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In the central nervous system, nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS). In the past 20 years, the studies in our group and other laboratories have suggested a significant involvement of nNOS in a variety of neurological and neuropsychiatric disorders. In particular, the interactions between the PDZ domain of nNOS and its adaptor proteins, including post-synaptic density 95, the carboxy-terminal PDZ ligand of nNOS, and the serotonin transporter, significantly influence the subcellular localization and functions of nNOS in the brain. The nNOS-mediated protein-protein interactions provide new attractive targets and guide the discovery of therapeutic drugs for neurological and neuropsychiatric disorders. Here, we summarize the work on the roles of nNOS and its association with multiple adaptor proteins on neurological and neuropsychiatric disorders.
Subject(s)
Humans , Nitric Oxide Synthase Type I/metabolism , Adaptor Proteins, Signal Transducing , Brain/metabolism , Nervous System DiseasesABSTRACT
In the central nervous system, nitric oxide (NO), a free gas with multitudinous bioactivities, is mainly produced from the oxidation of L-arginine by neuronal nitric oxide synthase (nNOS). In the past 20 years, the studies in our group and other laboratories have suggested a significant involvement of nNOS in a variety of neurological and neuropsychiatric disorders. In particular, the interactions between the PDZ domain of nNOS and its adaptor proteins, including post-synaptic density 95, the carboxy-terminal PDZ ligand of nNOS, and the serotonin transporter, significantly influence the subcellular localization and functions of nNOS in the brain. The nNOS-mediated protein-protein interactions provide new attractive targets and guide the discovery of therapeutic drugs for neurological and neuropsychiatric disorders. Here, we summarize the work on the roles of nNOS and its association with multiple adaptor proteins on neurological and neuropsychiatric disorders.
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OBJECTIVE@#To investigate the mechanism of valproic acid (VPA) -induced impairment of the dendritic spines and synapses in the prefrontal cortex (PFC) for causing core symptoms of autism spectrum disorder (ASD) in mice.@*METHODS@#Female C57 mice were subjected to injections of saline or VPA on gestational days 10 and 12, and the male offspring mice in the two groups were used as the normal control group and ASD model group (n=10), respectively. Another 20 male mice with fetal exposure to VPA were randomized into two groups for stereotactic injection of DMSO or Wortmannin into the PFC (n=10). Open field test, juvenile play test and 3-chamber test were used to evaluate autistic behaviors of the mice. The density of dendrite spines in the PFC was observed with Golgi staining. Western blotting and immunofluorescence staining were used to detect the expressions of p-PI3K, PI3K, p-AKT, AKT, p-mTOR, mTOR and the synaptic proteins PSD95, p-Syn, and Syn in the PFC of the mice.@*RESULTS@#Compared with the normal control mice, the mice with fetal exposure to VPA exhibited obvious autism-like behaviors with significantly decreased density of total, mushroom and stubby dendritic spines (P < 0.05) and increased filopodia dendritic spines (P < 0.05) in the PFC. The VPA-exposed mice also showed significantly increased expressions of p-PI3K/PI3K, p-AKT/AKT, and p-mTOR/mTOR (P < 0.01) and lowered expressions of PSD95 and p-Syn/Syn in the PFC (P < 0.05 or 0.001). Wortmannin injection into the PFC obviously improved the ASD-like phenotype and dendritic spine development, down-regulated PI3K/Akt/mTOR signaling pathway and up-regulated the synaptic proteins in VPA-exposed mice.@*CONCLUSION@#In male mice with fetal exposure to VPA, excessive activation of PI3K/Akt/mTOR signaling pathway and decreased expressions of the synaptic proteins PSD95 and p-Syn cause dendritic spine damage and synaptic development disturbance in the PFC, which eventually leads to ASD-like phenotype.
Subject(s)
Animals , Female , Male , Mice , Autism Spectrum Disorder/chemically induced , Autistic Disorder/chemically induced , Dendritic Spines , Disease Models, Animal , Phosphatidylinositol 3-Kinases , Prefrontal Cortex , Prenatal Exposure Delayed Effects , Valproic Acid/adverse effectsABSTRACT
Objective:To investigate the effect of GluA2-3Y which is an inhibitor of AMPA(α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid) receptor internalization on cognitive function and hippocampal postsynaptic protein expression in rats with chronic cerebral hypoperfusion.Methods:Forty-eight adult male SD rats were randomly divided into Sham group, 2VO group, high-dose GluA2-3Y group and low-dose GluA2-3Y group according to random number table, with 12 rats in each group.The chronic cerebral hypoperfusion model of rat was established by two vessel occlusion (2VO) while the Sham operation was performed in rats of Sham group.The rats in high dose GluA2-3Y group and low dose GluA2-3Y group were intraperitoneal injected with 3 μmol/kg and 0.03 μmol/kg GluA2-3Y respectively once a day for 2 weeks. Rats in 2VO group and Sham group were intraperitoneally injected with control peptide. Morris water maze test and new object recognition test were performed to evaluate the learning and memory ability of rats, and Western blot was used to evaluate the expression of Akt1、GSK3β、p-GSK3β、GluA2 and PSD-95 in rat hippocampus. The expressions of GluA2 and PSD-95 in rat hippocampus were evaluated by immunofluorescence. SPSS 23.0 software was used for data analysis. The comparison between multiple groups was analyzed by one-way ANOVA and repeated measurement ANOVA was used to analyze Morris water maze results. And independent-samples t-test was used for pairwise comparisons. Results:(1)In Morris water maze trials, the results of repeated measurement ANOVA showed that the interaction between group and time of escape latency of rats in each group was not significant ( F=0.79, P>0.05), and the group main effect and time main effect were significant ( F=24.44, 40.42, both P<0.05). On the 5th day of navigation trials, the escape latency of rats in 2VO group was longer than that in sham group ( t=5.87, P<0.05). The escape latency of rats in low dose GluA2-3Y group and high dose GluA2-3Y group were significantly shorter than that in 2VO group ( t=2.20, 3.41, both P<0.05), but there was no significant difference between low dose GluA2-3Y group and high dose GluA2-3Y group ( t=1.37, P>0.05). The target quadrant residence time and resolution coefficient ((14.57±1.40)s, (0.15±0.10)) in 2VO group were significantly lower than those in Sham group ((23.71±2.57)s, (0.40±0.06)) ( t=3.23, 2.24, both P<0.05), while the target quadrant residence time in high dose GluA2-3Y group ((20.19±1.53)s) and low dose GluA2-3Y group ((20.31±2.06)s) were longer than that in 2VO group( t=2.71, 2.35, both P<0.05). The discrimination coefficients in high dose GluA2-3Y group (0.47±0.10) and low dose GluA2-3Y group (0.59±0.06) were higher than that of 2VO group ( t=2.21, 3.94, both P<0.05). (2)The Western blot results showed that the expression of PSD-95 and GluA2 in hippocampus of rats in 2VO group were significantly lower than those in Sham group ( t=2.31, 2.20, both P<0.05), and the expression of PSD-95 in high dose GluA2-3Y group (1.026±0.056) was significantly higher than that in 2VO group ((0.760±0.061), t=2.49, P<0.05), while there was no significant difference between low-dose GluA2-3Y group and 2VO group( t=0.96, P>0.05). The expression of GluA2 in low-dose GluA2-3Y group was higher than that in 2VO Group ((1.130±0.087), (0.766±0.080), t=2.37, P<0.05), but there was no significant difference between high-dose GluA2-3Y group and 2VO group( t=1.06, P>0.05). (3) Immunofluorescence showed that compared with Sham group, the expression of PSD-95 and GluA2 in 2VO group decreased ( t=4.23, 2.57, P<0.05). Compared with 2VO group, the expression of PSD-95 and GluA2 in high dose GluA2-3Y group and low dose GluA2-3Y group increased significantly, and the differences were statistically significant (PSD-95: (7.757±0.578), (12.057±0.578), t=3.14, 6.96, both P<0.05; (9.721±0.950), (16.610±0.950), t=4.56, 9.34, both P<0.05). (4) The results of Western blot showed that the expression GSK3β in hippocampus of rats in each group were not statistically different( F=2.03, P>0.05). There were significant differences in the expression of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in hippocampus of rats in each group ( F=8.30, 4.76, 3.57, all P<0.05). Compared with Sham group, the levels of Akt1, p-GSK3β and the percentage of p-GSK3β/GSK3β in 2VO group were significantly lower ( t=3.00, 2.81, 3.17, all P<0.05). Compared with 2VO group, the levels of Akt1, p-GSK3β and p-GSK3β/GSK3β percentage in low dose GluA2-3Y group and high-dose GluA2-3Y group were significantly higher (Akt1: t=2.05, 5.20, both P<0.05; p-GSK3β: t=2.49, 4.15, both P<0.05; p-GSK3β/GSK3β percentage: t=2.30, 2.97, both P<0.05). Conclusion:GluA2-3Y, an AMPA receptor internalization inhibitor, can alleviate the cognitive impairment in rats with chronic cerebral hypoperfusion, which may be related to the increased expression of Akt1, p-GSK3β and postsynaptic proteins.
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Objective To investigate the effects of ephedrine on the expression levels of brain-derived neurotropic factor (BDNF) and postsynaptic density protein 95 (PSD95) and synapsin1 in PC12 cells, and to explore the mechanism of ephedrine cytotoxicity on PC12. Methods After PC12 cells were treated with different concentration of ephedrine, the cell survival rate was measured by the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. The morphology changes of PC12 cells were observed by an inverted microscope. Western blot was used to detect the protein expression levels of BDNF, PSD95 and synapsin1 in PC12 cells. Results Ephedrine decreased the viability of PC12 cell in a concentration-dependent manner,with an IC25 and IC50 of 0.536 mmol and 2.8 mmol, respectively, for PC12 cell death. As ephedrine concentration increased, PC12 cells became smaller in size, with blurred boundary blurred, reduced synapses and shorter axon lengths. The expression levels of BDNF and PSD95 increased significantly. Meanwhile the expression level of synapsin1 decreased. Conclusion The mechanism of ephedrine cytotoxicity on PC12 may be related to the expression levels of BDNF, PSD95 and synapsin1.
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In ischemic stroke, increased level of neuronal complex of nitric oxide synthase (nNOS)-postsynaptic density protein-95 (PSD-95) plays an important role in neuronal damage. We aimed to establish a screening model to identify compounds capable of uncoupling nNOS interaction with PSD-95. In this model, human embryonic kidney-293T (HEK-293T) cells were transfected with either pCDH-Flag-nNOS or pcDNA3.1-PSD-95 plasmid to obtain the protein of Flag-nNOS or PSD-95. Incubating Flag-nNOS with PSD-95 causes formation of the nNOS-PSD-95 complex. ZL006, a known uncoupler of nNOS-PSD-95 interaction, can disturb the interaction between Flag-nNOS and PSD-95, serving as a positive control. The method coupling antibodies to magnetic beads with glutaraldehyde was used to decrease the cost and increase the efficiency. To establish that our model is suitable for selecting nNOS-PSD-95 uncouplers, we evaluated the ability of IC87201, another reported uncoupler of nNOS-PSD-95 interaction, and structural analogs of ZL006. IC87201 and one structure analog of ZL006 showed uncoupling effect, supporting that our model can be used to select different types uncoupler blocking nNOS-PSD-95 interaction.
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Magnetic molecularly imprinted polymers(MMIPs) were prepared with ZL006 as template, acrylamide(AA) as the functional monomer, and acetonitrile as pore-forming agent; then Fourier transform infrared spectroscopy(FT-IR) and scanning electron microscopy(SEM) were used to characterize their forms and structures. Simultaneously, the MMIPs prepared previously were used as sorbents for dispersive magnetic solid phase extraction(DSPE) to capture and identify potential nNOS-PSD-95 uncouplers from extracts of Trifolium pratense and the the activities of the screened compounds were evaluated by the neuroprotective effect and co-immunoprecipitation test. The experiment revealed that the successfully synthesized MMIPs showed good dispersiveness, suitable particle size and good adsorption properties. Formononetin, prunetin and biochanin A were separated and enriched from Trifolium pratense by using the MMIPs as artificial antibodies and finally biochanin A was found to have higher cytoprotective action and uncoupling action according to the neuroprotective effect and co-immunoprecipitation test.
Subject(s)
Adsorption , Genistein , Chemistry , Molecular Imprinting , Phytochemicals , Chemistry , Polymers , Chemistry , Solid Phase Extraction , Spectroscopy, Fourier Transform Infrared , Trifolium , ChemistryABSTRACT
Objective:To study effects of neuroligin (NLG) on the proliferation and apoptosis in human neuroblastoma SH-SY5Y cells.Methods:The SH-SY5Y cells were cultured in vitro for 24 hours,and then transfected with NLG siRNA at dose of 50,100,200 μmol/L,respectively.MTT procedure was used to detect the cell proliferation,and expression levels of apoptosis gene including Bax or Bcl-2 and Bcl-xl were measured by RT-PCR.Results:Compared to control groups proliferation of SH-SY5Y cells were distinctly inhibited after NLG siRNA transfection accompany with a dose-dependent,which was caused by activation of apoptosis.Conclusions:NLG protect neuron by inhibiting apoptosis.
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AIM To explore the effects of Kaixin Powder (Polygalae Radix,Ginseng Radix et Rhizoma,Poria and Acori tatarinowii Rhizoma) on hippocampal long-term potentiation (LTP) in vivo in APP/PS1 transgenic mice and expression of PSD-95 in hippocampus CA1 area and cerebral cortex.METHODS Thirty-two 3-monthold male APP/PS1 mice were randomly divided into model group,Donepezil [0.75 mg/(kg · d)] group,Kaixin Powder [1.5,3 g/(kg · d)] groups.C57/BL6 mice were used as the control group.Kaixin Powder and Donepezil were administered to the APP/PS1 mice for three months,respectively.Afterwards,the LTP in vivo was recorded in a perforant pathway-dentate gyrus in the hippocampus.Immunohistochemical method was used for measuring the expression of PSD-95 in hippocampus CA1 area and cerebral cortex.RESULTS The fEPSPs slopes were significantly decreased in the model group as compared with the control group.Kaixin Powder or Donepezil treatment significantly enhanced the fEPSPs slopes in the model group.The average optical density of PSD-95 positive cells in hippocampus CA1 area and cerebral cortex was obviously decreased in the model group.Donepezil increased the average optical density of PSD-95 positive cells in hippocampus CA1 area.Kaixin Powder [1.5 g/(kg · d)] increased the average optical density of PSD-95 positive cells in hippocampus CA1 area and cerebral cortex.Kaixin Powder [3 g/(kg · d)] increased the average optical density of PSD-95 positive cells in cerebral cortex.CONCLUSION Kaixin Powder can promote the LTP formation in APP/PS1 transgenic mice and enhance synaptic plasticity,which may be related to the regulation of protein expression of PSD-95.
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Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by high heritability. Recently, autism, the most profound form of ASD, has been increasingly attributed to synaptic abnormalities. Postsynaptic density 95 (PSD95), encoding PSD protein-95, was found essential for synaptic formation, maturation and plasticity at a PSD of excitatory synapse. It is possibly a crucial candidate gene for the pathogenesis of ASD. To identify the relationship between the rs13331 of PSD95 gene and ASD, we performed a case-control study in 212 patients and 636 controls in a Chinese population by using a polymerase chain reaction-restriction fragment length polymerase (PCR-RFLP) assay. The results showed that in genetic analysis of the heterozygous model, an association between the T allele of the rs13331 and ASD was found in the dominant model (OR=1.709, 95% CI 1.227-2.382, P=0.002) and the additive model (OR=1.409, 95% CI=1.104-1.800, P=0.006). Our data indicate that the genetic mutation C>T at the rs13331 in the PSD95 gene is strikingly associated with an increased risk of ASD.
Subject(s)
Aged , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Autism Spectrum Disorder , Genetics , Case-Control Studies , China , Disks Large Homolog 4 Protein , Intracellular Signaling Peptides and Proteins , Genetics , Membrane Proteins , Genetics , Polymorphism, Restriction Fragment Length , Polymorphism, Single NucleotideABSTRACT
Objective To observe the impact of ginkgo biloba extract in rats with chronic cerebral ischemia on the expression of PSD-95 protein and the content of amino acid neurotransmitter.Methods A total of 42 SD rats were divided into the sham group (n=12), the model group (n=14) and the ginkgo biloba extract group (n=14) by random number table method. Cerebral ischemia rats were produced by permanent ligation of bilateral common carotid arteries . The rats in the ginkgo biloba group were intrgastric administrated with ginkgo biloba extract suspension 28 mg/kg daily for 40 days, since 2 hours later after the surgery. The rats in the sham and model groups were intragastric administrated with equal-Volume nomal saline daily for 40 days, since 2 hours later after the surgery. The expression of PSD-95 protein was detected by immunohistochemistry techniques with image analysis. The content of Glu and GABA in the thalamus was determinated by OPA-pre-column derivatization and HPLC fluorescence detection method.Results The expression of PSD-95 protein (cortex was 212.58 ± 45.02vs.244.20 ± 34.28, thalamus was 132.33 ± 28.32 vs.272.00 ± 62.14) were significantly lower in the cortex and thalamus of the model group than those of the sham group (P<0.01). The content of GABA (6 081.46 ± 2 388.91 mmol/Lvs.8 280.45 ± 3 388.49 mmol/L) in the thalamus of the model group rats was significantly lower than the sham group (P<0.05). Ginkgo biloba extract could significantly improve the expression of PSD-95 protein (cortex was 237.89 ± 34.41 vs.212.58 ± 45.02, thalamus was 226.18 ± 75.80 vs. 132.33 ± 28.32) in the cortex and thalamus of chronic cerebral ischemia rats (P<0.01), and significantly improve the content of Glu and GABA (Glu was 10 523.78 ± 3 639.72 mmol/L vs.6 081.46 ± 2 388.91 mmol/L, and GABA was 18 440.93 ± 7 476.88 mmol/Lvs.11 239.83 ± 4 411.79 mmol/L) in thalamus with chronic cerebral ischemic rats compared with the model group rats (P<0.01).Conclusion Ginkgo biloba extract could regulate the levels of Glu, GABA and selectly regulate the PSD-95 experssion in the cortex and thalamus of cerebral ischemia rats.
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Objective To explore the effect of serum testosterone level on the pathologically aggressive behavior and the synaptic plasticity in the prefrontal cortex of puberty rats after gonadectomy. Methods Thirty male rats, 21 days old, were randomly divided into 3 groups: gonadectomized group, model group and control group. The gonadectomized and model groups were given a series of standard stress from 21 days old to puberty to induce animal model of pathological aggressive behavior. Resident-intruder experiment was performed to observe the variation of aggressive behaviors of animals. Enzyme-linked immunosorbent assay was used to examine the serum testosterone level. Western blotting analysis was used to determine the expression of postsynaptics density-95 (PSD-95) and growth associated protein-43 (GAP-43) in the prefrontal cortex. Results Resident-intruder experiment showed that the latency to the first attack in the gonadectomized group decreased significantly (P<0.01,P<0.01) and the attack times after yield increased significantly compared with those in the other two groups (P<0.01,P<0.01). The serum testosterone in the gonadectomized group was significantly decreased compared with the other two groups as shown by ELISA results (P<0.01, P<0.01). In addition, the aggressive-related behavior indices had a moderate to high negative correlation with the testosterone level (P<0.01). Western blotting analysis showed that prefrontal cortex expression of PSD-95 and GAP-43 in the gonadectomized group was significantly lower than those in the other two groups(P<0.01, P<0.01). Conclusion Low serum testosterone level can cause damage to the neuroplasticity of prefrontal cortex in puberty rats, which might be related to the pathologically aggressive behavior.
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Aim To investigate the effect of polysac-charide of Cistanche deserticola ( CDPS) on the impro-ving ability of synaptic plasticity in memory acquisition impairment model mice induced by scopolamine. Methods The KM mice were randomly divided into six groups:scopolamine group, control group, CDPS-treated (25, 50, 100 mg·kg-1 ) group and donepezil group. Memory acquisition impairment model in mice was established with i. p. scopolamine (4 mg·kg-1 ) only once, and orally administered CDPS (25, 50, or 100 mg · kg-1 ) daily for 6 weeks before scopolamine injection. Experimental groups were subjected to step-down test and Morris water maze test. Western blot and RT-PCR analysis were used to examine the expression of GAP-43 , SYP and PSD-95 . Transmission electron microscope was used to observe the change of synaptic number and structures. Results CDPS (25,50,100 mg·kg-1 ) could shorten the incubation period of mice in the water maze test. Control group and CDPS-treated group swam longer in Q3 than scopolamine group. Mo-reover, CDPS (50,100 mg·kg-1 ) could significantly reduce the error times and extend the incubation period in the step-down test. The results of Western blot and RT-PCR showed that CDPS significantly improved the expression of GAP-43 at the dose of 25 ,50 mg · kg-1 and SYP at the dose of 25,50, 100 mg·kg-1 in hip-pocampus of mice. However, the biochemical assays did not reveal a significant difference in the basal hipp-ocampal levels of the PSD-95 . The ultra-thin speci-mens of hippocampus showed that the number of syn- apse was increased in CDPS-treated group. Conclu-sions Scopolamine can induce the learning and mem-ory deficits in mice to make related protein expression abnormalities in hippocampus mice, thus this causes the change of synaptic plasticity, which leads to a change in the ability of learning and memory. And CDPS can improve the expression of SYP and GAP-43 , increase number of synapses, recover synaptic plastici-ty, and improve the ability of learning and memory in mice.
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Glutamate receptors are important components of synaptic transmission in the nervous system. Especially, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors mediate most abundant excitatory synaptic transmission in the brain. There is elaborate mechanism of regulation of AMPA receptors including protein synthesis/degradation, intracellular trafficking, exocytosis/endocytosis and protein modification. In recent studies, it is revealed that functional dysregulation of AMPA receptors are related to major psychiatric disorders. In this review, we describe the structure and function of AMPA receptors in the synapse. We will introduce three steps of mechanism involving trafficking of AMPA receptors to neuronal membrane, lateral diffusion into synapses and synaptic retention by membrane proteins and postsynaptic scaffold proteins. Lastly, we will describe recent studies showing that regulation of AMPA receptors is important pathophysiological mechanism in psychiatric disorders.
Subject(s)
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid , Brain , Diethylpropion , Diffusion , Membrane Proteins , Membranes , Nervous System , Neurons , Propionates , Proteins , Receptors, AMPA , Receptors, Glutamate , Retention, Psychology , Synapses , Synaptic TransmissionABSTRACT
OBJECTIVE: Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels mediate the hyperpolarizationactivated currents (Ih) that participate in regulating neuronal membrane potential and contribute critically to pacemaker activity, promoting synchronization of neuronal networks. However, distinct regional and cellular localization of HCN channels in the brain have not been precisely defined. Aim of this study was to verify the precise cellular location of HCN1 channels in rat cerebellum to better understand the physiological role these channels play in synaptic transmission between CNS neurons. METHODS: HCN1 expression in rat brain was analyzed using immunohistochemistry and electron-microscopic observations. Postsynaptic density-95 (PSD-95), otherwise known as locating and clustering protein, was also examined to clarify its role in the subcellular location of HCN1 channels. In addition, to presume the binding of HCN1 channels with PSD-95, putative binding motifs in these channels were investigated using softwaresearching method. RESULTS: HCN1 channels were locally distributed at the presynaptic terminal of basket cell and exactly corresponded with the location of PSD-95. Moreover, nine putative SH3 domain of PSD-95 binding motifs were discovered in HCN1 channels from motif analysis. CONCLUSION: Distinct localization of HCN1 channels in rat cerebellum is possible, especially when analyzed in conjunction with the SH3 domain of PSD-95. Considering that HCN1 channels contribute to spontaneous rhythmic action potentials, it is suggested that HCN1 channels located at the presynaptic terminal of neurons may play an important role in synaptic plasticity.
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Animals , Rats , Action Potentials , Brain , Cerebellar Cortex , Cerebellum , Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels , Immunohistochemistry , Membrane Potentials , Neurons , Plastics , Presynaptic Terminals , src Homology Domains , Synaptic TransmissionABSTRACT
Here, we investigated the temporal change of post synapse signaling molecules, post synaptic density-95 (PSD-95) and neuronal nitric oxide synthase (nNOS) using immunohistochemistry during voluntary running with upregulated neurogenesis. Rate of running was stabilized after two weeks of the six week trial. By using immunohistochemsitry for phosphorylated cAMP response element binding protein (pCREB) and polysialylatedneural cell adhesion molecules (PSA-NCAM), we observed that the differentiation in dentate granule cells of adult mouse hippocampus increased at 1 and 2 weeks of voluntary running. We found that, at 6 weeks of voluntary running, the differentiation in dentate granule cells of adult mouse hippocampus returned to sedentary control levels. On the other hand, PSD-95 and nNOS immunoreactivity decreased in the inner molecular layer in the dentate gyrus of hippocampus after 1 and 2 weeks of voluntary running. At 6 weeks of voluntary running, the density of the PSD-95 and nNOS in the inner molecular layer was returned to the sedentary control level. The reactivity of nicotinamide dinucleotide phosphate diaphorase (NADPH-diaphorase), the marker of nitric oxide synthase activity, confirmed the change of nNOS in the inner molecular layer during voluntary running. These results demonstrate that the differentiation and the synaptic activity of granule cells during voluntary running are changed reciprocally once the rate of running has stabilized. These granule cell changes during voluntary running suggest an adaptation response to the new environment.
Subject(s)
Adult , Animals , Humans , Mice , Cell Adhesion Molecules , Cyclic AMP Response Element-Binding Protein , Dentate Gyrus , Hand , Hippocampus , Immunohistochemistry , Neurogenesis , Neurons , Niacinamide , Nitric Oxide Synthase , Nitric Oxide Synthase Type I , Running , SynapsesABSTRACT
The mechanism of central nervous system (CNS) dysfunction in uremia are multifactorial and only partially characterized. Studies using hippocampal formation (HF) evaluate the relationship between the uremia and memory impairment. Immunoblots with calcium permeable NMDA (N-methyl-D-aspartate) and AMPA (2-amino-3-hydroxy-5-methylisoxazole-4-propinoic acid) receptors and their associated PSD-95 proteins after chronic renal failure (CRF) provided significant new informations. CRF rats induced by 5/6 nephrectomized had significant effects on up-regulation of PSD-95 protein rather than those of calcium permeable NMDA and AMPA receptor subunits. Up-regulation of PSD-95 after CRF might be associated with the enhanced activity of NMDA and/or AMPA receptors, thereby leads to the intracellular Ca2+ accumulation and functional neuronal cell damage subsequently. Degradation of intermediate filament 200 (NF200) in the axon after CRF may induce an impairment of intracellular transport and eventual cellular dysfunction through destruction of the neuronal cytoarchitecture. These data suggest that up-regulation of PSD-95 in CRF may increase the functional derangement between the nerve cells and ultimately lead to memory impairment.
Subject(s)
Animals , Rats , alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid , Axons , Calcium , Central Nervous System , Hippocampus , Intermediate Filaments , Kidney Failure, Chronic , Memory , N-Methylaspartate , Neurons , Receptors, AMPA , Up-Regulation , UremiaABSTRACT
Objective To investigate the mechanism of the soluble A? oligomers-induced alteration of synaptic proteins. Methods This study applied immunocytochemistry technique to investigate the changes of the expression of postsynaptic density-95(PSD-95) in primary hippocampal neurons, which was exposed to A?_ 25-35 after NMDAR antagonist or agonist treatment. Results The results showed that A?_ 25-35 downregulated PSD-95 protein in a dose- and time-dependent manner. Treatment of cells with MK801 (a general NMDA receptor antagonist) prevented A?-induced PSD-95 degradation. Moreover, when extrasynaptic NMDA receptors were blocked by ifenprodil (a NR2B subunit specific antagonist), the A?-induced downregulation of PSD-95 was significantly attenuated. Whereas, when synaptic NMDA receptors were blocked by bicuculline (a GABA receptor antagonist) in combination with MK801, the PSD-95 degradation did not change significantly.Conclusion The results suggest that A?-induced downregulation of PSD-95 depends on NMDAR activity, and extrasynaptic NMDA receptors may be involved in A?-induced synaptic protein degradation.