzheimer's treatment.

Combining Anti-Mitochondrial Antibodies, Anti-Histone, and PLA2/COX Biomarkers to Increase Their Diagnostic Accuracy for Autism Spectrum Disorders

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social interaction and restricted and repetitive behaviors. Oxidative stress may be a critical link between mitochondrial dysfunction and ASD as reactive oxygen species (ROS) generated from pro-oxidant environmental toxicants and activated immune cells can result in mitochondrial failure. Recently, mitochondrial dysfunction, autoimmunity, and abnormal lipid mediators have been identified in multiple investigations as an acknowledged etiological mechanism of ASD that can be targeted for therapeutic intervention.

METHODS

The relationship between lipid mediator markers linked to inflammation induction, such as phospholipase A2/cyclooxygenase-2 (PLA2/Cox-2), and the mitochondrial dysfunction marker anti-mitochondrial antibodies (AMA-M2), and anti-histone autoantibodies in the etiology of ASD was investigated in this study using combined receiver operating characteristic (ROC) curve analyses. This study also sought to identify the linear combination for a given set of markers that optimizes the partial area under ROC curves. This study included 40 age- and sex-matched controls and 40 ASD youngsters. The plasma of both groups was tested for PLA2/COX-2, AMA-M2, and anti-histone autoantibodies' levels using ELISA kits. ROC curves and logistic regression models were used in the statistical analysis.

RESULTS

Using the integrated ROC curve analysis, a notable rise in the area under the curve was noticed. Additionally, the combined markers had markedly improved specificity and sensitivity.

CONCLUSIONS

The current study suggested that measuring the predictive value of selected biomarkers related to mitochondrial dysfunction, autoimmunity, and lipid metabolism in children with ASD using a ROC curve analysis could lead to a better understanding of the etiological mechanism of ASD as well as its relationship with metabolism.

Evaluation of the behavioral, histopathological, and immunohistochemical effects resulting from ventriculosubcutaneous shunt obstruction in kaolin-induced hydrocephalus in rats

PURPOSE

Hydrocephalus is a brain disease prevalent in the pediatric population that presents complex pathophysiology and multiple etiologies. The best treatment is still ventricular shunting. Mechanical obstruction is the most frequent complication, but the resulting pathological effects are still unknown.

OBJECTIVE

Evaluation and comparison of clinical, histopathological, and immunohistochemical aspects in the acute phase of experimental hydrocephalus induced by kaolin, after treatment with adapted shunt, and after shunt obstruction and posterior disobstruction.

METHODS

Wistar rats aged 7 days were used and divided into 4 groups: control group without kaolin injection (n = 6), untreated hydrocephalic group (n = 5), hydrocephalic group treated with ventriculosubcutaneous shunt (DVSC) (n = 7), and hydrocephalic group treated with shunt, posteriorly obstructed and disobstructed (n = 5). The animals were submitted to memory and spatial learning evaluation through the Morris water maze test. The rats were sacrificed at 28 days of age and histological analysis of the brains was performed with luxol fast blue, in addition to immunohistochemical analysis in order to evaluate reactive astrocytosis, inflammation, neuronal labeling, and apoptotic activity.

RESULTS

The group with shunt obstruction had worse performance in memory tests. Reactive astrocytosis was more evident in this group, as was the inflammatory response.

CONCLUSIONS

Obstruction of the shunt results in impaired performance of behavioral tests and causes irreversible histopathological changes when compared to findings in the group with treated hydrocephalus, even after unblocking the system. The developed model is feasible and efficient in simulating the clinical context of shunt dysfunction.

Regulation of Osteosarcoma Cell Proliferation, Migration, and Invasion by miR-143 and miR-199a Through COX-2 Targeting

Objective

To investigate the biological role of miR-143 and miR-199a in mediating the progression of osteosarcoma (OS) by targeting cyclooxygenase (COX-2).

Introduction

COX-2 plays a crucial role in the development and progression of OS. However, the specific regulatory mechanisms of COX-2 in OS are still not well understood.

Methods

The expression levels of COX-2, miR-143 and miR-199a in OS tissues were detected using immunohistochemistry, qPCR, or western blot assays. The targeting relationship between miRNAs and COX-2 was determined. The effect of miRNA and COX-2 on OS cells was evaluated in vitro and in vivo.

Results

COX-2 expression was upregulated while miR-143 and miR-199a were downregulated in OS tissues. miR-143 and miR-199a suppressed the proliferation, migration, and invasion of OS cells. The dual-luciferase reporter gene assay showed that COX-2 was a direct target of miR-143 and miR-199a. Genetic knockdown of COX-2 significantly suppressed cell proliferation, induced apoptosis, and inhibited migration and invasion of OS cells. The expression levels of COX-2 and PGE2 were decreased after the overexpression of miR-143 and miR-199a. Additionally, COX-2 silencing inhibited the tumorigenesis of OS and the synthesis of PGE2 in vivo.

Conclusions

miR-143 and miR-199a/COX-2 axis modulates the proliferation, invasion, and migration in osteosarcoma.

Long-term effect of indomethacin on a rat model of neonatal hypoxia ischemic encephalopathy through behavioral tests

BACKGROUND

Many medical experts prescribe indomethacin because of its anti-inflammatory, analgesic, tocolytic, and duct closure effects. This article presents an evaluation of the enduring impact of indomethacin on neonatal rats with hypoxic-ischemic (HI) insults, employing behavioral tests as a method of assessment.

METHODS

The experiment was conducted on male Wistar-Albino rats weighing 10 to 15 g, aged between seven and 10 days. The rats were divided into three groups using a random allocation method as follows: hypoxic ischemic encephalopathy (HIE) group, HIE treated with indomethacin group (INDO), and Sham group. A left common carotid artery ligation and hypoxia model was applied in both the HIE and INDO groups. The INDO group was treated with 4 mg/kg intraperitoneal indomethacin every 24 h for 3 days, while the Sham and HIE groups were given dimethylsulfoxide (DMSO). After 72 h, five rats from each group were sacrificed and brain tissue samples were stained with 2,3,5-Triphenyltetrazolium chloride (TCC) for infarct-volume measurement. Seven rats from each group were taken to the behavioral laboratory in the sixth postnatal week (PND42) and six from each group were sacrificed for the Evans blue (EB) experiment for blood-brain barrier (BBB) integrity evaluation. The open field (OF) test and Morris water maze (MWM) tests were performed. After behavioral tests, brain tissue were obtained and stained with TCC to assess the infarct volume.

RESULTS

The significant increase in the time spent in the central area and the frequency of crossing to the center in the INDO group compared with the HIE group indicated that indomethacin decreased anxiety-like behavior (p < 0.001, p < 0.05). However, the MWM test revealed that indomethacin did not positively affect learning and memory performance (p > 0.05). Additionally, indomethacin significantly reduced infarct volume and neuropathological grading in adolescence (p < 0.05), although not statistically significant in the early period. Moreover, the EB experiment demonstrated that indomethacin effectively increased BBB integrity (p < 0.05).

CONCLUSIONS

In this study, we have shown for the first time that indomethacin treatment can reduce levels of anxiety-like behavior and enhance levels of exploratory behavior in a neonatal rat model with HIE. It is necessary to determine whether nonsteroidal anti-inflammatory agents, such as indomethacin, should be used for adjuvant therapy in newborns with HIE.

The selective cyclooxygenase-2 inhibitor NS398 ameliorates cisplatin-induced impairments in mitochondrial and cognitive function

Chemobrain is a condition that negatively affects cognition in cancer patients undergoing active chemotherapy, as well as following chemotherapy cessation. Chemobrain is also known as chemotherapy-induced cognitive impairment (CICI) and has emerged as a significant medical contingency. There is no therapy to ameliorate this condition, hence identification of novel therapeutic strategies to prevent CICI is of great interest to cancer survivors. Utilizing the platinum-based chemotherapy cisplatin in an investigative approach for CICI, we identified increased expression of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2) in the adult mouse hippocampus, and in human cortical neuron cultures derived from induced pluripotent stem cells (iPSCs). Notably, administration of NS398, a selective COX-2 inhibitor, prevented CICI in vivo without negatively affecting the antitumor efficacy of cisplatin or potentiating tumor growth. Given that dysfunctional mitochondrial bioenergetics plays a prominent role in CICI, we explored the effects of NS398 in cisplatin-induced defects in human cortical mitochondria. We found that cisplatin significantly reduces mitochondrial membrane potential (MMP), increases matrix swelling, causes loss of cristae membrane integrity, impairs ATP production, as well as decreases cell viability and dendrite outgrowth. Pretreatment with NS398 in human cortical neurons attenuated mitochondrial dysfunction caused by cisplatin, while improving cell survival and neurite morphogenesis. These results suggest that aberrant COX-2 inflammatory pathways may contribute in cisplatin-induced mitochondrial damage and cognitive impairments. Therefore, COX-2 signaling may represent a viable therapeutic approach to improve the quality of life for cancer survivors experiencing CICI.

Inhibition of rat locus coeruleus neurons by prostaglandin E2 EP3 receptors: pharmacological characterization ex vivo

Prostaglandin E2 (PGE2) is an inflammatory mediator synthesized by the brain constitutive cyclooxygenase enzyme. PGE2 binds to G protein-coupled EP1-4 receptors (EP1 to Gq, EP2,4 to Gs, and EP3 to Gi/o). EP2, EP3 and EP4 receptors are expressed in the locus coeruleus (LC), the main noradrenergic nucleus in the brain. EP3 receptors have been explored in the central nervous system, although its role regulating the locus coeruleus neuron activity has not been pharmacologically defined. Our aim was to characterize the function of EP3 receptors in neurons of the LC. Thus, we studied the effect of EP3 receptor agonists on the firing activity of LC cells in rat brain slices by single-unit extracellular electrophysiological techniques. The EP3 receptor agonist sulprostone (0.15 nM-1.28 µM), PGE2 (0.31 nM-10.2 µM) and the PGE1 analogue misoprostol (0.31 nM-2.56 µM) inhibited the firing rate of LC neurons in a concentration-dependent manner (EC50 = 15 nM, 110 nM, and 51 nM, respectively). The EP3 receptor antagonist L-798,106 (3-10 µM), but not the EP2 (PF-04418948, 3-10 µM) or EP4 (L-161,982, 3-10 µM) receptor antagonists, caused rightward shifts in the concentration-effect curves for the EP3 receptor agonists. Sulprostone-induced effect was attenuated by the Gi/o protein blocker pertussis toxin (pertussis toxin, 500 ng ml-1) and the inhibitors of inwardly rectifying potassium channels (GIRK) BaCl2 (300 µM) and SCH-23390 (15 µM). In conclusion, LC neuron firing activity is regulated by EP3 receptors, presumably by an inhibitory Gi/o protein- and GIRK-mediated mechanism.

Bacteroides Fragilis in the gut microbiomes of Alzheimer's disease activates microglia and triggers pathogenesis in neuronal C/EBPβ transgenic mice

Gut dysbiosis contributes to Alzheimer's disease (AD) pathogenesis, and Bacteroides strains are selectively elevated in AD gut microbiota. However, it remains unknown which Bacteroides species and how their metabolites trigger AD pathologies. Here we show that Bacteroides fragilis and their metabolites 12-hydroxy-heptadecatrienoic acid (12-HHTrE) and Prostaglandin E2 (PGE2) activate microglia and induce AD pathogenesis in neuronal C/EBPβ transgenic mice. Recolonization of antibiotics cocktail-pretreated Thy1-C/EBPβ transgenic mice with AD patient fecal samples elicits AD pathologies, associated with C/EBPβ/Asparaginyl endopeptidase (AEP) pathway upregulation, microglia activation, and cognitive disorders compared to mice receiving healthy donors' fecal microbiota transplantation (FMT). Microbial 16S rRNA sequencing analysis shows higher abundance of proinflammatory Bacteroides fragilis in AD-FMT mice. Active components characterization from the sera and brains of the transplanted mice revealed that both 12-HHTrE and PGE2 activate primary microglia, fitting with poly-unsaturated fatty acid (PUFA) metabolites enrichment identified by metabolomics. Strikingly, recolonization with live but not dead Bacteroides fragilis elicited AD pathologies in Thy1-C/EBPβ transgenic mice, so did 12-HHTrE or PGE2 treatment alone. Collectively, our findings support a causal role for Bacteroides fragilis and the PUFA metabolites in activating microglia and inducing AD pathologies in Thy1- C/EBPβ transgenic mice.

HIV-1 Tat Upregulates TREM1 Expression in Human Microglia

Because microglia are a reservoir for HIV and are resistant to the cytopathic effects of HIV infection, they are a roadblock for any HIV cure strategy. We have previously identified that triggering receptor expressed on myeloid cells 1 (TREM1) plays a key role in human macrophage resistance to HIV-mediated cytopathogenesis. In this article, we show that HIV-infected human microglia express increased levels of TREM1 and are resistant to HIV-induced apoptosis. Moreover, upon genetic inhibition of TREM1, HIV-infected microglia undergo cell death in the absence of increased viral or proinflammatory cytokine expression or the targeting of uninfected cells. We also show that the expression of TREM1 is mediated by HIV Tat through a TLR4, TICAM1, PG-endoperoxide synthase 2, PGE synthase, and PGE2-dependent manner. These findings highlight the potential of TREM1 as a therapeutic target to eradicate HIV-infected microglia without inducing a proinflammatory response.

Peripheral Neuropathy in Diabetes Mellitus: Pathogenetic Mechanisms and Diagnostic Options

Diabetic neuropathy (DN) is one of the main microvascular complications of both type 1 and type 2 diabetes mellitus. Sometimes, this could already be present at the time of diagnosis for type 2 diabetes mellitus (T2DM), while it appears in subjects with type 1 diabetes mellitus (T1DM) almost 10 years after the onset of the disease. The impairment can involve both somatic fibers of the peripheral nervous system, with sensory-motor manifestations, as well as the autonomic system, with neurovegetative multiorgan manifestations through an impairment of sympathetic/parasympathetic conduction. It seems that, both indirectly and directly, the hyperglycemic state and oxygen delivery reduction through the vasa nervorum can determine inflammatory damage, which in turn is responsible for the alteration of the activity of the nerves. The symptoms and signs are therefore various, although symmetrical painful somatic neuropathy at the level of the lower limbs seems the most frequent manifestation. The pathophysiological aspects underlying the onset and progression of DN are not entirely clear. The purpose of this review is to shed light on the most recent discoveries in the pathophysiological and diagnostic fields concerning this complex and frequent complication of diabetes mellitus.

Rivastigmine Reverses the Decrease in Synapsin and Memory Caused by Homocysteine: Is There Relation to Inflammation?

Elevated levels of homocysteine (Hcy) in the blood, called hyperhomocysteinemia (HHcy), is a prevalent risk factor for it has been shown that Hcy induces oxidative stress and increases microglial activation and neuroinflammation, as well as causes cognitive impairment, which have been linked to the neurodegenerative process. This study aimed to evaluate the effect of mild hyperhomocysteinemia with or without ibuprofen and rivastigmine treatments on the behavior and neurochemical parameters in male rats. The chronic mild HHcy model was chemically induced in Wistar rats by subcutaneous administration of Hcy (4055 mg/kg body weight) twice daily for 30 days. Ibuprofen (40 mg/kg) and rivastigmine (0.5 mg/kg) were administered intraperitoneally once daily. Motor damage (open field, balance beam, rotarod, and vertical pole test), cognitive deficits (Y-maze), neurochemical parameters (oxidative status/antioxidant enzymatic defenses, presynaptic protein synapsin 1, inflammatory profile parameters, calcium binding adapter molecule 1 (Iba1), iNOS gene expression), and cholinergic anti-inflammatory pathway were investigated. Results showed that mild HHcy caused cognitive deficits in working memory, and impaired motor coordination reduced the amount of synapsin 1 protein, altered the neuroinflammatory picture, and caused changes in the activity of catalase and acetylcholinesterase enzymes. Both rivastigmine and ibuprofen treatments were able to mitigate this damage caused by mild HHcy. Together, these neurochemical changes may be associated with the mechanisms by which Hcy has been linked to a risk factor for AD. Treatments with rivastigmine and ibuprofen can effectively reduce the damage caused by increased Hcy levels.

The Function of NF-Kappa B During Epilepsy, a Potential Therapeutic Target

The transcriptional regulator nuclear factor kappa B (NF-κB) modulates cellular biological activity by binding to promoter regions in the nucleus and transcribing various protein-coding genes. The NF-κB pathway plays a major role in the expressing genes related to inflammation, including chemokines, interleukins, and tumor necrosis factor. It also transcribes genes that can promote neuronal survival or apoptosis. Epilepsy is one of the most common brain disorders and it not only causes death worldwide but also affects the day-to-day life of affected individuals. While epilepsy has diverse treatment options, there remain patients who are not sensitive to the existing treatment methods. Recent studies have implicated the critical role of NF-κB in epilepsy. It is upregulated in neurons, glial cells, and endothelial cells, due to neuronal loss, glial cell proliferation, blood-brain barrier dysfunction, and hippocampal sclerosis through the glutamate and γ-aminobutyric acid imbalance, ion concentration changes, and other mechanisms. In this review, we summarize the functional changes caused by the upregulation of NF-κB in the central nervous system during different periods after seizures. This review is the first to deconvolute the complicated functions of NF-κB, and speculate that the regulation of NF-κB can be a safe and effective treatment strategy for epilepsy.

Hippocampal Over-Expression of Cyclooxygenase-2 (COX-2) Is Associated with Susceptibility to Stress-Induced Anhedonia in Mice

The phenomenon of individual variability in susceptibility/resilience to stress and depression, in which the hippocampus plays a pivotal role, is attracting increasing attention. We investigated the potential role of hippocampal cyclooxygenase-2 (COX-2), which regulates plasticity, neuroimmune function, and stress responses that are all linked to this risk dichotomy. We used a four-week-long chronic mild stress (CMS) paradigm, in which mice could be stratified according to their susceptibility/resilience to anhedonia, a key feature of depression, to investigate hippocampal expression of COX-2, a marker of microglial activation Iba-1, and the proliferation marker Ki67. Rat exposure, social defeat, restraints, and tail suspension were used as stressors. We compared the effects of treatment with either the selective COX-2 inhibitor celecoxib (30 mg/kg/day) or citalopram (15 mg/kg/day). For the celecoxib and vehicle-treated mice, the Porsolt test was used. Anhedonic (susceptible) but not non-anhedonic (resilient) animals exhibited elevated COX-2 mRNA levels, increased numbers of COX-2 and Iba-1-positive cells in the dentate gyrus and the CA1 area, and decreased numbers of Ki67-positive cells in the subgranular zone of the hippocampus. Drug treatment decreased the percentage of anhedonic mice, normalized swimming activity, reduced behavioral despair, and improved conditioned fear memory. Hippocampal over-expression of COX-2 is associated with susceptibility to stress-induced anhedonia, and its pharmacological inhibition with celecoxib has antidepressant effects that are similar in size to those of citalopram.

Brief neuronal afterdischarges in the rat hippocampus lead to transient changes in oscillatory activity and to a very long-lasting decline in BOLD signals without inducing a hypoxic state

The effects of hippocampal neuronal afterdischarges (nAD) on hemodynamic parameters, such as blood-oxygen-level-dependent (BOLD) signals) and local cerebral blood volume (CBV) changes, as well as neuronal activity and metabolic parameters in the dentate gyrus, was investigated in rats by combining in vivo electrophysiology with functional magnetic resonance imaging (fMRI) or ¹H-nuclear magnetic resonance spectroscopy (¹H-NMRS). Brief electrical high-frequency pulse-burst stimulation of the right perforant pathway triggered nAD, a seizure-like activity, in the right dentate gyrus with a high incidence, a phenomenon that in turn caused a sustained decrease in BOLD signals for more than 30 min. The decrease was associated with a reduction in CBV but not with signs of hypoxic metabolism. nAD also triggered transient changes mainly in the low gamma frequency band that recovered within 20 min, so that the longer-lasting altered hemodynamics reflected a switch in blood supply rather than transient changes in ongoing neuronal activity. Even in the presence of reduced baseline BOLD signals, neurovascular coupling mechanisms remained intact, making long-lasting vasospasm unlikely. Subsequently generated nAD did not further alter the baseline BOLD signals. Similarly, nAD did not alter baseline BOLD signals when acetaminophen was previously administered, because acetaminophen alone had already caused a similar decrease in baseline BOLD signals as observed after the first nAD. Thus, at least two different blood supply states exist for the hippocampus, one low and one high, with both states allowing similar neuronal activity. Both acetaminophen and nAD switch from the high to the low blood supply state. As a result, the hemodynamic response function to an identical stimulus differed after nAD or acetaminophen, although the triggered neuronal activity was similar.

The effect of sulfasalazine in pentylenetetrazole-induced seizures in rats

We aimed to reveal the anti-convulsant effects sulfasalazine and its mechanism in pentylenetetrazole (PTZ)-induced seizures in rats. Forty-eight male Wistar albino rats (200-250 g) were randomly divided into two groups: 24 for electroencephalography (EEG) recording (group A) and 24 for behavioral studies (group B). About 70 mg/kg PTZ was used for behavioral studies after sulfasalazine administration and 35 mg/kg PTZ was used for EEG recording after sulfasalazine administration. Electrodes were implanted on the dura mater over the left frontal cortex and the reference electrode was implanted over the cerebellum for EEG recording. Racine's convulsion scale, first myoclonic jerk onset time, spike percentages, brain malondialdehyde (MDA), superoxide dismutase (SOD), and prostaglandin F2α (PGF2α) levels were evaluated between the groups. First myoclonic jerk onset time was significantly shorter in the saline group than both 250 and 500 mg/kg sulfasalazine groups (P<0.05). Racine's convulsion scores were significantly lower in the 250 and 500 mg/kg sulfasalazine groups than the saline group (P<0.05, P<0.001). The two sulfasalazine groups had lower spike percentages than the saline group (P<0.05). Significantly lower MDA and PGF2α levels were observed in the 250 and 500 mg/kg sulfasalazine groups compared with the saline group (P<0.05, P<0.001, respectively). SOD increased significantly in both sulfasalazine groups compared with the PTZ+saline group (P<0.05). Our study demonstrated that sulfasalazine had protective effects on PTZ-induced convulsions by protecting against oxidative and inflammatory damage associated with PTZ.

c-di-GMP Induces COX-2 Expression in Macrophages in a STING-Independent Manner

Many pathogen-associated molecular patterns (PAMPs), such as lipopolysaccharide (LPS) and lipoteichoic acid, are potent immunostimulatory molecules and promote the expression of cyclooxygenase 2 (COX-2). While the production of COX-2, and ultimately prostaglandin E₂, could be protective, persistent induction of COX-2 leads to inflamed environments that can result in septic shock and death. Bacterial derived cyclic dinucleotides (CDNs), c-di-GMP and c-di-AMP, are also PAMPs and have been shown to produce inflamed environments via the production of pro-inflammatory cytokines such as type I interferons. The well-characterized CDN immunostimulatory mechanism involves binding to stimulator of interferon genes (STING), which ultimately results in the phosphorylation of IRF3 or release of NF-κB to promote expression of type I IFN or pro-inflammatory cytokines. In this study, we sought to investigate if CDNs promote COX-2 expression. Using RAW macrophages as a model system, we reveal that c-di-GMP, but not c-di-AMP or the host-derived 2',3'-cGAMP, promotes COX-2 expression. Using analogues of CDNs, we show that the presence of two guanines and two 3',5'-phosphodiester linkages are requirements for the promotion of COX-2 expression by cyclic dinucleotides. Both c-di-GMP and LPS inductions of COX-2 expression in RAW macrophages are STING-independent and are regulated by Tpl2-MEK-ERK-CREB signaling; inhibitors of Tpl2, MEK, and ERK could attenuate COX-2 expression promoted by c-di-GMP. This work adds to the growing body of evidence that cyclic dinucleotides regulate pathways other than the STING-TBK1-IRF3 axis. Additionally, the differential COX-2 induction by c-di-GMP but not c-di-AMP or cGAMP suggests that the type and level of inflammation could be dictated by the nucleotide signature of the invading pathogen.

Homeostatic state of microglia in a rat model of chronic sleep restriction

Chronic sleep restriction (CSR) negatively impacts brain functions. Whether microglia, the brain's resident immune cells, play any role is unknown. We studied microglia responses to CSR using a rat model featuring slowly rotating wheels (3 h on/1 h off), which was previously shown to induce both homeostatic and adaptive responses in sleep and attention. Adult male rats were sleep restricted for 27 or 99 h. Control rats were housed in locked wheels. After 27 and/or 99 h of CSR, the number of cells immunoreactive for the microglia marker ionized calcium-binding adaptor molecule-1 (Iba1) and the density of Iba1 immunoreactivity were increased in 4/10 brain regions involved in sleep/wake regulation and cognition, including the prelimbic cortex, central amygdala, perifornical lateral hypothalamic area, and dorsal raphe nucleus. CSR neither induced mitosis in microglia (assessed with bromodeoxyuridine) nor impaired blood-brain barrier permeability (assessed with Evans Blue). Microglia appeared ramified in all treatment groups and, when examined quantitatively in the prelimbic cortex, their morphology was not affected by CSR. After 27 h, but not 99 h, of CSR, mRNA levels of the anti-inflammatory cytokine interleukin-10 were increased in the frontal cortex. Pro-inflammatory cytokine mRNA levels (tumor necrosis factor-α, interleukin-1β, and interleukin-6) were unchanged. Furthermore, cortical microglia were not immunoreactive for several pro- and anti-inflammatory markers tested, but were immunoreactive for the purinergic P2Y12 receptor. These results suggest that microglia respond to CSR while remaining in a physiological state and may contribute to the previously reported homeostatic and adaptive responses to CSR.

Celecoxib in a Preclinical Model of Repetitive Mild Traumatic Brain Injury: Hippocampal Learning Deficits Persist with Inflammatory and Excitotoxic Neuroprotection

Repetitive mild traumatic brain injuries (mTBIs) contribute to inflammation-induced neurodegeneration. Cycloxygenase (COX) enzymes produce inflammatory cytokines that influence the microglia response to neurotrauma. Celecoxib is a selective COX-2 inhibitor that is prescribed in some conditions of mTBI to alleviate symptoms of concussion, and has shown benefits in neurodegenerative conditions. We investigated molecular pathways of neuroinflammation in response to celecoxib treatment in a mouse model of repetetive mTBI. Fifteen mTBIs were delivered over 23 days in adult male C57BL/6J mice in one of four groups (control, celecoxib without impact, celecoxib with impact, and vehicle with impact). Cognitive function was assessed at 48 h and three months following the final mTBI. Morris Water Maze testing revealed impaired hippocampal spatial learning performance in the celecoxib treatment with the impact group compared to the vehicle with impact control in the acute phase, with celecoxib treatment providing no improvement compared with the control at chronic testing; mRNA analysis of the cerebral cortex and hippocampus revealed expression change, indicating significant improvement in microglial activation, inflammation, excitotoxicity, and neurodegeneration at chronic measurement. These data suggest that, in the acute phase following injury, celecoxib protected against neuroinflammation, but exacerbated clinical cognitive disturbance. Moreover, while there was evidence of neuroprotective alleviation of mTBI pathophysiology at chronic measurement, there remained no change in clinical features.

Conjugated Linoleic Acid and Brain Metabolism: A Possible Anti-Neuroinflammatory Role Mediated by PPARα Activation

Fatty acids play a crucial role in the brain as specific receptor ligands and as precursors of bioactive metabolites. Conjugated linoleic acid (CLA), a group of positional and geometric isomers of linoleic acid (LA, 18:2 n-6) present in meat and dairy products of ruminants and synthesized endogenously in non-ruminants and humans, has been shown to possess different nutritional properties associated with health benefits. Its ability to bind to peroxisome proliferator-activated receptor (PPAR) α, a nuclear receptor key regulator of fatty acid metabolism and inflammatory responses, partly mediates these beneficial effects. CLA is incorporated and metabolized into brain tissue where induces the biosynthesis of endogenous PPARα ligands palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), likely through a positive feedback mechanism where PPARα activation sustains its own cellular effects through ligand biosynthesis. In addition to PPARα, PEA and OEA may as well bind to other receptors such as TRPV1, further extending CLA own anti-neuroinflammatory actions. Future studies are needed to investigate whether dietary CLA may exert anti-inflammatory activity, particularly in the setting of neurodegenerative diseases and neuropsychiatric disorders with a neuroinflammatory basis.

Exploring the molecular approach of COX and LOX in Alzheimer's and Parkinson's disorder

Neuroinflammation is well established biomarker for the major neurodegenerative like Alzheimer's disease (AD) and Parkinson's disease (PD). Cytokines/chemokines excite phospholipase A2 and cyclooxygenases (COX), facilitating the release of arachidonic acid (AA) and docosahexaenoic acid (DHA) from membrane glycerophospholipids, in which the former is oxidized to produce pro-inflammatory eicosanoids (prostaglandins, leukotrienes and thromboxane's), which intensify the neuroinflammatory events in the brain. Similarly, resolvins and neuroprotectins are the metabolized products of docosahexaenoic acid, which exert an inhibitory effect on the production of eicosanoids. Furthermore, an oxidized product of arachidonic acid, lipoxin, is generated via 5-lipoxygenase (5-LOX) pathway, and contributes to the resolution of inflammation, along with anti-inflammatory actions. Moreover, DHA and its lipid mediators inhibit neuroinflammatory responses by blocking NF-κB, inhibiting eicosanoid production, preventing cytokine secretion and regulating leukocyte trafficking. Various epidemiological studies reported, elevated levels of COX-2 enzyme in patients with AD and PD, indicating its role in progression of the disease. Similarly, enhanced levels of 5-LOX and 12/15-LOX in PD models represent their role brain disorders, where the former is expressed in AD patients and the latter exhibits it involvement in PD. The present review elaborates the role of AA, DHA, eicosanoids and docosanoids, along with COX and LOX pathway which provides an opportunity to the researchers to understand the role of these lipid mediators in neurological disorders (AD and PD). The information gathered from the review will aid in facilitating the development of appropriate therapeutic options targeting COX and LOX pathway.

Inflammation in Bipolar Disorder (BD): Identification of new therapeutic targets

Bipolar disorder (BD) is a chronic and cyclic mental disorder, characterized by unusual mood swings between mania/hypomania and depression, raising concern in both scientific and medical communities due to its deleterious social and economic impact. Polypharmacy is the rule due to the partial effectiveness of available drugs. Disease course is often unremitting, resulting in frequent cognitive deficits over time. Despite all research efforts in identifying BD-associated molecular mechanisms, current knowledge remains limited. However, the involvement of inflammation in BD pathophysiology is increasingly consensual, with the immune system and neuroinflammation playing a key role in disease course. Evidence includes altered levels of cytokines and acute-phase proteins, pathological microglial activation, deregulation of Nrf2-Keap1 system and changes in biogenic amines neurotransmitters, whose expression is regulated by TNF-α, a pro-inflammatory cytokine highly involved in BD, pointing out inflammation as a novel and attractive therapeutic target for BD. As result, new therapeutic agents including non-steroidal anti-inflammatory drugs, N-acetylcysteine and GSK3 inhibitors have been incorporated in BD treatment. Taking into consideration the latest pre-clinical and clinical trials, in this review we discuss recent data regarding inflammation in BD, unveiling potential therapeutic approaches through direct or indirect modulation of inflammatory response.

Cyclooxygenase Inhibition Safety and Efficacy in Inflammation-Based Psychiatric Disorders

According to the World Health Organization, the major psychiatric and neurodevelopmental disorders include major depression, bipolar disorder, schizophrenia, and autism spectrum disorder. The potential role of inflammation in the onset and progression of these disorders is increasingly being studied. The use of non-steroidal anti-inflammatory drugs (NSAIDs), well-known cyclooxygenase (COX) inhibitors, combined with first-choice specific drugs have been long investigated. The adjunctive administration of COX inhibitors to classic clinical treatments seems to improve the prognosis of people who suffer from psychiatric disorders. In this review, a broad overview of the use of COX inhibitors in the treatment of inflammation-based psychiatric disorders is provided. For this purpose, a critical analysis of the use of COX inhibitors in the last ten years of clinical trials of the major psychiatric disorders was carried out.

Small molecules targeting cyclooxygenase/prostanoid cascade in experimental brain ischemia: Do they translate?

Acute brain ischemia accounts for most of stroke cases and constitutes a leading cause of deaths among adults and permanent disabilities in survivors. Currently, the intravenous thrombolysis is the only available medication for ischemic stroke; mechanical thrombectomy is an emerging alternative treatment for occlusion of large arteries and has shown some promise in selected subsets of patients. However, the overall narrow treatment window and potential risks largely limit the patient eligibility. New druggable targets are needed to innovate the treatment of brain ischemia. As the rate-limiting enzyme in the biosyntheses of prostanoids, cyclooxygenase (COX), particularly the inducible isoform COX-2, has long been implicated in mechanisms of acute stroke-induced brain injury and inflammation. However, the notion of therapeutically targeting COX has been diminished over the past two decades due to significant complications of the cardiovascular and cerebrovascular systems caused by long-term use of COX-2 inhibitor drugs. New treatment strategies targeting the downstream prostanoid signaling receptors regulating the deleterious effects of COX cascade have been proposed. As such, a large number of selective small molecules that negatively or positively modulate these important inflammatory regulators have been evaluated for neuroprotection and other beneficial effects in various animal models of brain ischemia. These timely preclinical studies, though not yet led to clinical innovation, provided new insights into the regulation of inflammatory reactions in the ischemic brain and could guide drug discovery efforts aiming for novel adjunctive strategies, along with current reperfusion therapy, to treat acute brain ischemia with higher specificity and longer therapeutic window.

Neuroinflammatory responses in Parkinson's disease: relevance of Ibuprofen in therapeutics

Parkinson's disease (PD) pathogenesis inevitably involves neuroinflammatory responses attained through contribution of both neuron and glial cells. Investigation done in both experimental models of PD and in samples of PD patients suggested the involvement of both central and peripheral inflammatory responses during PD pathogenesis. Such neuroinflammatory responses could be regulated by neuron-glia interaction which is one of the recently focused areas in the field of disease diagnosis, pathogenesis and therapeutics. Such aggravated neuroinflammatory responses during PD are very well associated with augmented levels of cyclooxygenase (COX). An increased expression of cyclooxygenase (COX) with a concomitant increase in the prostaglandin E2 (PGE2) levels has been observed during PD pathology. Ibuprofen is one of the non-steroidal anti-inflammatory drugs (NSAID) and clinically being used for PD patients. This review focuses on the neuroinflammatory responses during PD pathology as well as the effect of ibuprofen on various disease related signaling factors and mechanisms involving nitrosative stress, neurotransmission, neuronal communication and peroxisome proliferator-activated receptor-γ. Such mechanistic effect of ibuprofen has been mostly reported in experimental models of PD and clinical investigations are still required. Since oxidative neuronal death is one of the major neurodegenerative mechanisms in PD, the antioxidant capacity of ibuprofen along with its antidepressant effects have also been discussed. This review will direct the readers towards fulfilling the existing gaps in the mechanistic aspect of ibuprofen and enhance its clinical relevance in PD therapeutics and probably in other age-related neurodegenerative diseases.

Cyclooxygenase-2 inhibition prevents stress induced amygdala activation and anxiety-like behavior

Stress is a major risk factor for the development and exacerbation of mood and anxiety disorders, and recent studies have suggested inflammatory contributions to the pathogenesis of depression. Interestingly, pharmacological inhibition of cyclooxygenase-2 (COX-2) has shown promise in the treatment of affective disorders in small scale clinical studies; however, the mechanisms by which COX-2 inhibition affects behavioral domains relevant to affective disorders are not well understood. Here, we examined the effects of pharmacological inhibition of COX-2 with the highly selective inhibitor Lumiracoxib (LMX) on anxiety-like behavior and in vivo basolateral amygdala (BLA) neural activity in response to acute restraint stress exposure. In male mice, pretreatment with LMX prevented the increase in BLA calcium transients induced by restraint stress and prevented anxiogenic behavior seen after restraint stress exposure. Specifically, acute injection of LMX 5 mg kg^-1 reduced anxiety-like behavior in the light-dark box (LD) and elevated-zero maze (EZM). In addition, in vivo fiber photometry studies showed that acute stress increased calcium transients and the predicted action potential frequency of BLA neurons, which was also normalized by acute LMX pretreatment. These findings indicate pharmacological inhibition of COX-2 can prevent acute stress-induced increase in BLA cellular activity and anxiety-like behavior and provides insights into the neural mechanisms by which COX-2 inhibition could affect anxiety domain symptoms in patients with affective disorders.

Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target

Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.

The Role of Brain Cyclooxygenase-2 (Cox-2) Beyond Neuroinflammation: Neuronal Homeostasis in Memory and Anxiety

Cyclooxygenases are a group of heme-containing isozymes (namely Cox-1 and Cox-2) that catalyze the conversion of arachidonic acid to largely bioactive prostaglandins (PGs). Cox-1 is the ubiquitous housekeeping enzyme, and the mitogen-inducible Cox-2 is activated to cause inflammation. Interestingly, Cox-2 is constitutively expressed in the brain at the postsynaptic dendrites and excitatory terminals of the cortical and spinal cord neurons. Neuronal Cox-2 is activated in response to synaptic excitation to yield PGE₂, the predominant Cox-2 metabolite in the brain, which in turn stimulates the release of glutamate and neuronal firing in a retrograde fashion. Cox-2 is also engaged in the metabolism of new endocannabinoids from 2-arachidonoyl-glycerol to modulate their actions at presynaptic terminals. In addition to these interactions, the induction of neuronal Cox-2 is coupled to the trans-synaptic activation of the dopaminergic mesolimbic system and some serotoninergic receptors, which might contribute to the development of emotional behavior. Although much of the focus regarding the induction of Cox-2 in the brain has been centered on neuroinflammation-related neurodegenerative and psychiatric disorders, some evidence also suggests that Cox-2 release during neuronal signaling may be pivotal for the fine tuning of cortical networks to regulate behavior. This review compiles the evidence supporting the homeostatic role of neuronal Cox-2 in synaptic transmission and plasticity, since neuroinflammation is originally triggered by the induction of glial Cox-2 expression. The goal is to provide perspective on the roles of Cox-2 beyond neuroinflammation, such as those played in memory and anxiety, and whose evidence is still scant.

Rofecoxib Attenuates the Pathogenesis of Amyotrophic Lateral Sclerosis by Alleviating Cyclooxygenase-2-Mediated Mechanisms

Cyclooxygenase-2 (COX-2) is reported to be activated during the course of amyotrophic lateral sclerosis (ALS) development and progression. However, the roles of COX-2 in aggravating ALS and the underlying mechanism have been largely overlooked. To reveal the mechanisms, the canonical SOD1^G93A mouse model was used as an experimental model for ALS in the current study. In addition, a specific inhibitor of COX-2 activity, rofecoxib, was orally administered to SOD1^G93A mice. With this in vivo approach, we revealed that COX-2 proinflammatory signaling cascades were inhibited by rofecoxib in SOD1^G93A mice. Specifically, the protein levels of COX-2, interleukin (IL)-1β, and tumor necrosis factor (TNF)-α were elevated as a result of activation of astrocytes and microglia during the course of ALS development and progression. These proinflammatory reactions may contribute to the death of neurons by triggering the movement of astrocytes and microglia to neurons in the context of ALS. Treatment with rofecoxib alleviated this close association between glial cells and neurons and significantly decreased the density of inflammatory cells, which helped to restore the number of motor neurons in SOD1^G93A mice. Mechanistically, rofecoxib treatment decreased the expression of COX-2 and its downstream signaling targets, including IL-1β and TNF-α, by deactivating glial cells, which in turn ameliorated the progression of SOD1^G93A mice by postponing disease onset and modestly prolonging survival. Collectively, these results provide novel insights into the mechanisms of ALS and aid in the development of new drugs to improve the clinical treatment of ALS.

Peripheral-to-central immune communication at the area postrema glial-barrier following bleomycin-induced sterile lung injury in adult rats

The pathways for peripheral-to-central immune communication (P → C I-comm) following sterile lung injury (SLI) are unknown. SLI evokes systemic and central inflammation, which alters central respiratory control and viscerosensory transmission in the nucleus tractus solitarii (nTS). These functional changes coincide with increased interleukin-1 beta (IL-1β) in the area postrema, a sensory circumventricular organ that connects P → C I-comm to brainstem circuits that control homeostasis. We hypothesize that IL-1β and its downstream transcriptional target, cyclooxygenase-2 (COX-2), mediate P → C I-comm in the nTS. In a rodent model of SLI induced by intratracheal bleomycin (Bleo), the sigh frequency and duration of post-sigh apnea increased in Bleo- compared to saline- treated rats one week after injury. This SLI-dependent change in respiratory control occurred concurrently with augmented IL-1β and COX-2 immunoreactivity (IR) in the funiculus separans (FS), a barrier between the AP and the brainstem. At this barrier, increases in IL-1β and COX-2 IR were confined to processes that stained for glial fibrillary acidic protein (GFAP) and that projected basolaterally to the nTS. Further, FS radial-glia did not express TNF-α or IL-6 following SLI. To test our hypothesis, we blocked central COX-1/2 activity by intracerebroventricular (ICV) infusion of Indomethacin (Ind). Continuous ICV Ind treatment prevented Bleo-dependent increases in GFAP + and IL-1β + IR, and restored characteristics of sighs that reset the rhythm. These data indicate that changes in sighs following SLI depend partially on activation of a central COX-dependent P → C I-comm via radial-glia of the FS.

The efficacy and safety of selective COX-2 inhibitors for postoperative pain management in patients after total knee/hip arthroplasty: a meta-analysis

BACKGROUND

Many selective cyclooxygenase (COX-2) inhibitors are currently used in clinical practice. COX-2 inhibitors have good anti-inflammatory, analgesic, antipyretic effects, and gastrointestinal safety. However, the analgesic effects and adverse reactions of COX-2 after total knee/hip arthroplasty (TKA/THA) are not fully known.

OBJECTIVE

To evaluate the efficacy and safety of selective COX-2 inhibitors in postoperative pain management in patients receiving TKA/THA.

METHODS

Randomized controlled trials (RCTs) were retrieved from medical literature databases. Risk ratios (RR) Std mean difference (SMD) and 95% confidence intervals (CI) were calculated to analyze the primary and safety endpoints.

RESULTS

In total, 18 articles (23 trial comparisons) were retrieved comprising 3104 patients. Among them, 1910 patients (61.5%) were randomized to the experimental group whereas 1194 patients (38.5%) were randomized to the control group. The primary endpoints were the patients' VAS score at rest or on ambulation (within 3 days). We found that VAS score in patients that received selective COX-2 inhibitor was significantly lower compared to those of the control group.

CONCLUSION

This meta-analysis shows that selective COX-2 inhibitor therapy is effective, safe, and reliable in relieving postoperative pain of THA/TKA.

Regional Gene Expression of Inflammation and Oxidative Stress Responses Does Not Predict Neurodegeneration in Aging

Brain aging is accompanied by increased oxidative stress and what has been termed "neuroinflammation," which might contribute to age-related neurodegenerative diseases. We analyzed expression in the transcription of innate inflammatory response genes in eleven representative regions including frontal, parietal, inferior temporal, cingulate, occipital, entorhinal cortex, caudate, putamen, thalamus, substantia nigra, and cerebellar vermis in aging human brains. We probed members of the complement system, colony stimulating factor receptors, toll-like receptors, and pro- and anti-inflammatory cytokines in the brains of subjects with no neurological disease and neurofibrillary tangles (mean age: 47.1  ±  5.7 years) and those with no neurological disease and neurofibrillary pathology stages I-II (mean age: 70.6  ±  6.3 years). Although the entorhinal and frontal cortex were most altered, gene regulation patterns did not match regions with increased vulnerability. Analysis of false discovery rate thresholds revealed no differences for any gene in any region between the 2 groups, including cases in which individual comparisons analyzed using Student t or nonparametric tests showed apparent differences between groups. Moreover, gene expression of major anti-oxidative stress responses did not match neuroinflammation in aging or increased regional susceptibility to major neurodegenerative diseases.

A rat model of organophosphate-induced status epilepticus and the beneficial effects of EP2 receptor inhibition

This review describes an adult rat model of status epilepticus (SE) induced by diisopropyl fluorophosphate (DFP), and the beneficial outcomes of transient inhibition of the prostaglandin-E2 receptor EP2 with a small molecule antagonist, delayed by 2-4 h after SE onset. Administration of six doses of the selective EP2 antagonist TG6-10-1 over a 2-3 day period accelerates functional recovery, attenuates hippocampal neurodegeneration, neuroinflammation, gliosis and blood-brain barrier leakage, and prevents long-term cognitive deficits without blocking SE itself or altering acute seizure characteristics. This work has provided important information regarding organophosphate-induced seizure related pathologies in adults and revealed the effectiveness of delayed EP2 inhibition to combat these pathologies.

Antidepressant-like effects of β-caryophyllene on restraint plus stress-induced depression

Chronic stress is depressogenic by altering neurotrophic and neuroinflammatory environments of the organism. The endocannabinoid system controls cognitive and emotional responses related with stress through the interaction with endocannabinoid receptors. β-Caryophyllene (BCP) is a CB2 agonist that exhibited anti-inflammatory, analgesic effects but minimal psychoactive effects. To test if BCP exhibits antidepressant-like action, animals were chronically restrained with additional stressors for 28 days, and BCP (25, 50, 100 mg/kg) was intraperitoneally injected once a day during the stress inflicting period. Then despair related behaviors and hippocampal expression of neurotrophic, inflammatory and cannabinoid receptor levels were measured. To test the effect of BCP on long-term depression, field potentials were measured during the application of lipopolysaccharide and low frequency stimulation. In the tail suspension test and forced swim test, chronic stress-induced despair behaviors were reduced by BCP. Also BCP improved the stress-related changes in the hippocampal expression of COX-2, BDNF, and CB2 receptor expression. In organotypic hippocampal slices, BCP reduced the lipopolysaccharide-induced intensification of the long-term depression. In conclusion, BCP improved chronic stress related behavioral and biochemical changes. These results suggest that BCP may be effective in treating depression and stress related mental illnesses.

Blood-Brain Barrier Is the Major Site for a Rapid and Dramatic Prostanoid Increase upon Brain Global Ischemia

We and others have demonstrated a rapid and dramatic increase in brain prostanoids upon decapitation-induced brain global ischemia and injury. However, the mechanism for this induction, including the cell types involved, are unknown. In the present study, we have validated and applied a pharmacological approach to inhibit prostanoid synthesis in the blood-brain barrier including endothelial cells. Our results indicate that a nonspecific cyclooxygenase (COX) inhibitor, ketorolac, does not pass the blood-brain barrier and does not enter red blood cells but penetrates endothelial cells. Ketorolac treatment did not affect basal prostanoid levels but completely prevented prostanoid induction upon global ischemia. These data indicate that basal prostanoids are synthesized in brain parenchyma cells, while inducible prostanoids are synthesized in the blood-brain barrier, most likely in endothelial cells. However, future studies with cell and COX isoform-specific gene ablation are needed to further validate this conclusion. These findings identify endothelial cells as a possible target for the development of pharmacological approaches to selectively attenuate inducible prostanoid pools without affecting basal levels under brain ischemia, trauma, surgery, and other related conditions.

Monoacylglycerol lipase blockade impairs fine motor coordination and triggers cerebellar neuroinflammation through cyclooxygenase-2

Monoacylglycerol lipase (MAGL) is the main enzyme implicated in the degradation of the most abundant endocannabinoid in the brain, 2-arachidonoylglycerol (2-AG), producing arachidonic acid (AA) and glycerol. MAGL pharmacological inhibition with JZL184 or genetic deletion results in an exacerbated 2-AG signaling and reduced synthesis of prostaglandins (PGs), due to the reduced AA precursor levels. We found that acute JZL184 administration, previously described to exert anti-inflammatory effects, and MAGL knockout (KO) mice display cerebellar, but not hippocampal, microglial reactivity, accompanied with increased expression of the mRNA levels of neuroinflammatory markers, such as cyclooxygenase-2 (COX-2). Notably, this neuroinflammatory phenotype correlated with relevant motor coordination impairment in the beam-walking and the footprint tests. Treatment with the COX-2 inhibitor NS398 during 5 days prevented the deficits in cerebellar function and the cerebellar microglia reactivity in MAGL KO, without affecting hippocampal reactivity. Altogether, this study reveals the brain region-specific response to MAGL inhibition, with an important role of COX-2 in the cerebellar deficits associated, which should be taken into account for the use of MAGL inhibitors as anti-inflammatory drugs.

Cyclooxygenase-2 inhibition reduces anxiety-like behavior and normalizes enhanced amygdala glutamatergic transmission following chronic oral corticosterone treatment

Chronic stress increases the probability of receiving an anxiety, depression, or chronic illness diagnosis. Pharmacological interventions that reduce the behavioral and physiological effects of chronic stress in animal models may represent novel approaches for the treatment of stress-related psychiatric disorders. Here, we examined the effects of cyclooxygenase-2 (COX-2) inhibition on anxiety-like behaviors and amygdala glutamatergic signaling after chronic non-invasive oral corticosterone (CORT) administration in mice. Treatment with the highly selective COX-2 inhibitor Lumiracoxib (LMX) reversed anxiety-like behavior induced by chronic CORT. Specifically, acute and repeated administration of LMX 5 mg kg⁻¹ reduced chronic CORT-induced anxiety-like behavior measured using the elevated-plus maze, elevated-zero maze, and light-dark box tests. In contrast, LMX did not affect anxiety-like behaviors in naïve mice. Ex vivo electrophysiology studies revealed that repeated LMX treatment normalized chronic CORT-induced increases in spontaneous excitatory glutamatergic currents recorded from anterior, but not posterior, basolateral amygdala neurons. These data indicate COX-2 inhibition can reverse chronic CORT-induced increases in anxiety-like behaviors and amygdala glutamatergic signaling, and support further clinical investigation of selective COX-2 inhibitors for the treatment of affective and stress-related psychiatric disorders.

Galangin Prevents Increased Susceptibility to Pentylenetetrazol-Stimulated Seizures by Prostaglandin E2

Epilepsy is one of the most common chronic neurological diseases. It is characterized by recurrent epileptic seizures, where one-third of patients are refractory to existing treatments. Evidence revealed the association between neuroinflammation and increased susceptibility to seizures since there is a pronounced increase in the expression of key inflammatory mediators, such as prostaglandin E₂ (PGE₂), during seizures. The purpose of this study was to investigate whether PGE₂ increases susceptibility to pentylenetetrazol-induced (PTZ) seizures. Subsequently, we evaluated if the flavonoid isolated from the plant Piper aleyreanum (galangin) presented any anticonvulsive effects. Our results demonstrated that the group treated with PGE₂ increased susceptibility to PTZ and caused myoclonic and generalized seizures, which increased seizure duration and electroencephalographic wave amplitudes. Furthermore, treatment with PGE₂ and PTZ increased IBA-1 (microglial marker), GFAP (astrocytic marker), 4-HNE (lipid peroxidation marker), VCAM-1 (vascular cell adhesion molecule 1), and p-PKAIIα (phosphorylated cAMP-dependent protein kinase) immunocontent. Indeed, galangin prevented behavioral and electroencephalographic seizures, reactive species production, decreased microglial and astrocytic immunocontent, as well as decreased VCAM-1 immunocontent and p-PKA/PKA ratio induced by PGE₂/PTZ. Therefore, this study suggests galangin may have an antagonizing role on PGE₂-induced effects, reducing cerebral inflammation and protecting from excitatory effects evidenced by administrating PGE₂ and PTZ. However, further studies are needed to investigate the clinical implications of the findings and their underlying mechanisms.

Suppressing pro-inflammatory prostaglandin signaling attenuates excitotoxicity-associated neuronal inflammation and injury

Glutamate receptor-mediated excitotoxicity is a common pathogenic process in many neurological conditions including epilepsy. Prolonged seizures induce elevations in extracellular glutamate that contribute to excitotoxic damage, which in turn can trigger chronic neuroinflammatory reactions, leading to secondary damage to the brain. Blocking key inflammatory pathways could prevent such secondary brain injury following the initial excitotoxic insults. Prostaglandin E2 (PGE₂) has emerged as an important mediator of neuroinflammation-associated injury, in large part via activating its EP2 receptor subtype. Herein, we investigated the effects of EP2 receptor inhibition on excitotoxicity-associated neuronal inflammation and injury in vivo. Utilizing a bioavailable and brain-permeant compound, TG6-10-1, we found that pharmacological inhibition of EP2 receptor after a one-hour episode of kainate-induced status epilepticus (SE) in mice reduced seizure-promoted functional deficits, cytokine induction, reactive gliosis, blood-brain barrier impairment, and hippocampal damage. Our preclinical findings endorse the feasibility of blocking PGE₂/EP2 signaling as an adjunctive strategy to treat prolonged seizures. The promising benefits from EP2 receptor inhibition should also be relevant to other neurological conditions in which excitotoxicity-associated secondary damage to the brain represents a pathogenic event.

Postnatal changes in constitutive cyclooxygenase‑2 expression in the mice hippocampus and its function in synaptic plasticity

Although the expression of cyclooxygenase-2 (COX-2) is closely associated with inflammation in the brain, it is constitutively expressed in the brain, and its expression is regulated by synaptic activity. The present study investigated postnatal expression of COX-2 in the hippocampus in C57BL/6 mice at postnatal days (P) 1, 7, 14, 28, and 56. In addition, the presented study examined the effects of COX-2 on synaptic plasticity through Arc, phosphorylated cAMP response element-binding protein (pCREB), N-methyl-d-aspartate receptor 1 (GluN1), and GluN2A/2B immunohistochemistry, which was performed on COX-2 knockout (KO) and wild-type (WT) mice. Extremely weak COX-2 immunoreactivity was detected in the hippocampal CA1-3 areas in addition to the dentate gyrus at P1. Conversely, COX-2 immunoreactivity was observed in the stratum pyramidale of the CA1-3 regions and in the outer granule cell layer of the dentate gyrus at P7. Additionally, although peak COX-2 immunoreactivity was observed in all hippocampal sub-regions, including the dentate gyrus at P14, it was significantly decreased at P14. Finally, COX-2 immunoreactivity and the distribution pattern seen at P56 in the hippocampal CA1-3 regions were similar to those observed at P28, whereas, they were identified in the inner half of the granule cell layer of the dentate gyrus. The western blot analysis revealed that the COX-2 protein levels peaked at P14 and were decreased at P28 and P56. Additionally, the number of Arc and pCREB immunoreactive cells as well as GluN1 and GluN2A/2B immunoreactivity of COX-2 KO mice were significantly decreased in the dentate gyrus when compared with that in WT mice. Taken together, the results of the present study suggest that COX-2 serves an important role in synaptic plasticity in the dentate gyrus and changes in the levels of its constitutive expression are associated with the hippocampal dentate gyrus postnatal development.

The COX-2/prostanoid signaling cascades in seizure disorders

Introduction：A robust neuroinflammatory response is a prevalent feature of multiple neurological disorders, including epilepsy and acute status epilepticus. One component of this neuroinflammatory reaction is the induction of cyclooxygenase-2 (COX-2), synthesis of several prostaglandins and endocannabinoid metabolites, and subsequent activation of prostaglandin and related receptors. Neuroinflammation mediated by COX-2 and its downstream effectors has received considerable attention as a potential target class to ameliorate the deleterious consequences of neurological injury. Areas covered: Here we describe the roles of COX-2 as a major inflammatory mediator. In addition, we discuss the receptors for prostanoids PGE₂, prostaglandin D2, and PGF_2α as potential therapeutic targets for inflammation-driven diseases. The consequences of prostanoid receptor activation after seizure activity are discussed with an emphasis on the utilization of small molecules to modulate prostanoid receptor activity. Expert opinion: Limited clinical trial experience is supportive but not definitive for a role of the COX signaling cascade in epileptogenesis. The cardiotoxicity associated with chronic coxib use, and the expectation that COX-2 inhibition will influence the levels of endocannabinoids, leukotrienes, and lipoxins as well as the prostaglandins and their endocannabinoid metabolite analogs, is shifting attention toward downstream synthases and receptors that mediate inflammation in the brain.

Evaluation of Two Potent and Selective PET Radioligands to Image COX-1 and COX-2 in Rhesus Monkeys

This study assessed whether the newly developed PET radioligands ¹¹C-PS13 and ¹¹C-MC1 could image constitutive levels of cyclooxygenase (COX)-1 and COX-2, respectively, in rhesus monkeys. Methods: After intravenous injection of either radioligand, 24 whole-body PET scans were performed. To measure enzyme-specific uptake, scans of the 2 radioligands were also performed after administration of a nonradioactive drug preferential for either COX-1 or COX-2. Concurrent venous samples were obtained to measure parent radioligand concentrations. SUVs were calculated from 10 to 90 min. Results: ¹¹C-PS13 showed specific uptake in most organs, including spleen, gastrointestinal tract, kidneys, and brain, which was blocked by COX-1, but not COX-2, preferential inhibitors. Specific uptake of ¹¹C-MC1 was not observed in any organ except the ovaries and possibly kidneys. Conclusion: The findings suggest that ¹¹C-PS13 has adequate signal in monkeys to justify its extension to human subjects. In contrast, ¹¹C-MC1 is unlikely to show significant signal in healthy humans, though it may be able to do so in inflammatory conditions.

The phospholipase A2 pathway controls a synaptic cholesterol ester cycle and synapse damage

The cellular prion protein (PrP^C) acts as a scaffold protein that organises signalling complexes. In synaptosomes, the aggregation of PrP^C by amyloid-β (Aβ) oligomers attracts and activates cytoplasmic phospholipase A₂ (cPLA₂), leading to synapse degeneration. The signalling platform is dependent on cholesterol released from cholesterol esters by cholesterol ester hydrolases (CEHs). The activation of cPLA₂ requires cholesterol released from cholesterol esters by cholesterol ester hydrolases (CEHs), enzymes dependent upon platelet activating factor (PAF) released by activated cPLA₂ This demonstrates a positive feedback system in which activated cPLA₂ increased cholesterol concentrations, which in turn facilitated cPLA₂ activation. PAF was also required for the incorporation of the tyrosine kinase Fyn and cyclooxygenase (COX)-2 into Aβ-PrP^C-cPLA₂ complexes. As a failure to deactivate signalling complexes can lead to pathology, the mechanisms involved in their dispersal were studied. PAF facilitated the incorporation of acyl-coenzyme A:cholesterol acyltransferase (ACAT)-1 into Aβ-PrP^C-cPLA₂-COX-2-Fyn complexes. The esterification of cholesterol reduced cholesterol concentrations, causing dispersal of Aβ-PrP^C-cPLA₂-COX-2-Fyn complexes and the cessation of signalling. This study identifies PAF as a key mediator regulating the cholesterol ester cycle, activation of cPLA₂ and COX-2 within synapses, and synapse damage.

Discovery of 2-Piperidinyl Phenyl Benzamides and Trisubstituted Pyrimidines as Positive Allosteric Modulators of the Prostaglandin Receptor EP2

Prostaglandin E2 (PGE2) via its Gαs-coupled EP2 receptor protects cerebral cortical neurons from excitotoxic and anoxic injury, though EP2 receptor activation can also cause secondary neurotoxicity in chronic inflammation. We performed a high-throughput screen of a library of 292 000 small molecules and identified several compounds that have a 2-piperidinyl phenyl benzamide or trisubstituted pyrimidine core as positive modulators for human EP2 receptor. The most active compounds increased the potency of PGE2 on EP2 receptor 4-5-fold at 20 μM without altering efficacy, indicative of an allosteric mechanism. These compounds did not augment the activity of the other Gαs-coupled PGE2 receptor subtype EP4 and showed neuroprotection against N-methyl-d-aspartate (NMDA)-induced excitotoxicity. These newly developed compounds represent second-generation allosteric potentiators for EP2 receptor and shed light on a promising neuroprotective strategy. They should prove valuable as molecular tools to achieve a better understanding of the dichotomous action of brain EP2 receptor activation.

Synthesis, Characterization, and Biodistribution of Quantum Dot-Celecoxib Conjugate in Mouse Paw Edema Model

Increased risk of cardiovascular side effects has been reported with many of the drugs in the market, including nonsteroidal anti-inflammatory drugs (NSAIDs). Hence, it is critical to thoroughly evaluate the biodistribution and pharmacokinetic properties of the drugs. Presently nanotechnology in combination with noninvasive imaging techniques such as magnetic resonance imaging (MRI), computed axial tomography (CAT), and positron emission tomography (PET) provides a better estimate of the spatio-temporal distribution of therapeutic molecules. Optical imaging using quantum dot- (QD-) tagged biological macromolecules is emerging as a fast, economical, sensitive, and safer alternative for theranostic purposes. In the present study, we report the nanoconjugates of mercaptopropionic acid- (MPA-) capped CdTe quantum dots (QDs) and Celecoxib for bio-imaging in carrageenan-induced mouse paw edema model of inflammation. QD-Celecoxib conjugates were characterized by fluorescence, FT-IR, NMR, and zeta-potential studies. In vivo imaging of QD-Celecoxib conjugates showed clear localization in the inflamed tissue of mouse paw within 3 h, with a gradual increase reaching a maximum and a later decline. This decrease of fluorescence in the paw region is followed by an increase in urinary bladder region, suggesting the possible excretion of QD-drug conjugates from mice within 24 h.

Maintenance of the Innate Seizure Threshold by Cyclooxygenase-2 is Not Influenced by the Translational Silencer, T-cell Intracellular Antigen-1

Activity of neuronal cyclooxygenase-2 (COX-2), a primary source of PG synthesis in the normal brain, is enhanced by excitatory neurotransmission and this is thought to be involved in seizure suppression. Results herein showing that the incidence of pentylenetetrazole (PTZ)-induced convulsions is suppressed in transgenic mice overexpressing COX-2 in neurons support this notion. T-cell intracellular antigen-1 (TIA-1) is an mRNA binding protein that is known to bind to COX-2 mRNA and repress its translation in non-neuronal cell types. An examination of the expression profile of TIA-1 protein in the normal brain indicated that it is expressed broadly by neurons, including those that express COX-2. However, whether TIA-1 regulates COX-2 protein levels in neurons is not known. The purpose of this study was to test the possibility that deletion of TIA-1 increases basal COX-2 expression in neurons and consequently raises the seizure threshold. Results demonstrate that neither the basal nor seizure-induced expression profiles of COX-2 were altered in mice lacking a functional TIA-1 gene suggesting that TIA-1 does not contribute to regulation of COX-2 protein expression in neurons. The acute PTZ-induced seizure threshold was also unchanged in mice lacking TIA-1 protein, indicating that this RNA binding protein does not influence the innate seizure threshold. Nevertheless, the results raise the possibility that the level of neuronal COX-2 expression may be a determinant of the innate seizure threshold and suggest that a better understanding of the regulation of COX-2 expression in the brain could provide new insight into the molecular mechanisms that suppress seizure induction.

Celecoxib Prevents Cognitive Impairment and Neuroinflammation in Soluble Amyloid β-treated Rats

Recent findings suggest that soluble forms of amyloid-β (sAβ) peptide contribute to synaptic and cognitive dysfunctions in early stages of Alzheimer's disease (AD). On the other hand, neuroinflammation and cyclooxygenase-2 (COX-2) enzyme have gained increased interest as key factors involved early in AD, although the signaling pathways and pathophysiologic mechanisms underlying a link between sAβ-induced neurotoxicity and inflammation are still unclear. Here, we investigated the effects of selective COX-2 enzyme inhibition on neuropathological alterations induced by sAβ administration in rats. To this purpose, animals received an intracerebroventricular (icv) injection of predominantly monomeric forms of sAβ and, 7 days after, behavioral as well as biochemical parameters and neurotransmitter alterations were evaluated. During this period, rats also received a sub-chronic treatment with celecoxib. Biochemical results demonstrated that icv sAβ injection significantly increased both COX-2 and pro-inflammatory cytokines expression in the hippocampus (Hipp) of treated rats. In addition, the number of hypertrophic microglial cells and astrocytes were upregulated in sAβ-treated group. Interestingly, rats treated with sAβ showed long-term memory deficits, as confirmed by a significant reduction of discrimination index in the novel object recognition test, along with reduced brain-derived neurotrophic factor expression and increased noradrenaline levels in the Hipp. Systemic administration of celecoxib prevented behavioral dysfunctions, as well as biochemical and neurotransmitter alterations. In conclusion, our results suggest that sAβ neurotoxicity might be associated to COX-2-mediated inflammatory pathways and that early treatment with selective COX-2 inhibitor might provide potential remedies to counterbalance the sAβ-induced effects.

PM2.5 exposure stimulates COX-2-mediated excitatory synaptic transmission via ROS-NF-κB pathway

Long-term exposure to fine particulate matter (PM_2.5) has been reported to be closely associated with the neuroinflammation and synaptic dysfunction, but the mechanisms underlying the process remain unclear. Cyclooxygenase-2 (COX-2) is a key player in neuroinflammation, and has been also implicated in the glutamatergic excitotoxicity and synaptic plasticity. Thus, we hypothesized that COX-2 was involved in PM_2.5-promoted neuroinflammation and synaptic dysfunction. Our results revealed that PM_2.5 elevated COX-2 expression in primary cultured hippocampal neurons and increased the amplitude of field excitatory postsynaptic potentials (fEPSPs) in hippocampal brain slices. And the administration of NS398 (a COX-2 inhibitor) prevented the increased fEPSPs. PM_2.5 also induced intracellular reactive oxygen species (ROS) generation accompanied with glutathione (GSH) depletion and the loss of mitochondrial membrane potential (MMP), and the ROS inhibitor, N-acetyl-L-cystein (NAC) suppressed the COX-2 overexpression and the increased fEPSPs. Furthermore, the nuclear factor kappa B (NF-κB) was involved in ROS-induced COX-2 and fEPSP in response to PM_2.5 exposure. These findings indicated that PM_2.5 activated COX-2 expression and enhanced the synaptic transmission through ROS-NF-κB pathway, and provided possible biomarkers and specific interventions for PM_2.5-induced neurological damage.