Receptor NR2B Research Articles

Postnatal Neuronal Nogo-A Knockdown Decreased the Message of Glutamatergic Synaptic Proteins.

It is well known that oligodendrocyte-associated Nogo-A protein is an important regulator of axonal outgrowth and an important inhibitor of functional recovery and anatomical plasticity after central nervous system (CNS) injury. Abundant studies of oligodendrocyte-associated Nogo-A function in the uninjured rodent have suggested a role in neuronal development and synaptic function. On the other hand, the roles of neuron-associated (i.e., neuronal) Nogo-A have not been fully investigated. We have previously shown that neuronal Nogo-A influence dendritic spine density and morphology in pyramidal neurons of the intact neocortex. To further examine the role of neuronal Nogo-A in this synaptic population, we designed an RNAi directed against Nogo-A, delivered to the developing rat sensorimotor cortex using a neurotropic viral vector adeno-associated virus (AAV) 2/8. We examined the transduced neocortex for molecules important for synaptic plasticity, including N-Methyl-D-Aspartate (NMDA) receptor subunits GRIN2A; glutamate receptor subunit epsilon-1 (NR2A), and GRIN2B; glutamate receptor subunit epsilon-2 (NR2B), as well as postsynaptic density-95 (PSD-95). Furthermore, we also determined the density of excitatory synapses by examining the presynaptic protein vesicular glutamate transporter 1 (vGLut1) as a marker for potential excitatory synapses. Our results showed that neuronal Nogo-A knockdown in postnatal pyramidal neurons of the sensorimotor cortex led to a significant decrease in NMDA receptor subunits NR2A and NR2B messenger RNA when examined as adults. However, there was no difference in PSD-95 expression in comparison to controls. In addition, the decrease in the number of vGlut1(+) puncta on branches of apical dendrites of pyramidal neurons indicated the loss of synapses that have a strong influence on direct current entering the dendrite. Taken together, these results indicate that neuronal Nogo-A may regulate synaptic plasticity by modulating the components of excitatory synapses. This finding represents a novel role in excitatory synaptic formation for neuronal Nogo-A in developing neurons of the uninjured CNS.

Anxiolytic effects of Enterococcus faecalis 2001 on a mouse model of colitis

Ulcerative colitis (UC) is a refractory inflammatory bowel disease, which is known to cause psychiatric disorders such as anxiety and depression at a high rate in addition to peripheral inflammatory symptoms. However, the pathogenesis of these psychiatric disorders remains mostly unknown. While prior research revealed that the Enterococcus faecalis 2001 (EF-2001) suppressed UC-like symptoms and accompanying depressive-like behaviors, observed in a UC model using dextran sulfate sodium (DSS), whether it has an anxiolytic effect remains unclear. Therefore, we examined whether EF-2001 attenuates DSS-induced anxiety-like behaviors. Treatment with 2% DSS for seven days induced UC-like symptoms and anxiety-like behavior through the hole-board test, increased serum lipopolysaccharide (LPS) and corticosterone concentration, and p-glucocorticoid receptor (GR) in the prefrontal cortex (PFC), and decreased N-methyl-d-aspartate receptor subunit (NR) 2A and NR2B expression levels in the PFC. Interestingly, these changes were reversed by EF-2001 administration. Further, EF-2001 administration enhanced CAMKII/CREB/BDNF-Drebrin pathways in the PFC of DSS-treated mice, and labeling of p-GR, p-CAMKII, and p-CREB showed colocalization with neurons. EF-2001 attenuated anxiety-like behavior by reducing serum LPS and corticosterone levels linked to the improvement of UC symptoms and by facilitating the CAMKII/CREB/BDNF-Drebrin pathways in the PFC. Our findings suggest a close relationship between UC and anxiety.

Ciprofol alleviates remifentanil-induced hyperalgesia by regulating α2GABAARs, NR2B, and P-CaMKIIα levels in the spinal cord and hippocampus.

Several studies have shown that propofol administration during surgery effectively attenuates remifentanil-induced hyperalgesia (RIH). Ciprofol, a novel intravenous sedative agent analogous to propofol, has not yet been proven efficacious in alleviating RIH. The present study aimed to investigate the effect of ciprofol on RIH and the possible mechanisms involved. The RIH model was established by an infusion of remifentanil (1 μg·kg-1·min-1) 60min in rats with incisional pain. Ciprofol (0.1, 0.25, and 0.4 mg·kg-1·min-1) was simultaneously infused to evaluate its effect on RIH. The antinociception of ciprofol was verified by measured paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). γ-aminobutyric acid type A receptor α2 subunit (α2GABAAR), N-methyl-d-aspartate receptor NR2B subunit (NR2B), calcium/calmodulin-dependent protein kinase II α (CaMKIIα), and phosphorylated CaMKIIα (P-CaMKIIα) in the spinal cord and hippocampus of rats were assessed by western blotting and immunohistochemistry. The results showed that ciprofol dose-dependently increased PWMT and PWTL values in RIH rats. Moreover, ciprofol upregulated α2GABAAR and downregulated NR2B and P-CaMKIIα in the rat spinal cord and hippocampus. Ciprofol alleviates RIH effectively, and the anti-hyperalgesic mechanisms may involve increasing α2GABAAR levels and decreasing NR2B and P-CaMKIIα levels in the spinal cord and hippocampus.

Blockade of adenosine A2A receptors reverses early spatial memory defects in the APP/PS1 mouse model of Alzheimer’s disease by promoting synaptic plasticity of adult-born granule cells

BackgroundThe over-activation of adenosine A2A receptors (A2AR) is closely implicated in cognitive impairments of Alzheimer's disease (AD). Growing evidence shows that A2AR blockade possesses neuroprotective effects on AD. Spatial navigation impairment is an early manifestation of cognitive deficits in AD. However, whether A2AR blockade can prevent early impairments in spatial cognitive function and the underlying mechanism is still unclear.MethodsA transgenic APP/PS1 mouse model of AD amyloidosis was used in this study. Behavioral tests were conducted to observe the protective effects of A2AR blockade on early spatial memory deficits in 4-month old APP/PS1 mice. To investigate the underlying synaptic mechanism of the protective effects of A2AR blockade, we further examined long-term potentiation (LTP) and network excitation/inhibition balance of dentate gyrus (DG) region, which is relevant to unique synaptic functions of immature adult-born granule cells (abGCs). Subsequently, the protective effects of A2AR blockade on dendritic morphology and synaptic plasticity of 6-week-old abGCs was investigated using retrovirus infection and electrophysiological recordings. The molecular mechanisms underlying neuroprotective properties of A2AR blockade on the synaptic plasticity of abGCs were further explored using molecular biology methods.ResultsAPP/PS1 mice displayed DG-dependent spatial memory deficits at an early stage. Additionally, impaired LTP and an imbalance in network excitation/inhibition were observed in the DG region of APP/PS1 mice, indicating synaptic structural and functional abnormalities of abGCs. A2AR was found to be upregulated in the hippocampus of the APP/PS1 mouse model of AD. Treatment with the selective A2AR antagonist SCH58261 for three weeks significantly ameliorated spatial memory deficits in APP/PS1 mice and markedly restored LTP and network excitation/inhibition balance in the DG region. Moreover, SCH58261 treatment restored dendritic morphology complexity and enhanced synaptic plasticity of abGCs in APP/PS1 mice. Furthermore, SCH58261 treatment alleviated the impairment of synaptic plasticity in abGCs. It achieved this by remodeling the subunit composition of NMDA receptors and increasing the proportion of NR2B receptors in abGCs of APP/PS1 mice.ConclusionsBlockade of A2AR improves early spatial memory deficits in APP/PS1 mice, possibly by reversing synaptic defects of abGCs. This finding suggests that A2AR blockade could be a potential therapy for AD.

The beneficial effects of vortioxetine on BDNF, CREB, S100B, β amyloid, and glutamate NR2b receptors in chronic unpredictable mild stress model of depression.

Depression, one of the most significant mental disorders, is still poorly understood in terms of its pathogenetic mechanisms despite its well-recognized association with stress. The current study's goal was to ascertain how the novel antidepressant drug vortioxetine (VOR) affected the BDNF (brain-derived neurotrophic factor), S100, amyloid β (Aβ), CREB (cAMP response element-binding protein), and NR2B, as well as its impact on depression-like behaviors, and tissue damage in an experimental rodent model of depression caused by chronic unpredictable stress. We employed twenty-eight Wistar albino male rats, and we randomly divided them into four groups, each consisting of 7 rats: control, CUMS (chronic unpredictable mild stress), CUMS+vortioxetine (CUMS+VOR), and CUMS+fluoxetine (CUMS+FLU). Sucrose preference and forced swimming tests (SPT and FST, respectively), PCR, ELISA, and histopathological and immunohistochemical evaluation were made on brains. The behaviors of reduced immobility in the FST and increased sucrose preference were observed in the CUMS group and they improved in the groups treated with VOR and FLU. Compared with the control group, the group exposed to CUMS showed increased Aβ and decreased BDNF, CREB, and S-100 expressions, as well as neuronal degeneration (p<0.001). VOR and FLU treatment ameliorate the findings. This study demonstrated significant ameliorative effects of VOR in an experimental model of chronic unpredictable depression to reduce brain tissue damage and depression-like behaviors in rats. Effects of CUMS on the brain and possible effects of VOR.

Chinese Tuina remodels the synaptic structure in neuropathic pain rats by downregulating the expression of N-methyl D-aspartate receptor subtype 2B and postsynaptic density protein-95 in the spinal cord dorsal horn.

To investigate whether the Chinese massage system, Tuina, exerts analgesic effects in a rat model of chronic constriction injury (CCI) by remodeling the synaptic structure in the spinal cord dorsal horn (SCDH). Sixty-nine male Sprague-Dawley rats were randomly and evenly divided into the normal group, sham group, CCI group, CCI + Tuina group, CCI + MK-801 [an -methyl D-aspartate receptor subtype 2B (NR2B) antagonist] group, and CCI + MK-801 + Tuina group. The neuropathic pain model was established using CCI with right sciatic nerve ligation. Tuina was administered 4 d after CCI surgery, using pressing manipulation for 10 min, once daily. Motor function was observed with the inclined plate test, and pain behaviors were observed by the Von Frey test and acetone spray test. At 19 d after surgery, the L3-L5 spinal cord segments were removed. Glutamate, interleukin 1β (IL-1β), and tumor necrosis factor-α (TNF-α) levels were detected by enzyme-linked immunosorbent assay. The protein expression levels of NR2B and postsynaptic density protein-95 (PSD-95) were detected by Western blot, and the synaptic structure was observed by transmission electron microscopy (TEM). CCI reduced motor function and caused mechanical and cold allodynia in rats, increased glutamate concentration and TNF-α and IL-1β levels, and increased expression of synapse-related proteins NR2B and PSD-95 in the SCDH. TEM revealed that the synaptic structure of SCDH neurons was altered. Most of these disease-induced changes were reversed by Tuina and intrathecal injection of MK-801 ( < 0.05 or < 0.01). For the majority of experiments, no significant differences were found between the CCI + MK-801 and CCI + MK-801 + Tuina groups. Chinese Tuina can alleviate pain by remodeling the synaptic structure, and NR2B and PSD-95 receptors in the SCDH may be among its targets.

Activation of N-Methyl-D-aspartate receptor contributed to the ultrasonic modulation of neurons in vitro

Ultrasound stimulation is increasingly used to investigate brain function and treat brain diseases due to its high level of safety and precise spatiotemporal resolution. Therefore, it is crucial to understand the underlying mechanisms involved in ultrasound brain stimulation. In this study, we investigate the role of NMDA receptors in mediating the effects of ultrasound on primary hippocampal neurons in mice. Our results show that ultrasound alone can activate heterologous NMDA receptor subunits, including NR1A, NR2A, and NR2B, in 293T cells, as well as endogenous NMDA receptors in primary neurons. This activation leads to an influx of calcium and an increase in nuclear c-Fos expression in primary neurons that have not been pre-treated with an NMDA receptor inhibitor. In conclusion, our findings demonstrate that NMDA receptors contribute to neuronal activation by ultrasound stimulation in vitro, providing insight into the molecular mechanisms of ultrasound neuromodulation and a new mediator for the sonogenetics technique.

Cyclic adenosine monophosphate-elevating agents inhibit amyloid-beta internalization and neurotoxicity: their action in Alzheimer's disease prevention.

Cyclic adenosine monophosphate-elevating agents inhibit amyloid-beta internalization and neurotoxicity: their action in Alzheimer's disease prevention.

Effect of caffeine supplementation during treadmill exercise on hippocampal genes expression levels in adolescent rats

Objectives: The usage of caffeine, a psychostimulant that is included in many foods and drinks, is rising, especially among young people. Also, caffeine works as an ergogenic substance during exercise to improve performance, and strength. In this study, our aim was to investigate the effect of caffeine consumption and exercise on hippocampal learning and memory functions in early life. Methods: Postnatal 28 days old Wistar albino male rats (n = 28) were randomly divided into 4 groups; control group (C), caffeine group (Cf), exercise group (E), caffeine+exercise group (CfE). Caffeine was dissolved in drinking water (0.3 g/L) and the treadmill exercise was applied 3 days a week. Following, the rats were applied to Morris Water Maze Test (MWMT) and open field test. N-methyl-D-aspartate (NMDA) receptors NR2A, NR2B, and brain-derived neurotrophic factor (BDNF) gene expression levels were investigated in hippocampus tissue by RT-PCR. Results: In MWMT, there was no significant difference in terms of learning and memory functions and hippocampal gene expression levels of the groups (p &amp;gt; 0.05). In the open field test, the time spent in the center was decreased in the CfE group, and the number of entries to the center was decreased in the E and CfE groups compared to the control group (p &amp;lt; 0.05). Conclusions: We assumed that caffeine given with exercise application caused anxiety behavior but did not affect learning and memory. There is a need for new studies investigating the effect of caffeine on exercise with different doses and durations depending on age.

Lycium barbarum Ameliorates Neural Damage Induced by Experimental Ischemic Stroke and Radiation Exposure.

Ischemic stroke and cranial radiotherapy may induce brain inflammatory response, oxidative stress, apoptosis and neuronal loss, and impairment of neurogenesis. Lycium barbarum has anti-oxidation, anti-inflammatory, anti-tumor and anti-aging properties, may produce both neuroprotective and radioprotective effects. In this narrative review paper, we described the neuroprotective effect of Lycium barbarum in different animal models of experimental ischemic stroke and limited studies in irradiated animal models. Relevant molecular mechanisms are also summarized. It has been shown that in experimental ischemic stroke models, Lycium barbarum produces neuroprotective effects by modulating neuroinflammatory factors such as cytokines and chemokines, reactive oxygen species, and neurotransmitter and receptor systems. In irradiation animal models, Lycium barbarum prevents radiation-induced loss of hippocampal interneurons. Given its minimal side-effects, these preclinical studies suggest that Lycium barbarum may be a promising radio-neuro-protective drug that can be used as an adjunct treatment to radiotherapy for brain tumor and in the treatment of ischemic stroke. At molecular levels, Lycium barbarum may regulate PI3K/Akt/GSK-3β, PI3K/Akt/mTOR, PKCε/Nrf2/HO-1, keap1-Nrf2/HO-1, and NR2A and NR2B receptor- related signal transduction pathways to produce neuroprotective effects.

Antidepressant-like effect of CP-101,606: Evidence of mTOR pathway activation

BackgroundAs a non-competitive N-methyl d-aspartate receptor antagonist, ketamine exerts rapid-onset and long-lasting antidepressant effects on depression, but some side effects limit its use. To identify a safer compound that may provide similar antidepressant effects, here we investigated whether CP-101,606, a selective NR2B receptor inhibitor, provides similar antidepressant effects and explored its underlying mechanisms. MethodsTo mimic depressive-like behavior, mice were subjected to chronic unpredictable mild stress (CUMS) for 21 days. Mice were treated with CP-101,606 at 10, 20, and 40 mg/kg doses for 7, 14, and 21 days, respectively, followed by a sucrose preference test (SPT), tail suspension test (TST), and forced swimming test (FST). Western blot analysis was performed on several targets (mTOR, p-mTOR, p70S6K, p-p70S6K, PSD-95, and GluA1), along with immunohistochemistry (GluA1) and immunofluorescence (p-mTOR) assays, using hippocampal tissue. ResultsCP-101,606 at 20 and 40 mg/kg doses for 7 and 14 days and fluoxetine 10 mg/kg and CP-101606 20 mg/kg for 21 days ameliorated depression-like behaviors in the SPT, TST, and FST. The effects of CP-101,606 were associated with a reversal of the CUMS-induced decrease in mTOR (Ser2448) and p70S6K (Thr389) phosphorylation and increasing PSD95 and GluA1 synthesis in the hippocampus. ConclusionsOur results demonstrate that CP-101,606 produces antidepressant effects in CUMS mice, which may be mediated by mTOR signaling cascade upregulation. Our findings suggest the possible utility of CP-101,606 as a treatment for depression.

Erythropoietin ameliorates cognitive deficits by improving hippocampal and synaptic damage in streptozotocin-induced diabetic mice

Recent studies have shown that erythropoietin (EPO) is an effective neuroprotective and neurotrophic agent for neurological disorders, such as traumatic brain injury and Alzheimer's disease. However, the effectiveness of EPO administration against diabetic cognitive impairments has rarely been examined. In this study, we investigated the effects of EPO on streptozotocin (STZ)-induced male C57BL/6 J mice. Then, we sought to clarify the mechanisms of EPO-mediated neuroprotection in high-glucose (HG)-stimulated HT22 cells. In vivo, we found that STZ-induced diabetic mice showed impaired spatial learning and memory, which was alleviated by EPO treatment. EPO also significantly lowered elevated fasting blood glucose levels, improved pancreatic and hippocampal damage, and restored oxidative stress in the STZ-induced diabetic mice. In vitro, EPO markedly increased cell viability, restrained the expression of pro-apoptotic Bax, enhanced the expression of pro-caspase 3, anti-apoptotic Bcl-2, brain-derived neurotrophic factor (BDNF) and postsynaptic density 95 (PSD-95), and attenuated the upregulation of N-methyl-d-aspartic acid (NMDA) receptor subunits NR1, NR2A and NR2B in HG-induced HT22 cells. The protective effects of EPO was obviously abolished by treatment with an NMDA receptor agonist. Our findings revealed that EPO impedes hippocampal and synaptic damage and neuronal apoptosis by regulating BDNF and PSD-95 expression through NMDA receptors, thereby ameliorating cognitive impairments in mice with T1DM.

The effects of sodium benzoate exposure on learning and neurobehavior during the prepubertal period in rats

Abstract Objectives Exposure to food additives, especially during the critical development period, has been associated with some behavioral disorders and learning difficulties in childhood. In this study, we aimed to evaluate the impact of sodium benzoate (NaB) on learning and neurobehavior in prepubertal rats. Methods A total of male rats (4-week-old) were divided into three groups as the control (CG), experiment 1 (NaB-ADI (acceptable daily intake) dose, Exp1G), and experiment 2 (NaB-NOAEL (no observed adverse effect level) dose, Exp2G) groups and NaB was administered by oral gavage for six weeks. Changes in learning, memory, motor activity and neurobehavior were evaluated by Morris water maze and open field tests. At the end of the experiment, rats’ hippocampi were extracted; NR1, NR2A, NR2B, and nAChRα7 receptor concentrations and mRNA expressions were determined. Results Neurobehavioral tests supported the possibility of increased anxiety and decreased motivation in the Exp1G. Also, molecular tests showed that NR2B receptor protein and mRNA expression levels significantly increased in Exp2G compared to CG. Conclusions Our study showed that NaB administration in the prepubertal period may cause increased anxiety, decreased motivation, and attention with ADI dose. Furthermore, NOAEL dose administration may lead to an increase in NR2B receptor levels. In light of these results, NaB consumption in childhood may affect hippocampal functions related to learning and neurobehavior.

Acute intrahippocampal administration of melanin-concentrating hormone impairs memory consolidation and decreases the expression of MCHR-1 and TrkB receptors

Interest in the role of melanin-concentrating hormone (MCH) in memory processes has increased in recent years, with some studies reporting memory-enhancing effects, while others report deleterious effects. Due to these discrepancies, this study seeks to provide new evidence about the role of MCH in memory consolidation and its relation with BDNF/TrkB system. To this end, in the first experiment, increased doses of MCH were acutely administered in both hippocampi to groups of male rats (25, 50, 200, and 500 ng). Microinjections were carried out immediately after finishing the sample trial of two hippocampal-dependent behavioral tasks: the Novel Object Recognition Test (NORT) and the modified Elevated Plus Maze (mEPM) test. Results indicated that a dose of 200 ng of MCH or higher impaired memory consolidation in both tasks. A second experiment was performed in which a dose of 200 ng of MCH was administered alone or co-administered with the MCHR-1 antagonist ATC-0175 at the end of the sample trial in the NORT. Results showed that MCH impaired memory consolidation, while the co-administration with ATC-0175 reverted this detrimental effect. Moreover, MCH induced a significant decrease in hippocampal MCHR-1 and TrkB expression with no modification in the expression of BDNF and NMDA receptor subunits NR1, NR2A, and NR2B. These results suggest that MCH in vivo elicits pro-amnesic effects in the rat hippocampus by decreasing the availability of its receptor and TrkB receptors, thus linking both endogenous systems to memory processes.

The State of the Dopaminergic and Glutamatergic Systems in the Valproic Acid Mouse Model of Autism Spectrum Disorder.

Autism Spectrum Disorder (ASD) is a progressive neurodevelopmental disorder mainly characterized by deficits in social communication and stereotyped behaviors and interests. Here, we aimed to investigate the state of several key players in the dopamine and glutamate neurotransmission systems in the valproic acid (VPA) animal model that was administered to E12.5 pregnant females as a single dose (450 mg/kg). We report no alterations in the number of mesencephalic dopamine neurons or in protein levels of tyrosine hydroxylase in either the striatum or the nucleus accumbens. In females prenatally exposed to VPA, levels of dopamine were slightly decreased while the ratio of DOPAC/dopamine was increased in the dorsal striatum, suggesting increased turn-over of dopamine tone. In turn, levels of D1 and D2 dopamine receptor mRNAs were increased in the nucleus accumbens of VPA mice suggesting upregulation of the corresponding receptors. We also report decreased protein levels of striatal parvalbumin and increased levels of p-mTOR in the cerebellum and the motor cortex of VPA mice. mRNA levels of mGluR1, mGluR4, and mGluR5 and the glutamate receptor subunits NR1, NR2A, and NR2B were not altered by VPA, nor were protein levels of NR1, NR2A, and NR2B and those of BDNF and TrkB. These findings are of interest as clinical trials aiming at the dopamine and glutamate systems are being considered.

Design and In-silico Molecular Docking of NMDA NR2B Receptor Antagonist and Pharmacokinetic Prediction of Some Piperazine Sulfonyl Amine Derivatives for Alzheimer’s Disease

Alzheimer's disease is a rare and progressive neurologic disease caused by degeneration of neurons within the brain that causes the brain to shrink (atrophy) and brain cells to die. In the US, approximately 5.5 million people are affected, and the prevalence worldwide is estimated to be as high as 24 million. Treatment is available to reduce the symptoms but no permanent cure. NMDA receptors play a crucial role in the treatment of Alzheimer's. Our aim and objective of the present work are to design some piperazine sulfonyl amine derivatives for treating Alzheimer's disease. To achieve this objective, we have docked the designed ligands with NMDA receptors. In our study, we have designed some piperazine sulfonyl amine derivatives, which were then subjected to virtual screening. The three-dimensional crystal structure of the selected protein NMDA receptor subunit NR2B (PDB Id: 3JPW) was retrieved from the RCSB Protein Data Bank (PDB). The ligands that showed low binding energy were further predicted for pharmacokinetic properties, and Lipinski's rule of 5 and the results are discussed. The final 19 compounds were used to develop a pharmacophore. The finalized 19 compounds were subjected to various in silico screening processes like drug-likeness, ADME properties and toxicity prediction. All 19 compounds exhibited good draggability nature, while ligands SE-B-15 and SE-B-12 were carcinogenic and SE-E-2 and SE-E-13 were prone to cause immunotoxicity. Ligands SE – C – 13 and SE – B – 2 exhibited good docking scores and best pharmacokinetic properties.

Down-regulation of NR2B receptors contributes to the analgesic and antianxiety effects of enriched environment mediated by endocannabinoid system in the inflammatory pain mice

Chronic pain states are highly prevalent and yet poorly controlled by currently available analgesics. It has been reported that enriched environment (EE), as a new way of endogenous pharmacotherapy, is effective in attenuating chronic inflammatory pain. However, the underlying molecular mechanisms are still not fully understood. NMDA NR2B receptor plays a critical role in pain transmission and modulation. Thus, in this study, we aimed at the effect of EE on the NR2B receptors expression in the prefrontal cortex, hippocampus and thalamus in the inflammatory pain mice. The results showed a significant increase of NR2B receptors in the thalamus of mice at 7 d following injection of CFA in the subcutaneous of the bottom of the left hind paw. EE significantly reduced the duration of mechanical hypersensitivity and anxiety-related behavior and the expression of NR2B receptors as compared to the standard condition. Furthermore, EE significantly increased 2-arachidonoylglycero (2-AG) levels at 7 d in the inflammatory pain mice as compared to the standard condition, and the effect of EE on the behavior and the expression of NR2B receptors was abolished by intraperitoneal injection of AM281 (a selective antagonist of CB1 receptor). Elevated 2-AG levels by intraperitoneal injection of JZL184 (a selective inhibitor of MAGL, the enzyme responsible for 2-AG hydrolysis) produced the same effect as EE. Results from this study provide the evidence that EE mimics endocannabinoids to take analgesic and anti-anxiety activities by decreasing the expression of the NR2B receptors via the CB1 receptor in the thalamus, pending further studies.

The role of sex and ovarian hormones in hippocampal damage and cognitive deficits induced by chronic exposure to hypobaric hypoxia.

PurposeThis study aims to investigate the role of sex and ovarian hormones in hippocampal damage and cognitive deficits and behavioral dysfunction in rats induced by chronic exposure to hypobaric hypoxia.MethodsSix-week-old male and female SD rats were housed for 3 months either in a real altitude (4,250 m) environment as the model of chronic hypobaric-hypoxia (CHH) or in a plain as controls. The animal behavioral and hippocampal neurons at subcellular, molecular, and ultrastructural levels were characterized after CHH exposure.ResultsAfter 3 months of CHH exposure, (1) male CHH rats’ serum testosterone level was lower than male controls’ whereas female CHH rats’ serum estradiol level was higher than female controls’; (2) Morris water maze test finds that male rats showed more learning and spatial memory deficits than female rats; (3) male rats showed more severe hippocampal damage, hippocampal inflammation, oxidative stress and decreased hippocampal integrity (neurogenesis and dendritic spine density) than female rats; (4) Western blot analysis shows that, compared with the male control group, in male CHH group’s hippocampus, expression of nNOS, HO-1, and Bax protein increased whereas that of Bcl-2 protein decreased; (5) Expression of PON2 protein in male rats (CHH and controls) was lower than female rats (CHH and controls). In addition, CHH exposure decreased the expression of PON2 protein in both male and female rats; (6) qPCR analysis reveals that CHH exposure reduced the gene expression of N-methyl-D-aspartate receptor NR2A and NR2B subunits in male rats’ hippocampus. In addition, compared with the sham CHH group, the expression level of PON2 protein decreased in the OVX-CHH group’s hippocampus whereas oxidative stress, neuroinflammation, and degeneration of hippocampal neurons increased in the OVX-CHH group’s hippocampus.ConclusionAfter CHH exposure, male rats were significantly more likely than female rats to develop hippocampal damage, hippocampal neuroinflammation, and cognitive decline and deficits, suggesting that sex and ovarian hormones were significantly involved in regulating the rats’ susceptibility to CHH exposure-induced hippocampal damage.

The Effect of Stilbene Glycosides on the Hippocampal Neurons and N-methyl D-aspartate Receptor Subtype 2B Receptors in Alzheimer’s Disease Rats

Our study investigated the effect of stilbene glycosides (TSG) on hippocampal neurons and NMDAR2B receptors in Alzheimer’s disease (AD). 40 SPF-grade male rats aged 8 weeks and weighted 0.3 kg were divided into control group (DG group), model group (WG group) (stereotactic injection of Aβ into hippocampus), low TSG group, and high TSG group followed by analysis of NR2B receptor level in hippocampus by immunohistochemical (IHC) staining and hippocampal neuronal apoptosis. The escape period of WG group and TSG treatment group was significantly longer than DG group (P &lt; 0.05) with more significant improvement in TSG group than WG group (P &lt; 0.05); NR2B positive number in WG group (140.31±2.81) was significantly lower than DG group (162.07±4.61) and TSG group (P &lt; 0.05); WG and TSG group had a significantly higher apoptosis rate than DG group (P &lt; 0.05). In addition, NR2B and NR1 expression in WG group was decreased slightly (P &lt; 0.05) with a higher clu level (P &lt; 0.05) which was decreased after TSG treatment (P &lt; 0.05). However, NR2B and NR1 levels showed a significant increase trend after TSG treatment. In conclusion, TSG can effectively reduce the increase of Aβ in the hippocampus, promote NR2B expression, reduce apoptosis and improve the learning ability of rats.

Protective effects of Zuogui Jiangtang Jieyu Formula on hippocampal neurons in rats of diabetes complicated with depression via the TRP/KYN metabolic pathway

ObjectiveTo explore the protective effects and mechanism of Zuogui Jiangtang Jieyu Formula (左归降糖解郁方, ZGJTJYF) on hippocampal neurons in rats of diabetes complicated with depression (DD) via the TRP/KYN metabolic pathway. Methods(i) In vivo experiments: 60 specified pathogen free (SPF) grade male Sprague-Dawley (SD) rats were randomly divided into six groups with 10 rats in each groups: control, DD model, positive (1.8 mg/kg fluoxetine + 0.18 g/kg metformin), high-dose ZGJTJYF (ZGJTJYF-H, 40.500 g/kg ZGJTJYF), middle-dose ZGJTJYF (ZGJTJYF-M, 20.250 g/kg ZGJTJYF), and low-dose ZGJTJYF (ZGJTJYF-L, 10.125 g/kg ZGJTJYF) groups. Except for the control group, other groups were established DD model by high-fat emulsion intake with single tail vein streptozotocin (STZ) and four weeks of chronic unpredictable mild stress (CUMS). All drug administration groups were treated by gavage during CUMS modeling, and the control and model groups were given equal amount of distilled water. After four weeks, the serum levels of blood glucose and glycosylated hemoglobin were measured to determine the hypoglycemic effect of ZGJTJYF. Moreover, the open field test and Morris water maze test were performed to evaluate the antidepressant effect of ZGJTJYF. Changes in 5-hydroxytryptamine (5-HT) level were detected via high-performance liquid chromatography with electrochemical detection (HPLC-ECD); the levels of tryptophan (TRP), kynurenine (KYN), and indoleamine 2,3-dioxygenase (IDO) in the hippocampus were detected using enzyme-linked immunosorbent assay (ELISA); the protein expression levels of synaptophysin (SYN) and postsynaptic density material-95 (PSD-95) were detected via immunohistochemistry (IHC); and the protein expression levels of N-methyl-D-aspartate receptor (NR) 2A and NR2B were detected using Western blot. (ii) In vitro experiments: five SPF grade SD pregnant rats (E16 – 18) were used to obtain primary hippocampal neurons (Ne), six SD new-born rats were used to collected primary astrocytes (As) and microglia (MG), and to establish a Ne-As-MG co-culture system. All co-culture systems were divided into six groups: control (PBS), model [150 mmol/L glucose + 200 μmol/L corticosterone (G&P) + PBS], blank (G&P + blank serum), positive (G&P + positive drug-containing serum), ZGJTJYF (G&P + ZGJTJYF serum), and 1-methyl-D-tryptophan (1-MT, IDO inhibitor) (G&P + 1-MT) groups. After 18 h of intervention by corresponding treatment, immunofluorescence was used to analyze the protein expression levels of SYN, PSD-95, NR2A, and NR2B; ELISA was performed to measure the levels of interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α , and TRP/KYN metabolic pathway-related factors [TRP, KYN, kynurenine acid (KYNA), quinolinic acid (QUIN)]. Results(i) In vivo experimental<italic/> results showed that ZGJTJYF-M and ZGJTJYF-L significantly improved the elevated blood glucose state of DD rats (P < 0.01 and P < 0.05, respectively); ZGJTJYF-H, ZGJTJYF-M, and ZGJTJYF-L increased their autonomous activity, learning, and memory ability (P < 0.01, P < 0.01, and P < 0.05, respectively). Moreover, the levels of 5-HT and TRP were significantly increased (P < 0.01), and the levels of KYN and IDO were significantly decreased in the hippocampus (P < 0.01) of rats after ZGJTJYF-M treatment. The protein expression levels of SYN and PSD-95 were significantly upregulated in hippocampal neurons (P < 0.01), while the abnormal activation of NR2A and NR2B was markedly inhibited in hippocampus (P < 0.05) of rats after ZGJTJYF-M treatment. (ii) In vitro experimental results showed that ZGJTJYF-containing serum significantly increased the protein expression levels of SYN and PSD-95 in hippocampal neurons (P < 0.01), decreased the levels of IL-1β (P < 0.01), IL-6 (P < 0.05), TNF-α (P < 0.01), IDO (P < 0.05), KYN (P < 0.05), and QUIN (P < 0.01), and increased the levels of TRP and KYNA (P < 0.01) in the simulated DD state. ZGJTJYF also had an significantly inhibitory effect on the abnormal activation of NR2A and NR2B in neurons (P < 0.05) in a stimulated DD state. ConclusionZGJTJYF can effectively improve 5-HT deficiency in the hippocampus of rats by inhibiting IDO expression and regulating the TRP/KYN metabolic pathway, and it has a favorable protective effect on hippocampal neuron injury caused by DD. Therefore, ZGJTJYF is an effective potential therapeutic drug for the prevention and treatment of DD.