Occupational exposure to 1-bromopropane (1-BP) induces learning and memory deficits. However, no therapeutic strategies are currently available. Accumulating evidence has suggested that N-methyl-D-aspartate receptors (NMDARs) and neuroinflammation are involved in the cognitive impairments in neurodegenerative diseases. In this study we aimed to investigate whether the noncompetitive NMDAR antagonist MK801 protects against 1-BP-induced cognitive dysfunction. Male Wistar rats were administered with MK801 (0.1 mg/kg) prior to 1-BP intoxication (800 mg/kg). Their cognitive performance was evaluated by the Morris water maze test. The brains of rats were dissected for biochemical, neuropathological, and immunological analyses. We found that the spatial learning and memory were significantly impaired in the 1-BP group, and this was associated with neurodegeneration in both the hippocampus (especially CA1 and CA3) and cortex. Besides, the protein levels of phosphorylated NMDARs were increased after 1-BP exposure. MK801 ameliorated the 1-BP-induced cognitive impairments and degeneration of neurons in the hippocampus and cortex. Mechanistically, MK801 abrogated the 1-BP-induced disruption of excitatory and inhibitory amino-acid balance and NMDAR abnormalities. Subsequently, MK801 inhibited the microglial activation and release of pro-inflammatory cytokines in 1-BP-treated rats. Our findings, for the first time, revealed that MK801 protected against 1-BP-induced cognitive dysfunction by ameliorating NMDAR function and blocking microglial activation, which might provide a potential target for the treatment of 1-BP poisoning.
Animals ; Brain ; drug effects ; metabolism ; pathology ; Cognitive Dysfunction ; drug therapy ; metabolism ; pathology ; Disease Models, Animal ; Dizocilpine Maleate ; pharmacology ; Excitatory Amino Acid Antagonists ; pharmacology ; Hydrocarbons, Brominated ; Inflammasomes ; drug effects ; metabolism ; Male ; Maze Learning ; drug effects ; physiology ; Microglia ; drug effects ; metabolism ; pathology ; NLR Family, Pyrin Domain-Containing 3 Protein ; metabolism ; Neurons ; drug effects ; metabolism ; pathology ; Nootropic Agents ; pharmacology ; Random Allocation ; Rats, Wistar ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; metabolism ; Spatial Memory ; drug effects ; physiology ; Specific Pathogen-Free Organisms

OBJECTIVETo explore the possible neurophysiologic mechanisms of propofol and N-methyl-D- aspartate (NMDA) receptor antagonist against learning-memory impairment of depressed rats without olfactory bulbs.

METHODSModels of depressed rats without olfactory bulbs were established. For the factorial design in analysis of variance, two intervention factors were included: electroconvulsive shock groups (with and without a course of electroconvulsive shock) and drug intervention groups [intraperotoneal (ip) injection of saline, NMDA receptor antagonist MK-801 and propofol. A total of 60 adult depressed rats without olfactory bulbs were randomly divided into 6 experimental groups (n=10 per group): ip injection of 5 ml saline; ip injection of 5 ml of 10 mg/kg MK-801; ip injection of 5 ml of 10 mg/kg MK-801 and a course of electroconvulsive shock; ip injection of 5 ml of 200 mg/kg propofol; ip injection of 5 ml of 200 mg/kg propofol and a course of electroconvulsive shock; and ip injection of 5 ml saline and a course of electroconvulsive shock. The learning-memory abilities of the rats was evaluated by the Morris water maze test. The content of glutamic acid in the hippocampus was detected by high-performance liquid chromatography. The expressions of p-AT8Ser202 in the hippocampus were determined by Western blot analysis.

RESULTSPropofol, MK-801 or electroconvulsive shock alone induced learning-memory impairment in depressed rats, as proven by extended evasive latency time and shortened space probe time. Glutamic acid content in the hippocampus of depressed rats was significantly up-regulated by electroconvulsive shock and down-regulated by propofol, but MK-801 had no significant effect on glutamic acid content. Levels of phosphorylated Tau protein p-AT8Ser202 in the hippocampus was up-regulated by electroconvulsive shock but was reduced by propofol and MK-801 alone. Propofol prevented learning-memory impairment and reduced glutamic acid content and p-AT8Ser202 levels induced by electroconvulsive shock.

CONCLUSIONElectroconvulsive shock might reduce learning-memory impairment caused by protein Tau hyperphosphorylation in depressed rats by down-regulating glutamate content.

Animals ; Depression ; psychology ; Dizocilpine Maleate ; pharmacology ; Electroshock ; Glutamic Acid ; analysis ; Learning Disorders ; prevention & control ; Male ; Memory Disorders ; prevention & control ; Phosphorylation ; Propofol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; tau Proteins ; metabolism

Schizophrenia, described as the worst disease affecting mankind, is a severe and disabling mental disorder. Schizophrenia is characterized by complicated symptoms and still lacks a diagnostic neuropathology, so developing schizophrenia animal models which have quantifiable measures tested in a similar fashion in both humans and animals will play a key role in new therapeutic approaches. According to the symptoms of cognitive impairment and emotional disorder, the N-methyl-d-aspartate (NMDA)-receptor antagonist MK-801 was applied to induce schizophrenia-like behavior in mice. Locomotor activity and prepulse inhibition (PPI) were selected as indices and the effect of clozapine was also investigated in this model. The results showed that compared with the normal group, MK-801-treated mice exhibited significantly increased locomotor activity and impaired PPI, and pre-exposure to clozapine could ameliorate the abnormality and make it back to normal level. These findings suggest that the model we established could be a useful tool for antipsychotic drug screening.
Animals ; Antipsychotic Agents ; pharmacology ; Clozapine ; pharmacology ; Disease Models, Animal ; Dizocilpine Maleate ; Inhibition (Psychology) ; Male ; Mice ; Motor Activity ; drug effects ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; Schizophrenia ; chemically induced ; physiopathology

The study was to investigate the role of homocysteine (Hcy) which was released by hippocampal glial cells and its relationship with NMDA receptor and AMPA receptor in depression induced by chronic unpredictable mild stress (CUMS), and explore the mechanism of changes of Glu/Glu receptor in glial cells and neurons. CUMS-induced depression model was established. The body weight of rats was weighed on the 1st, 7th, 14th, and 21st days during the experiment. The behavioral performances were observed by means of sucrose consumption test, open field test and tail suspension test. Intrahippocampal microinjection of Hcy, NMDA receptor antagonist MK-801 and AMPA receptor antagonist NBQX was performed under stereotaxic guide cannula. The concentration of Glu and the expression of its receptors' subunits were detected respectively by high performance liquid chromatography (HPLC) and Western blot. The Hcy content and the levels of phosphorylation of NMDA receptor and AMPA receptor in hippocampus were separately determined by enzyme linked immunosorbent assay (ELISA). The results showed that CUMS significantly induced the depression-like behaviors in rats, and the content of Glu and Hcy, the expression of NMDA receptors' subunits NR1/NR2B and the level of phosphorylation of NMDA receptor (p-NMDAR) in hippocampus increased significantly, while the expression of AMPA receptors' subunits GluR2/3 and the level of phosphorylation of AMPA receptor (p-AMPAR) decreased significantly. Microinjection of Hcy into hippocampus resulted in similar animal depression-like behaviors and increased Glu content compared to the CON/SAL group, the expression of NR1/NR2B/GluR2/3 and the level of p-NMDAR increased significantly, but the level of p-AMPAR reduced observably. Intrahippocampal injections of MK-801 effectively improved the depression-like behaviors induced by CUMS and Hcy, and attenuated the elevation of Glu content induced by Hcy in hippocampus, whereas NBQX could not improve the depression-like behaviors, but also decreased the Glu content induced by Hcy remarkably. These results suggest that CUMS may contribute to the production and release of Hcy via hippocampal astrocytes. Through the increase of expression of NR1/NR2B/GluR2/3 and level of p-NMDAR, and the decrease of level of p-AMPAR, Hcy results in elevation of Glu level, which leads to depression-like behaviors in the end. In a word, the Hcy released by astrocytes plays an important role in stress-induced elevation of Glu content and variation of NMDA/AMPA receptors in hippocampus.
Animals ; Behavior, Animal ; Depression ; metabolism ; Dizocilpine Maleate ; pharmacology ; Glutamic Acid ; metabolism ; Hippocampus ; metabolism ; Homocysteine ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA ; metabolism ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Signal Transduction ; Stress, Psychological

The present study was to investigate the role of the quinolinic acid (QUIN) and its relationship with N-methyl-D-aspartic acid (NMDA) receptor and metabotropic glutamate receptor 1 (mGluR1) in depression induced by chronic unpredictable mild stress (CUMS) in hippocampus. CUMS-induced depression model was established in Sprague-Dawley rats. Intrahippocampal injections of QUIN, QUIN antagonist Ro61-8048, non-competitive NMDA receptor antagonist MK-801 and mGluR1 antagonist AIDA were respectively adopted by rat brain stereotaxic coordinates. The behavioral observations were conducted by measurement of weight changes, sucrose preference test, open-field test and tail suspension test. The concentration of glutamic acid (Glu) and the expression of its receptor subunits in hippocampus were detected by HPLC and Western blot, respectively. The QUIN content in hippocampus was determined by enzyme linked immunosorbent assay (ELISA). The result showed that CUMS significantly induced the depressive-like behaviors in rats, increased the contents of QUIN and Glu, and upregulated the expression of NMDA receptor subunits NR2B and mGluR1 in hippocampus. Microinjection of QUIN into hippocampus resulted in animal depressive-like behaviors, and increased the content of Glu and the expression of NR2B and mGluR1 significantly. QUIN antagonist Ro61-8048 effectively restrained the depression-like behaviors induced by CUMS, and decreased the content of Glu and the expression of NR2B and mGluR1 significantly. Intrahippocampal injections of MK-801 and AIDA effectively improved the depression-like behaviors induced by CUMS and decreased the Glu content. The results suggest that CUMS may contribute to the production and release of QUIN in hippocampal microglia. QUIN results in elevation of Glu level via NMDA receptor and mGluR1, and the increase of expression of NR2B and mGluR1 in hippocampus, which leads to depression-like behaviors in the end.
Animals ; Behavior, Animal ; Depression ; drug therapy ; Dizocilpine Maleate ; pharmacology ; Glutamic Acid ; metabolism ; Hippocampus ; drug effects ; metabolism ; Quinolinic Acid ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, Metabotropic Glutamate ; metabolism ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Stress, Psychological

This study explored the effect of the excitatory amino acid receptor antagonists on the impairment of learning-memory and the hyperphosphorylation of Tau protein induced by electroconvulsive shock (ECT) in depressed rats, in order to provide experimental evidence for the study on neuropsychological mechanisms improving learning and memory impairment and the clinical intervention treatment. The analysis of variance of factorial design set up two intervention factors which were the electroconvulsive shock (two level: no disposition; a course of ECT) and the excitatory amino acid receptor antagonists (three level: iv saline; iv NMDA receptor antagonist MK-801; iv AMPA receptor antagonist DNQX). Forty-eight adult Wistar-Kyoto (WKY) rats (an animal model for depressive behavior) were randomly divided into six experimental groups (n = 8 in each group): saline (iv 2 mL saline through the tail veins of WKY rats ); MK-801 (iv 2 mL 5 mg/kg MK-801 through the tail veins of WKY rats) ; DNQX (iv 2 mL 5 mg/kg DNQX through the tail veins of WKY rats ); saline + ECT (iv 2 mL saline through the tail veins of WKY rats and giving a course of ECT); MK-801 + ECT (iv 2 mL 5 mg/kg MK-801 through the tail veins of WKY rats and giving a course of ECT); DNQX + ECT (iv 2 mL 5 mg/kg DNQX through the tail veins of WKY rats and giving a course of ECT). The Morris water maze test started within 1 day after the finish of the course of ECT to evaluate learning and memory. The hippocampus was removed from rats within 1 day after the finish of Morris water maze test. The content of glutamate in the hippocampus of rats was detected by high performance liquid chromatography. The contents of Tau protein which included Tau5 (total Tau protein), p-PHF1(Ser396/404), p-AT8(Ser199/202) and p-12E8(Ser262) in the hippocampus of rats were detected by immunohistochemistry staining (SP) and Western blot. The results showed that ECT and the glutamate ionic receptor blockers (NMDA receptor antagonist MK-801 and AMPA receptor antagonist DNQX) induced the impairment of learning and memory in depressed rats with extended evasive latency time and shortened space exploration time. And the two factors presented a subtractive effect. ECT significantly up-regulated the content of glutamate in the hippocampus of depressed rats which were not affected by the glutamate ionic receptor blockers. ECT and the glutamate ionic receptor blockers did not affect the total Tau protein in the hippocampus of rats. ECT up-regulated the hyperphosphorylation of Tau protein in the hippocampus of depressed rats, while the glutamate ionic receptor blockers down-regulated it, and combination of the two factors presented a subtractive effect. Our results indicate that ECT up-regulates the content of glutamate in the hippocampus of depressed rats, which up-regulates the hyperphosphorylation of Tau protein resulting in the impairment of learning and memory in depressed rats.
Animals ; Disease Models, Animal ; Dizocilpine Maleate ; pharmacology ; Electroshock ; adverse effects ; Excitatory Amino Acid Antagonists ; pharmacology ; Glutamic Acid ; metabolism ; Hippocampus ; metabolism ; Learning ; Memory ; Memory Disorders ; Phosphorylation ; Quinoxalines ; pharmacology ; Rats ; Rats, Inbred WKY ; Rats, Sprague-Dawley ; Receptors, AMPA ; antagonists & inhibitors ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; tau Proteins ; metabolism

OBJECTIVETo explore the effects of propofol and dizocilpine maleate (MK-801) on the cognitive abilities the hyperphosphorylation of Tau protein of rats after the electroconvulsive therapy.

METHODSTwo intervention factors including electroconvulsive shock therapy (ECT) (two levels: not applied and one treatment course) and drug intervention (three levels: intravenous saline,intravenous MK-801, and intravenous propofol). The morris water maze test started within 1 day after ECT to evaluate the learning-memory. The glutamate level in the hippocampus of rats was determined by high-performance liquid chromatography. The Tau protein that includes Tau5 (total Tau protein), PHF-1 (pSer(396/404)), AT8 (pSer(199/202)), and 12E8 (pSer(262)) in the hippocampus of rats was determined using Western blotting.

RESULTSPropofol, MK-801, and ECT could induce the impairment of learning-memory in depressed rats. The electroconvulsive shock significantly up-regulated the glutamate level, which was reduces by the propofol. The ECT up-regulated the hyperphosphorylation of Tau protein in the hippocampus of depressed rats, which was reduced by propofol and MK-801.

CONCLUSIONBoth propofol and MK-801 could protect against the impairment of learning-memory and reduce the hyperphosphorylation of Tau protein induced by ECT in depressed rats.

Animals ; Depression ; metabolism ; psychology ; Disease Models, Animal ; Dizocilpine Maleate ; pharmacology ; Electroconvulsive Therapy ; Glutamic Acid ; metabolism ; Hippocampus ; drug effects ; metabolism ; Male ; Maze Learning ; drug effects ; Memory ; drug effects ; Phosphorylation ; drug effects ; Propofol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; tau Proteins ; metabolism

OBJECTIVETo study changes in the expression levels of parvalbumin (PV), glutamate decarboxylase 67 (GAD67) and K+-Cl- cotransporter 2 (KCC2) in the brain tissue of rats with schizophrenia (SZ) induced by dizocilpine (MK-801), and to investigate the mechanism involving gamma-aminobutyric acid (GABA) by which NMDA receptor blocker induces SZ in the perinatal period.

METHODSThirty-six neonatal male Sprague-Dawley rats were randomly assigned to two batches on postnatal day 6. Each batch was divided into normal control (treated by 0.9% normal saline), SZ-development model (treated by subcutaneous injection of 0.1 mg/kg MK-801 on postnatal days 7-10; bid), and SZ-chronic medication model groups (treated by intraperitoneal injection of 0.2 mg/kg MK-801 on postnatal days 47-60; qd). On postnatal day 63, the brain tissue of the first batch of rats was obtained and then fixed with paraform for histological sections; expression levels of PV and GAD67 in the medial prefrontal cortex (mPFC) and hippocampus CA1 were measured by immunohistochemistry. Simultaneously, the second batch of rats was sacrificed and the mPFC and hippocampus were obtained and homogenized; expression levels of KCC2 in the mPFC and hippocampus were measured by Western blot.

RESULTSExpression levels of PV and GAD67 in the mPFC and hippocampus CA1 were significantly lower in the SZ-development and chronic medication model groups than in the normal control group (P<0.05). Expression levels of KCC2 in the mPFC and hippocampus were significantly lower in the SZ-development model group than in the SZ-chronic medication model and normal control groups (P<0.05).

CONCLUSIONSThe expression changes of PV and GAD67 in SZ can be simulated using the SZ development model induced by MK-801, which might affect the development of the GABA system in the PFC and hippocampus by downregulating KCC2 expression.

Animals ; CA1 Region, Hippocampal ; chemistry ; Dizocilpine Maleate ; pharmacology ; Glutamate Decarboxylase ; analysis ; Immunohistochemistry ; Male ; Parvalbumins ; analysis ; Prefrontal Cortex ; chemistry ; Rats ; Rats, Sprague-Dawley ; Schizophrenia ; etiology ; metabolism ; Symporters ; analysis

OBJECTIVE: To investigate the mechanism of myopia following intravitreous injection of MK801 (dizocipine maleate) intravitreous injected. METHODS: Three-week-old guinea pigs were divided into six groups: group A (control), group B (3 weeks form-deprivation in right eye), group C ( 3 weeks form-deprivation in right eye + saline), group D (3 weeks form-deprivation in right eye + MK801 1ng), group E (3 weeks form-deprivation in right eye + MK801 10 ng), group F (3 weeks form-deprivation in right eye + MK801 100 ng). The refraction and axial length of the eyes were measured. ncNOS was measured by hybridization in situ, and cyclic GMP (cGMP) concentrations by radioimmunochemistry. The correlation between MK801 concentration and diopter degree, axial length of the eyes, and levels of ncNOS or cyclic GMP were analyzed with linear correlation in the groups C-F. RESULTS: Diopter degree was decreased, axial eye length was shorted and levels of ncNOS and c-GMP were decreased in groups C, D, E and F dependent on the concentration of MK801. The diopter degree had positive correlation with MK801 concentration (r=0.702, P<0.05), while the axial eye length and the levels of ncNOS and cGMP were negatively correlated (r=-0.736, -0.637, -0.725, P<0.05) CONCLUSION MK801 injected into the vitreous humor can restrain myopia by down-regulated the expression of the nitric oxide-cyclic GMP signaling pathway. The effect is concentration dependent.
Animals ; Cyclic GMP ; metabolism ; Dizocilpine Maleate ; administration & dosage ; pharmacology ; Down-Regulation ; Female ; Form Perception ; physiology ; Guinea Pigs ; Injections, Intraocular ; Male ; Myopia ; physiopathology ; Nitric Oxide Synthase Type I ; metabolism ; Sensory Deprivation ; physiology ; Signal Transduction ; drug effects ; Vitreous Body ; drug effects

The present study was to investigate the role of dopamine D1 receptors and its relationship with glutamate, N-methyl-D-aspartic acid (NMDA) receptor and α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptor in depression induced by chronic unpredictable mild stress (CUMS). CUMS-induced depression model was established in Sprague-Dawley rats, and intrahippocampal microinjections of D1 dopamine receptor agonist SKF38393, non-competitive NMDA receptor antagonist MK-801 and AMPA receptor antagonist NBQX were respectively adopted by rat brain stereotaxic coordinates. The behavioral observations were conducted by measurement of weight changes, sucrose preference test, open-field test and tail suspension test. The concentration of glutamic acid and the expression of its receptors' subunits were detected by HPLC and Western blot, respectively. The results showed that, compared with control group, CUMS rats showed depression-like behavioral changes, higher concentration of glutamic acid, lower expressions of NMDA receptor (NR1) and AMPA receptor (GluR2/3) in hippocampus. Pretreatment with injection of SKF38393 could rescue such depression effect of CUMS, decrease the concentration of glutamic acid, and increase the expressions of NMDA receptor (NR1), AMPA receptor (GluR2/3) in hippocampus. Pretreatment with MK-801 could enhance the antidepressant effect of SKF38393, while NBQX weakened. These results suggest that agonists of D1 dopamine receptor could reduce the concentration of glutamic acid in hippocampus, and its antidepressant effect may be mediated by AMPA receptor partially.
2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine ; pharmacology ; Animals ; Depression ; etiology ; physiopathology ; Dizocilpine Maleate ; pharmacology ; Excitatory Amino Acid Antagonists ; Glutamates ; metabolism ; Hippocampus ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; Receptors, AMPA ; metabolism ; Receptors, Dopamine D1 ; agonists ; physiology ; Stress, Physiological ; physiology