The role of NMDA glutamate receptors in lung injury caused by chronic long-term intermittent hypobaric hypoxia

Chronic intermittent hypoxia (CIH), a component of sleep apnea-hypopnea syndrome, is suggested to cause damage to lung tissue, and the role of glutamate is not well studied. We used a chronic long-term intermittent hypobaric hypoxia (CLTIHH) model of rats to find out if such procedure causes lung injury and the potential effect of N-methyl-D-aspartate receptors (NMDARs) by using receptor antagonist MK-801 (dizocilpine). Thirty-two rats were placed into four groups; a control and three CLTIHH groups where rats were placed into a low-pressure chamber set to 430 mmHg for 5 h/day, 5 days/week, for 5 weeks. Only one group received MK-801 (0.3 mg/kg, ip) daily. We evaluated tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and nuclear factor (NF)-kB for the inflammatory process, superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), glutathione peroxidase (GPX), total antioxidant status (TAS), and total oxidant status (TOS) for oxidative stress, and caspase-9 levels. Blood plasma, bronchoalveolar fluid (BALF), and lung tissue extracts were evaluated. Both oxidant and inflammatory parameters were significantly increased in all the mediums of the CLTIHH groups except the group that received MK-801. Significant evidence was collected on MK-801 alleviating the effect of CLTIHH. Histological evaluations revealed lung damage and fibrotic changes in the CLTIHH groups. It was first shown that the CLTIHH procedure caused chronic lung injury, and that inflammation and oxidant stress were influential in the formation of lung injury. Secondly, NMDAR antagonist MK-801 effectively inhibited the development of lung injury and fibrosis.

NMDA Receptor Antagonist MK801 Protects Against 1-Bromopropane-Induced Cognitive Dysfunction / 神经科学通报·英文版

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.

α-humulene improves schizophrenia via NRG1/ErbB4 signaling pathway / 中草药

Objective: To study the treating mechanism of α-humulene on the schizophrenic mice. Methods: The schizophrenic models were established by dizocilpine maleate (MK801), then different concentrations of α-humulene were used to treat the mice by intragastric administration. Open-field experiment and PPI test were carried out to evaluate the spontaneous activity and sensorimotor gating function of mice. Moreover, the frontal cortex MDA, NO levels and hippocampal NRG1, ErbB4 protein expression was detected. Results: The spontaneous activity, sensorimotor gating function, MDA, NO, NRG1 and ErbB4 levels were significantly changed in model mice when compared with normal mice (P < 0.01). Compared with model group, different concentrations of α-humulene notably inhibited spontaneous activity, improved PPI value, increased NO and MDA content, down-regulated ErbB4 and NRG1 protein expression (P < 0.05, P < 0.01). Conclusion: The schizophrenia abnormal behavior of mice was improved by α-humulene via down-regulating NRG1/ErbB4 signaling pathway, so as to achieve the purpose of treating schizophrenia.

Recapitulation of Neuropsychiatric Behavioral Features in Mice Using Acute Low-dose MK-801 Administration

Despite some innate limitations, animal models are a potent investigative tool when used to model specific symptoms of a disorder. For example, MK-801, an N-methyl-D-aspartate receptor antagonist, is used as a pharmacological tool to induce symptoms found in some neuropsychiatric disorders. However, a close examination of literature suggests that the application window of MK-801 doses is relatively narrow between individual behavioral paradigms, necessitating careful characterization of the evoked behavioral aberrations and the doses used to induce them. Moreover, variation in behaviors depending on the animal strain, gender of the subject, and the timing of administration is observed, making it difficult to compare the behavioral characteristics reported in different studies. We aim to characterize the behavioral aberrations induced by different doses of MK-801 in CD-1 mice and create a ready reference for future studies. We used CD-1 mice to recapitulate behavioral impairments resulting from acute administration of MK-801. In 0.1 mg kg⁻¹, we observed diminished spontaneous alteration during the Y-maze test, while 0.12 mg kg⁻¹ resulted in hyperlocomotion and social deficit. Mice treated with 0.2 and 0.3 mg kg⁻¹ of MK-801 demonstrated a decreased self-grooming. Finally, all doses significantly impaired cliff avoidance behaviors suggesting increased impulsivity. These results affirm that MK-801 can effectively model various symptoms of different neuropsychiatric disorders in a dose-dependent manner. The observed sensitivity against spatial-memory impairment and impulsive behaviors at low concentration of MK-801 suggest that MK801 may modulate cognitive function and impulsivity in even lower concentration before it can modulate other behavioral domains.

Effect of dizocilpine (MK-801) on the working memory of rats on a three-panel runway apparatus

Background: Understanding the processes underlying cognitive functions is a prerequisite to develop strategies for the treatment of cognitive deficits. There is a great need for valid animal models for investigating the cognitive enhancing effects of potential therapeutics. Many studies have investigated animal models of cognitive deficits by using animals treated with compounds that compromise cognitive abilities. Glutamate, an excitatory neurotransmitter and abundantly distributed in the central nervous system is involved in memory processes through N-methyl-d-aspartate (NMDA) receptors. The behavioural consequences of blocking the NMDA receptor provide the rationale for cognitive impairment as an animal model for the cognitive deficits associated with dementia. Authors investigated the effect of dizocilpine (MK-801), an NMDA-receptor antagonist (non-competitive) on the working memory in rats using the three-panel runway apparatus.Methods: Total 24 trained male albino rats were randomly divided into 4 groups of 6 animals each. Varying doses of MK-801 were administered to the animals. Working memory errors and latency periods were evaluated on the three panel Runway apparatus.Results: Treatment with MK-801 at the dose of 0.03mg/ kg did not result in any significant change in working memory errors or latency period in comparison to saline control. MK-801 treatment at dose of 0.1mg/kg and 0.3mg/kg resulted in a significant increase in the number of working memory errors and latency period as compared to control.Conclusions: Authors conclude that MK-801 treatment in the dose of 0.1mg/ kg and 0.3mg/kg resulted in working memory deficits on the three-panel runway apparatus. Rats with cognitive deficits induced by the prototypical N-methyl-d-aspartate (NMDA) receptor antagonist MK-801 may provide a relevant animal model of dementia based on the mechanistic approach of blocking NMDA/glutamatergic signalling.

Effects of neonatal MK-801 exposure on recognition memory and excitatory-inhibitory balance of hippocampus in adult female rats / 中华行为医学与脑科学杂志

Objective To investigate the long-term effects of repeated neonatal administration of dizocipline maleate (MK-801),the glutamate N-methyl-D-aspartate (NMDA) receptor antagonist,on recognition memory and hippocampal excitatory-inhibitory balance at the synaptic level in adult female rats.Methods Neonatal female Sprague-Dawley (SD) rats were randomly divided into model group and control group.Rats were administrated subcutaneously with MK-801 or normal saline from postnatal day (PND) 5 to PND14 (0.25 mg/kg,twice daily).(1) Object-in-context recognition test was performed on PND73-75.(2)The expression levels of vesicular glutamate transporter 1 (VGLUT1) and vesicular GABA transporter (VGAT) in hippocampus were detected by immunohistochemical staining.Results (1) The preference index of model group for new objects was significantly lower than that of the control group (t =-2.762,P=0.012).(2) There was no significant difference in the expression of VGLUT1 in hippocampus of MK-801 mode group(P＞0.05).Compared with control group(48.19±2.10),the VGAT level of model group in CA1 (39.60±2.19) was lower.Compared with control group (CA1:(0.99±0.05),CA3:(1.28±0.02),the ratio of VGLUT1/VGAT was significantly upregulated in CA1(1.16±0.05) and CA3(1.44±0.03) (P＜0.05).Conclusion Early NMDA receptor inhibition produces long-term deleterious effects on associative recognition memory and excitatory-inhibitory balance of hippocampus in female rats.These biochemical abnormalities may contribute to cognitive impairments observed in this study.

ω-3PUFAs Prevent MK-801-induced Cognitive Impairment in Schizophrenic Rats via the CREB/BDNF/TrkB Pathway / 华中科技大学学报（医学）（英德文版）

This study was to determine the protective effect of ω-3 polyunsaturated fatty acids (ω-3PUFAs) on MK-801-induced cognitive impairment in schizophrenia (SZ) rats and the underlying mechanism.A rat model of schizophrenia was induced by MK-801.The cognitive function of rats was assessed using a Morris water maze.The number of hippocampal neurons was measured by Nissl staining.The expression of CREB,p-CREB,BDNF,TrkB,p-TrkB,AKT,p-AKT,ERK,and p-ERK in the hippocampus of rats was detected by Western blotting.The results showed that ω-3PUFAs attenuated MK-801-induced cognitive,impairment and hippocampal neurons loss,reversed the injury of the CREB/BDNF/TrtB pathway induced by MK-801,and antagonized MK-801-induced down-regulation of p-AKT and p-ERK in the hippocampus of rats.In conclusion,ω-3PUFAs enhances the CREB/BDNF/TrkB pathway by activating ERK and AKT,thereby increasing the synaptic plasticity and decreashng neuron loss,and antagonizing MK-801-induced cognitive impairment in schizophrenic rats.

Fraccionamiento guiado por bioensayo e identificación de blancos moleculares de potencial acción antipsicótica de cuatro plantas medicinales peruanas / Fractionation guided by bioassay and identification of molecular targets of potential antipsychotic action of four Peruvian medicinal plants

El principal síntoma de la esquizofrenia es la psicosis, caracterizada principalmente por la aparición de alucinaciones y delusiones. En esta investigación, se llevó a cabo el fraccionamiento biodirigido de extractos etanólicos (EE) de 4 plantas (6078, 6518, 7158 y 6521) usadas en la medicina tradicional Peruana para el tratamiento de psicosis. Los extractos y fracciones fueron probados en el modelo animal murino de hiperactividad inducida por Dizocilpina o MK-801(antagonista del receptor de glutamato tipo N-metil D-aspartato). Se utilizó la prueba de campo abierto (OFT) para medir la hiperactividad y la prueba de inhibición del sobresalto por prepulso (PPI) para medir la respuesta de sobresalto. En la prueba de campo abierto, la fracción apolar A del EE 7158 (p<0.05), la fracción D del EE 6078 (p <0.001) y la fracción A (p<0.05) y D (p<0.001) del EE 6518 (p<0.001) suprimieron los efectos del MK-801. En la prueba de PPI fueron activas las fracciones A, C y D (7158); A, B y C (6078); y todas las fracciones del extracto 6518. Adicionalmente, los ensayos de unión a radioligando y ensayos funcionales indican que los cuatro EEs tienen un efecto sobre receptores involucrados en esquizofrenia.

Effects of MK801 on the depression-like behaviors and damaged hippocampus in diabetes with depression rats / 中华行为医学与脑科学杂志

Objective To investigate the effects of dizocilpine(MK801) on depressive-like behaviors and damaged hippocampus in rats with diabetes-related depression.MethodsThe animal models of diabetes-related depression were established and they were randomly divided into two groups based on random number table: model group and MK801 group,while 6 rats were included in each group.And another six health rats were regarded as control group.The Open-field test was used to detect the activities.The damage of hippocampus was valued by HE staining,Nissl staining,and Tunel staining.The protein expressions of Bax,Bcl-2 in hippocampus were detected by Western blot.ResultsThe number of activities was significant decreased in Open-field test in model group when compared with control.Hippocampal neurons vacuoles,Nissl bodies were decreased and apoptotic cells were increased in hippocampus in model group as well.Furthermore,the expression of Bax was significant up-regulated(94.57±7.97,P<0.01),while the Bcl-2 was declined(24.65±5.26,P<0.01).Compared with the model group,the animals in MK801 group exhibited increased activities(12.50±4.42,P<0.01),which accompany with an increased Nissl body(133.55±16.74,P<0.01) and a decreased apoptosis(22.50±6.35,P<0.01).Moreover,the expression of Bax was decreased and the Bcl-2 was increased in MK801 group when they were contrasted to model(33.00±4.57,P<0.01).Conclusion MK801 is a significant element to regulate the expression of apoptosis protein including Bax,Bcl-2,and to protecte the hippocampal neuron in rats with diabetes-related depression effectively.

Effect of ω-3PUFAs on cognitive deficit in rats with schizophrenia / 中华行为医学与脑科学杂志

Objective To investigate the antagonistic effect of ω-3PUFAs on cognitive impairment in MK-801-induced schizophrenia (SZ) rats and its mechanism.Methods Rat model of schizophrenia was induced by MK-801.Morris water maze was used to detect the change of cognitive function in rats.The number of neonatal neurons in hippocampus was detected by Brdu staining.CREB,p-CREB,BDNF,TrkB and p-TrkB levels were detected by Weston Blot.Results MK-801 induced schizophrenia-like cognitive impairment (the escape latency in the water maze test was (6.51±3.10)s for Ctr group,(15.27±6.20)s for Mod group;acrossing times was (4.63±1.06) times for Ctr group,(2.00±1.15) times for Mod group),reduced the number of neonatal neurons in hippocampus (the relative level of neonatal neuron number per unit area,Mod/Ctr was 0.656±0.066) and impaired the CREB/BDNF/TrkB pathway (the relative level of gray value,Mod/Ctr:CREB was 0.393±0.065,p-CREB was 0.591±0.015,BDNF was 0.716±0.115,TrkB was 0.787±0.029,p-TrkB was 0.586±0.013).ω-3PUFAs improved the CREB/BDNF/TrkB pathway activity by increasing CREB and TrKB level and their phosphorylation (the relative level of gray value,Pre/Ctr:CREB was 1.139±0.111,p-CREB was 0.845±0.243,BDNF was 0.864±0.133,TrkB was 0.916±0.022,p-TrkB was 0.952±0.047),and then recovered the number of neonatal neurons in hippocampus (the relative level of neonatal neuron number per unit area,Pre/ Ctr was 1.183±0.101),thereby reduced the cognitive dysfunction in schizophrenia rats(the escape latency in the water maze was (7.44±4.55)s for Pre;acrossing times was (3.86±1.68) times for Pre).Conclusion ω-3PUFAs can relieve the MK-801-induced schizophrenia-like cognitive impairment.

On antipsychotic effects of l-Scoulerine / 中国药理学通报

Aim To study the antipsychotic effects of l-Scoulerine ( l-SLR) . Methods NMDAreceptorantag-onist MK-801 was used to induce the positive and neg-ative symptoms of schizophrenia and cognitive impair-ment in animal models. The effects of l-SLR were eval-uated on schizophrenia induced by MK-801 and on ex-trapyramidal system. Results l-SLR (10,15 mg · kg - 1 , ip) could suppress pre-pulse inhibition damage in rats induced by MK-801 (0. 3 mg·kg - 1 , ip); l-SLR(30 mg·kg - 1 , ip) could inhibit climbing behav-iors in mice induced by apomorphine, which suggested that l-SLR had significant inhibiting effects on the posi-tive symptoms of schizophrenia by MK-801 and apo-morphine. l-SLR could also induce social contact inhi-bition and cognitive impairment induced by MK-801 (0. 2 mg · kg - 1 , ip), which proposed that l-SLR could improve the negative symptoms and cognitive im-pairment by MK-801. Catalepsy in mice could be caused by the treatment dose of haloperidol (0. 8 mg· kg - 1 , ip), not by that of l-SLR(30 mg·kg - 1 , ip). Conclusion I-SLR has significant effects on the posi-tive and negative symptoms of schizophrenia and cogni-tive impairment and, the effect of l-SLR under effective dose on extrapyramidal system is obviously much less than that of haloperidol and l-SPD.

Effects of Icariin on MK-801-induced Schizophrenia Model in Mice / 中国康复理论与实践

Objective To investigate the effects of icariin, a major active component of traditional Chinese herb Epimedium on schizo-phrenia animal model. Methods MK-801, a N-methyl-D-aspartate (NMDA) receptor antagonist, was intraperitoneally injected into mice to establish a schizophrenia animal model. The open field behavior test infrared detection system was used to measure the mobility of mice in order to find the best optimal dose. 40 mice were randomly divided in to control group, model group, risperidone group and icariin group with 10 mice in each group. The risperidone group and the icariin group were given 0.1 mg/kg risperidone and 50 mg/kg icariin respectively. All groups were injected with 0.6 mg/kg MK-801 0.1 ml intraperitoneally, except the control group. The total distance and the central dis-tance within 210 minutes were tested. Results The total distance and the central distance were significantly longer in the model group than in the control group (P0.05). Conclusion Icariin may improve the positive and negative symptoms of schizophrenia mice, which may be beneficial to schizo-phrenia therapy.

Behavioral alterations and demyelization of the corpus callosum in the mouse model of MK-801 induced schizophrenia / 中国神经精神疾病杂志

Objective To explore the role of white matter injuries in the schizophrenia induced by the NMDA re-ceptor antagonist. Methods Adult male C57BL/6J mice (8 week old) were equally divided into four groups. One group was sub-chronically treated with saline solution, and the other three groups were intraperitoneally treated with MK-801 at dose of 0.025 mg/mL (M1), 0.050 mg/mL (M2) and 0.100 mg/mL (M3) in a volume 10 ml per kilogram body weight. All ani-mals were tested using Morris water maze at the 9th-15th day and using the Hole Board exploration as well as Rota Rod performance tests on the 16th day. The myelin basic protein (MBP) and the ultrastructure of the myelin sheaths in the cor-pus callosum were then examined using immunohistochemical methods, transmission electron microscope technique and stereological methods. Results The repeated sub-chronic MK-801 treatment did not induce impairment of spatial learning and memory in Morris water maze. The MK-801 treatment at 0.25 mg/kg and 1.00 mg/kg but not at 0.50 mg/kg resulted in less exploration to a new environment. The myelin staining with anti-MBP antibody was less intense in all three schizo-phrenic groups when compared to saline control group (P<0.01). Furthermore, MK-801 treatment caused pathological al-terations of the myelin sheaths including segmental demyelination of myelinated fibers and splitting of myelin sheath lamel- lae in schizophrenic groups. The ratio of the injured myelinated nerve fibers in the corpus callosum of MK-801 treated mice [M3 group, (22.42 ± 4.24)%] was significantly higher when compared to the control mice [(3.84 ± 1.35)%,P<0.01)]. Conclusions The present study demonstrated the white matter damages, mainly low MBP expression and segmental demye-lization in the corpus callosum in the mice sub-chronic treated with MK-801, indicating that the white matter changes might be involved in the schizophrenia induced by NMDA antagonist.

Efecto de la adiinistración intracerebral de mk801 y (-) nicotina en las conceentraciones extracelulares de glu y gaba en el núcleo pedunculopontino de ratas / Effect of the Mk801 and (-) Nicotine Intracerebral Administration on Glu and Gaba Extracellular Concentration in the Pedunculopontine Nucleus from Rats

Aunque la manipulación farmacológica de los sistemas glutamatérgico y colinérgico se ha tratado en modelos experimentales de enfermedad de Parkinson (EP), pocos autores han realizado estudios de esta temática a nivel del núcleo pedunculopontino (NPP). El presente trabajo aborda los cambios en las concentraciones extracelulares (CE) de glutamato (Glu) y ácido δ-amino butírico (GABA) en el NPP de ratas hemiparkinsonizadas por inyección de 6-hidroxidopamina (6-OHDA) y sometidas a infusión local de MK-801 (10 µmol/L) o (-) nicotina (10 mM). La infusión se realizó mediante microdiálisis cerebral y la determinación de CE de neurotransmisores se realizó a través de cromatografía líquida de alta resolución acoplada a detección de fluorescencia. La infusión de MK-801 en el NPP produjo disminución significativa de CE de Glu (p< 0,01) y de GABA (p < 0,01) en ratas hemiparkinsonizadas y controles. La infusión de (-) nicotina mostró un incremento significativo de CE de Glu (p < 0,001) y GABA (p< 0,001) en el NPP de ratas hemiparkinsonizadas y controles. El bloqueo local de receptores NMDA por MK-801 facilita la interacción de Glu con sus receptores metabotrópicos que participan en mecanismos de inhibición presináptica y bloquean la liberación de neurotransmisores. Mientras que la infusión de nicotina en el NPP suma los efectos de activación de los receptores nicotínicos a los cambios conocidos en la neurotransmisión glutamatérgica y gabaérgica en el NPP en parkinsonismo. La infusión de fármacos glutamatérgicos y colinérgicos en el NPP, impone un reajuste a la neurotransmisión a este nivel que se añade a los cambios neuroquímicos asociados a denervación dopaminérgica.

Although the pharmacological manipulation of the glutamatergic and cholinergic systems have been studied in animal models of Parkinson´s disease (PD), only some authors have done work on this topic at the pedunculopontine nucleus (PPN). The present work studied the changes in glutamate (Glu) and δ-aminobutyric acid (GABA) extracellular concentrations (EC) in the PPN from hemiparkinsonian rats by 6hydroxydopamine injection. The rats were locally perfused by MK-801 (10 µmol/L) or (-) nicotine (10 mM) solutions by cerebral microdyalisis. The biochemical studies were carried out through high performance liquid chromatography coupled to fluorescence detection. MK-801 infusion induced a significant decrease of Glu (p< 0.01) and GABA (p< 0.01) EC in PPN. On the other hand (-) nicotine infusion induced a significant increase of Glu (p< 0.001) and GABA (p< 0.001) EC in PPN from hemiparkinsonian rats. The local blockade of NMDA receptors by MK-801 infusion facilitates the interaction between Glu and their metabotropic receptors that take part in presynaptic inhibition mechanisms and interfere with neurotransmitters release. Meanwhile, the nicotine infusion sums the effects of nicotinic receptor activation with the glutamatergic and gabaergic neurotransmission changes produced in the PPN in the parkinsonian condition. The cholinergic and glutamergic drug infusion in PPN impose a new adjustment to the neurotransmition at this level that is added to the neurochemical changes associated to dopaminergic denervation.

Antiallodynic Effects of Electroacupuncture Combined with MK-801 Treatment through the Regulation of p35/p25 in Experimental Diabetic Neuropathy

The anti-allodynic effect of NMDA receptor antagonist and acupuncture treatments were explored through spinal p35 regulation of diabetic neuropathic rat. We evaluated the change over time of p35/p25 protein levels in the spinal cord compared with behavioral responses to thermal and mechanical stimulation in streptozotocin (STZ)-induced diabetic rats. Additionally, we studied p35 expression when electroacupuncture (EA) and a sub-effective dose of NMDA (N-methyl-D-aspartate) receptor antagonist (MK-801) were used to treat hyperalgesia in the diabetic neuropathic pain (DNP). Thermal paw withdrawal latency (PWL) and mechanical paw withdrawal threshold (PWT) were significantly decreased in the early stage of diabetes in rats. p35 expression after STZ injection gradually decreased from 1 week to 4 weeks compared to normal controls. p25 expression in 4-week diabetic rats was significantly higher than that of 2-week diabetic rats, and thermal PWL in 4-week diabetic rats showed delayed responses to painful thermal stimulation compared with those at 2 weeks. EA applied to the SP-9 point (2 Hz frequency) significantly prevented the thermal and mechanical hyperalgesia in the DNP rat. Additionally, EA combined with MK-801 prolonged anti-hyperalgesia, increased p35 expression, and decreased the cleavage of p35 to p25 during diabetic neuropathic pain. In this study we show EA combined with a sub-effective dose of MK-801 treatment in DNP induced by STZ that is related to p35/p25 expression in spinal cord.

Expression analysis of neuregulin 1 gene in schizophrenia model rats / 中华行为医学与脑科学杂志

ObjectiveTo analyze the gene expression of neuregulin1 (Nrg1)mRNA and protein in encephalic region and peripheral blood,and to explore the consistency of the expression in central and peripheral in schizophrenia model rat induced by dizocilpine maleate ( MK801 ).Methods30 adult male SD rats were randomly divided into 3 groups ( 10 cases per group):model group injected with MK801 (0.6 mg/kg and 100μl/20 g)on the right rear of ventrolateral compartment,control group 1 ( no treatment) and control group 2 injected with equal volume normal saline.Nrg1 mRNA was measured in peripheral blood and in prefrontal lobe by using semiquantitative RT-PCR in 3 groups,and Nrg1 protein was measured in encephalic region (prefrontal lobe,dentate band and hippocamp) by using immunohistochemistry.ResultsThere was significant difference of the amount of Nrg1 mRNA among 3 groups (for center:F=9.141,P =0.001 ;for peripheral blood F =8.389,P =0.001 ),and it was higher in model group ( center:2.08 ± 0.64; peripheral blood:1.43 ± 0.46) than that in two control groups ( control group1,center:1.17 ± 0.42,peripheral blood:0.78 ± 0.39 ; control group 2,center:1.31 ± 0.44,peripheral blood:0.79 ± 0.37 ),but no statistical significant difference existed between two control groups.There was positive correlation of Nrg1 mRNA between center and periphery.There was significant difference of Nrg1 protein in prefrontal lobe,dentate band and hippocamp among 3 groups ( F value was 7.275,21.50 and 4.619,and P value was 0.003,0.000 and 0.019,respectively),and it was higher in model( 7.71 ± 2.55,11.67 ± 1.83and 10.18 ±2.08,respectively)than that in two control groups( control group 1:4.89 ± 1.06,7.53 ± 1.14 and 7.10 ± 2.52,respectively; control group 2:5.31 ± 1.39,8.10 ± 1.60 and 7.81 ± 2.50),but no statistical significant difference existed between two control groups.ConclusionMK801 can effect on the expression of Nrg1 gene,Nrg1 mRNA and protein increase in MK801 model rat,and the change is synchronous between center and periphery.

Concentration change of DA, DOPAC, Glu and GABA in brain tissues in schizophrenia developmental model rats induced by MK-801 / 中南大学学报(医学版)

Objective To explore the related neurobiochemical mechanism by comparing the concentration change of dopamine (DA),dihydroxy-phenyl acetic acid (DOPAC),glutamate (Glu),and γ-aminobutyric acid (GABA) in the brain tissues in schizophrenia (SZ) developmental model rats and chronic medication model rats.Methods A total of 60 neonatal male Spragur-Dawley (SD) rats were randomly assigned to 3 groups at the postnatal day 6:an SZ developmental rat model group (subcutaneous injection with MK-801 at the postnatal day 7-10,0.1 mg/kg,Bid),a chronic medication model group (intraperitoneal injection at the postnatal day 47-60,0.2 mg/kg,Qd),and a normal control group (injection with O.9％ normal saline during the corresponding periods).DA,DOPAC,Glu,and GABA of the tissue homogenate from the medial prefrontal cortex (mPFC) and hippocampus were examined with Coularray electrochemic detection by high performance liquid chromatogram technique.The utilization rate of DA and Glu was calculated.Results Compared with the normal control group,the concentration of DA and DOPAC in the mPFC and the hippocampus in the SZ developmental model group significantly decreased ( P ＜ 0.05 ),and the GABA concentration and Glu utilization rate in the mPFC also decreased (P ＜ 0.05 ).Compared with the chronic medication model group,the DA concentration of the mPFC in the SZ developmental group decreased ( P ＜ 0.05 ),and the DOPAC concentration and the utility rate of DA in the hippocampus also decreased (P ＜0.01,P ＜0.05,respectively).Conclusion The activities of DA,Glu and GABA system decrease in the mPFC and the DA system function reduces in the hippocampus of SZ developmental rats.

Implication of Glutamatergic Mechanism for the Behavioral Changes Resulting from Early Maternal Separation during the Development in Juvenile Rats / 대한정신약물학회지

OBJECTIVE: Early maternal separation (EMS) during the development has been known to influence the alteration of behavior in adulthood. Nitric oxide (NO) may have been implicated to play a crucial role in the neurodevelopment as an intracellular and intercellular messenger. This study was designed to investigate the neurochemical mechanism of the behavioral changes resulting from EMS during the development in juvenile rats. METHODS: Experimental group consisted of subjects that were removed and weaned from the day on postnatal day 15. Control group were the litters that experienced no EMS until postnatal day 21. On postnatal day 15 and 36, the locomotor activity (LA) was measured. On postnatal day 36 the behavioral changes in the forced swimming test (FST) were also measured. Test drugs were intraperitoneally injected including MK-801 (0.5 mg/kg), N omega-nitro-L-arginine (L-NA, 20 mg/kg), paroxetine (20 mg/kg), and bupropion (150 mg/kg). RESULTS:EMS produced the decrease of LA significantly in juvenile rats (p<0.001). Both MK-801 and L-NA increased LA in experimental group (p<0.001) and control group (p<0.05). The degree of increase was higher in experimental group than in control group. However, both paroxetine and bupropion increased LA in experimental group (p<0.001, p<0.05), but not in control group. In the FST, immobility was significantly increased in experimental group compared with control group (p<0.001). The increases of immobility in experimental group were abolished after injecting MK-801, L-NA, paroxetine, and bupropion, respectively. CONCLUSION: These results indicate that EMS during the development can lead to behavioral abnormalities in juvenile rats. The underlying neurochemical mechanism of this behavioral changes may be, in part, related to the glutamatergic NMDA-NO pathway. This suggests that glutamatergic NMDA-NO pathway vulnerable to stress may predispose to depression.

Effect of Berberine on Cell Survival in the Developing Rat Brain Damaged by MK-801

Berberine is an isoquinoline alkaloid isolated from goldenthread, Coptidis Rhizoma and shown to have many biological and pharmacological effects. We previously reported that berberine promotes cell survival and differentiation of neural stem cells. To examine whether berberine has survival promoting effect on damaged neuronal cells, we generated a cellular model under oxidative stress and an neonatal animal model of degenerating brain disease by injecting MK-801. MK801, a noncompetitive antagonist of N-methyl-d-aspartate (NMDA) receptors, acts as a neurotoxin in developing rats by inhibiting NMDA receptors and induce neuronal cell death. We found that the survival rate of the SH-SY5Y cells under oxidative stress was increased by 287% and 344%, when treated with 1.5 and 3.0microg/ml berberine, respectively. In the developing rats injected by MK801, we observed that TUNEL positive apoptotic cells were outspread in entire brain. The cell death was decreased more than 3 fold in the brains of the MK-801-induced neurodegenerative animal model when berberine was treated to the model animals. This suggests that berberine promotes activity dependent cell survival mediated by NMDA receptor because berberine is known to activate neurons by blocking K+ current or lowering the threshold of the action potential. Taken together, berberine has neuroprotective effect on damaged neurons and neurodegenerating brains of neonatal animal model induced by MK-801 administration.

The Effects of Glutamate NMDA Receptor Antagonist MK-801 on Gastrointestinal Motility after Middle Cerebral Artery Occlusion in Rats

This study was performed to investigate the role of glutamate neurotransmitter system on gastrointestinal motility in a middle cerebral artery occlusion (MCAO) model of rats. The right middle cerebral artery was occluded by surgical operation, and intestinal transit and geometric center as a parameter of gastrointestinal motility and expression of c-Fos protein in the insular cortex and cingulate cortex were measured at 2 and 12 h after MCAO. Intestinal transit was 66.3+/-7.5% and 62.3+/-5.7% 2 and 12 h after sham operation, respectively, and MCAO significantly decreased intestinal transit to 39.0+/-3.5% and 47.0+/-5.1% at 2 and 12 h after the occlusion, respectively (p<0.01). The geometric center was 5.6+/-0.4 and 5.2+/-0.9 at 2 and 12 h after sham operation, respectively, and MCAO significantly decreased geometric center to 2.9+/-0.8 and 3.0+/-0.3 at 2 and 12 h after the occlusion, respectively (p<0.01). In control animals, injection of atropine decreased intestinal transit to 35.9+/-5.2%, and injection of glutamate NMDA receptor antagonist, MK-801, decreased intestinal transit to 28.8+/-9.5%. Pretreatment with MK-801, a glutamate NMDA receptor antagonist, in the MCAO group decreased intestinal transit to 11.8+/-3.2%, which was significantly decreased compared to MCAO group (p<0.01). MCAO markedly increased the expression of c-Fos protein in the insular cortex and cingulate cortex ipsilateral to the occlusion 2 h after MCAO, and pretreatment with MK-801 produced marked reduction of c-Fos protein expression compared to MCAO group (p<0.01). These results suggest that modulation of gastrointestinal motility after MCAO might be partially mediated through a glutamate NMDA receptor system.