Methylene blue offers neuroprotection after intracerebral hemorrhage in rats through the PI3K/Akt/GSK3β signaling pathway

Methotrimeprazine is a neuroprotective antiviral in JEV infection via adaptive ER stress and autophagy

Japanese encephalitis virus (JEV) pathogenesis is driven by a combination of neuronal death and neuroinflammation. We tested 42 FDA-approved drugs that were shown to induce autophagy for antiviral effects. Four drugs were tested in the JE mouse model based on in vitro protective effects on neuronal cell death, inhibition of viral replication, and anti-inflammatory effects. The antipsychotic phenothiazines Methotrimeprazine (MTP) & Trifluoperazine showed a significant survival benefit with reduced virus titers in the brain, prevention of BBB breach, and inhibition of neuroinflammation. Both drugs were potent mTOR-independent autophagy flux inducers. MTP inhibited SERCA channel functioning, and induced an adaptive ER stress response in diverse cell types. Pharmacological rescue of ER stress blocked autophagy and antiviral effect. MTP did not alter translation of viral RNA, but exerted autophagy-dependent antiviral effect by inhibiting JEV replication complexes. Drug-induced autophagy resulted in reduced NLRP3 protein levels, and attenuation of inflammatory cytokine/chemokine release from infected microglial cells. Our study suggests that MTP exerts a combined antiviral and anti-inflammatory effect in JEV infection, and has therapeutic potential for JE treatment.

Levosimendan inhibits disulfide tau oligomerization and ameliorates tau pathology in TauP301L-BiFC mice

Tau oligomers play critical roles in tau pathology and are responsible for neuronal cell death and transmitting the disease in the brain. Accordingly, preventing tau oligomerization has become an important therapeutic strategy to treat tauopathies, including Alzheimer's disease. However, progress has been slow because detecting tau oligomers in the cellular context is difficult. Working toward tau-targeted drug discovery, our group has developed a tau-BiFC platform to monitor and quantify tau oligomerization. By using the tau-BiFC platform, we screened libraries with FDA-approved and passed phase I drugs and identified levosimendan as a potent anti-tau agent that inhibits tau oligomerization. ¹⁴C-isotope labeling of levosimendan revealed that levosimendan covalently bound to tau cysteines, directly inhibiting disulfide-linked tau oligomerization. In addition, levosimendan disassembles tau oligomers into monomers, rescuing neurons from aggregation states. In comparison, the well-known anti-tau agents methylene blue and LMTM failed to protect neurons from tau-mediated toxicity, generating high-molecular-weight tau oligomers. Levosimendan displayed robust potency against tau oligomerization and rescued cognitive declines induced by tauopathy in the Tau^P301L-BiFC mouse model. Our data present the potential of levosimendan as a disease-modifying drug for tauopathies.

Semaglutide, a novel glucagon-like peptide-1 agonist, amends experimental autoimmune encephalomyelitis-induced multiple sclerosis in mice: Involvement of the PI3K/Akt/GSK-3β pathway

Multiple sclerosis (MS) is a disabling neurodegenerative disease that causes demyelination and axonal degeneration of the central nervous system. Current treatments are partially effective in managing MS relapses and have a negligible impact on treating MS cognitive deficits and cannot enhance neuronal remyelination, imposing a need for a new MS remedy. Semaglutide, a novel glucagon-like peptide-1 agonist, has recently displayed a neuroprotective effect on several neurodegenerative diseases, suggesting that it may have a protective effect in MS. Therefore, this study was conducted to investigate the influence of semaglutide on experimental autoimmune encephalomyelitis (EAE)-induced MS in mice. Here, EAE was induced in mice using spinal cord homogenate, which eventually altered the mice's cognitive and motor functions, similar to what is observed in MS. Interestingly, intraperitoneally administered semaglutide (25 nmol/kg/day) amended EAE-induced cognitive and motor deficits observed in novel object recognition, open field, rotarod, and grip strength tests. Moreover, histological examination revealed that semaglutide treatment attenuated hippocampal damage and corpus callosum demyelination caused by EAE. Additionally, biochemical testing revealed that semaglutide activates the PI3K/Akt axis, which eventually hampers GSK-3β activity. GSK-3β activity inhibition attenuates demyelination and triggers remyelination through CREB/BDNF; furthermore, it boosts Nrf2 and SOD levels, protecting the mice from EAE-induced oxidative stress. Additionally, GSK-3β inhibition minimizes neuroinflammation, as reflected by decreased NF-kβ and TNF-α levels. In conclusion, semaglutide has a neuroprotective effect in EAE-induced MS in mice, which is mediated by activating the ramified PI3K/Akt/GSK-3β pathway.

MicroRNAs modulate neuroinflammation after intracerebral hemorrhage: Prospects for new therapy

Intracerebral hemorrhage (ICH) is the most common subtype of hemorrhagic stroke. After ICH, blood components extravasate from vessels into the brain, activating immune cells and causing them to release a series of inflammatory mediators. Immune cells, together with inflammatory mediators, lead to neuroinflammation in the perihematomal region and the whole brain, and neuroinflammation is closely related to secondary brain injury as well as functional recovery of the brain. Despite recent progress in understanding the pathophysiology of ICH, there is still no effective treatment for this disease. MicroRNAs (miRNAs) are non-coding RNAs 17-25 nucleotides in length that are generated naturally in the human body. They bind complementarily to messenger RNAs and suppress translation, thus regulating gene expression at the post-transcriptional level. They have been found to regulate the pathophysiological process of ICH, particularly the neuroinflammatory cascade. Multiple preclinical studies have shown that manipulating the expression and activity of miRNAs can modulate immune cell activities, influence neuroinflammatory responses, and ultimately affect neurological functions after ICH. This implicates the potentially crucial roles of miRNAs in post-ICH neuroinflammation and indicates the possibility of applying miRNA-based therapeutics for this disease. Thus, this review aims to address the pathophysiological roles and molecular underpinnings of miRNAs in the regulation of neuroinflammation after ICH. With a more sophisticated understanding of ICH and miRNAs, it is possible to translate these findings into new pharmacological therapies for ICH.

Paeoniflorin Ameliorates Colonic Fibrosis in Rats with Postinfectious Irritable Bowel Syndrome by Inhibiting the Leptin/LepRb Pathway

Postinfectious irritable bowel syndrome (PI-IBS) is a highly prevalent gastrointestinal disorder associated with immune dysregulation and depression- and anxiety-like behaviors. Through traditional medicine, the active ingredient of Paeoniae Radix called paeoniflorin (PF) was previously found to prevent the symptoms of PI-IBS. However, there is limited information on the effects of PF on intestinal function and depression- and anxiety-like symptoms in PI-IBS animal models. Here, we aimed to determine the effects of PF treatment on the symptoms of PI-IBS in a rat model. The PI-IBS rat model was established via early postnatal sibling deprivation (EPSD), trinitrobenzenesulfonic acid (TNBS), and chronic unpredictable mild stress (CUMS) stimulation and then treated with different dosages of PF (10, 20, and 40 mg/kg) and leptin (1 and 10 mg/kg). The fecal water content and body weight were measured to evaluate the intestinal function, while the two-bottle test for sucrose intake, open field test (OFT), and elevated plus maze test (EMT) were performed to assess behavioral changes. The serum leptin levels were also measured using an enzyme-linked immunosorbent assay. Furthermore, the expressions of leptin and its receptor, LepRb, were detected in colonic mucosal tissues through an immunohistochemical assay. The activation of the PI3K/AKT signaling pathway and the expression of brain-derived neurotrophic factor (BDNF) were also detected via western blotting. After the experimental period, the PI-IBS rats presented decreased body weight and increased fecal water content, which coincided with elevated leptin levels and heightened depression- and anxiety-like behaviors (e.g., low sucrose intake, less frequency in the center areas during OFT, and fewer activities in the open arms during EMT). However, the PF treatment ameliorated these observed symptoms. Furthermore, PF not only inhibited leptin/LepRb expression but also reduced the PI3K/AKT phosphorylation and BDNF expression in PI-IBS rats. Notably, cotreatment with leptin (10 mg/kg) reduced the effects of PF (20 mg/kg) on colonic fibrosis, leptin/LepRb expression, and PI3K/AKT activation. Therefore, our findings suggest that leptin is targeted by PF via the leptin/LepRb pathway, consequently ameliorating the symptoms of PI-IBS. Our study also contributes novel insights for elucidating the pharmacological action of PF on gastrointestinal disorders and may be used for the clinical treatment of PI-IBS in the future.

TIPE2 attenuates neuroinflammation and brain injury through Bcl-2/Bax/cleaved caspase-3 apoptotic pathways after intracerebral hemorrhage in mice

BACKGROUND

Intracerebral hemorrhage (ICH) is a serious disease with high mortality and morbidity, and effective treatment is limited. A large amount of evidence suggests that the inflammatory response contributes to secondary brain damage following ICH. TIPE2 is an essential negative regulator of both innate and adaptive immunity, and depletion of TIPE2 causes inflammatory disease. However, the possible role of TIPE2 following ICH has not been reported.

METHODS

In this study, we investigated TIPE2 levels and inflammation in microglia treated with erythrocyte lysate in vitro. In addition, we analyzed the role of Bcl-2/Bax/cleaved caspase-3 apoptotic pathways in ICH mice. Furthermore, we observed proinflammatory cytokine production, BBB disruption, cerebral water content and neurological damage in ICH mice.

RESULTS

We found that TIPE2 levels were significantly decreased in erythrocyte lysate-treated microglia compared to control microglia.Upregulation of TIPE2 decreased microglia activation and cytokine production and accelerated brain damage in ICH mice. Furthermore, upregulation of TIPE2 decreased the higher ratio of Blc-2/Bax and increased cleaved caspase-3 levels in ICH mice. In addition, upregulation of TIPE2 attenuated proinflammatory cytokine production, BBB disruption, and severe brain inflammation after ICH.

CONCLUSION

These results demonstrated that TIPE2 was negatively correlated with the pathogenesis of ICH, which prevented brain injury and attenuated deleterious inflammatory responses following ICH. TIPE2 might serve as a novel target for ICH therapy.

Molecular Mechanisms of the Neuroprotective Effect of Methylene Blue

Methylene blue (MB) is the first fully synthetic compound that had found its way into medicine over 120 years ago as a treatment against malaria. MB has been approved for the treatment of methemoglobinemia, but there are premises for its repurposing as a neuroprotective agent based on the efficacy of this compound demonstrated in the models of Alzheimer's, Parkinson's, and Huntington's diseases, traumatic brain injury, amyotrophic lateral sclerosis, depressive disorders, etc. However, the goal of this review was not so much to focus on the therapeutic effects of MB in the treatment of various neurodegeneration diseases, but to delve into the mechanisms of direct or indirect effect of this drug on the signaling pathways. MB can act as an alternative electron carrier in the mitochondrial respiratory chain in the case of dysfunctional electron transport chain. It also displays the anti-inflammatory and anti-apoptotic effects, inhibits monoamine oxidase (MAO) and nitric oxide synthase (NOS), activates signaling pathways involved in the mitochondrial pool renewal (mitochondrial biogenesis and autophagy), and prevents aggregation of misfolded proteins. Comprehensive understanding of all aspects of direct and indirect influence of MB, and not just some of its effects, can help in further research of this compound, including its clinical applications.

Identification of potential key circular RNAs related to cognitive impairment after chronic constriction injury of the sciatic nerve

Chronic neuropathic pain is commonly accompanied by cognitive impairment. However, the underlying mechanism in the occurrence of cognitive deficits under constant nociceptive irritation remains elusive. Herein, we established a chronic neuropathic pain model by chronic constriction injury (CCI) of the unilateral sciatic nerve in rats. Behavioral tests indicated that CCI rats with long-term nociceptive threshold decline developed significant dysfunction of working memory and recognitive memory starting at 14 days and lasting for at least 21 days. Afterward, circRNA expression profiles in the hippocampus of CCI and sham rats were analyzed via high-throughput sequencing to explore the potential key factors associated with cognitive impairment induced by ongoing nociception, which showed 76 differentially expressed circRNAs, 39 upregulated and 37 downregulated, in the CCI group. These differentially expressed circRNA host genes were validated to be primarily associated with inflammation and apoptotic signaling pathways according to GO/KEGG analysis and the circRNA-miRNA-mRNA network, which was also confirmed through the analysis of neuroinflammation and neuronal apoptosis. Consequently, we assumed that enhanced neuroinflammation and neuronal apoptosis might act as potential regulators of cognitive impairment induced by chronic neuropathic pain. The identification of the regulatory mechanism would provide promising clinical biomarkers or therapeutic targets in the diagnostic prediction and intervention treatment of memory deficits under neuropathic pain conditions.

The neuroprotection of cerebrolysin after spontaneous intracerebral hemorrhage through regulates necroptosis via Akt/ GSK3β signaling pathway

PURPOSE

Spontaneous intracerebral hemorrhage (ICH) is a major cause of death and disability with a huge economic burden worldwide. Cerebrolysin (CBL) has been previously used as a nootropic drug. Necroptosis is a programmed cell death mechanism that plays a vital role in neuronal cell death after ICH. However, the precise role of necroptosis in CBL neuroprotection following ICH has not been confirmed.

METHODS

In the present study, we aimed to investigate the neuroprotective effects and potential molecular mechanisms of CBL in ICH-induced early brain injury (EBI) by regulating neural necroptosis in the C57BL/6 mice model. Mortality, neurological score, brain water content, and neuronal death were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Evans blue extravasation, Western blotting, and quantitative real-time polymerase chain reaction (PCR).

RESULTS

The results show that CBL treatment markedly increased the survival rate, neurological score, and neuron survival, and downregulated the protein expression of RIP1 and RIP3, which indicated that CBL-mediated inhibition of necroptosis, and ameliorated neuronal death after ICH. The neuroprotective capacity of CBL is partly dependent on the Akt/GSK3β signaling pathway.

CONCLUSIONS

CBL improves neurological outcomes in mice and reduces neuronal death by protecting against neural necroptosis.

17β-Estradiol Attenuates Intracerebral Hemorrhage-Induced Blood-Brain Barrier Injury and Oxidative Stress Through SRC3-Mediated PI3K/Akt Signaling Pathway in a Mouse Model

Estrogen is neuroprotective in brain injury models, and steroid receptor cofactor 3 (SRC3) mediates estrogen signaling. We aimed to investigate whether and how SRC3 is involved in the neuroprotective effects of 17ß-estradiol (E2) in a mouse model of intracerebral hemorrhage (ICH). Ovariectomized female mice were treated with E2 after autologous blood injection-induced ICH. Brain damage was assessed by neurological deficit score, brain water content, and oxidative stress levels. Blood–brain barrier (BBB) integrity was evaluated by Evan's blue extravasation and claudin-5, ZO-1, and occludin levels. SRC3 expression and PI3K/Akt signaling pathway were examined in ICH mice treated with E2. The effect of SRC3 on E2-mediated neuroprotection was determined by examining neurological outcomes in SRC3-deficient mice undergone ICH and E2 treatment. We found that E2 alleviated ICH-induced brain edema and neurological deficits, protected BBB integrity, and suppressed oxidative stress. E2 enhanced SRC3 expression and PI3K-/Akt signaling pathway. SRC3 deficiency abolished the protective effects of E2 on ICH-induced neurological deficits, brain edema, and BBB integrity. Our results suggest that E2 suppresses ICH-induced brain injury and SRC3 plays a critical role in E2-mediated neuroprotection.

Ultrasound-Guided Continuous Thoracic Paravertebral Infusion of Methylene Blue in the Treatment of Postherpetic Neuralgia: A Prospective, Randomized, Controlled Study

Introduction

Postherpetic neuralgia (PHN) is the most common complication of herpes zoster. Methylene blue (MB) is an inhibitor of nitric oxide synthesis with potentially analgesic and anti-inflammatory properties. Studies have demonstrated that thoracic paravertebral single MB injection is effective in treating chronic pain. However, there are rare reports of the efficacy of continuous thoracic paravertebral infusion of MB for pain management in PHN patients. The purpose of this study was to evaluate the therapeutic effects of continuous thoracic paravertebral infusion of MB on PHN.

Methods

A total of 104 PHN patients were randomly divided into two groups: the control group (continuous thoracic paravertebral infusion of 5% lidocaine in a total volume of 300 ml) and the MB group (continuous thoracic paravertebral infusion of 5% lidocaine plus 0.2% MB in a total volume of 300 ml). All patients were evaluated using the Numerical Rating Scale (NRS), Insomnia Severity Index (ISI), Patient Health Questionnaire-9 (PHQ-9), 36-Item Short-Form Health Survey (SF-36), and medication doses before and after the procedure. The effective treatment rate and adverse complications were recorded 6 months after the procedure.

Results

In both groups, the NRS scores, ISI scores, PHQ-9 scores, and rescue medication dosages were significantly decreased at different time points after treatment compared to baseline, while the SF-36 scores were evidently improved at different time points after treatment compared to baseline. Compared with the control group, the MB group had significantly reduced NRS scores, ISI scores, PHQ-9 scores, and rescue medication dosages at each observation time point. Furthermore, the SF-36 scores in the MB group were significantly higher than those in the control group at each observation time point. The total effective treatment rate of the MB group was higher than that of the control group 6 months after the procedure. No severe adverse complications were observed in either group.

Conclusions

Ultrasound-guided continuous thoracic paravertebral infusion with MB is a safe and effective therapy for PHN. Continuous infusion with MB can significantly reduce pain intensity, improve pain-related depression, increase quality of life, and decrease the amount of rescue medicine with no serious adverse complications.

Therapeutic modulation of the phosphatidylinositol 3-kinases (PI3K) pathway in cerebral ischemic injury

The cerebral ischemic reperfusion injury may leads to morbidity and mortality in patients. phosphatidylinositol 3-kinase (PI3K) signaling pathway has been believed to work in association with its downstream targets, other receptors, and pathways that may offer antioxidant, anti-inflammatory, anti-apoptotic effects, neuroprotective role in neuronal excitotoxicity. This review elaborates the mechanistic interventions of the PI3K pathway in cerebral ischemic injury in context to nuclear factor erythroid 2-related factor 2 (Nrf2) regulation, Hypoxia-inducible factor 1 signaling (HIF-1), growth factors, Endothelial NOS (eNOS) proinflammatory cytokines, Erythropoietin (EPO), Phosphatase and tensin homologous protein of chromosome 10 gene (PTEN) signaling, NF-κB/Notch signaling, c-Jun N-terminal kinase (JNK) and Glycogen synthase kinase-3β (GSK-3β) signaling pathway. Evidences showing the activation of PI3K inhibits apoptotic pathway, which results in its neuroprotective effect in ischemic injury. Despite discussing the therapeutic role of the PI3K pathway in treating cerebral ischemic injury, the review also enlighten the selective modulation of PI3K pathway with activators and inhibitors which may provide promising results in clinical and preclinical settings.

Protein kinase inhibitors in traumatic brain injury and repair: New roles of nanomedicine

Traumatic brain injury (TBI) causes physical injury to the cell membranes of neurons, glial and axons causing the release of several neurochemicals including glutamate and cytokines altering cell-signaling pathways. Upregulation of mitogen associated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) occurs that is largely responsible for cell death. The pharmacological blockade of these pathways results in cell survival. In this review role of several protein kinase inhibitors on TBI induced oxidative stress, blood-brain barrier breakdown, brain edema formation, and resulting brain pathology is discussed in the light of current literature.

Effect of Methylene Blue and PI3K-Akt Pathway Inhibitors on the Neurovascular System after Chronic Cerebral Hypoperfusion in Rats

Methylene blue (MB) has a protective effect on cognitive decline caused by chronic hypoperfusion, but the specific mechanism is not clear. This article aims to determine whether MB protects vascular neurons through PI3K/Akt and plays a role in improving cognitive impairment. Molecular biological methods, the hippocampal neuronal density test, the hippocampal vascular network density test, and dynamic enhanced magnetic resonance imaging (MRI) were used to detect the blood-brain barrier permeability and Evans blue leakage rate in the hippocampus. We also observed and evaluated the changes in the above results after administration of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway protein inhibitor LY294002. There were significant differences for cerebral blood flow (CBF) between the chronic cerebral hypoperfusion (CCH) + MB group (100 ml/100 g/min) and the CCH group (60 ml/100 g/min, P < 0.05). After using LY294002, the CBF of the CCH + MB + LY294002 group dropped to 82 ml/100 g/min. The vascular density in the CCH + MB group was 23%, which is significantly higher than that in the CCH group (15.1%) (P < 0.05). The vascular density (17.5%) in the CCH + MB + LY294002 group was significantly higher than that in the CCH group but lower than that in the CCH + MB group. Western blotting results showed that one week after intraperitoneal injection of MB, the expression of t-Akt and p-Akt in the CCH + MB group was increased after CCH, and LY294002 partially blocked this up-regulation effect (CCH + MB + LY294002 group). MB is a potential therapy for the relief of mild cognitive impairment associated with CCH, vascular dementia, and Alzheimer's disease.

Comparative Study Regarding the Properties of Methylene Blue and Proflavine and Their Optimal Concentrations for In Vitro and In Vivo Applications

Methylene blue and proflavine are fluorescent dyes used to stain nucleic acid from the molecular level to the tissue level. Already clinically used for sentinel node mapping, detection of neuroendocrine tumors, methemoglobinemia, septic shock, ifosfamide-induced encephalopathy, and photodynamic inactivation of RNA viruses, the antimicrobial, anti-inflammatory, and antioxidant effect of methylene blue has been demonstrated in different in vitro and in vivo studies. Proflavine was used as a disinfectant and bacteriostatic agent against many gram-positive bacteria, as well as a urinary antiseptic involved in highlighting cell nuclei. At the tissue level, the anti-inflammatory effects of methylene blue protect against pulmonary, renal, cardiac, pancreatic, ischemic-reperfusion lesions, and fevers. First used for their antiseptic and antiviral activity, respectively, methylene blue and proflavine turned out to be excellent dyes for diagnostic and treatment purposes. In vitro and in vivo studies demonstrated that both dyes are efficient as perfusion and tissue tracers and permitted to evaluate the minimal efficient concentration in different species, as well as their pharmacokinetics and toxicity. This review aims to identify the optimal concentrations of methylene blue and proflavine that can be used for in vivo experiments to highlight the vascularization of the skin in the case of a perforasome (both as a tissue tracer and in vascular mapping), as well as their effects on tissues. This review is intended to be a comparative and critical presentation of the possible applications of methylene blue (MB) and proflavine (PRO) in the surgical field, and the relevant biomedical findings from specialized literature to date are discussed as well.

Treatment With Liraglutide Exerts Neuroprotection After Hypoxic-Ischemic Brain Injury in Neonatal Rats via the PI3K/AKT/GSK3β Pathway

Neonatal hypoxic–ischemic (HI) brain injury is a detrimental disease, which results in high mortality and long-term neurological deficits. Nevertheless, the treatment options for this disease are limited. Thus, the aim of the present study was to assess the role of liraglutide in neonatal HI brain injury in rats and investigate the associated mechanisms. The results showed that treatment with liraglutide significantly reduced infarct volume and ameliorated cerebral edema, decreased inflammatory response, promoted the recovery of tissue structure, and improved prognosis following HI brain injury. Moreover, treatment with liraglutide inhibited apoptosis and promoted neuronal survival both in the rat model and following oxygen-glucose deprivation (OGD) insult. LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), partially reversed these therapeutic effects, suggesting that the PI3K/protein kinase B (Akt) pathway was involved. In conclusion, our data revealed that treatment with liraglutide exerts neuroprotection after neonatal HI brain injury via the PI3K/Akt/glycogen synthase kinase-3β (GSK3β) pathway and may be a promising therapy for this disease.

Multifunctional compounds lithium chloride and methylene Blue attenuate the negative effects of diisopropylfluorophosphate on axonal transport in rat cortical neurons

Organophosphates (OPs) are valuable as pesticides in agriculture and for controlling deadly vector-borne illnesses; however, they are highly toxic and associated with many deleterious health effects in humans including long-term neurological impairments. Antidotal treatment regimens are available to combat the symptoms of acute OP toxicity, which result from the irreversible inhibition of acetylcholinesterase (AChE). However, there are no established treatments for the long-term neurological consequences of OP exposure. In addition to AChE, OPs can negatively affect multiple protein targets as well as biological processes such as axonal transport. Given the fundamental nature of axonal transport to neuronal health, we rationalized that this process might serve as a general focus area for novel therapeutic strategies against OP toxicity. In the studies described here, we employed a multi-target, phenotypic screening, and drug repurposing strategy for the evaluations of potential novel OP-treatments using a primary neuronal culture model and time-lapse live imaging microscopy. Two multi-target compounds, lithium chloride (LiCl) and methylene blue (MB), which are FDA-approved for other indications, were evaluated for their ability to prevent the negative effects of the OP, diisopropylfluorophosphate (DFP) on axonal transport. The results indicated that both LiCl and MB prevented DFP-induced impairments in anterograde and retrograde axonal transport velocities in a concentration dependent manner. While in vivo studies will be required to confirm our in vitro findings, these experiments support the potential of LiCl and MB as repurposed drugs for the treatment of the long-term neurological deficits associated with OP exposure (currently an unmet medical need).

Methylene Blue in the Treatment of Neuropsychiatric Disorders

Methylene blue is a long-established drug with complex pharmacology and multiple clinical indications. Its diverse mechanisms of action are most likely responsible for the large variety of its clinical effects. Of interest to psychiatrists, methylene blue has antidepressant, anxiolytic, and neuroprotective properties documented by both animal and human studies. Its stabilizing effect on mitochondrial function and dose-dependent effect on the generation of reactive oxygen species are of significant heuristic value. For these reasons, methylene blue holds promise as a proof-of-concept treatment of organic/neurodegenerative disorders and as a neuroprotective agent in general. In psychiatry, methylene blue has been used for over a century. It was tried successfully in the treatment of psychotic and mood disorders and as a memory enhancer in fear-extinction training. Particularly promising results have been obtained in both short- and long-term treatment of bipolar disorder. In these studies, methylene blue produced an antidepressant and anxiolytic effect without risk of a switch into mania. Long-term use of methylene blue in bipolar disorder led to a better stabilization and a reduction in residual symptoms of the illness. It is usually well tolerated, but caution is needed in the light of its inhibitory effect on monoamine oxidase A.