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

Descending activation pathways in spinal cord are essential for inducing and modulating autokinesis, but whether the effects of general anesthetic agents on the descending pathways are involved in initiation of skeletal muscle relaxation or not, as well as the underlying mechanisms on excitatory amino acid receptors still remain unclear. In order to explore the mechanisms underlying etomidate's effects on descending activation of spinal cord motoneurons (MNs), the conventional intracellular recording techniques in MNs of spinal cord slices isolated from neonatal rats (7-14 days old) were performed to observe and analyze the actions of etomidate on excitatory postsynaptic potential (EPSP) elicited by electrical stimulation of the ipsilateral ventrolateral funiculus (VLF), which was named VLF-EPSP. Etomidate at 0.3, 3.0 (correspond to clinical concentration) and 30.0 µmol/L were in turn perfused to MN with steadily recorded VLF-EPSPs. At low concentration (0.3 µmol/L), etomidate increased duration, area under curve and/or half-width of VLF-EPSP and N-methyl-D-aspartate (NMDA) receptor-mediated VLF-EPSP component (all P < 0.05), as well as amplitude, area under curve and half-width of non-NMDA receptor-mediated VLF-EPSP component (all P < 0.05), or decreased amplitude and area under curve of VLF-EPSP, its NMDA receptor component, and non-NMDA receptor component (all P < 0.05). However, at 3.0 and 30.0 µmol/L, it was only observed that etomidate exerted inhibitory effects on amplitude and/or duration and/or area under curve of VLF-EPSP (P < 0.05 or P < 0.01) with concentration- and time-dependent properties. Moreover, NMDA receptor-mediated VLF-EPSP component was more sensitive to etomidate at ≥ 3.0 µmol/L than non-NMDA receptor-mediated VLF-EPSP component did. As a conclusion, etomidate, at different concentrations, exerts differential effects on VLF-EPSP and glutamate receptors mediating the synaptic transmission of descending activation of MNs in neonatal rat spinal cord in vitro.
Anesthetics, Intravenous ; pharmacology ; Animals ; Animals, Newborn ; Efferent Pathways ; physiology ; Electric Stimulation ; Etomidate ; pharmacology ; Excitatory Postsynaptic Potentials ; drug effects ; physiology ; Female ; In Vitro Techniques ; Male ; Motor Neurons ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; drug effects ; physiology ; Spinal Cord ; physiology

Alcoholism ; drug therapy ; metabolism ; physiopathology ; Animals ; Drugs, Chinese Herbal ; pharmacology ; therapeutic use ; Hippocampus ; metabolism ; Learning ; drug effects ; physiology ; Male ; Memory ; drug effects ; physiology ; Phytotherapy ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; genetics ; metabolism ; Superoxide Dismutase ; metabolism

OBJECTIVETo study the effects of ketamine combined with penehyclidine hydrochloride on the learning and memory abilities and the expression of synaptophysin in the hippocampus CA3 region in the brain of neonatal rats.

METHODSEighty seven-day-old Sprague-Dawly rats were randomly intraperitoneally injected with 50 mg/kg of ketamine (K group), 2 mg/kg of penehyclidine hydrochloride (P group), 50 mg/kg of ketamine plus 2 mg/kg penehyclidine hydrochloride (PK group) or normal saline (control group). The rats were trained and tested in a Morris water maze 14 days after administration. The immunhistochemical method was used to ascertain the expression of synaptophysin in the hippocampus CA3 region 24 hrs, 14 days and 28 days after administration.

RESULTSIn the Morris water maze training, the rats in the PK group performed worst, followed by the K group. The rats from the P and NS groups performed well. Compared with the NS group, the expression of synaptophysin in the K and the PK groups decreased significantly 24 hrs and 14 days after administration (p<0.05). The PK group had lower synaptophysin expression than the K group 24 hrs and 14 days after administration (p<0.05). Up to 28 days after administration, the synaptophysin expression increased in all of the four groups and there were no significant differences between groups.

CONCLUSIONSKetamine combined with penehyclidine hydrochloride may inhibit more significantly learning and memory abilities and the synaptophysin expression in the hippocampus CA3 region than ketamine alone in neonatal rats. Penehyclidine hydrochloride alone has no effect on learning and memory abilities and the synaptophysin expression. The synaptophysin expression may increase to a normal level by training and with increasing age.

Animals ; Animals, Newborn ; Cholinergic Antagonists ; pharmacology ; Drug Therapy, Combination ; Excitatory Amino Acid Antagonists ; pharmacology ; Hippocampus ; chemistry ; drug effects ; Ketamine ; pharmacology ; Maze Learning ; drug effects ; Memory ; drug effects ; Quinuclidines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; physiology ; Synaptophysin ; analysis

OBJECTIVETo study the effect and the possible mechanism of IL-6 on NMDA-excited neuronal discharges of rats in vitro.

METHODSThe cerebellar slices were prepared and spontaneous discharges of single cerebellar interposed nuclear (IN) neurons were recorded by extracellular recordings. The cerebellar slices were perfused with artificial cerebral spinal fluid (ACSF) containing N-methyl-D-aspartate (NMDA), IL-6, JAK inhibitor AG490. The changes in firing activities of the neurons treated with the drugs were recorded. The levels of phosphorylation at serine 897 site of NMDA receptor subunit 1 (NR1) in the neurons treated with various drugs mentioned above were detected by Western blot.

RESULTSThe discharge rates of the neurons that were treated with IL-6 together with NMDA were significantly lower than those of the neurons treated with NMDA alone. AG490 partially blocked the inhibitory effect of IL-6 on the NMDA-stimulated neuronal firing activity. The treatment of the neurons with IL6 and NMDA led to a concentration-dependent suppression of the phospho-NR1 expression relative to those neurons treated with NMDA alone. AG490 blocked the effect of the IL-6-induced depression of phospho-NR1 expression.

CONCLUSIONIL-6 inhibits NMDA-stimulated neuronal firing activity, and simultaneously down-regulates the phosphorylation of NR1 at serine 897 site.

Animals ; Cerebellum ; drug effects ; metabolism ; In Vitro Techniques ; Interleukin-6 ; pharmacology ; N-Methylaspartate ; pharmacology ; Nerve Growth Factors ; metabolism ; Neurons ; drug effects ; metabolism ; physiology ; Phosphorylation ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; metabolism

Intravenous anesthetics are known to cause amnesia, but the underlying molecular mechanisms remain elusive. To identify a possible molecular mechanism, we recently turned our attention to a key intracellular signaling pathway organized by a family of mitogen-activated protein kinases (MAPKs). As a prominent synapse-to-nucleus superhighway, MAPKs couple surface glutamate receptors to nuclear transcriptional events essential for the development and/or maintenance of different forms of synaptic plasticity (long-term potentiation and long-term depression) and memory formation. To define the role of MAPK-dependent transcription in the amnesic property of anesthetics, we conducted a series of studies to examine the effect of a prototype intravenous anesthetic propofol on the MAPK response to N-methyl-D-aspartate receptor (NMDAR) stimulation in hippocampal neurons. Our results suggest that propofol possesses the ability to inhibit NMDAR-mediated activation of a classic subclass of MAPKs, extracellular signal-regulated protein kinase 1/2 (ERK1/2). Concurrent inhibition of transcriptional activity also occurs as a result of inhibited responses of ERK1/2 to NMDA. These findings provide first evidence for an inhibitory modulation of the NMDAR-MAPK pathway by an intravenous anesthetic and introduce a new avenue to elucidate a transcription-dependent mechanism processing the amnesic effect of anesthetics.
Amnesia ; chemically induced ; enzymology ; Anesthetics, Intravenous ; pharmacology ; Animals ; Cells, Cultured ; Extracellular Signal-Regulated MAP Kinases ; drug effects ; metabolism ; Hippocampus ; cytology ; drug effects ; enzymology ; Long-Term Potentiation ; drug effects ; physiology ; Memory ; drug effects ; physiology ; Mitogen-Activated Protein Kinase 1 ; drug effects ; Mitogen-Activated Protein Kinase 3 ; drug effects ; Neurons ; drug effects ; enzymology ; Propofol ; pharmacology ; Rats ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Signal Transduction ; drug effects ; physiology ; Transcriptional Activation ; drug effects

OBJECTIVETo investigate changes in synaptic and extrasynaptic N-methyl-D-aspartate receptors (NMDAR) during the development of cultured rat hippocampal neurons.

METHODSSynaptic and extrasynaptic NMDAR channel currents were recorded from 1-day-old rat hippocampal neurons cultured for 1 and 2 weeks with patch-clamp technique in whole-cell configuration and outside-out configuration, respectively.

RESULTSThe amplitude of NMDAR-mediated miniature excited postsynaptic current (Meps(CNMDA)) decreased in neurons cultured for 2 weeks as compared with that recorded in neurons cultured for 1 week, and the 2-week neurons showed also much lowered sensitivity to selective NR2B blocker ifenprodil. The amplitude and open probability of extrasynaptic NMDAR in the 2-week neurons were significantly higher than those in the 1-week neurons, but the neurons differred little in conduction and reverse potential. Ifenprodil decreased the high conductance and open probability in both neurons, but the effect was more potent in the 2-week ones.

CONCLUSIONSThere can be developmental changes in synaptic and extrasynaptic NMDAR channel currents in cultured rat hippocampal neurons, indicating that different NMDAR subtypes are expressed in the synaptic and extrasynaptic regions during the development of the hippocampal neurons. In 1-week neurons, NR2B are predominant both in synaptic and extrasynaptic regions, and at 2 weeks, synaptic NR2B are replaced by NR2A but NR2B still remains the predominant subtypes outside the synapses.

Animals ; Animals, Newborn ; Cells, Cultured ; Excitatory Amino Acid Antagonists ; pharmacology ; Excitatory Postsynaptic Potentials ; drug effects ; physiology ; Hippocampus ; cytology ; Neurons ; cytology ; physiology ; Patch-Clamp Techniques ; Piperidines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; physiology ; Synapses ; physiology ; Synaptic Transmission ; physiology ; Time Factors

AIMTo investigate effect of ginkgo biloba extract (GBE) on N-methyl-D-aspartate (NMDA)-activated currents (I(NMDA)) and evaluate further the modulatory effects of Micro-GBE/Nano-GBE.

METHODSBy means of whole-cell patch clamp technique, NMDA-activated currents from acutely isolated rat hippocampal neurons were recored.

RESULTSThe majority of the neurons examined (81.8%, 90/110) were sensitive to NMDA (1 mmol/L) and its co-agonist Gly (10 micromol/L). NMDA activated an inward current, which manifested apparent desensitization and could be blocked by its specific antagonist MK-801. After the neurons were treated with Micro/Nano GBE (0.1 mg/ml) followed by the application of NMDA (1 mmol/L) and Gly (10 micromol/L) for 30 s, it was show that NMDA-activated currents were obviously inhibited (P < 0.01, n = 8). The inhibitory rate were 40% +/- 17% and 64% +/- 15% respectively. It showed that the modulatory effect of Nano-GBE (dissolved in the stander extracellular solution) on NMDA-activated current was significantly higher than that of Micro-GBE (dissolved in DMSO) (P < 0.05).

CONCLUSIONThe inward currents activated by NMDA could be depressed by Micro-GBE and Nano-GBE. The modulatory effects of GBE on NMDA-activated current are expected to contribute to the neuroprotective effects of ginkgo biloba extracts. In addition, at the same concentration, the modulatory effect of Nano-GBE on NMDA-activated current is better than that of Micro-GBE.

Animals ; Cells, Cultured ; Ginkgo biloba ; Hippocampus ; drug effects ; physiology ; N-Methylaspartate ; pharmacology ; Neurons ; drug effects ; physiology ; Patch-Clamp Techniques ; Plant Extracts ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; drug effects

OBJECTIVETo study the role of N-methyl-D-aspartate receptor and Ca(2+) in acute intoxicated encephalopathy induced by 1, 2-dichloroethane (1, 2-DCE) in vitro.

METHODSNeurocytes of new born rats were cultured in vitro, which were administered with different doses of 1, 2-DCE, and NMDAR and Ca(2+) antagonists including Ketamine and Nimodiping respectively. The cell morphologic structures were observed under light microscope, and its proliferation was detected by Cell Counting Kit-VIII.

RESULTS1, 2-DCE could damage the normal morphological structure of neurocytes: the cell body swelled and broke down, the karyon slurred or disappeared, the axone became shorten and thick, connection of neurocytes was reduced, the cell membrane was half-baked, injury of neurocytes became severer with the increase of the dose of 1, 2-DCE. There was no statistical difference in the proliferation of neurocytes between every 1, 2-DCE groups (P > 0.05), but there was significantly statistical difference between 1, 2-DCE groups, the control group, and the retarder groups (P < 0.01).

CONCLUSION1, 2-DCE can damage the normal morphological structure of neurocytes, and the damage will become severer with the increase of the dose of 1, 2-DCE. However, the cell morphologic structures and proliferation of antagonist groups are much better than those in the 1, 2-DCE groups.

Animals ; Calcium ; antagonists & inhibitors ; physiology ; Cells, Cultured ; Ethylene Dichlorides ; toxicity ; Neurons ; drug effects ; pathology ; Rats ; Rats, Sprague-Dawley ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors ; physiology

OBJECTIVETo study the effect of glycine site/NMDA (N-methyl-D-aspartate) receptor antagonist MRZ2/576 on the conditioned place preference (CPP) and locomotor activity induced by morphine in mice.

METHODSDifferent doses (1.25, 2.5 and 5 mg/kg, i.p.) of MRZ2/576 were used to evaluate the effect of MRZ2/576 on the acquisition and expression of CPP induced by morphine (5 mg/kg) in mice. In addition, we examined the locomotor activity of mice in conditioning and testing phase of CPP paradigm.

RESULTSMRZ2/576 alone could not establish place preference, but a 5 mg/kg dose of MRZ2/576 could block both acquisition and expression of morphine-induced CPP. In testing phase of CPP, there was no statistical difference for locomotor activity between the groups; injection of MRZ2/576 showed a dose-dependent decrease of locomotor activity on both control and morphine-treated mice, especially 5 mg/kg of MRZ2/576 significantly suppressed the locomotor activity of mice.

CONCLUSIONBased on the present results, we assume that MRZ2/576 can antagonize the rewarding effect of morphine, suggesting that this glycine site/NMDA receptor antagonist could be used to treat addictions due to its light side effect profile.

Animals ; Conditioning (Psychology) ; drug effects ; Excitatory Amino Acid Antagonists ; pharmacology ; Magnesium ; physiology ; Male ; Mice ; Mice, Inbred ICR ; Morphine ; pharmacology ; Motor Activity ; drug effects ; Phthalazines ; pharmacology ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors