NMDA Receptor Blocker Research Articles

Evaluation of SK-N-SH Cells as a Model for NMDA Receptor Induced Toxicity.

Over the years, the number of patients with neurodegenerative diseases is constantly rising illustrating the need for new neuroprotective drugs. A promising treatment approach is the reduction of excitotoxicity induced by rising (S)-glutamate levels and subsequent NMDA receptor overactivation. To facilitate the search for new NMDA receptor inhibitors neuronal cell models are needed. In this study, we evaluated the suitability of human SK-N-SH cells to serve as a cell model for neurodegeneration induced by NMDA receptor overstimulation. The cytoprotective effect of the unselective NMDA receptor blocker ketamine as well as the GluN2B-selective inhibitor WMS14-10 was evaluated utilizing different cell viability assays, such as endpoint (LDH, CCK-8, DAPI/FACS) and time dependent methods (bioimpedance). Non-differentiated as well as differentiated SK-N-SH cells express GluN1 and GluN2B subunits. Furthermore, 50 mM (S)-glutamate led to an instantaneous decrease in cell survival. Only application of unselective channel blocker ketamine could protect differentiated cells against this effect, while the selective inhibitor WMS14-10 did not significantly increase cell survival. SK-N-SH cells show an increased sensitivity to (S)-glutamate mediated cytotoxicity with higher differentiation level, that is only partially induced by NMDA receptor overstimulation. Furthermore, we showed that only unselective NMDA receptor inhibition can partially reverse (S)-glutamate-induced toxicity.

Administration of low dose intranasal ketamine exerts a neuroprotective effect on whole brain irradiation injury model in wistar rats.

Exposure to ionizing radiation leads to oxidative stress and neuroinflammation, resulting in neurocognitive impairments. Adverse effects are also associated with glutamate-induced excitotoxicity due to alterations in the composition of glutamate receptors. Ketamine, which is a noncompetitive NMDA glutamate receptor antagonist, has been stated to exert an impact on glutamatergic receptors. This study aims to reveal the possible alleviating or preventive effects of ketamine, which maintains glutamate homeostasis and decreases neurodegeneration, in a radiation-induced neurotoxicity model. Twenty-one female Wistar Queryrats were included in the study and 14 of these underwent whole brain irradiation (IR) with a 20 Gray single dose. Animals were allocated into three groups. Group 1: Normal control; Group 2: Placebo / IR + Saline; Group 3: IR + Ketamine. Ketamine was administered in addition to IR to rats in Group 3. The one-way ANOVA statistical test was used to compare groups. The value of p < 0.05 was considered statistically significant. When administered in addition to irradiation, ketamine treatment significantly increased scores in the three-chamber sociability test, open field test, and passive avoidance learning test. It also raised neuron counts in the hippocampal CA1 and CA3 regions as well as in Purkinje cells, and enhanced levels of brain-derived neurotrophic factor and tyrosine receptor kinase-B. Furthermore, ketamine administration resulted in decreased levels of glial fibrillary acidic protein, malondialdehyde, and tumor necrosis factor-alpha, indicating a reduction in neuroinflammation and oxidative stress. Ketamine exerted a significant protective impact on radiation-induced neurocognitive impairments and enhanced social-memory capacity by reducing neuronal loss, oxidative stress, and neuroinflammation. Our findings suggest that ketamine is beneficial in the treatment or prevention of neurodegeneration via the regulation of the BDNF/TrkB signaling pathway besides decreasing neuroinflammation and blocking NMDA receptors.

Neuronal activation sequences in lateral prefrontal cortex encode visuospatial working memory during virtual navigation

Working memory (WM) is the ability to maintain and manipulate information ‘in mind’. The neural codes underlying WM have been a matter of debate. We simultaneously recorded the activity of hundreds of neurons in the lateral prefrontal cortex of male macaque monkeys during a visuospatial WM task that required navigation in a virtual 3D environment. Here, we demonstrate distinct neuronal activation sequences (NASs) that encode remembered target locations in the virtual environment. This NAS code outperformed the persistent firing code for remembered locations during the virtual reality task, but not during a classical WM task using stationary stimuli and constraining eye movements. Finally, blocking NMDA receptors using low doses of ketamine deteriorated the NAS code and behavioral performance selectively during the WM task. These results reveal the versatility and adaptability of neural codes supporting working memory function in the primate lateral prefrontal cortex.

COMPARISON BETWEEN NEBULISATION OF MGSO4 20 MG/KGBW WITH KETAMINE 0.5 MG/KGBW ON THE INCIDENT OF POST-OPERATIVE SORE THROAT DUE TO ENDOTRACHEAL INTUBATION IN PATIENTS UNDERGOING GENERAL ANESTHESIA IN DR. HASAN SADIKIN HOSPITALS BANDUNG

Post Operative Sore Throat (POST) is a Symptoms often experienced by patients after surgery under general anesthesia and endotracheal intubation. The incidence of POST is between 21-71.8. POST causes discomfort to patients which can prolong hospital stay. In this study, a comparison was made between MgSO4 nebulization 20 mg/ KgBW and ketamine nebulization 0.5 mg/ KgBW on the incidence of POST after general anesthesia at RSUP Dr. Hasan Sadikin Bandung . This study used a double blind randomized controlled trial design. 72 elective surgery patients were randomly divided into 2 groups. Group M was given MgSO4 nebulization while group K was given ketamine nebulization. Nebulization was performed 15 minutes before induction of general anesthesia. POST monitoring was performed at 1, 4 and 24 hours after extubation using POST scoring. In this study, it was found that the incidence of POST in group M, namely the 1st hour of 13.5, the 4th hour of 10.8 and the 24th hour of 0 was lower than that in group K, namely the 1st hour of 28.5, the 4th hour of 32.5 and the 24th hour of 0. Statistical test results p0.033 showed a significant difference in group M better than group K at the 4th hour in reducing the incidence of POST. MgSO4 and ketamine have antinociceptive and anti-inflammatory effects with the mechanism of action of blocking NMDA receptors that inhibit calcium influx that avoids central sensitization. MgSO4 also has a muscle relaxing effect and reduces airway mucus secretion, thus reducing the risk of trauma during endotracheal intubation. The conclusion of this study is that MgSO4 nebulization shows a lower incidence of POST than ketamine nebulization.

Deux cents ans d’histoire des usages et mésusages du protoxyde d’azote

Deux cents ans d’histoire des usages et mésusages du protoxyde d’azote

Estimating the Ca2+ Block of NMDA Receptors with Single-Channel Electrophysiology.

In vertebrate central neurons, NMDA receptors are glutamate- and glycine-gated ion channels that allow the passage of Na+ and Ca2+ ions into the cell when these neurotransmitters are simultaneously present. The passage of Ca2+ is critical for initiating the cellular processes underlying various forms of synaptic plasticity. These Ca2+ ions can autoregulate the NMDA receptor signal through multiple distinct mechanisms to reduce the total flux of cations. One such mechanism is the ability of Ca2+ ions to exclude the passage of Na+ ions resulting in a reduced unitary current conductance. In contrast to the well-characterized Mg2+ block, this "channel block" mechanism is voltage-independent. In this chapter, we discuss theoretical and experimental considerations for the study of channel block by Ca2+ using single-channel patch-clamp electrophysiology. We focus on two classic methodologies to quantify the dependence of unitary channel conductance on external concentrations of Ca2+ as the basis for quantifying Ca2+ block.

Astrocyte β-Adrenergic Receptor Activity Regulates NMDA Receptor Signaling of Medial Prefrontal Cortex Pyramidal Neurons.

Glutamate spillover from the synapse is tightly regulated by astrocytes, limiting the activation of extrasynaptically located NMDA receptors (NMDAR). The processes of astrocytes are dynamic and can modulate synaptic physiology. Though norepinephrine (NE) and β-adrenergic receptor (β-AR) activity can modify astrocyte volume, this has yet to be confirmed outside of sensory cortical areas, nor has the effect of noradrenergic signaling on glutamate spillover and neuronal NMDAR activity been explored. We monitored changes to astrocyte process volume in response to noradrenergic agonists in the medial prefrontal cortex of male and female mice. Both NE and the β-AR agonist isoproterenol (ISO) increased process volume by ∼20%, significantly higher than changes seen when astrocytes had G-protein signaling blocked by GDPβS. We measured the effect of β-AR signaling on evoked NMDAR currents. While ISO did not affect single stimulus excitatory currents of Layer 5 pyramidal neurons, ISO reduced NMDAR currents evoked by 10 stimuli at 50 Hz, which elicits glutamate spillover, by 18%. After isolating extrasynaptic NMDARs by blocking synaptic NMDARs with the activity-dependent NMDAR blocker MK-801, ISO similarly reduced extrasynaptic NMDAR currents in response to 10 stimuli by 18%. Finally, blocking β-AR signaling in the astrocyte network by loading them with GDPβS reversed the ISO effect on 10 stimuli-evoked NMDAR currents. These results demonstrate that astrocyte β-AR activity reduces extrasynaptic NMDAR recruitment, suggesting that glutamate spillover is reduced.

A Network Model of the Modulation of γ Oscillations by NMDA Receptors in Cerebral Cortex.

Psychotic drugs such as ketamine induce symptoms close to schizophrenia and stimulate the production of γ oscillations, as also seen in patients, but the underlying mechanisms are still unclear. Here, we have used computational models of cortical networks generating γ oscillations, and have integrated the action of drugs such as ketamine to partially block NMDA receptors (NMDARs). The model can reproduce the paradoxical increase of γ oscillations by NMDA receptor antagonists, assuming that antagonists affect NMDA receptors with higher affinity on inhibitory interneurons. We next used the model to compare the responsiveness of the network to external stimuli, and found that when NMDA channels are blocked, an increase of γ power is observed altogether with an increase of network responsiveness. However, this responsiveness increase applies not only to γ states, but also to asynchronous states with no apparent γ. We conclude that NMDA antagonists induce an increased excitability state, which may or may not produce γ oscillations, but the response to external inputs is exacerbated, which may explain phenomena such as altered perception or hallucinations.

Mechanisms of initiation of cortical spreading depression

BackgroundThere is increasing evidence from human and animal studies that cortical spreading depression (CSD) is the neurophysiological correlate of migraine aura and a trigger of migraine pain mechanisms. The mechanisms of initiation of CSD in the brain of migraineurs remain unknown, and the mechanisms of initiation of experimentally induced CSD in normally metabolizing brain tissue remain incompletely understood and controversial. Here, we investigated the mechanisms of CSD initiation by focal application of KCl in mouse cerebral cortex slices.MethodsHigh KCl puffs of increasing duration up to the threshold duration eliciting a CSD were applied on layer 2/3 whilst the membrane potential of a pyramidal neuron located very close to the site of KCl application and the intrinsic optic signal were simultaneously recorded. This was done before and after the application of a specific blocker of either NMDA or AMPA glutamate receptors (NMDARs, AMPARs) or voltage-gated Ca2+ (CaV) channels. If the drug blocked CSD, stimuli up to 12–15 times the threshold were applied.ResultsBlocking either NMDARs with MK-801 or CaV channels with Ni2+ completely inhibited CSD initiation by both CSD threshold and largely suprathreshold KCl stimuli. Inhibiting AMPARs with NBQX was without effect on the CSD threshold and velocity. Analysis of the CSD subthreshold and threshold neuronal depolarizations in control conditions and in the presence of MK-801 or Ni2+ revealed that the mechanism underlying ignition of CSD by a threshold stimulus (and not by a just subthreshold stimulus) is the CaV-dependent activation of a threshold level of NMDARs (and/or of channels whose opening depends on the latter). The delay of several seconds with which this occurs underlies the delay of CSD initiation relative to the rapid neuronal depolarization produced by KCl.ConclusionsBoth NMDARs and CaV channels are necessary for CSD initiation, which is not determined by the extracellular K+ or neuronal depolarization levels per se, but requires the CaV-dependent activation of a threshold level of NMDARs. This occurs with a delay of several seconds relative to the rapid depolarization produced by the KCl stimulus. Our data give insights into potential mechanisms of CSD initiation in migraine.

NMDA Receptors in the Rat Paraventricular Thalamic Nucleus Reduce the Naloxone-induced Morphine Withdrawal.

NMDA receptors have a significant role in the development of opioid physical dependence. Evidence demonstrated that a drug of abuse enhances neuronal excitability in the Paraventricular Nucleus (PVT). The current research studied whether blocking NMDA receptors through the administration of MK801 in the PVT nucleus could affect the development of Morphine (Mor) dependence and hence the behavioral indices induced by morphine withdrawal in rats. Male Wistar rats weighing 250-300 g were used. For induction of drug dependence, we injected Mor subcutaneously (s.c.) (6, 16, 26, 36, 46, 56, and 66 mg/kg, 2 ml/kg) at an interval of 24 hours for 7 days. Animals were divided into two groups in which the NMDA receptor antagonist, MK801 (20 mM in 0.1 ml), or its vehicle were applied into the PVT nucleus for 7 days before each Mor administration. On day 8, after injection of naloxone (Nal, 2.5 mg/kg, i.p.), withdrawal behaviors were checked for 25 min. The current results demonstrated that the blockade of the NMDA receptor in the PVT nucleus significantly increased withdrawal behaviors provoked by the application of Nal in morphinedependent (Mor-d) rats. We concluded that the NMDA receptor in the PVT nucleus changes the development of Mor dependence.

COMPARATIVE EVALUATION OF EPIDURAL BUPIVACAINE WITH MAGNESIUM SULPHATE AND LEVOBUPIVACAINE WITH MAGNESIUM SULPHATE IN GERIATRIC AGE GROUP IN LOWER LIMB SURGERIES

Introduction :Bupivacaine is local anaesthetic drug consist of R &amp; S enantiomers. Levobupivacaine a cardiostable S enantiomer of Bupivaciane. Magnesium sulphate a promising noncompititive blocker of NMDA receptor by inhibition calcium Inux in cell. We want to study addition of Magnesium Sulphate to both Bupivacaine 0.5% &amp; Levobupivacaine 0.5% for epidural anaesthesia in lower limb surgeries. to compare efcacy of epidural Inj. Bupivac Aims &amp; Objectives: aine 0.5% plus Magnesium sulphate with Inj. Levobupivacaine 0.5% plus Magnesium Sulphate on onset of sensory &amp; motor blockade, intraoperative hemodynamics , requirement of rst analgesiac &amp; side effects in elderly patients posted for lower limb surgeries. A randomised prospective double blind Material and Method: study in 60 geriatric patient posted for lower limb surgeries. After epidural space identication Inj. Bupivacaine 0.5% 14 ml + 50mg MgSo4 in 1 ml NS in group B or Inj. Levobupivacaine 0.5% 14 ml + 50mg MgSo4 in 1 ml NS in group L. Onset of sensory blockade and motor blockade, two segment regression, demand of rst analgesic, intraoperative hemodynamics and postoperative complications were documented and compared Observation: Mean time required for onset of sensory block was 6.27±1.48 min in Group B and 6.3±1.76 min in group L respectively. onset motor block times of 7.43±1.38 in group B while 8.13±1.81 mins in group L which were No statistically signicant difference. Group L required 20.1±4.87 mins for reaching maximum sensory block compared to 13.33±2.17 mins in group B which was statistically signicant difference with early achievement of higher sensory level in group B. The time required for two segment regression was longer, at 133±19.01 minutes in group B compared to 114.47±10.28 minutes in the group L which found statistically signicant difference. Group B required rst analgesics quite latter 241.33±29.39 at mins compared to 203±20.54 mins in group L. This was found to be statistically signicant difference indicating that Bupivacaine is having longer duration of analgesia compared to Levobupivacaine. 3 patients had hypotension in group while 1 in group L. Shivering noticed 6 in Group L compared to 3 in group B. vomiting in 3 patients in each group.only 1 patient had itching in group b. Intraoperative hemodynamic parameters were having statistically insignicant difference. Conclusion: We can conclude that effect of Magnesium sulphate as an additive to Levobupivacaine and Bupivacaine provide good haemodynamic and respiratory stability, Comparable onset of sensory and motor blockade with prolongation of postoperative analgesia in bupivacaine group indicating that Bupivacaine with Magnesium sulphate provides prolonged analgesia as compared to Levobupivacaine with Magnesium Sulphate.

The Pathological Effects of Circulating Hydrophobic Bile Acids in Alzheimer's Disease.

Recent clinical studies have revealed that the serum levels of toxic hydrophobic bile acids (deoxy cholic acid, lithocholic acid [LCA], and glycoursodeoxycholic acid) are significantly higher in patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (aMCI) when compared to control subjects. The elevated serum bile acids may be the result of hepatic peroxisomal dysfunction. Circulating hydrophobic bile acids are able to disrupt the blood-brain barrier and promote the formation of amyloid-β plaques through enhancing the oxidation of docosahexaenoic acid. Hydrophobic bile acid may find their ways into the neurons via the apical sodium-dependent bile acid transporter. It has been shown that hydrophobic bile acids impose their pathological effects by activating farnesoid X receptor and suppressing bile acid synthesis in the brain, blocking NMDA receptors, lowering brain oxysterol levels, and interfering with 17β-estradiol actions such as LCA by binding to E2 receptors (molecular modelling data exclusive to this paper). Hydrophobic bile acids may interfere with the sonic hedgehog signaling through alteration of cell membrane rafts and reducing brain 24(S)-hydroxycholesterol. This article will 1) analyze the pathological roles of circulating hydrophobic bile acids in the brain, 2) propose therapeutic approaches, and 3) conclude that consideration be given to reducing/monitoring toxic bile acid levels in patients with AD or aMCI, prior/in combination with other treatments.

NMDA receptors- regulatory function and pathophysiological significance for pancreatic beta cells.

Due to its unique features amongst ionotropic glutamate receptors, the NMDA receptor is of special interest in the physiological context but even more as adrug target. In the pathophysiology of metabolic disorders, particularly type 2 diabetes mellitus, there is evidence that NMDA receptor activation contributes to disease progression by impairing beta cell function. Consequently, channel inhibitors are suggested for treatment, but up to now there are many unanswered questions about the signaling pathways NMDA receptors are interfering with in the islets of Langerhans. In this review we give an overview about channel structure and function with special regard to the pancreatic beta cells and the regulation of insulin secretion. We sum up which signaling pathways from brain research have already been transferred to the beta cell, and what still needs to be proven. The main focus is on the relationship between an over-stimulated NMDA receptor and the production of reactive oxygen species, the amount of which is crucial forbeta cell function. Finally, pilot studies using NMDA receptor blockers to protect the islet from dysfunction arereviewed and future perspectives for the use of such compounds in the context of impaired glucose homeostasis are discussed.

Altered Expression and In Vivo Activity of mGlu5 Variant a Receptors in the Striatum of BTBR Mice: Novel Insights Into the Pathophysiology of Adult Idiopathic Forms of Autism Spectrum Disorders.

mGlu5 metabotropic glutamate receptors are considered as candidate drug targets in the treatment of "monogenic" forms of autism spectrum disorders (ASD), such as Fragile- X syndrome (FXS). However, despite promising preclinical data, clinical trials using mGlu5 receptor antagonists to treat FXS showed no beneficial effects. Here, we studied the expression and function of mGlu5 receptors in the striatum of adult BTBR mice, which model idiopathic forms of ASD, and behavioral phenotype. Behavioral tests were associated with biochemistry analysis including qPCR and western blot for mRNA and protein expression. In vivo analysis of polyphosphoinositides hydrolysis was performed to study the mGlu5-mediated intracellular signaling in the striatum of adult BTBR mice under basal conditions and after MTEP exposure. Expression of mGlu5 receptors and mGlu5 receptor-mediated polyphosphoinositides hydrolysis were considerably high in the striatum of BTBR mice, sensitive to MTEP treatment. Changes in the expression of genes encoding for proteins involved in excitatory and inhibitory neurotransmission and synaptic plasticity, including Fmr1, Dlg4, Shank3, Brd4, bdnf-exon IX, Mef2c, and Arc, GriA2, Glun1, Nr2A, and Grm1, Grm2, GriA1, and Gad1 were also found. Behaviorally, BTBR mice showed high repetitive stereotypical behaviors, including self-grooming and deficits in social interactions. Acute or repeated injections with MTEP reversed the stereotyped behavior and the social interaction deficit. Similar effects were observed with the NMDA receptor blockers MK-801 or ketamine. These findings support a pivotal role of mGlu5 receptor abnormal expression and function in idiopathic ASD adult forms and unveil novel potential targets for therapy.

Intravenous Magnesium Sulfate for Acute Pain Management After Laparotomy Surgery: A Case Series

Introduction: Perioperative pain management is indicated to relieve patient complaints, allow early mobilization after surgery, reduce the duration of hospital stay, and provide a better level of satisfaction. This study aims to describe the use of magnesium sulfate in post-laparotomy patients.&#x0D; Case presentation: There were two cases, and the first was a 41-year-old female patient with endometrial cysts and adenomyosis who underwent laparotomy under general anesthesia. The patient was given magnesium sulfate 30 mg/kgBW 20 minutes before induction, then a continuous dose via a syringe pump 10 mg/kgBW/hour until the operation was completed. This patient showed an NRS scale 1 hour after surgery 1/10 and after 24 hours a maximum of 3/10. The second case was a 42-year-old female patient with suspected Leimiosarcoma who underwent a total hysterectomy and bilateral salpingoovorectomy under general anesthesia. Patients also received the same administration of magnesium sulfate and were assessed on the NRS scale up to 2 hours postoperatively 1/10 and after 24 hours a maximum of 2/10.&#x0D; Conclusion: Magnesium sulfate is used as an adjuvant in postoperative analgesia and analgesic therapy to treat acute or chronic pain and has antinociceptive effects due to NMDA receptor blocking, making it useful for the prevention of central sensitization.

Correction to: A potential of methoxpropamine to be a widespread recreational drug: it blocks NMDA receptors and inhibits NMDA receptor-mediated synaptic transmission in a brain preparation of mice

Correction to: A potential of methoxpropamine to be a widespread recreational drug: it blocks NMDA receptors and inhibits NMDA receptor-mediated synaptic transmission in a brain preparation of mice

HDAC2 in Primary Sensory Neurons Constitutively Restrains Chronic Pain by Repressing α2δ-1 Expression and Associated NMDA Receptor Activity.

α2δ-1 (encoded by the Cacna2d1 gene) is a newly discovered NMDA receptor-interacting protein and is the therapeutic target of gabapentinoids (e.g., gabapentin and pregabalin) frequently used for treating patients with neuropathic pain. Nerve injury causes sustained α2δ-1 upregulation in the dorsal root ganglion (DRG), which promotes NMDA receptor synaptic trafficking and activation in the spinal dorsal horn, a hallmark of chronic neuropathic pain. However, little is known about how nerve injury initiates and maintains the high expression level of α2δ-1 to sustain chronic pain. Here, we show that nerve injury caused histone hyperacetylation and diminished enrichment of histone deacetylase-2 (HDAC2), but not HDAC3, at the Cacna2d1 promoter in the DRG. Strikingly, Hdac2 knockdown or conditional knockout in DRG neurons in male and female mice consistently induced long-lasting mechanical pain hypersensitivity, which was readily reversed by blocking NMDA receptors, inhibiting α2δ-1 with gabapentin or disrupting the α2δ-1-NMDA receptor interaction at the spinal cord level. Hdac2 deletion in DRG neurons increased histone acetylation levels at the Cacna2d1 promoter, upregulated α2δ-1 in the DRG, and potentiated α2δ-1-dependent NMDA receptor activity at primary afferent central terminals in the spinal dorsal horn. Correspondingly, Hdac2 knockdown-induced pain hypersensitivity was blunted in Cacna2d1 knockout mice. Thus, our findings reveal that HDAC2 functions as a pivotal transcriptional repressor of neuropathic pain via constitutively suppressing α2δ-1 expression and ensuing presynaptic NMDA receptor activity in the spinal cord. HDAC2 enrichment levels at the Cacna2d1 promoter in DRG neurons constitute a unique epigenetic mechanism that governs acute-to-chronic pain transition.SIGNIFICANCE STATEMENT Excess α2δ-1 proteins produced after nerve injury directly interact with glutamate NMDA receptors to potentiate synaptic NMDA receptor activity in the spinal cord, a prominent mechanism of nerve pain. Because α2δ-1 upregulation after nerve injury is long lasting, gabapentinoids relieve pain symptoms only temporarily. Our study demonstrates for the first time the unexpected role of intrinsic HDAC2 activity at the α2δ-1 gene promoter in limiting α2δ-1 gene transcription, NMDA receptor-dependent synaptic plasticity, and chronic pain development after nerve injury. These findings challenge the prevailing view about the role of general HDAC activity in promoting chronic pain. Restoring the repressive HDAC2 function and/or reducing histone acetylation at the α2δ-1 gene promoter in primary sensory neurons could lead to long-lasting relief of nerve pain.

Mechanisms underpinning Carpolobia lutea G. Don ethanol extract's neurorestorative and antipsychotic-like activities in an NMDA receptor antagonist model of schizophrenia

Ethnopharmacological relevancePersistent ketamine insults to the central nervous system block NMDA receptors and disrupt putative neurotransmission, oxido–nitrosative, and inflammatory pathways, resulting in schizophrenia-like symptoms in animals. Previously, the ethnomedicinal benefits of Carpolobia lutea against insomnia, migraine headache, and insanity has been documented, but the mechanisms of action remain incomplete. Aim of the studyPresently, we explored the neuro-therapeutic role of Carpolobia lutea ethanol extract (C. lutea) in ketamine-induced schizophrenia-like symptoms in mice. Materials and methodsSixty-four male Swiss (22 ± 2 g) mice were randomly assigned into eight groups (n = 8/group) and exposed to a reversal ketamine model of schizophrenia. For 14 days, either distilled water (10 mL/kg; p.o.) or ketamine (20 mg/kg; i.p.) was administered, following possible reversal treatments with C. lutea (100, 200, 400, and 800 mg/kg; p.o.), haloperidol (1 mg/kg, p.o.), or clozapine (5 mg/kg; p.o.) beginning on days 8–14. During the experiment, a battery of behavioral characterizations defining schizophrenia-like symptoms were obtained using ANY-maze software, followed by neurochemical, oxido-inflammatory and histological assessments in the mice brains. ResultsA 7-day reversal treatment with C. lutea reversed predictors of positive, negative and cognitive symptoms of schizophrenia. C. lutea also mitigated ketamine-induced neurochemical derangements as evidenced by modulations of dopamine, glutamate, norepinephrine and serotonin neurotransmission. Also, the increased acetylcholinesterase activity, malondialdehyde nitrite, interleukin-6 and tumor necrosis-factor-α concentrations were reversed by C. lutea accompanied with elevated levels of catalase, superoxide dismutase and reduced glutathione. Furthermore, C. lutea reversed ketamine-induced neuronal alterations in the prefrontal cortex, hippocampus and cerebellum sections of the brain. ConclusionThese findings suggest that C. lutea reverses the cardinal symptoms of ketamine-induced schizophrenia in a dose-dependent fashion by modulating the oxido-inflammatory and neurotransmitter-related mechanisms.

Memantine enhances the cisplatin-induced apoptosis in A2780 ovarian cancer cells via CyclinD1 and hTERT inhibition

Cisplatin is the first-line treatment for ovarian cancer. Therefore, the use of effective compounds with synergistic effects can be considered a new strategy. Memantine is an NMDA receptors blocker which is overexpressed in cancers, including ovarian cancer and thus can be an efficient adjunct in cancer treatment. In this study, the MTT test, Flow cytometry, and DAPI staining was used to examine the combined effect of cisplatin with memantine. A study on Cyclin D1 and hTERT expression levels were conducted by qRT-PCR, and also cell cycle study of treated cells was performed. Our findings demonstrated that memantine enhances cytotoxicity in A2780 ovarian cancer cells. Apoptosis was also enhanced in cells treated with the combination of memantine and cisplatin. Memantine reduced the expression of Cyclin D1 and hTERT in A2780 cells and decreased the number of cancer cells in the cell cycle's growth and division phase. Our study suggests that memantine can be considered a potent adjuvant in the treatment of ovarian cancer.

Derivatives of methoxetamine and major methoxetamine metabolites potently block NMDA receptors

N-Methyl-D-aspartate receptors (NMDARs) in the brain are influenced by psychoactive drugs such as 2-(2-chlorophenyl)-2-(methylamino)cyclohexan-1-one (ketamine) and its analog 2-(ethylamino)-2-(3-methoxyphenyl)-cyclohexanone (methoxetamine). The recreational methoxetamine use can cause several toxicities and methoxetamine-related deaths have also been reported. Therefore, it has been banned in many countries. Since 2020, methoxetamine derivatives, 2-(ethylamino)-2-(m-tolyl)cyclohexan-1-one (deoxymethoxetamine) and 2-(isopropylamino)-2-(3-methoxyphenyl)cyclohexan-1-one (methoxisopropamine), have been sold online as designer drugs. However, how deoxymethoxetamine and methoxisopropamine act on NMDARs remains unknown. In this study, we first performed in silico docking studies of NMDARs, and deoxymethoxetamine and methoxisopropamine in addition to the major methoxetamine metabolites, 2-amino-2-(3-methoxyphenyl)-cyclohexanone (N-desethyl methoxetamine) and 2-(ethylamino)-2-(3-hydroxyphenyl)-cyclohexanone (O-desmethyl methoxetamine). The docking study suggested each compound interacts with NMDARs. We also determined the half-maximal inhibitory concentration (IC50s) of the methoxetamine-related compounds for NMDARs using NMDAR-expressing cartwheel interneurons of mice and patch-clamp recordings. We found that the IC50s of methoxetamine, deoxymethoxetamine, methoxisopropamine, N-desethyl methoxetamine, and O-desmethyl methoxetamine for NMDARs were 0.524, 0.679, 0.661, 1.649, and 0.227 μM, respectively. These results indicate that the methoxetamine-related compounds act as potent NMDAR blockers. Thus, deoxymethoxetamine and methoxisopropamine, both of which may cause damage by blocking NMDARs, are serious concerns. N-Desethyl methoxetamine and O-desmethyl methoxetamine may cause several adverse effects when methoxetamine is metabolized.