The protective effects of Ferrostatin-1 against inflammation-induced preterm birth and fetal brain injury.

INTRODUCTION: Recent studies have suggested the involvement of ferroptosis in preterm birth. Despite compelling evidence, the underlying mechanism remains unknown. This investigation aimed to determine the therapeutic effects of Ferrostatin-1 (Fer-1), an inhibitor of ferroptosis, in preterm birth and fetal brain injury. METHODS: Human placenta samples and clinical data of participants were collected to ascertain whether placental ferroptosis was associated with preterm birth. Lipopolysaccharide (LPS)-induced preterm birth mouse model was used to examine the protective effects of Fer-1 on preterm birth. Fetal brain tissues and offspring mice at 5 and 8 weeks were studied to determine the effects of Fer-1 on the cognitive function of offspring. RESULTS: We examined the mechanism of spontaneous preterm birth and discovered that placental ferroptosis was associated with preterm birth. Fer-1 inhibited preterm birth by ameliorating placental ferroptosis and maternal inflammation, thus improving LPS-induced intrauterine inflammation to maintain pregnancy. Antenatal administration of Fer-1 prevented LPS-induced fetal brain damage in the acute phase and improved long-term neurodevelopmental impairments by improving placental neuroendocrine signaling and maintaining placental function. CONCLUSION: Fer-1 inhibited preterm birth and fetal brain injury by inhibiting maternal inflammation and improving placental function. Our findings provide a novel therapeutic strategy for preterm birth.

Ferrostatin-1 and 3-Methyladenine Ameliorate Ferroptosis in OVA-Induced Asthma Model and in IL-13-Challenged BEAS-2B Cells.

Ferroptosis was reported to be involved in the occurrence and development of asthma. However, the potential mechanism underlying the role of ferroptosis in asthma remains unclear. In this study, we established the mouse asthma model following the ovalbumin (OVA) method in C57BL/6 mice and the cell model with IL-13 induction in bronchial epithelial cells (BEAS-2B cells). Treatment of ferrostatin-1 (Ferr-1) and 3-methyladenine (3-MA) decreased iron deposition in IL-13-induced BEAS-2B cells and lung tissues of asthma mice, opposite to that in bronchoalveolar lavage fluid (BALF). Meanwhile, excessive lipid peroxidation asthma model in vivo and in vitro was alleviated by Ferr-1 or 3-MA treatment. In addition, Ferr-1 and 3-MA inhibited the expression of LC-3 in these cells and lung tissues of mice. Moreover, Ferr-1 and 3-MA also suppressed the production of inflammatory cytokines (IL-1ß, IL-6, and TNF-α) and oxidative stress factors (ROS and MDA), while promoting the level of SOD, in vivo and in vitro. Furthermore, application of Ferr-1 exhibited a greater inhibitory effect on iron release and lipid peroxidation in IL-13-induced BEAS-2B cells and asthma mice than 3-MA, accompanied with a weaker effect on ferritinophagy than 3-MA. Collectively, Ferr-1 and 3-MA ameliorated asthma in vivo and in vitro through inhibiting ferroptosis, providing a new strategy for the clinical treatment of asthma.

1-Phenylcyclohexan-1-amine hydrochloride (PCA HCl) alters mesolimbic dopamine system accompanied by neuroplastic changes: A neuropsychopharmacological evaluation in rodents.

The recreational use of N-methyl-D-aspartate (NMDA) antagonist phencyclidine (PCP) and ketamine have grown rapidly due to their psychotomimetic properties. These compounds induce both non-fatal and fatal adverse effects and despite the enhanced regulation, they are continuously synthesized and are being sold in the illegal drug market, including 1-phenylcyclohexan-1-amine hydrochloride (PCA). Therefore, we evaluated its abuse potential through the conditioned-place preference (CPP), self-administration, and locomotor sensitization paradigms. Pretreatment with SCH 2 3390 and haloperidol was also performed during a CPP test. We used ELISA to measure dopamine (DA) levels and western blotting to determine effects on the DA-related proteins as well as on phosphorylated CREB, deltaFosB, and brain-derived neurotrophic factor (BDNF) in the ventral tegmental area (VTA) and nucleus accumbens (NAc). Finally, we examined the effects on brain wave activity using electroencephalography (EEG). PCA induced CPP in mice and was self-administered by rats, suggesting that PCA has rewarding and reinforcing properties. PCA increased locomotor of mice on the first treatment and challenge days. SCH 23390 and haloperidol blocked the CPP. PCA altered the DA, tyrosine hydroxylase, dopamine D1 and D2 receptors as well as p-CREB and deltaFosB. Also, PCA altered the delta and gamma waves in the brain, which were then normalized by SCH 2 3390 and haloperidol. The present findings indicate that PCA may induce abuse potential through the dopaminergic system and probably accompanied with alterations in brain wave activity which is similar to that of other psychotomimetic NMDA antagonists. We advocate thorough monitoring of PCP analogs as they pose potential harm to public health.

Ferrostatin-1 protects auditory hair cells from cisplatin-induced ototoxicity in vitro and in vivo.

Cisplatin is used in a wide variety of malignancies, but cisplatin-induced ototoxicity remains a major issue in clinical practice. Experimental evidence indicates that ferroptosis plays a key role in mediating the unwanted cytotoxicity effect caused by cisplatin. However, the role of ferroptosis in cisplatin-induced ototoxicity requires elucidation. Ferrostatin-1 (Fer-1) was identified as a potent inhibitor of ferroptosis and radical-trapping antioxidant with its ability to reduce the accumulation of lipid peroxides and chain-carrying peroxyl radicals. In the current study, we investigated the effects of Fer-1 in cisplatin-induced ototoxicity in in vitro, ex vivo, and in vivo models. We found, for the first time that Fer-1 efficiently alleviated cisplatin-induced cytotoxicity in HEI-OC1 cells via a concentration-dependent manner. Furthermore, Fer-1 mitigated cisplatin cytotoxicity in transgenic zebrafish sensory hair cells. In HEI-OC1 cells, Fer-1 pretreatment not only drastically reduced the generation of intracellular reactive oxygen species but also remarkably decreased lipid peroxidation levels induced by cisplatin. This was not only ascribed to the inhibition of 4-hydroxynonenal, the final product of lipid peroxides, but also to the promotion of glutathione peroxidase 4, the protein marker of ferroptosis. MitoTracker staining and transmission electron microscopy of mitochondrial morphology suggested that in HEI-OC1 cells, Fer-1 can effectively abrogate mitochondrial damage resulting from the interaction with cisplatin. In addition, Fer-1 pretreatment of cochlear explants substantially protected hair cells from cisplatin-induced damage. Therefore, our results demonstrated that ferroptosis might be involved in cisplatin ototoxicity. Fer-1 administration mitigated cisplatin-induced hair cell damage, further investigations are required to elucidate the molecular mechanisms of its otoprotective effect.

Loss of Cardiac Ferritin H Facilitates Cardiomyopathy via Slc7a11-Mediated Ferroptosis.

RATIONALE: Maintaining iron homeostasis is essential for proper cardiac function. Both iron deficiency and iron overload are associated with cardiomyopathy and heart failure via complex mechanisms. Although ferritin plays a central role in iron metabolism by storing excess cellular iron, the molecular function of ferritin in cardiomyocytes remains unknown. OBJECTIVE: To characterize the functional role of Fth (ferritin H) in mediating cardiac iron homeostasis and heart disease. METHODS AND RESULTS: Mice expressing a conditional Fth knockout allele were crossed with 2 distinct Cre recombinase-expressing mouse lines, resulting in offspring that lack Fth expression specifically in myocytes (MCK-Cre) or cardiomyocytes (Myh6-Cre). Mice lacking Fth in cardiomyocytes had decreased cardiac iron levels and increased oxidative stress, resulting in mild cardiac injury upon aging. However, feeding these mice a high-iron diet caused severe cardiac injury and hypertrophic cardiomyopathy, with molecular features typical of ferroptosis, including reduced glutathione (GSH) levels and increased lipid peroxidation. Ferrostatin-1, a specific inhibitor of ferroptosis, rescued this phenotype, supporting the notion that ferroptosis plays a pathophysiological role in the heart. Finally, we found that Fth-deficient cardiomyocytes have reduced expression of the ferroptosis regulator Slc7a11, and overexpressing Slc7a11 selectively in cardiomyocytes increased GSH levels and prevented cardiac ferroptosis. CONCLUSIONS: Our findings provide compelling evidence that ferritin plays a major role in protecting against cardiac ferroptosis and subsequent heart failure, thereby providing a possible new therapeutic target for patients at risk of developing cardiomyopathy.

Inhibitors of cellular stress overcome acute effects of ethanol on hippocampal plasticity and learning.

Ethanol intoxication can produce marked changes in cognitive function including states in which the ability to learn and remember new information is completely disrupted. These defects likely reflect changes in the synaptic plasticity thought to underlie memory formation. We have studied mechanisms contributing to the adverse effects of ethanol on hippocampal long-term potentiation (LTP) and provided evidence that ethanol-mediated LTP inhibition involves a form of metaplasticity resulting from local metabolism of ethanol to acetaldehyde and untimely activation of N-methyl-d-aspartate receptors (NMDARs), both of which are neuronal stressors. In the present studies, we sought to understand the role of cellular stress in LTP defects, and demonstrate that ethanol's effects on LTP in the CA1 hippocampal region are overcome by agents that inhibit cellular stress responses, including ISRIB, a specific inhibitor of integrated stress responses, and GW3965, an agonist that acts at liver X receptors (LXRs) and dampens cellular stress. The agents that alter LTP inhibition also prevent the adverse effects of acute ethanol on one trial inhibitory avoidance learning. Unexpectedly, we found that the LXR agonist but not ISRIB overcomes effects of ethanol on synaptic responses mediated by N-methyl-d-aspartate receptors (NMDARs). These results have implications for understanding the adverse effects of ethanol and possibly for identifying novel paths to treatments that can prevent or overcome ethanol-induced cognitive dysfunction.

Pretreatment with Roxadustat (FG-4592) Attenuates Folic Acid-Induced Kidney Injury through Antiferroptosis via Akt/GSK-3ß/Nrf2 Pathway.

Folic acid- (FA-) induced kidney injury is characterized by the tubule damage due to the disturbance of the antioxidant system and subsequent interstitial fibrosis. FG-4592 is an inhibitor of prolyl hydroxylase of hypoxia-inducible factor (HIF), an antioxidant factor. The present study investigated the protective role of FG-4592 pretreatment at the early stage of the kidney injury and long-term impact on the progression of renal fibrosis. FG-4592 was administrated two days before FA injection in mice. On the second day after FA injection, the mice with FG-4592 pretreatment showed an improved renal function, compared with those without FG-4592 pretreatment, indicated by biochemical and histological parameters; meanwhile, the cellular content of iron, malondialdehyde, and 4-hydroxynonenal histologically decreased, implying the suppression of iron accumulation and lipid peroxidation. Simultaneously, upregulation of HIF-1α was found, along with Nrf2 activation, which was reflected by increased nuclear translocation and high-expression of downstream proteins, including heme-oxygenase1, glutathione peroxidase4, and cystine/glutamate transporter, as well as ferroportin. Correspondingly, the elevated levels of antioxidative enzymes and glutathione, as well as reduced iron accumulation, were observed, suggesting a lower risk of occurrence of ferroptosis with FG-4592 pretreatment. This was confirmed by reversed pathological parameters and improved renal function in FA-treated mice with the administration of ferrostatin-1, a specific ferroptosis inhibitor. Furthermore, a signal pathway study indicated that Nrf2 activation was associated with increased phosphorylation of Akt and GSK-3ß, verified by the use of an inhibitor of the PI3K that phosphorylates Akt. Moreover, FG-4592 pretreatment also decreased macrophage infiltration and expression of inflammatory factors TNF-α and IL-1ß. On the 14th day after FA injection, FG-4592 pretreatment decreased collagen deposition and expression of fibrosis biomarkers. These findings suggest that the protective role of FG-4592 pretreatment is achieved mainly by decreasing ferroptosis at the early stage of FA-induced kidney injury via Akt/GSK-3ß-mediated Nrf2 activation, which retards the fibrosis progression.

Integrated Stress Response Inhibitor Reverses Sex-Dependent Behavioral and Cell-Specific Deficits after Mild Repetitive Head Trauma.

Mild repetitive traumatic brain injury (rTBI) induces chronic behavioral and cognitive alterations and increases the risk for dementia. Currently, there are no therapeutic strategies to prevent or mitigate chronic deficits associated with rTBI. Previously we developed an animal model of rTBI that recapitulates the cognitive and behavioral deficits observed in humans. We now report that rTBI results in an increase in risk-taking behavior in male but not female mice. This behavioral phenotype is associated with chronic activation of the integrated stress response and cell-specific synaptic alterations in the type A subtype of layer V pyramidal neurons in the medial prefrontal cortex. Strikingly, by briefly treating animals weeks after injury with ISRIB, a selective inhibitor of the integrated stress response (ISR), we (1) relieve ISR activation, (2) reverse the increased risk-taking behavioral phenotype and maintain this reversal, and (3) restore cell-specific synaptic function in the affected mice. Our results indicate that targeting the ISR even at late time points after injury can permanently reverse behavioral changes. As such, pharmacological inhibition of the ISR emerges as a promising avenue to combat rTBI-induced behavioral dysfunction.

Calcilytics inhibit the proliferation and migration of human prostate cancer PC-3 cells.

The carcinogenesis and development of prostate cancer are mediated by enhanced Ca2+ signaling. In the present study, the pharmacological profile of the Ca2+-sensing receptor (CaSR) antagonists (calcilytics) was examined in human prostate cancer PC-3 cells. NPS2143 and Calhex 231 blocked extracellular Ca2+-induced increases in cytosolic [Ca2+]. NPS2143 and Calhex 231 inhibited cell proliferation (IC50 = 7.4 and 10.3 µM, respectively) and migration. The exposure to NPS2143 or Calhex 231 down-regulated CaSR protein expression. These results demonstrated that calcilytics inhibited cell proliferation/migration and down-regulated CaSR expression in human prostate cancer cells, suggesting their potential as novel therapeutic drugs for prostate cancer.

Dorsolateral Prefrontal Cortex Impairment in Methoxetamine-Induced Psychosis: An 18F-FDG PET/CT Case Study.

Novel psychoactive substances (NPSs) have currently become a major public health concern because of relatively easy accessibility to these compounds and difficulty in identifying them with routine laboratory techniques. Here, we report the 18F-fluorodeoxyglucose positron emission tomography/computerized tomography (18F-FDG PET/CT) case study of a 23-year-old man who developed a substance-induced psychotic disorder after having intravenously injected himself with an unspecified amount of methoxetamine (MXE), a ketamine derivative hallucinogen. From a clinical perspective, a blunted affective responsiveness with diminished social drive and sense of purpose, along with a profound detachment from the environment, was observed. Psychometric and neuropsychological assessments highlighted severe dissociative symptoms and lack of motivation, along with a mild impairment of verbal fluency, working memory, and attention. Patient's 18F-FDG PET/CT scans displayed a significant bilateral deficit of tracer uptake within the dorsolateral prefrontal cortex (DLPFC). DLPFC activity is critical to goal-oriented cognitive functions, including working memory and sustained attention. DLPFC is also involved in both the temporal integration across multiple sensory modes and in the volitional control of actions, leading to the possibility to construct logically coherent temporal configurations of thought, speech, and behavior. This report highlights that a single acute MXE intoxication may produce severe brain impairment.

Inhibiting the integrated stress response pathway prevents aberrant chondrocyte differentiation thereby alleviating chondrodysplasia.

The integrated stress response (ISR) is activated by diverse forms of cellular stress, including endoplasmic reticulum (ER) stress, and is associated with diseases. However, the molecular mechanism(s) whereby the ISR impacts on differentiation is incompletely understood. Here, we exploited a mouse model of Metaphyseal Chondrodysplasia type Schmid (MCDS) to provide insight into the impact of the ISR on cell fate. We show the protein kinase RNA-like ER kinase (PERK) pathway that mediates preferential synthesis of ATF4 and CHOP, dominates in causing dysplasia by reverting chondrocyte differentiation via ATF4-directed transactivation of Sox9. Chondrocyte survival is enabled, cell autonomously, by CHOP and dual CHOP-ATF4 transactivation of Fgf21. Treatment of mutant mice with a chemical inhibitor of PERK signaling prevents the differentiation defects and ameliorates chondrodysplasia. By preventing aberrant differentiation, titrated inhibition of the ISR emerges as a rationale therapeutic strategy for stress-induced skeletal disorders.

Phencyclidine-like in vivo effects of methoxetamine in mice and rats.

Methoxetamine (MXE) is a novel drug of abuse that is structurally similar to phencyclidine (PCP). In the present study, rats were trained to discriminate PCP from saline and substitution tests were performed with arylcyclohexylamines PCP, eticyclidine (PCE), tenocyclidine (TCP), and MXE. PCP and PCE engendered PCP-lever selection in all subjects, whereas MXE and TCP produced PCP-lever selection in animals that did not display behavioral disruption. Last, the substituted tryptamine dipropyltryptamine (DPT) produced moderate PCP-lever selection and elicited behavioral disruption in all subjects at the highest dose tested. Immediately following the final substitution test in the drug discrimination experiment, the same rats and a separate group of experimentally-naïve rats were implanted with osmotic mini-pumps delivering continuous PCP infusions for 11 days. Consistent with PCP withdrawal, disruption of food-maintained operant responding was observed when the pumps were removed, but cumulative MXE administration dose-dependently reversed this effect. A third group of rats self-administered several unit doses of PCP and MXE. Results of the self-administration tests revealed that MXE was a less effective reinforcer than PCP. Lastly, mice were implanted with radiotelemetry probes to simultaneously monitor thermoregulatory and locomotor responses following injections of PCP, PCE, or MXE. All three arylcyclohexylamines elicited dose-dependent hypothermic effects, but only PCP produced increases in locomotor activity. Together, these findings indicate that MXE elicits PCP-like interoceptive effects, but reduced reinforcing and locomotor stimulant effects in vivo. This article is part of the Special Issue entitled 'Designer Drugs and Legal Highs.'

Methoxetamine produces rapid and sustained antidepressant effects probably via glutamatergic and serotonergic mechanisms.

Depression afflicts around 16% of the world's population, making it one of the leading causes of disease burden worldwide. Despite a number of antidepressants available today, the delayed onset time and low remission rate of these treatments are still a major challenge. The N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has shown to produce rapid and sustained antidepressant effects and has paved the way for a new generation of glutamate-based antidepressants. Methoxetamine (MXE) is a ketamine analogue that acts as an NMDA receptor antagonist and a serotonin reuptake inhibitor. However, no studies have evaluated the antidepressant effects of MXE. Here, we assessed whether MXE produces antidepressant effects and explored possible mechanisms underlying its effects. Mice were treated with MXE (2.5, 5, or 10 mg/kg) and their behavior was evaluated 30 min and 24 h later in an array of behavioral experiments used for screening antidepressant drugs. A separate group of mice were treated with NBQX, an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, or ketanserin, a 5HT2 receptor antagonist, before MXE (5 mg/kg) administration in the forced swimming test (FST). We also investigated the effect of MXE on glutamatergic- and serotonergic-related genes in the mouse hippocampus using quantitative real-time PCR. MXE produced antidepressant effects 30 min after treatment that persisted for 24 h. Both NBQX and ketanserin blocked the antidepressant effects of MXE in the FST. MXE also altered hippocampal glutamatergic- and serotonergic gene expressions. These results suggest that MXE has rapid and sustained antidepressant effects, possibly mediated by the glutamatergic and serotonergic system.

Caffeic Acid Cyclohexylamide Rescues Lethal Inflammation in Septic Mice through Inhibition of IκB Kinase in Innate Immune Process.

Targeting myeloid differentiation protein 2 (MD-2) or Toll-like receptor 4 (TLR4) with small molecule inhibitor rescues the systemic inflammatory response syndrome (SIRS) in sepsis due to infection with Gram-negative bacteria but not other microbes. Herein, we provided IκB kinase ß (IKKß) in innate immune process as a molecular target of caffeic acid cyclohexylamide (CGA-JK3) in the treatment of polymicrobial TLR agonists-induced lethal inflammation. CGA-JK3 ameliorated E. coli lipopolysaccharide (LPS, MD-2/TLR4 agonist)-induced endotoxic shock, cecal ligation and puncture (CLP)-challenged septic shock or LPS plus D-galactosamine (GalN)-induced acute liver failure (ALF) in C57BL/6J mice. As a molecular basis, CGA-JK3 inhibited IKKß-catalyzed kinase activity in a competitive mechanism with respect to ATP, displaced fluorescent ATP probe from the complex with IKKß, and docked at the ATP-binding active site on the crystal structure of human IKKß. Furthermore, CGA-JK3 inhibited IKKß-catalyzed IκB phosphorylation, which is an axis leading to IκB degradation in the activating pathway of nuclear factor-κB (NF-κB), in macrophages stimulated with TLR (1/2, 2/6, 4, 5, 7, 9) agonists from Gram-positive/negative bacteria and viruses. CGA-JK3 consequently interrupted IKKß-inducible NF-κB activation and NF-κB-regulated expression of TNF-α, IL-1α or HMGB-1 gene, thereby improving TLRs-associated redundant inflammatory responses in endotoxemia, polymicrobial sepsis and ALF.

Local administration of a hedgehog agonist accelerates fracture healing in a mouse model.

Bone fracture healing is processed through multiple biological stages including the transition from cartilaginous callus to bony callus formation. Because of its specific, temporal and indispensable functions demonstrated by mouse genetic studies, Hedgehog (Hh) signaling is one of the most potent signaling pathways involved in these processes, but the effect of Hh-signaling activation by small compounds on the repair process had not yet been addressed. Here we examined therapeutic effects of local and one shot-administration of the Hh agonist known as smoothened agonist (SAG) on bone fracture healing in a mouse model. A quantitative analysis with three-dimensional micro-computed tomography showed that SAG administration increased the size of both the cartilaginous callus and bony callus at 14 days after the surgery. A histological analysis showed that SAG administration increased the number of cells expressing a proliferation marker and a chondrocyte marker in cartilaginous callus as well as the cells expressing an osteoblast marker in bony callus. These results indicate that the SAG administration resulted in an enhancement of callus formation during bone fracture healing, which is at least in part mediated by an increase in chondrocyte proliferation in cartilaginous callus and the promotion of bone formation in bony callus. Therapeutic strategies with a SAG-mediated protocol may thus be useful for the treatment of bone fractures.

"Trip-Sitting" in the Black Hole: A Netnographic Study of Dissociation and Indigenous Harm Reduction.

An array of dissociative novel psychoactive substances, including "methoxetamine," "3-MeO-PCP," and "methoxphenidine," have emerged as substitutes for the illicit substance "ketamine." A netographic research methodology aimed to describe online, dissociative novel psychoactive substance users' perceptions of risk, informed knowledge around use, and indigenous harm-reduction practices as advocated within online drug fora, so as to provide credible information which can be used to inform public online health education and drug prevention. Systematic Internet searches were performed using the terms "synthetic dissociative," "methoxetamine," "methoxphenidine," "diphenidine," "3-MeO-PCP," "4-MeO-PCP," "2-MDP," and "dissociative research chemical" in combination with "forum." Following screening of 3,476 forum threads with removal of duplicates and exclusion criteria, 90 user trip reports and 115 fora threads from seven drug fora websites were analyzed by conducting content analysis. Five themes emerged with 43 categories. The findings illustrated how forum activity within the cyber drug user community disseminated and exchanged "communal folk pharmacology" relating to the use of dissociative novel psychoactive substances. Further research and consistent monitoring of Internet drug fora are advised to explore variations in harm-reduction tactics throughout dissociative NPS populations, and to consider how existing harm-reduction initiatives are influencing these hard-to-reach groups.

Methoxetamine, a novel psychoactive substance with serious adverse pharmacological effects: a review of case reports and preclinical findings.

An increasing number of novel psychoactive substances are currently available and sold as 'legal highs' or 'research chemicals' accompanied by the indication that they are 'not for human consumption'. Among those that have emerged in the last few years, methoxetamine (MXE) owes its wide popularity to its easy access on the Internet and its reputation of being a 'safe' drug. MXE is an arylcyclohexylamine with a chemical structure analogous to ketamine and phencyclidine, and similar noncompetitive glutamate N-methyl D-aspartate receptor antagonist properties. Yet, very recent preclinical data highlighted a stimulatory effect of MXE on dopamine neurotransmission within the mesolimbic pathway. The aim of this review is to provide an updated review of the behavioral and toxicological effects of MXE as well as the latest findings on its pharmacology that might explain sought effects and frequent occurrence of adverse effects. In light of the growing number of intoxications induced by MXE, knowledge of its short-term and long-term effects is urgently needed. However, the hypothetical rapid antidepressant activity of MXE suggested by its chemical analogy with ketamine and supported by recent preclinical findings deserves further investigation.

The ketamine-like compound methoxetamine substitutes for ketamine in the self-administration paradigm and enhances mesolimbic dopaminergic transmission.

RATIONALE: Recently, an increasing number of emergency cases due to a novel ketamine-like drug, methoxetamine (MXE), were reported in several countries. However, very little is known about the neuropsychopharmacological and reinforcing profile of this compound. OBJECTIVES: Our study aims to investigate the effects of MXE on self-administration (SA) behaviour in comparison to ketamine and on dopaminergic transmission. METHODS: A SA substitution study was performed in male rats trained to intravenously (IV) self-administer ketamine. At responding stability, rats were exposed to sequential phases of MXE substitution at different dosages (starting from 0.5 and then decreasing to 0.25 and 0.125 mg/kg). Standard electrophysiological techniques were used to record changes in firing activities of ventral tegmental area (VTA) dopamine neurons projecting to the nucleus accumbens (NAc) shell after acute injection of cumulative doses of MXE (0.031-0.5 mg/kg IV). Finally, in vivo microdialysis was performed in freely moving rats to evaluate the effect of acute MXE administration (0.125, 0.25 and 0.5 mg/kg IV) on dopamine release in the NAc shell. RESULTS: MXE 0.125 and 0.25 mg/kg, but not 0.5 mg/kg, substituted for ketamine SA. MXE also induced a dose-dependent stimulation of firing rate (p < 0.0001) and burst firing (p < 0.05) of NAc-projecting VTA dopamine neurons. Consistently, MXE significantly (p < 0.05) increased dopamine extracellular levels in the NAc shell at 0.5 and 0.25 mg/kg with different time onsets, i.e. at 40 and 100 min, respectively. CONCLUSIONS: This study, while confirming the reinforcing effects of MXE, highlights an electrophysiological and neurochemical profile predictive of its addictive properties.

Methoxetamine: An early report on the motivations for use, effect profile and prevalence of use in a UK clubbing sample.

INTRODUCTION AND AIMS: To assess the prevalence of use and subjective effect profile of methoxetamine among a group of polydrug users. DESIGN AND METHODS: Cross-sectional, anonymous, online survey of UK-based polydrug users was conducted. Prevalence of lifetime, last year and last month use, sourcing of the drugs, motivations for use, and subjective effect and risk profile compared with that of ketamine were measured. RESULTS: There were 7700 UK-based polydrug users, of whom 326 reported recent use of methoxetamine. Of the whole sample, 4.2% reported last 12 month use of methoxetamine compared with 24.5% for ketamine. The most common route of use was intranasal and the predominate effect described as psychedelic. Of the 15.5% of last year users of ketamine reporting last year use of methoxetamine, only 18.7% reported that they thought methoxetamine was less damaging to their kidneys or bladder than ketamine. Its broad effect profile, based on participants' first experience of use, was very similar to that of ketamine. Almost one-third of users reported that they did not intend to try the drug again. DISCUSSION AND CONCLUSIONS: Methoxetamine appears to have a broadly similar effect profile to that of ketamine. Only a minority of participants were motivated to use it because they believed it was less damaging to their kidneys or bladder than ketamine. The impact of the recent temporary banning order on availability and use of both methoxetamine and ketamine should be monitored carefully.

Simultaneous inhibition of JAK and SYK kinases ameliorates chronic and destructive arthritis in mice.

INTRODUCTION: Despite the broad spectrum of antirheumatic drugs, RA is still not well controlled in up to 30-50 % of patients. Inhibition of JAK kinases by means of the pan-JAK inhibitor tofacitinib has demonstrated to be effective even in difficult-to-treat patients. Here, we discuss whether the efficacy of JAK inhibition can be improved by simultaneously inhibiting SYK kinase, since both kinases mediate complementary and non-redundant pathways in RA. METHODS: Efficacy of dual JAK + SYK inhibition with selective small molecule inhibitors was evaluated in chronic G6PI-induced arthritis, a non-self-remitting and destructive arthritis model in mice. Clinical and histopathological scores, as well as cytokine and anti-G6PI antibody production were assessed in both preventive and curative protocols. Potential immunotoxicity was also evaluated in G6PI-induced arthritis and in a 28-day TDAR model, by analysing the effects of JAK + SYK inhibition on hematological parameters, lymphoid organs, leukocyte subsets and cell function. RESULTS: Simultaneous JAK + SYK inhibition completely prevented mice from developing arthritis. This therapeutic strategy was also very effective in ameliorating already established arthritis. Dual kinase inhibition immediately resulted in greatly decreased clinical and histopathological scores and led to disease remission in over 70 % of the animals. In contrast, single JAK inhibition and anti-TNF therapy (etanercept) were able to stop disease progression but not to revert it. Dual kinase inhibition decreased Treg and NK cell counts to the same extent as single JAK inhibition but overall cytotoxicity remained intact. Interestingly, treatment discontinuation rapidly reversed such immune cell reduction without compromising clinical efficacy, suggesting long-lasting curative effects. Dual kinase inhibition reduced the Th1/Th17 cytokine cascade and the differentiation and function of joint cells, in particular osteoclasts and fibroblast-like synoviocytes. CONCLUSIONS: Concurrent JAK + SYK inhibition resulted in higher efficacy than single kinase inhibition and TNF blockade in a chronic and severe arthritis model. Thus, blockade of multiple immune signals with dual JAK + SYK inhibition represents a reasonable therapeutic strategy for RA, in particular in patients with inadequate responses to current treatments. Our data supports the multiplicity of events underlying this heterogeneous and complex disease.