Effects Of MK-801 Research Articles

Contrasting Effects of Oxytocin on MK801-Induced Social and Non-Social Behavior Impairment and Hyperactivity in a Genetic Rat Model of Schizophrenia-Linked Features.

Social withdrawal in rodents is a measure of asociality, an important negative symptom of schizophrenia. The Roman high- (RHA) and low-avoidance (RLA) rat strains have been reported to exhibit differential profiles in schizophrenia-relevant behavioral phenotypes. This investigation was focused on the study of social and non-social behavior of these two rat strains following acute administration of dizocilpine (MK801, an NMDA receptor antagonist), a pharmacological model of schizophrenia-like features used to produce asociality and hyperactivity. Also, since oxytocin (OXT) has been proposed as a natural antipsychotic and a potential adjunctive therapy for social deficits in schizophrenia, we have evaluated the effects of OXT administration and its ability to reverse the MK801-impairing effects on social and non-social behavior and MK801-induced hyperactivity. MK801 administration produced hyperlocomotion and a decrease in social and non-social behavior in both rat strains, but these drug effects were clearly more marked in RHA rats. OXT (0.04 mg/kg and 0.2 mg/kg) attenuated MK801-induced hyperlocomotion in both rat strains, although this effect was more marked in RHA rats. The MK801-decreasing effect on exploration of the "social hole" was moderately but significantly attenuated only in RLA rats. This study is the first to demonstrate the differential effects of OXT on MK801-induced impairments in the two Roman rat strains, providing some support for the potential therapeutic effects of OXT against schizophrenia-like symptoms, including both a positive-like symptom (i.e., MK801-induced hyperlocomotion) and a negative-like symptom (i.e., MK801 decrease in social behavior), while highlighting the importance of the genetic background (i.e., the rat strain) in influencing the effects of both MK801 and oxytocin.

Mouse Exploratory Behaviour in the Open Field with and without NAT-1 EEG Device: Effects of MK801 and Scopolamine.

One aspect of reproducibility in preclinical research that is frequently overlooked is the physical condition in which physiological, pharmacological, or behavioural recordings are conducted. In this study, the physical conditions of mice were altered through the attachments of wireless electrophysiological recording devices (Neural Activity Tracker-1, NAT-1). NAT-1 devices are miniaturised multichannel devices with onboard memory for direct high-resolution recording of brain activity for >48 h. Such devices may limit the mobility of animals and affect their behavioural performance due to the added weight (total weight of approximately 3.4 g). The mice were additionally treated with saline (control), N-methyl-D-aspartate (NMDA) receptor antagonist MK801 (0.85 mg/kg), or the muscarinic acetylcholine receptor blocker scopolamine (0.65 mg/kg) to allow exploration of the effect of NAT-1 attachments in pharmacologically treated mice. We found only minimal differences in behavioural outcomes with NAT-1 attachments in standard parameters of locomotor activity widely reported for the open field test between the drug treatments. Hypoactivity was globally observed as a consistent outcome in the MK801-treated mice and hyperactivity in scopolamine groups regardless of NAT-1 attachments. These data collectively confirm the reproducibility for combined behavioural, pharmacological, and physiological endpoints even in the presence of lightweight wireless data loggers. The NAT-1 therefore constitutes a pertinent tool for investigating brain activity in, e.g., drug discovery and models of neuropsychiatric and/or neurodegenerative diseases with minimal effects on pharmacological and behavioural outcomes.

Neuroprotective effects of MK-801 against cerebral ischemia reperfusion

Introduction& Objective: Cerebral ischemia/reperfusion (I/R) injury, the second cause of death globally, involves increased NMDA receptor activity leading to neuronal damage due to excessive sodium and calcium ion entry. Therefore, targeting NMDA receptor may potentially reduce cell death induced by brain injury. Our study aimed to investigate the role of NMDA receptors in hippocampal neuronal activity induced by I/R. MethodsIn this study, Wistar rats were divided into four groups: sham, I/R, I/R + MK801, and I/R + NMDA. Cerebral I/R injury was induced by temporarily occluding the common and vertebral carotid arteries, followed by reperfusion. MK801 or NMDA was administered to the rats after a specific reperfusion time. Neuronal density and cell morphology in the hippocampal CA1 region were assessed using Nissl and H&E staining. The expression of BDNF, p-CREB, and c-fos was evaluated through Western blot analysis. Additionally, neuronal activity in CA1 pyramidal neurons were examined using single unit recording technique. ResultsOur results showed that cerebral I/R injury caused significant damage to CA1 pyramidal neurons compared to the sham group. However, treatment with MK-801 improved hippocampal cell survival compared to the I/R group. Furthermore, MK-801 administration in I/R rats increased BDNF, c-fos, and p-CREB levels while decreasing cleaved caspase-3 activity compared to the I/R group. Additionally, electrophysiological data showed that MK-801 increased firing rates of CA1 pyramidal neurons during the reperfusion phase. ConclusionMK-801 shows promise as a therapeutic agent for cerebral I/R injury by enhancing cell survival, upregulating neuroplasticity factors, and increasing firing rates of CA1 pyramidal neurons. It exerts a specific protective effect against cerebral I/R injury.

Protein Kinase A Inhibitor Attenuates the Antinociceptive Effect of NMDA-Receptor Channel Antagonists in the Capsaicin Test in Mice.

Acute nociceptive pain in mice caused by subcutaneous (intraplantar) injection of TRPV1 ion channel agonist capsaicin (1.6 μg/mouse) and the effects of protein kinase A inhibitor H-89 (0.05 mg/mouse, intraplantar injection) and NMDA receptor channel antagonists MK-801 (7.5 and 15 μg/mouse, topical application) and hemantane (0.5 mg/mouse, topical application) on the pain were assessed. MK-801 and hemantane were found to reduce the duration of the pain response. H-89 did not significantly affect the pain in animals, but preliminary administration of this drug abolished the antinociceptive effect of MK-801 (7.5 μg/mouse) and weakens the effect of hemantane (0.5 mg/mouse).

Neurochemical Effects of the Adipokinetic Hormone/Red Pigment Concentrating Hormone Family of Peptides in MK-801-Induced Schizophrenia Rat Model

Objective: Adipokinetic hormone (AKH) plays a role in sugar and lipid metabolism in insects. Previous studies of AKH showed memory improvements in a schizophrenia rat model that displayed memory impairment and reduced depression in a rat olfactory bulbectomy model. In this study, we investigated the effects of the adipokinetic hormone/red pigment-concentrating hormone (AKH/RPCH) family of peptides on brain neurotransmitter levels and brain neurochemistry in a schizophrenia rat model. Materials and Methods: We administered AKH/RPCH peptides for 4 days sub-chronically, both in naive rats and also in the MK-801-induced schizophrenia rat model. Liquid chromatography-mass spectrometry apparatus was used for targeted and untargeted analysis of rat neurochemistry. Results: Increased brain glutamate levels characteristic of MK-801 peptide-treated rats were significantly reduced by AKH. Furthermore, AKH also increased brain dopamine levels in both naive and MK-801 rats. Metabolomic studies have shown that AKH affects lipid and glutamate metabolism, while hypertrehalosaemic hormone plays a role in sugar metabolism and inflammation. Conclusion: According to our results, AKH might affect dopaminergic and glutamatergic systems and reverse the effects of MK-801, possibly affecting NMDA receptors.

The effect of MK-801 on stress-ethanol cross-sensitization is dissociable from its effects on nNOS activity.

Locomotor behavioral sensitization represents an animal model for understanding neuroadaptive processes related to repeated drug exposure. Repeated stress can elicit a cross-sensitization to the stimulant response of ethanol, which involves neuronal nitric oxide synthase (nNOS). Activation of N-methyl d-aspartate (NMDA) glutamate receptors triggers nNOS and the synthesis of nitric oxide (NO). In this study, we investigated the effects of blocking NMDA receptors using the NMDA receptor antagonist MK-801 on the cross-sensitization between restraint stress and ethanol. We also evaluated the nNOS activity in the prefrontal cortex (PFC) and hippocampus. Mice were pretreated with saline or MK-801 30min before an injection of saline or stress exposure for 14 days. On the following day, they were challenged with either saline or 1.8g/kg ethanol. Swiss male mice pretreated with 0.25mg/kg MK-801 exhibited a sensitized response to ethanol. Moreover, MK-801 potentiated the cross-sensitization between stress and ethanol. However, MK-801 prevented the enhanced nNOS activity in stress-exposed groups (challenged with saline or ethanol) in the PFC; the antagonist also prevented the ethanol-induced increase in nNOS activity and reduced this enzyme activity in mice exposed to stress in the hippocampus. These data indicate that systemic treatment with the NMDA antagonist potentiated, rather than blocked, ethanol-induced behavioral sensitization and that this effect is dissociable from the capacity of NMDA antagonists to reduce ethanol/stress-induced NOS stimulation in the PFC and hippocampus.

Enhanced methamphetamine sensitisation in a rat model of the brain-derived neurotrophic factor Val66Met variant: Sex differences and dopamine receptor gene expression

Brain-derived neurotrophic factor (BDNF) and the Val66Met polymorphism may play a role in the development of psychosis and schizophrenia. The aim of this study was to investigate long-term effects of methamphetamine (Meth) on psychosis-like behaviour and dopamine receptor and dopamine transporter gene expression in a novel rat model of the BDNF Val66Met polymorphism. At the end of a 7-day subchronic Meth treatment, female rats with the Met/Met genotype selectively showed locomotor hyperactivity sensitisation to the acute effect of Meth. Male rats showed tolerance to Meth irrespective of Val66Met genotype. Two weeks later, female Met/Met rats showed increased locomotor activity following both saline treatment or a low dose of Meth, a hyperactivity which was not observed in other genotypes or in males. Baseline PPI did not differ between the groups but the disruption of PPI by acute treatment with apomorphine was absent in Meth-pretreated Met/Met rats. Female Met/Met rats selectively showed down-regulation of dopamine D2 receptor gene expression in striatum. Behavioural effects of MK-801 or its locomotor sensitisation by prior Meth pretreatment were not influenced by genotype. These data suggest a selective vulnerability of female Met/Met rats to short-term and long-term effects of Meth, which could model increased vulnerability to psychosis development associated with the BDNF Val66Met polymorphism.

The Effects of MK-801 on Apoptosis in a Traumatic Brain Injury Model in Rat Pups

Traumatic brain injury (TBI) is an essential cause of morbidity and mortality during childhood. Trauma causes some changes that result in delayed and elongated damage known as secondary injury, which is characterized by neuronal apoptosis. Based on this information, the aim of this study was to investigate the effect of MK-801, a competitive NMDA receptor antagonist, on apoptosis against hippocampal damage in rat pups after TBI. Forty-two, 10-day-old Wistar Albino rats were randomly divided into three groups: Control, a Trauma, and Treatment groups, each having fourteen rats. TBI was created by blunt trauma model. MK-801, was injected intraperitoneally at the doses of 1 mg/kg of body weight immediately after induction of TBI. The hippocampus tissues were harvested 4 days after TBI. Then CA1 and dentate gyrus (DG) regions were evaluated in terms of immunoreactivity with BAX, cytochrome C, and caspase 3. Based on this evaluation, the control group showed weakly BAX and Cytochrome C immunoreactivities in hippocampus, but elevated reactions were observed in TBI group. Especially, it was determined that the cytochrome c immunoreactivity was granular form in the neurons of hippocampus DG region. In the Treatment group decreased BAX and Cytochrome C immunoreactivities. While a weak caspase-3 immunoreactivity was observed in control group, stronger immunoreactivity was determined both DG and CA1 region of hippocampus in TBI group. In the Treatment group, caspase-3 immunoreactivity decreased in hippocampus region when compared to TBI group. Our results showed that treatment with MK-801 may significantly decreased apoptosis through BAX, Cytochrome C and caspase-3 pathway.

Aberrant Dopamine System Function in the Ferrous Amyloid Buthionine (FAB) Rat Model of Alzheimer's Disease.

Antipsychotics increase the risk of death in elderly patients with Alzheimer's disease (AD). Thus, there is an immediate need for novel therapies to treat comorbid psychosis in AD. Psychosis has been attributed to a dysregulation of the dopamine system and is associated with aberrant regulation by the hippocampus. Given that the hippocampus is a key site of pathology in AD, we posit that aberrant regulation of the dopamine system may contribute to comorbid psychosis in AD. A ferrous amyloid buthionine (FAB) rodent model was used to model a sporadic form of AD. FAB rats displayed functional hippocampal alterations, which were accompanied by decreases in spontaneous, low-frequency oscillations and increases in the firing rates of putative pyramidal neurons. Additionally, FAB rats exhibited increases in dopamine neuron population activity and augmented responses to the locomotor-inducing effects of MK-801, as is consistent with rodent models of psychosis-like symptomatology. Further, working memory deficits in the Y-maze, consistent with an AD-like phenotype, were observed in FAB rats. These data suggest that the aberrant hippocampal activity observed in AD may contribute to dopamine-dependent psychosis, and that the FAB model may be useful for the investigation of comorbid psychosis related to AD. Understanding the pathophysiology that leads to comorbid psychosis in AD will ultimately lead to the discovery of novel targets for the treatment of this disease.

GLP-1 agonist Liraglutide prevents MK‑801–induced schizophrenia‑like behaviors and BDNF, CREB, p-CREB, Trk-B expressions in the hippocampus and prefrontal cortex in Balb/c mice

Glucagon-like peptide 1 (GLP-1) agonists are among the agents that can be used to treat type 2 diabetes mellitus, and they have also been reported to have neuroprotective effects. This study examined the effects of GLP-1 agonist Liraglutide on CREB, BDNF, Trk-B expression and emotional/cognitive behaviors in an experimental schizophrenia-like behavior model induced by MK-801. MK-801 (0.25 mg/kg, 0.1 ml/kg body weight) and/or Liraglutide (300 mcg/kg) were injected intraperitoneally once a day for 7 weeks into 8–10 weeks old male Balb/c mice (n = 78). Mice were randomly divided into 5 groups: Saline+Saline, MK-801 +Saline, Liraglutide+Saline, MK-801 +Liraglutide co-treatment, and Liraglutide+MK-801 co-treatment. A Morris water maze test, an elevated plus maze test, and an open field test were performed after injection. Western blots were performed on mice' hippocampus and PFC for BDNF, Trk-B, CREB, and p-CREB expression. Our study found that MK-801 impaired emotional and cognitive functions in mice. MK-801 administration did not affect Liraglutide's positive effects on spatial learning and memory activity in the Liraglutide+MK-801 group. Liraglutide administration (Liraglutide+MK-801 group) improved the BDNF/Trk-B and p-CREB/CREB ratio in the hippocampus, and the p-CREB/CREB ratio in the PFC to the control group level. The negative effects of MK-801 on cognitive behavior were not reversed by Liraglutide in the MK-801 +Liraglutide group. In conclusion, Liraglutide does not affect NMDA receptor blockade-induced emotional and cognitive behaviors. However, it has a protective effect against cognitive impairment. Furthermore, it is possible that the GLP-1 receptors in the hippocampus and PFC are involved in the modulation of NMDA receptor activity through CREB activation/deactivation.

Effects of Transient Administration of the NMDA Receptor Antagonist MK-801 in Drosophila melanogaster Activity, Sleep, and Negative Geotaxis.

MK-801, also called dizocilpine, is an N-methyl-D-aspartate (NMDA) receptor antagonist widely used in animal research to model schizophrenia-like phenotypes. Although its effects in rodents are well characterised, little is known about the outcomes of this drug in other organisms. In this study, we characterise the effects of MK-801 on the locomotion, sleep, and negative geotaxis of the fruit fly Drosophila melanogaster. We observed that acute (24 h) and chronic (7 days) administration of MK-801 enhanced negative geotaxis activity in the forced climbing assay for all tested concentrations (0.15 mM, 0.3 mM, and 0.6 mM). Moreover, acute administration, but not chronic, increased the flies' locomotion in a dose-dependent matter. Finally, average sleep duration was not affected by any concentration or administration protocol. Our results indicate that acute MK-801 could be used to model hyperactivity phenotypes in Drosophila melanogaster. Overall, this study provides further evidence that the NMDA receptor system is functionally conserved in flies, suggesting the usefulness of this model to investigate several phenotypes as a complement and replacement of the rodent models within drug discovery.

Effects of antipsychotics, haloperidol and olanzapine, on the expression of apoptosis-related genes in mouse mHippoE-2 cells and rat hippocampus.

Objective. Modified levels of pro- (caspase3, Bax) and anti-apoptotic (Bcl-2) regulatory proteins have been detected in certain brain areas of schizophrenic patients indicating a possible dysregulation of apoptosis. In the present study, effects of antipsychotics, haloperidol (HAL) and olanzapine (OLA), on the gene expression of caspase3 (casp3), Bax and Bcl-2 were studied in vitro in mouse hippocampal mHippoE-2 cell line and in vivo in the hippocampus of MK-801 animal schizophrenia model with the aim to provide evidence that antipsychotics may affect the activity of apoptosis-related markers. Methods. mHippoE-2 cells were incubated with MK-801 (20 µM), HAL (10 µM), and OLA (10 µM) alone or combined, MK-801+HAL/OLA, for 24, 48, and 72 h. Male Sprague Dawley rats were injected with saline or MK-801 (0.5 mg/kg) for 6 days and since the 7th day, they were treated with vehicle (VEH), HAL (1 mg/kg) or OLA (2 mg/kg) for the next 7 days. The casp3, Bax and Bcl-2 gene expression in mHippoE-2 cells and rat hippocampus was measured by RT-PCR. Results. In mHippoE-2 cells, casp3 gene expression was increased by MK-801 and OLA treatments alone for 48 h, HAL treatment alone for 24 and 72 h, and co-treatment with MK-801+OLA for 24 and 72 h compared to controls. HAL and OLA suppressed the stimulatory effect of MK-801 on casp3 mRNA levels in cells after 48 h of incubation. Bax mRNA levels in mHippoE-2 cells were decreased after HAL treatment for 24 and 48 h, and also after co-treatment with MK-801+HAL for 72 h. In vivo, MK-801 decreased mRNA levels of both pro-apoptotic markers, casp3 and Bax, in hippocampus of VEH-treated rats and Bax mRNA levels in hippocampus of HAL-treated animals. OLA reversed the inhibitory effect of MK-801 on casp3 expression in the VEH-treated animals. Neither MK-801 nor antipsychotics induced changes in the gene expression of anti-apoptotic marker Bcl-2 in mHippoE-2 cells as well as hippocampus of rats. Conclusions. The results of the present study demonstrate that antipsychotics, HAL and OLA, may affect mRNA levels of pro-apoptotic markers in hippocampal cells in vitro, but not in vivo. The obtained data do not clearly support the assumed potentiating role of MK-801 in inducing apoptosis in specific brain areas and a possible protective role of antipsychotics against induction of apoptosis. The obtained data may contribute to a deeper insight into the neurodevelopmental changes connected with schizophrenia.

Multi-Regulatory Effects of Agmatine on Akt/GSK-3β/β-Catenin Signaling Pathway in SH-SY5Y cells: A Potential Explanation for its Conflicting Roles in Schizophrenia

Objectives: Schizophrenia is a common psychiatric disease with its complex neurobiology. The current knowledge about the neurobiology of schizophrenia is based on dopaminergic and glutamatergic dysregulation of the central nervous system. The facts that all current antipsychotic drugs act on dopaminergic D2 receptor antagonism and glutamatergic N-Methyl D-Aspartate (NMDA) receptor antagonists reveal schizophrenia-like behavioral and structural alteration in rodents and humans are the major evidences of these hypotheses. However, they are not sufficient to explain the disease neurobiology and lead novel therapeutics. In recent years, it has been shown that the functions of certain intracellular pathways are disrupted in schizophrenia, especially Akt/glycogen synthase kinase 3beta (GSK-3β)/β-catenin signaling pathway. Certain studies showed that GSK-3β inhibition accompanied to the effects of antipsychotic drugs and specific inhibition of the GSK-3β might be a valuable approach for the novel treatments for schizophrenia. Agmatine is an endogenous amine that interacts with many receptors and enzymes including adrenergic, glutamatergic, cholinergic, serotonergic and imidazoline receptors and nitric oxide synthase enzyme. The limited number of studies showed conflicting results about the role of agmatine on schizophrenia and there was no study to evaluate the intracellular molecular mechanisms of agmatine`s schizophrenia-related effects. Herein, we aimed to investigate the effects of agmatine on MK-801 induced neurotoxicity and the disruption of the Akt/GSK-3β/β-catenin signaling pathway in SH-SY5Y human neuroblastoma cells. Methods: SH-SY5Y cells were grouped as the medium, agmatine (50μM), agmatine (100μM), olanzapine (10μM), MK-801 (100μM), MK-801+Agmatine (50μM), MK-801+Agmatine (100μM) and MK-801+Olanzapine (10μM). Real-time cell analysis (RTCA), real-time polymerase chain reaction (Rt-PCR) and western blot (WB) were used for monitoring the cell viabilities, quantifying gene and protein expressions, respectively. Cell viabilities monitored for the 24 hours and comparative viabilities (%) were calculated at the 6th, 12th and 24th hours of treatments. Akt, GSK-3β and β-Catenin gene expressions phosphorylated (p) and non-phosphorylated protein expressions were investigated at the 24th hour of treatments. Results: In RTCA, MK-801 administration decreased cell viabilities at the 6th (p<0.01) and 24th (p<0.001) hours compared to medium in cells. Agmatine (50μM) and agmatine (100μM) pre-treatments increased the cell viabilities at the 6th (p<0.05), 12th (p<0.01), and 24th (p<0.05) hours while olanzapine at 24th (p<0.05) compared to MK-801. In Rt-PCR, MK-801 administration increased GSK-3B decreased CTNNB1 gene expressions (p<0.001) compared to the medium. Agmatine (50μM) and olanzapine reversed (p<0.001) the effects of MK-801 for both gene expressions while agmatine (100μM) reversed (p<0.001) only GSK-3B. In WB, MK-801 administration decreased the p-GSK-3β/GSK-3β ratio compared to medium while only agmatine (50μM) increased the ratio compared to MK-801 administration. Conclusion: Herein, it has been shown that agmatine had a neuroprotective effect on MK-801 induced cell toxicity in SH-SY5Y cells. Our results have suggested a low dose (50μM) agmatine shows antipsychotic like effects on Akt/GSK-3β/β-catenin signaling pathway in SH-SY5Y cells bot, not high dose (100μM). We have suggested that these doses dependent regulatory effects of agmatine might be a possible explanation for its conflicting role in schizophrenia.

The effects of Memantine and MK801 on NMDA receptor switching 2B and 2A subunits in hippocampal cell culture.

Background: Schizophrenia (SCZ) is a severe and chronic neurodevelopmental disorder which onset begins in adolescence or early adulthood. Notwithstanding, the brain dysfunction occurs before the disease and involves the NMDA receptor switch from GluN2B to GluN2A at early neonatal period. We have recently postulated memantine (MEM) as an effective experimental treatment, which may have its root on the modulation of NMDA receptor subunit turnover during the postnatal period by preventing glutamatergic hypofunction in the maternal deprivation model of SCZ. Methods: To explore this possibility, here we have evaluated the turn-over of pre and postsynaptic glutamatergic synaptic components by using primary mouse hippocampal neurons during the synaptic formation period. Results: MK801 stimulation prevented the GluN2B to GluN2A molecular switch at 11 days in vitro (DIV). Importantly, vesicular glutamate transporter 2 (VGLUT2) was also reduced at this time point. MEM treatment reverted these effects by normalizing GluN2B, GluN2A and overexpressing VGLUT2 expression. Conclusion: Our data supports a mechanism by which behavioral abnormalities previously observed in animals after maternal deprivation may be prevented by MEM treatment by regulation of the glutamatergic synaptic molecular composition.

ATTENUATION OF OXIDATIVE STRESS AND NEUROTOXICITY BY MK-801 (DIZOCILPINE) ON DIPENTYLPHTHALATE-INDUCED COGNITIVE DYSFUNCTION IN MICE

Objectives: The aim of our research is to study the effect of dipentylphthalate (DPeP), a plasticizer on cognition and various oxidative stress markers in mice, and to explore the modulatory effects of MK-801. Methods: In the present study, experimental mice were orally treated with two doses (33 and 100 mg/kg) of DPeP for 28 days. Cognitive functions were assessed using spatial navigation task on Morris water maze (MWM) and step-down latency (SDL) in passive avoidance apparatus. Oxidative stress was assessed by examining the levels of malondialdehyde (MDA), glutathione (GSH), ferric-reducing antioxidant power (FRAP), and 8-hydroxy-deoxyguanosine (8-OH-dG) levels in whole brain of mice. Results: DPeP exposure led to a statistically significant increase of latency in spatial navigation task and significant decline in the SDL in passive avoidance apparatus when compared to the control groups. Oxidative stress markers showed a significant increase following DPeP administration as seen with rise in levels of MDA, 8-OH-dG, and a fall in GSH and FRAP levels. Conclusion: The present data suggest that DPeP could adversely affect learning and memory functions in mice by an oxidative stress-mediated neuronal damage and pre-administration of MK-801 has the potential to attenuate these effects.

Effects of D-Serine and MK-801 on Neuropathic Pain and Functional Recovery in a Rat Model of Spinal Cord Injury.

ObjectiveNeuropathic pain is a common secondary complication of spinal cord injury (SCI). N-methyl-D-aspartate (NMDA) receptor activation is critical for hypersensitivity in neuropathic pain. This activation requires the binding of both glutamate and the D-serine co-agonist to the NMDA glycine site. We evaluated the effects of D-serine on neuropathic pain after SCI and explored the underlying molecular mechanisms. MethodsAnesthetized rats underwent T9 spinal cord contusion (130 kdyn). D-serine (500 and 1,000 mg/kg) and MK-801 hydrogen maleate (2.0 mg/kg) were injected daily for 2 weeks, starting the day after SCI. Functional outcomes were assessed according to the Basso, Beattie, and Bresnahan scale, while histological outcomes were evaluated based on lesion volume and spared tissue area. Mechanical allodynia and thermal hyperalgesia were evaluated by measuring the withdrawal threshold of a von Frey filament and hot/cold plate latency. Western blotting was performed to determine the expression levels of Trpv1, Nav1.9, calcitonin gene-related peptide (CGRP), and β-actin in damaged tissue. ResultsThe withdrawal threshold values and latency of the D-serine group were significantly lower than those of the noninjection group. The MK-801 group showed higher threshold values and latencies than the other groups. Western blotting showed increased Nav1.9 and Trpv1 levels and lower CGRP levels in the D-serine group, whereas the MK-801 group showed the opposite results. ConclusionD-serine increases neuropathic pain after traumatic SCI by mediating the NMDA receptor. NMDA receptor antagonists alleviate neuropathic pain after traumatic SCI.

Frequency-specific medial septal nucleus deep brain stimulation improves spatial memory in MK-801-treated male rats

BackgroundFew treatments exist for the cognitive symptoms of schizophrenia. Pharmacological agents resulting in glutamate N-methyl-d-aspartate (NMDA) receptor hypofunction, such as MK-801, mimic many of these symptoms and disrupt neural activity. Recent evidence suggests that deep brain stimulation (DBS) of the medial septal nucleus (MSN) can modulate medial prefrontal cortex (mPFC) and hippocampal activity and improve spatial memory. ObjectiveHere, we examine the effects of acute MK-801 administration on oscillatory activity within the septohippocampal circuit and behavior. We also evaluate the potential for MSN stimulation to improve cognitive behavioral measures following MK-801 administration. Methods59 Sprague Dawley male rats received either acute intraperitoneal (IP) saline vehicle injections or MK-801 (0.1 mg/kg). Theta (5–12 Hz), low gamma (30–50 Hz) and high frequency oscillatory (HFO) power were analyzed in the mPFC, MSN, thalamus and hippocampus. Rats underwent MSN theta (7.7 Hz), gamma (100 Hz) or no stimulation during behavioral tasks (Novel object recognition (NOR), elevated plus maze, Barnes maze (BM)). ResultsInjection of MK-801 resulted in frequency-specific changes in oscillatory activity, decreasing theta while increasing HFO power. Theta, but not gamma, stimulation enhanced the anxiolytic effects of MK-801 on the elevated plus maze. While MK-801 treated rats exhibited spatial memory deficits on the Barnes maze, those that also received MSN theta, but not gamma, stimulation found the escape hole sooner. ConclusionsThese findings demonstrate that acute MK-801 administration leads to altered neural activity in the septohippocampal circuit and impaired spatial memory. Further, these findings suggest that MSN theta-frequency stimulation improves specific spatial memory deficits and may be a possible treatment for cognitive impairments caused by NMDA hypofunction.

Discrimination of motor and sensorimotor effects of phencyclidine and MK-801: Involvement of GluN2C-containing NMDA receptors in psychosis-like models

Non-competitive NMDA receptor (NMDA-R) antagonists like ketamine, phencyclidine (PCP) and MK-801 are routinely used as pharmacological models of schizophrenia. However, the NMDA-R subtypes, neuronal types (e.g., GABA vs. glutamatergic neurons) and brain regions involved in psychotomimetic actions are not fully understood. PCP activates thalamo-cortical circuits after NMDA-R blockade in reticular thalamic GABAergic neurons. GluN2C subunits are densely expressed in thalamus and cerebellum. Therefore, we examined their involvement in the behavioral and functional effects elicited by PCP and MK-801 using GluN2C knockout (GluN2CKO) and wild-type mice, under the working hypothesis that psychotomimetic effects should be attenuated in mutant mice. PCP and MK-801 induced a disorganized and meandered hyperlocomotion in both genotypes. Interestingly, stereotyped behaviors like circling/rotation, rearings and ataxia signs were dramatically reduced in GluN2CKO mice, indicating a better motor coordination in absence of GluN2C subunits. In contrast, other motor or sensorimotor (pre-pulse inhibition of the startle response) aspects of the behavioral syndrome remained unaltered by GluN2C deletion. PCP and MK-801 evoked a general pattern of c-fos activation in mouse brain (including thalamo-cortical networks) but not in the cerebellum, where they markedly reduced c-fos expression, with significant genotype differences paralleling those in motor coordination. Finally, resting-state fMRI showed an enhanced cortico-thalamic-cerebellar connectivity in GluN2CKO mice, less affected by MK-801 than controls.Hence, the GluN2C subunit allows the dissection of the behavioral alterations induced by PCP and MK-801, showing that some motor effects (in particular, motor incoordination), but not deficits in sensorimotor gating, likely depend on GluN2C-containing NMDA-R blockade in cerebellar circuits.

Effect of MK-801, an antagonist of NMDA receptor in the pedunculopontine tegmental nucleus, on cardiovascular parameters in normotensive and hydralazine hypotensive rats.

Objective(s):In the present study, the cardiovascular effects of glutamate NMDA receptor of the pedunculopontine tegmental nucleus (PPT) in normotensive and hydralazine (HLZ) hypotensive rats were evaluated. Materials and Methods:In the normotensive condition, MK-801(1 nmol; an NMDA receptor antagonist) and L-glutamate (L-Glu, 50 nmol an agonist) alone and together were microinjected into the nucleus using a stereotaxic device. In hypotensive condition, 2 min after induction of hypotension by HLZ (10 mg/kg, intravenous), drugs, same as in normotensive condition, were microinjected into the PPT. Recorded mean arterial pressure (MAP), systolic blood pressure (SBP), and heart rate (HR) were recorded throughout the experiment by a Power lab apparatus that was connected to a catheter inserted into the femoral arty. The cardiovascular changes (Δ) induced by microinjection drugs were computed and statistically analyzed.Results:In the normotensive condition, L-Glu significantly increased ΔMAP and ΔSBP (P<0.001) and decreased ΔHR (P<0.01) compared with the control. MK-801 alone significantly increased HR (P<0.05) while co-injected with L-Glu + MK-801 it significantly attenuated the L-Glu effect on ΔMAP and ΔSBP but augmented ΔHR (P<0.01). In the hydralazine hypotension condition, L-Glu significantly improved hypotension (P<0.01) and deteriorated bradycardia induced by HLZ (P<0.05). MK-801 alone did not significantly affect ΔMAP, ΔSBP, and ΔHR but when co-injected with L-Glu (L-Glu + MK-801) it could significantly attenuate the cardiovascular effect of L-Glu in the PPT. Conclusion:We found that activation of NMDA receptors of the glutamatergic system in the PPT evoked blood pressure and inhibited HR in both normotensive and hypotensive conditions in rats.

MP07-20 CENTRALLY ADMINISTERED CORTICOTROPIN-RELEASING FACTOR INDUCES FACILITATION OF THE RAT MICTURITION VIA BRAIN GLUTAMATERGIC RECEPTORS

You have accessJournal of UrologyCME1 May 2022MP07-20 CENTRALLY ADMINISTERED CORTICOTROPIN-RELEASING FACTOR INDUCES FACILITATION OF THE RAT MICTURITION VIA BRAIN GLUTAMATERGIC RECEPTORS Takahiro Shimizu, Yurika Hata, Suo Zou, Masaki Yamamoto, Hideaki Ono, Yohei Shimizu, Takaaki Aratake, Shogo Shimizu, Youichirou Higashi, Takashi Karashima, and Motoaki Saito Takahiro ShimizuTakahiro Shimizu More articles by this author , Yurika HataYurika Hata More articles by this author , Suo ZouSuo Zou More articles by this author , Masaki YamamotoMasaki Yamamoto More articles by this author , Hideaki OnoHideaki Ono More articles by this author , Yohei ShimizuYohei Shimizu More articles by this author , Takaaki AratakeTakaaki Aratake More articles by this author , Shogo ShimizuShogo Shimizu More articles by this author , Youichirou HigashiYouichirou Higashi More articles by this author , Takashi KarashimaTakashi Karashima More articles by this author , and Motoaki SaitoMotoaki Saito More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002529.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Roles of brain corticotropin-releasing factor (CRF), a representative stress-related neuropeptide, in regulation of the micturition are still controversial. In this study, we examined the effects of centrally administered CRF on the rat micturition and central mechanisms for the CRF-induced responses, focusing on brain CRF1/CRF2 receptor subtypes and glutamatergic receptors (NMDA and AMPA subtypes). METHODS: In urethane anesthetized (0.8 g/kg, ip) male Wistar rats (300-450 g), a catheter was inserted into the bladder to perform cystometry (CMG, 12 ml/h saline infusion). CRF (1 or 3 nmol/rat) or vehicle was intracerebroventricularly (icv) administered 3 h after the surgery. In some rats, effects of icv pretreated CP154526 (CP, CRF1 antagonist, 30 or 100 nmol/rat), K41498 (K, CRF2 antagonist, 30 nmol/rat), MK-801 (MK, NMDA receptor antagonist, 3 or 10 nmol/rat) or DNQX (AMPA receptor antagonist, 1 or 3 nmol/rat) on the CRF (3 nmol/rat, icv)-induced responses were examined. Continuous CMG and evaluation of intercontraction intervals (ICI) and maximal voiding pressure (MVP) were started 1 h before the first icv administration. When performing single CMG 3 h after the surgery, after 4-5 times of single CMG, CRF (3 nmol/rat) or vehicle was icv administered, then single CMG was performed during 60-120 min after the administration. RESULTS: CRF dose-dependently shortened ICI (Fig. 1A) without changing MVP (data not shown). The CRF-induced ICI shortening was suppressed by CP, MK-801 and DNQX (Fig. 1B and Fig. 2), but not by K (data not shown). Compared to the vehicle-treated group, CRF significantly reduced single-voided volume and bladder capacity without changing post void residual volume or voiding efficiency (Table 1). CONCLUSIONS: Centrally administered CRF induces facilitation of the rat micturition via brain CRF1, NMDA and AMPA receptors, therefore, brain CRF1 receptors might be new therapeutic targets for neurogenic bladder overactivity. Source of Funding: JSPS KAKENHI (#20K07827), Takeda Science Foundation © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e123 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Takahiro Shimizu More articles by this author Yurika Hata More articles by this author Suo Zou More articles by this author Masaki Yamamoto More articles by this author Hideaki Ono More articles by this author Yohei Shimizu More articles by this author Takaaki Aratake More articles by this author Shogo Shimizu More articles by this author Youichirou Higashi More articles by this author Takashi Karashima More articles by this author Motoaki Saito More articles by this author Expand All Advertisement PDF DownloadLoading ...