OBJECTIVES: To investigate the effect of orexin-A-mediated regulation of ionotropic glutamate receptors for promoting motor function recovery in rats with spinal cord injury (SCI). METHODS: Thirty-six newborn SD rats (aged 7-14 days) were randomized into 6 groups (n=6), including a normal control group, a sham-operated group, and 4 SCI groups with daily intrathecal injection of saline, DNQX, orexin-A, or orexin-A+DNQX for 3 consecutive days after PCI. Motor function of the rats were evaluated using blood-brain barrier (BBB) score and inclined plane test 1 day before and at 1, 3, and 7 days after SCI. For patch-clamp experiment, spinal cord slices from newborn rats in the control, sham-operated, SCI, and SCI+orexin groups were prepared, and ventral horn neurons were acutely isolated to determine the reversal potential and dynamic indicators of glutamate receptor-mediated currents under glutamate perfusion. RESULTS: At 3 and 7 days after SCI, the orexin-A-treated rats showed significantly higher BBB scores and grip tilt angles than those with other interventions. Compared with those treated with DNQX alone, the rats receiving the combined treatment with orexin and DNQX had significantly higher BBB scores and grip tilt angles on day 7 after PCI. In the patch-clamp experiment, the ventral horn neurons from SCI rat models exhibited obviously higher reversal potential and greater rise slope of glutamate current with shorter decay time than those from sham-operated and orexin-treated rats. CONCLUSIONS Orexin-A promotes motor function recovery in rats after SCI possibly by improving the function of the ionotropic glutamate receptors.
Animals ; Spinal Cord Injuries/drug therapy* ; Rats ; Rats, Sprague-Dawley ; Receptors, Ionotropic Glutamate/metabolism* ; Recovery of Function/drug effects* ; Orexins/pharmacology* ; Male ; Female ; Animals, Newborn ; Neuropeptides/pharmacology* ; Intracellular Signaling Peptides and Proteins/pharmacology*

This study investigated the effect of Suanzaoren Decoction on the expression of N-methyl-D-aspartate receptors(NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors(AMPAR) in the hippocampus and synaptic plasticity in rats with conditioned fear-induced anxiety. The effect of Suanzaoren Decoction on rat behaviors were evaluated through open field experiment, elevated plus maze experiment, and light/dark box experiment. Enzyme-linked immunosorbent assay(ELISA) was used to measure the levels of glutamate(Glu) and γ-aminobutyric acid(GABA) in the rat hippocampus. Real-time fluorescence quantitative PCR(qRT-PCR) and Western blot were employed to assess the gene and protein expression of ionotropic glutamate receptors in the hippocampal region. Transmission electron microscopy was utilized to observe the changes in the ultrastructure of synaptic neurons in the hippocampal region. Long-term potentiation(LTP) detection technique was employed to record the changes in population spike(PS) amplitude in the hippocampal region of mice in each group. The behavioral results showed that compared with the model group, the Suanzaoren Decoction group effectively increased the number of entries into open arms, time spent in open arms, percentage of time spent in open arms out of total movement time, number of entries into open arms out of total entries into both arms(P<0.01), and significantly increased the time spent in the light box and the number of shuttle crossings(P<0.01). There was an increasing trend in the number of grid crossings, entries into the center grid, and time spent in the center grid, indicating a significant anxiolytic effect. ELISA results showed that compared with the model group, the Suanzaoren Decoction group exhibited significantly reduced levels of Glu, Glu/GABA ratio(P<0.01), and significantly increased levels of GABA(P<0.01) in the rat hippocampus. Furthermore, Suanzaoren Decoction significantly decreased the gene and protein expression of NMDAR(GluN2B and GluN2A) and AMPAR(GluA1 and GluA2) compared with the model group. Transmission electron microscopy results demonstrated improvements in synapses, neuronal cells, and organelles in the hippocampal region of the Suanzaoren Decoction group compared with the model group. LTP detection results showed a significant increase in the PS amplitude changes in the hippocampal region of Suanzaoren Decoction group from 5 to 35 min compared with the model group(P<0.05, P<0.01). In conclusion, Suanzaoren Decoction exhibits significant anxiolytic effects, which may be attributed to the reduction in NMDAR and AMPAR expression levels and the improvement of synaptic plasticity.
Rats ; Mice ; Animals ; Receptors, Ionotropic Glutamate/metabolism* ; Hippocampus ; Neuronal Plasticity ; Receptors, N-Methyl-D-Aspartate/genetics* ; Anxiety/genetics* ; gamma-Aminobutyric Acid

OBJECTIVE: To evaluate the association of GRIK2 and NLGN1 with autism spectrum disorder in a Chinese population. METHODS: We performed spatio-temporal expression analysis of GRIK2 and NLGN1 in the developing prefrontal cortex, and examined the expression of the genes in ASD cases and healthy controls using the GSE38322 data set. Following, we performed a case-control study in a Chinese population. RESULTS: The analysis using the publicly available expression data showed that GRIK2 and NLGN1 may have a role in the development of human brain and contribute to the risk of ASD. Later genetic analysis in the Chinese population showed that the GRIK2 rs6922753 for the T allele, TC genotype and dominant model played a significant protective role in ASD susceptibility (respectively: OR=0.840, p=0.023; OR=0.802, p=0.038; OR=0.791, p=0.020). The NLGN1 rs9855544 for the G allele and GG genotype played a significant protective role in ASD susceptibility (respectively: OR=0.844, p=0.019; OR=0.717, p=0.022). After adjusting p values, the statistical significance was lost (p>0.05). CONCLUSION: Our results suggested that GRIK2 rs6922753 and NLGN1 rs9855544 might not confer susceptibility to ASD in the Chinese population.
Alleles ; Asian Continental Ancestry Group ; Autism Spectrum Disorder ; Autistic Disorder ; Brain ; Case-Control Studies ; Dataset ; Genotype ; Glutamic Acid ; Humans ; Prefrontal Cortex ; Receptors, Ionotropic Glutamate

PURPOSE: Alpha1 (alpha1)-adrenoceptor antagonists are widely used to treat lower urinary tract symptoms. These drugs not only act on peripheral tissues, but also cross the blood-brain barrier and affect the central nervous system. Therefore, alpha1-adrenoceptor antagonists may enhance brain functions. In the present study, we investigated the effects of tamsulosin, an alpha1-adrenoceptor antagonist, on short-term memory, as well as spatial learning and memory, in rats. METHODS: The step-down avoidance test was used to evaluate short-term memory, and an eight-arm radial maze test was used to evaluate spatial learning and memory. TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling) staining was performed in order to evaluate the effect of tamsulosin on apoptosis in the hippocampal dentate gyrus. Patch clamp recordings were used to evaluate the effect of tamsulosin on ionotropic glutamate receptors, such as N-methyl-D-aspartate (NMDA), amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA), and kainate receptors, in hippocampal CA1 neurons. RESULTS: Tamsulosin treatment improved short-term memory, as well as spatial learning and memory, without altering apoptosis. The amplitudes of NMDA-induced ion currents were dose-dependently increased by tamsulosin. However, the amplitudes of AMPA- and kainate-induced ion currents were not affected by tamsulosin. CONCLUSIONS: Tamsulosin enhanced memory function by activating NMDA receptor-mediated ion currents in the hippocampus without initiating apoptosis. The present study suggests the possibility of using tamsulosin to enhance memory under normal conditions, in addition to its use in treating overactive bladder.
Animals ; Apoptosis ; Blood-Brain Barrier ; Brain ; Central Nervous System ; Dentate Gyrus ; Hippocampus* ; In Situ Nick-End Labeling ; Learning ; Lower Urinary Tract Symptoms ; Memory* ; Memory, Short-Term ; N-Methylaspartate ; Neurons ; Patch-Clamp Techniques ; Rats* ; Receptors, Ionotropic Glutamate ; Receptors, Kainic Acid ; Receptors, N-Methyl-D-Aspartate ; Urinary Bladder, Overactive

Dopamine has long time considered as the main player in drug addiction. However, growing body of literature strongly supports a role for glutamate in addiction. 2-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors, one of the ionotropic glutamate receptors, are known to be involved in different forms of synaptic plasticity, and behaviors such as learning and memory. As drug addiction is a chronic brain disease with characteristics of craving and relapse, it is often considered as a maladapted form of drug-induced long-term memory. Experimental evidence strongly indicates that AMPA receptor has an important role in the development of drug addiction. Studies with animal models of drug addiction, such as behavioral sensitization and drug self-administration, demonstrate that AMPA receptor-mediated synaptic plasticity may underlie the neuronal mechanisms for such important characteristics of addiction as drug craving.
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid ; Brain Diseases ; Diethylpropion ; Dopamine ; Glutamic Acid ; Learning ; Memory ; Memory, Long-Term ; Models, Animal ; Neurons ; Nucleus Accumbens ; Plastics* ; Receptors, AMPA* ; Receptors, Ionotropic Glutamate ; Recurrence ; Street Drugs* ; Substance-Related Disorders

In the present study, the modulatory effect of AMPA receptors on gamma-aminobutyric acid (GABA) transporter current was investigated on enzymatically isolated horizontal cells of carp retina. The GABA transporter current elicited by 1 mmol/L GABA was decreased immediately after pre-application of AMPA (30 mumol/L or 3 mmol/L) for 50 s. Application of 10 mmol/L BAPTA in intracellular solution inhibited the suppression effect of AMPA on GABA transporter current. The suppression effect induced by co-application of 3 mmol/L AMPA and 3 mmol/L NMDA was similar to that of 3 mmol/L AMPA or 3 mmol/L NMDA alone. These results suggest that the activation of AMPA receptors inhibits GABA transporter-mediated current by affecting intracellular Ca(2+) processes in the retinal horizontal cells, which is identical with the modulatory effect of NMDA receptors on GABA transporters.
Animals ; Carps ; Egtazic Acid ; analogs & derivatives ; pharmacology ; GABA Plasma Membrane Transport Proteins ; metabolism ; Receptors, Ionotropic Glutamate ; metabolism ; Retinal Horizontal Cells ; metabolism ; gamma-Aminobutyric Acid ; pharmacology

BACKGROUND: Ionotropic glutamate receptors of the N-methyl-D-aspartate receptor (NMDAR) type are expressed on keratinocytes and play a role in the proliferation, differentiation, and cornification of keratinocytes. However, the expression profile of NMDAR and its role in cutaneous malignancy is unclear. OBJECTIVE: We analyzed the expression of NMDAR-1 in cutaneous squamous cell carcinoma (SCC) and investigated the relationship between NMDAR-1 expression and clinicopathological parameters. METHODS: Thirty-two patients with biopsy-proven cutaneous SCC were enrolled in this study. Each patient was analyzed for tumor diameter, location, local recurrence, and metastasis by conducting a chart review. The SCC specimens were histologically divided into differentiated and undifferentiated groups based on Broders' system. NMDAR-1 expression was examined by performing immunohistochemistry, and the relative staining intensity in the SCCs was graded into 5 levels. According to the staining intensity of NMDAR-1, the specimens were categorized into two groups: the higher group and the lower group. RESULTS: Fifteen (88%) of 17 tumors in the higher group were differentiated SCC, whereas 14 (93%) of 15 tumors in the lower group were undifferentiated SCC. In addition, NMDAR-1 expression was inversely correlated with metastasis (p=0.049). Local recurrence was associated with a lower staining intensity, but the results were not statistically significant. CONCLUSION: Our results demonstrate that NMDAR-1 expression in cutaneous SCC is significantly correlated with its differentiation and metastasis. Therefore, it may be a prognostic indicator for cutaneous SCC.
Carcinoma, Squamous Cell ; Humans ; Immunohistochemistry ; Keratinocytes ; N-Methylaspartate ; Neoplasm Metastasis ; Receptors, Ionotropic Glutamate ; Recurrence

BACKGROUND: Glutamate is the predominant excitatory neurotransmitter in the central and peripheral nervous system and has known to be involved in nociceptive transmission and central sensitization. It acts through ligand gated ionotropic glutamate receptors (iGluRs) and G protein-coupled metabotropic glutamate receptors (mGluRs). And mGlu 1, 5 receptors have been recognized to play a role in nociceptive processing. We want to investigate whether central mGluR1 and mGluR5 antagonists could reverse the behavioral signs of weight bearing and secondary mechanical hyperalgesia induced by chronic knee joint inflammation. METHODS: MGluR1 antagonist, (RS)-1-aminoindan-1,5-dicarboxylic acid (AIDA: 25, 50, 100 microM/10 microliter, n = 7 per group) and selective mGluR5 antagonist, 2-methyl-6-(phenylethynyl)-pyridine (MPEP: 25, 100, 200 nM/10 microliter, n = 7 per group) were injected intrathecally 5 days after Complete Freund's Adjuvant (CFA, 150 microliter) injection into knee joint and behavior signs of weight bearing and secondary mechanical hyperalgesia were observed. RESULTS: CFA significantly reduced the magnitude of right hind paw weight bearing and decreased the withdrawal threshold to mechanical stimulation compared to contralateral side. Higher dose of AIDA (100 microM) significantly reversed the reduction of weight bearing, but MPEP did not. AIDA reversed the decrease of the paw withdrawal threshold to mechanical stimulation at the dosage of 50 and 100 microM respectively. MPEP significantly increased the paw withdrawal threshold to mechanical stimulation in a dose dependent manner. CONCLUSIONS: Group I mGluRs were involved in maintenance of primary and secondary mechanical hyperalgesia.
Animals ; Arthritis ; Central Nervous System Sensitization ; Freund's Adjuvant ; Glutamic Acid ; Hyperalgesia ; Inflammation ; Knee Joint* ; Knee* ; Neurotransmitter Agents ; Peripheral Nervous System ; Rats* ; Receptors, Ionotropic Glutamate ; Receptors, Metabotropic Glutamate ; Weight-Bearing

This study examined the effects of N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and kainate on basal and electrically-evoked release of acetylcholine (ACh) from the rat hippocampal and striatal slices which were preincubated with [3H]choline. Unexpectedly, the basal and evoked ACh release were not affected at all by the treatment with NMDA (3~100microM), AMPA (1~100microM) or kainate (1~100microM) in hippocampal slices. However, in striatal slices, under the Mg2 -free medium, 30microM NMDA increased the basal ACh release with significant decrease of the electrically- evoked releases. The treatment with 1microM MK-801 not only reversed the 30microM NMDA-induced decrease of the evoked ACh release, but also attenuated the facilitatory effect of 30microM NMDA on the basal ACh release. The treatment with either 30microM AMPA or 100microM kainate increased the basal ACh release without any effects on the evoked release. The treatment with 10microM NBQX abolished the AMPA- or kainate-induced increase of the basal ACh release. Interestingly, NBQX significantly attenuated the evoked release when it was treated with AMPA, although it did not affect the evoked release alone without AMPA. These observations demonstrate that in hippocampal slices, ionotropic glutamate receptors do not modulate the ACh release in cholinergic terminals, whereas in striatal slices, activations of ionotropic glutamate receptors increase the basal ACh release though NMDA may decrease the electrically-evoked ACh release.
Acetylcholine* ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid* ; Animals ; Diethylpropion ; Dizocilpine Maleate ; Hippocampus ; Kainic Acid* ; N-Methylaspartate* ; Rats* ; Receptors, Ionotropic Glutamate

Ca2+ influx appears to be important for triggering myoblast fusion. It remains, however, unclear how Ca2+ influx rises prior to myoblast fusion. Recently, several studies suggested that NMDA receptors may be involved in Ca2+ mobilization of muscle, and that Ca2+ influx is mediated by NMDA receptors in C2C12 myoblasts. Here, we report that other types of ionotropic glutamate receptors, non-NMDA receptors (AMPA and KA receptors), are also involved in Ca2+ influx in myoblasts. To explore which subtypes of non-NMDA receptors are expressed in C2C12 myogenic cells, RT-PCR was performed, and the results revealed that KA receptor subunits were expressed in both myoblasts and myotubes. However, AMPA receptor was not detected in myoblasts but expressed in myotubes. Using a Ca2+ imaging system, Ca2+ influx mediated by these receptors was directly measured in a single myoblast cell. Intracellular Ca2+ level was increased by KA, but not by AMPA. These results were consistent with RT-PCR data. In addition, KA-induced intracellular Ca2+ increase was completely suppressed by treatment of nifedifine, a L-type Ca2+ channel blocker. Furthermore, KA stimulated myoblast fusion in a dose-dependent manner. CNQX inhibited not only KA-induced myoblast fusion but also spontaneous myoblast fusion. Therefore, these results suggest that KA receptors are involved in intracellular Ca2+ increase in myoblasts and then may play an important role in myoblast fusion.
6-Cyano-7-nitroquinoxaline-2,3-dione ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid ; Kainic Acid* ; Muscle Fibers, Skeletal ; Myoblasts ; Receptors, AMPA ; Receptors, Ionotropic Glutamate ; Receptors, Kainic Acid* ; Receptors, N-Methyl-D-Aspartate