Effects of esketamine on depression-like behavior and dendritic spine plasticity in the prefrontal cortex neurons of spared nerve injury-induced depressed mice

The present study utilized the spared nerve injury (SNI) to create a mouse model of depression to investigate the impact of esketamine on depressive-like behaviors, on the expression of PSD-95 and CRMP2 proteins, and on changes in neuronal dendritic spine plasticity in the prefrontal cortex (PFC). Depressive-like behavioral tests were performed 1 h after esketamine treatment, and the PFC tissues were obtained on the fourth day after completing the behavioral tests. Then, dendritic spine density and morphology in the PFC were measured using Golgi staining, and CRMP2 and PSD-95 proteins were obtained from PFC tissue by western blotting. The results of this study showed that esketamine significantly increased the immobility time in the forced swimming test and tail suspension test. In the open field test, esketamine increased the time spent in the open arms, the time spent in the central area, and the total distance covered. It also increased the protein expression levels of CRMP2 and PSD-95 in addition to the total and mature dendritic spine density of the PFC in SNI-depressed mice. Esketamine can significantly improve depression-like behaviors in SNI-depressed mice and promote an increase in dendritic spine density and maturation in the PFC. These effects may be associated with changes in CRMP2 and PSD-95 expression.

Effects of ICG-001 on autistic behaviors and the development of hippocampal dendritic spine morphology in rats / 中华实用儿科临床杂志

Objective:To explore the effects of the compound ICG-001 on autism-like behaviors and the morphological development of dendritic spines in hippocampal pyramidal neurons of rats.Methods:Healthy Wistar rats were mated.The offspring were divided into the saline-treated group, ICG-001 control group, Sodium valproate (VPA) group and ICG-001 treatment group by using the random number table method.Each group had 12 rats.Social interaction, repetitive, compulsive and anxiety-like behaviors in rodents were assessed by three-chambered social approach, marble burying, open-field and elevated plus maze tests.The number of neuronal nuclei (NeuN)-positive neurons in the hippocampal CA1 region was calculated by the immunofluorescence method.Golgi staining was carried out to detect the density and morphological changes of dendritic spines in hippocampal pyramidal neurons of rats.The expression of phosphorylated LIM kinase 1(LIMK1), phosphorylated actin binding protein(Cofilin), fibros actin (F-actin) and developmentally-regulated brain protein A (Drebrin A) was examined by Western blot.The univariate analysis was made to examine whether the difference was statistically significant, and the data between groups were compared by the Tukey method. Results:(1) In the three-chambered social approach test, the rats in the saline-treated group, ICG-001 control group, VPA group and ICG-001 treatment group spent (219.42±5.38) s, (218.67±10.12) s, (126.58±5.02) s, and (218.58±6.63) s in the chamber, respectively.The corresponding preference score of the said 4 groups were 0.43±0.05, 0.43±0.04, 0.22±0.01 and 0.42±0.04, respectively.Compared with the VPA group, the ICG-001 treatment group spent longer time in the chamber and had a higher preference score (all P<0.05). (2) In the marble burying experiment, the number of marbles buried in said 4 groups were 9.13±0.52, 9.08±0.64, 15.13±0.82 and 9.42±0.86, respectively.ICG-001-treated rats buried markedly less marbles than VPA-exposed rats ( P<0.05). (3) In the open-field test, the rats in the said 4 groups spent (82.33±1.83) s, (81.32±4.19) s, (45.51±3.02) s and (81.44±3.19) s in the center area, respectively.Administration of ICG-001 significantly increased the time that VPA-exposed rats spent in the center area ( P<0.05). (4)In the elevated plus maze trial, the rats in the said 4 groups spent (107.75±7.23) s, (106.08±7.50) s, (63.42±1.91) s and (106.67±7.07) s in open arms, respectively.ICG-001 treatment notably increased the time that VPA-exposed rats spent in open arms ( P<0.05). (5) Immunofluorescence analysis results revealed that the number of NeuN-positive cells in the hippocampal CA1 region of said 4 groups was (41.83±1.17)×10 4/μm 2, (41.00±0.77)×10 4/μm 2, (27.17±0.95)×10 4/μm 2 and (40.00±0.90)×10 4/μm 2, respectively.ICG-001 treatment normalized the alteration in the number of NeuN-containing neurons in VPA-exposed rats ( P<0.05). (6) Golgi staining showed that the density of dendritic spines in hippocampal CA1 pyramidal neurons of said 4 groups was (0.74±0.04)/μm, (0.73±0.03)/μm, (0.49±0.03)/μm and (0.70±0.02) /μm, respectively.Of all types of dendritic spines, mushroom spines accounted for (0.49±0.02)%, (0.49±0.02)%, (0.33±0.02)% and (0.43±0.02) % in said 4 groups.Thin spines accounted for (0.27±0.02)%, (0.26±0.02)%, (0.34±0.01)% and (0.26±0.01) % in said 4 groups, respectively.Compared with the VPA group, the ICG-001 treatment group showed a significant increase in the density of dendritic spines in hippocampal CA1 pyramidal neurons ( P<0.05). After ICG-001 treatment, the number of mushroom spines greatly increased and the number of thin spines sharply decreased in VPA-exposed rats (all P<0.05). (7) According to Western blot test results, the phosphorylated LIMK1/LIMK1 ratio of the hippocampus in said 4 groups were 100.33±2.30, 99.34±2.28, 57.76±4.10 and 99.13±1.90, respectively.The phosphorylated Cofilin /Cofilin ratio were 100.18±2.43, 100.18±1.70, 57.12±1.88 and 99.53±1.69, respectively.The F-actin/globular actin(G-actin) ratio were 100.07±0.86, 99.99±1.72, 51.19±1.23 and 99.28±3.17, respectively.The expression level of Drebrin A were 100.79±1.19, 100.12±2.04, 52.86±3.26 and 99.97±2.44, respectively.Administration of ICG-001 effectively prevented the decrease of phosphorylated LIMK1, phosphorylated Cofilin, F-actin and Drebrin A in the hippocampus of VPA-exposed rats (all P<0.05). Conclusions:ICG-001 regulates the LIMK1/Cofilin signaling pathway, promotes the generation of F-actin, increases the expression of Drebrin A, and thereby alleviates autistic-associated symptoms.

Neuronal Histone Methyltransferase EZH2 Regulates Neuronal Morphogenesis, Synaptic Plasticity, and Cognitive Behavior in Mice / 神经科学通报·英文版

The histone methyltransferase enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2)-mediated trimethylation of histone H3 lysine 27 (H3K27me3) regulates neural stem cell proliferation and fate specificity through silencing different gene sets in the central nervous system. Here, we explored the function of EZH2 in early post-mitotic neurons by generating a neuron-specific Ezh2 conditional knockout mouse line. The results showed that a lack of neuronal EZH2 led to delayed neuronal migration, more complex dendritic arborization, and increased dendritic spine density. Transcriptome analysis revealed that neuronal EZH2-regulated genes are related to neuronal morphogenesis. In particular, the gene encoding p21-activated kinase 3 (Pak3) was identified as a target gene suppressed by EZH2 and H3K27me3, and expression of the dominant negative Pak3 reversed Ezh2 knockout-induced higher dendritic spine density. Finally, the lack of neuronal EZH2 resulted in impaired memory behaviors in adult mice. Our results demonstrated that neuronal EZH2 acts to control multiple steps of neuronal morphogenesis during development, and has long-lasting effects on cognitive function in adult mice.

Electroacupuncture inhibits dendritic spine remodeling through the srGAP3-Rac1 signaling pathway in rats with SNL

Previous studies have shown that peripheral nerve injury can lead to abnormal dendritic spine remodeling in spinal dorsal horn neurons. Inhibition of abnormal dendritic spine remodeling can relieve neuropathic pain. Electroacupuncture (EA) has a beneficial effect on the treatment of neuropathic pain, but the specific mechanism remains unclear. Evidence has shown that slit-robo GTPase activating protein 3 (srGAP3) and Rho GTPase (Rac1) play very important roles in dendritic spine remodeling. Here, we used srGAP3 siRNA and Rac1 activator CN04 to confirm the relationship between SrGAP3 and Rac1 and their roles in improving neuropathic pain with EA. Spinal nerve ligation (SNL) was used as the experimental model, and thermal withdrawal latency (TWL), mechanical withdrawal threshold (MWT), Western blotting, immunohistochemistry and Golgi-Cox staining were used to examine changes in behavioral performance, protein expression and dendritic spines. More dendritic spines and higher expression levels of srGAP3 were found in the initial phase of neuropathic pain. During the maintenance phase, dendritic spines were more mature, which was consistent with lower expression levels of srGAP3 and higher expression levels of Rac1-GTP. EA during the maintenance phase reduced the density and maturity of dendritic spines of rats with SNL, increased the levels of srGAP3 and reduced the levels of Rac1-GTP, while srGAP3 siRNA and CN04 reversed the therapeutic effects of EA. These results suggest that dendritic spines have different manifestations in different stages of neuropathic pain and that EA may inhibit the abnormal dendritic spine remodeling by regulating the srGAP3/Rac1 signaling pathway to alleviate neuropathic pain.

Mechanism of valproic acid-induced dendritic spine and synaptic impairment in the prefrontal cortex for causing core autistic symptoms in mice / 南方医科大学学报

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.

Multiple Mild Stimulations Reduce Membrane Distribution of CX3CR1 Promoted by Annexin a1 in Microglia to Attenuate Excessive Dendritic Spine Pruning and Cognitive Deficits Caused by a Transient Ischemic Attack in Mice / 神经科学通报·英文版

A transient ischemic attack (TIA) can cause reversible and delayed impairment of cognition, but the specific mechanisms are still unclear. Annexin a1 (ANXA1) is a phospholipid-binding protein. Here, we confirmed that cognition and hippocampal synapses were impaired in TIA-treated mice, and this could be rescued by multiple mild stimulations (MMS). TIA promoted the interaction of ANXA1 and CX3CR1, increased the membrane distribution of CX3CR1 in microglia, and thus enhanced the CX3CR1 and CX3CL1 interaction. These phenomena induced by TIA could be reversed by MMS. Meanwhile, the CX3CR1 membrane distribution and CX3CR1-CX3CL1 interaction were upregulated in primary cultured microglia overexpressing ANXA1, and the spine density was significantly reduced in co-cultured microglia overexpressing ANXA1 and neurons. Moreover, ANXA1 overexpression in microglia abolished the protection of MMS after TIA. Collectively, our study provides a potential strategy for treating the delayed synaptic injury caused by TIA.

Research progress on the structural plasticity of neurons in the visual cortex / 中华实验眼科杂志

During the development of visual cortex, the structure of neurons will adaptively change and adjust according to the changes of external environment, which shows structural plasticity.The experience-dependent plasticity of visual cortex is based on the structural changes of neurons, which mainly include change of synaptic connections, disappearance or increase of dendritic spines, turnover of dendritic spines, changes in the size of dendritic spines, changes in postsynaptic density and alterations of perineuronal nets.The structural changes of neurons have significant influence on the plasticity of visual cortex function and structure, and are highly associated with some molecules or non-neuronal components such as paired immunoglobulin-like receptor B, Ly-6/neurotoxin-like protein 1, Nogo, microglia and extracellular matrix and so on.In addition, external intervention factors such as abnormal visual experience and environmental enrichment can have significant impact on the regulation of the structural changes of neurons, and finally influence the development of visual function and the recovery from visual impairment.In comparison with the functional studies, studies on the structural plasticity of visual cortical neurons depend on the state-of-the-art imaging techniques at cellular or sub-cellular level with more visualizable and convincing results.The constant exploration of the structural plasticity of visual cortex will enhance our understanding of visual development-related diseases, such as amblyopia, and lay the foundation for related basic research and innovative treatments.Advances in the structural plasticity of visual cortex were reviewed in this article.

Cranial irradiation alters dendritic spine density and morphology in the young rat hippocampus / 中华放射医学与防护杂志

Objective:To explore the changes of dendritic spine morphology and structure in dentate gyrus(DG) and CA1 areas of hippocampus of young rats, so as to provide a direct morphological basis for studying the molecular mechanism of radiation cognitive impairment.Methods:21-day-old Sprague-Dawley (SD) rats were given a single dose of 10 Gy whole brain irradiation. The changes of cognitive function, dendritic spine density and morphological changes in DG and CA1 areas of hippocampus were observed 1 and 3 months after irradiation, and the expression of postsynaptic density protein (PSD95) was detected by Western blot.Results:The cognitive impairment was observed in young rats 3 months after irradiation. The density of dendritic spines in DG area of hippocampus was decreased significantly by 39.06% and 29.27% at 1 and 3 months after irradiation ( t=14.96, 12.35, P<0.05), respectively. The density of dendritic spines in the basal dendrites of hippocampal CA1 area was decreased by 33.40% ( t=10.39, P<0.05) 1 month after irradiation, but had no significant change at 3 months after irradiation. While the density of dendritic spines in the apical dendrites of CA1 region did not change significantly at 1 and 3 months after irradiation. In addition, the morphology of dendritic spines in DG and CA1 regions of hippocampus was dynamically changed after irradiation. The expression of PSD95 protein was decreased by 24.6% and 50.5% ( t=2.97, 9.27, P<0.05) at 1 and 3 months after irradiation, respectively. Conclusions:This study reported the density and morphological changes of dendritic spines in different brain regions of hippocampus of young rats after ionizing radiation, suggesting that PSD95 may participate in the occurrence of radiation-induced cognitive impairment by affecting the structure and morphology of dendritic spines and reducing synaptic plasticity.

Rac1 Modulates Excitatory Synaptic Transmission in Mouse Retinal Ganglion Cells / 神经科学通报·英文版

Ras-related C3 botulinum toxin substrate 1 (Rac1), a member of the Rho GTPase family which plays important roles in dendritic spine morphology and plasticity, is a key regulator of cytoskeletal reorganization in dendrites and spines. Here, we investigated whether and how Rac1 modulates synaptic transmission in mouse retinal ganglion cells (RGCs) using selective conditional knockout of Rac1 (Rac1-cKO). Rac1-cKO significantly reduced the frequency of AMPA receptor-mediated miniature excitatory postsynaptic currents, while glycine/GABA receptor-mediated miniature inhibitory postsynaptic currents were not affected. Although the total GluA1 protein level was increased in Rac1-cKO mice, its expression in the membrane component was unchanged. Rac1-cKO did not affect spine-like branch density in single dendrites, but significantly reduced the dendritic complexity, which resulted in a decrease in the total number of dendritic spine-like branches. These results suggest that Rac1 selectively affects excitatory synaptic transmission in RGCs by modulating dendritic complexity.

Recent advance in role of Drebrin in neural development and cognitive disorders / 中华神经医学杂志

Developmentally regulated brain protein (Drebrin),which is a kind ofactin binding protein,mainly distributes in the neuronal dendritic spines.It plays an important role in the processes of formation of dendritic spines,adjustment of synaptic morphology,and memory keep.The quantity and distribution of Drebrin changed in some of the central nervous system diseases such as Alzheimer's disease in brain tissues.Researchers have made much effort to find the correlation of them,but the exact mechanism is unclear.A more in-depth study on mechanism of Drebrin in the central nervous system disease and correlation of Drebrin with associated molecule has great significance to exploration of more effective therapeutic targets.

Protective effect of hydrogen gas on neurons and dendritic spines of hippocampus CA1 region in rats after global cerebral ischemia/reperfusion injury / 中华神经医学杂志

Objective To explore the protective effect of in-taking high concentration hydrogen gas on neurons and dendritic spines in hippocampus CA1 region of rats after globe cerebral ischemia/reperfusion (I/R) injury and its mechanism.Methods Four-vessel occlusion (4VO) was used to establish the models of global cerebral I/R injury in rats.One hundred and twenty healthy male Sprague-Dawley rats were randomly divided into 3 groups using a random number table:sham-operated group (inhaled 67％ N2 and 67％ O2,n=40),model group (inhaled 67％ N2 and 67％ O2 during reperfusion,n=40),and treatment group (inhaled 67％ H2 and 67％ O2 during reperfusion,n=40).After 72 h,5 and 9 d reperfusion,neuron-specific nuclear (NeuN) protein expression in the pyramidal neurons of the hippocampal CA1 region was detected with immumohistochemical staining and the positive cells were counted.And the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) in serum were tested with colorimetry.Water maze test was used to measure the spatial orientation and memory function and Golgi staining to detect the number of dendritic spines in neurons 9 d after reperfusion.Results (1) Immunohistochemical staining of NeuN results showed that as compared with those in the model group,the neurons ofhippocampus CA1 region were significantly closer to normal with relatively intact structure,and the number of positive neurons was significantly increased in the treatment group 72 h,5 d,and 9 d after reperfusion (P＜0.05).With the reperfusion time being prolonged,the number of NeuN stained positive neurons at different time points of reperfusion in model group was gradually decreased (P＜0.05),and the numeric of the NeuN stained positive neurons at different time points of reperfusion in treatment group was slightly declined without significant difference (P＞0.05).(2) The serum SOD activity in the treatment group was significantly higher than that in the model group and sham-operated group (P＜0.05),while the MDA content in the treatment group was significantly lower than that in model group 72 h,5 d,and 9 d after reperfusion (P＜0.05).And with the reperfusion time being prolonged,the SOD activity at different time points of reperfusion showed no significant difference among the difference groups (P＞0.05).But the MDA content at different time points ofreperfusion between model group and treatment group was significantly different (P＜0.05);with the reperfusion time being prolonged,the MDA content was gradually decreased in both groups.(3) Nine d after reperfusion,water maze test found that the incubation period of treatment group was significantly shorter than that of model group (P＜0.05);the IV quadrant swimming time of space exploration in the treatment group was significantly longer than that in the model group (P＜0.05).(4) Golgi staining showed that the complexity of the neuronal dendrites branch and the number of dendritic spines of neurons in the hippocampal CA1 region of treatment group were increased than those in the model group;high-power oil microscopy indicated that the density of dendritic spines in the treatment group was significantly higher than that in the model group (P＜0.05).Conclusion In-taking of high concentrations hydrogen gas during reperfusion can definitely protect neurons in hippocampal CA1 region after globe cerebral I/R injury,and improve learning and memory function,whose mechanism may be related to hydrogen protecting the structure and function of neurons and dendritic spines,and inhibiting oxidative stress to reduce oxidative damage.

Effect of lipopolysaccharide-mediated infection during pregnancy on the expression of mineralocorticoid receptor and dendritic spines in hippocampus of rat offspring / 中华实用儿科临床杂志

Objective To observe the effect of lipopolysaccharide (LPS)-mediated infection during pregnancy on the expression of mineralocorticoid receptor (MR) and density of dendritic spines in CA1 region of the dorsal hippocampus of rat offspring,so as to explore the mechanisms for learning and memory injury of rat offspring which were infected during prenatal period,then to provide scientific experimental evidence for the prevention of prenatal infection-induced delayed neuropsychiatric sequelae which contributed to learning and memory dysfunction.Methods Ten-week-old female Sprague-Dawley rats (n =30) were matched with male rats (1 ∶ 1).Pregnant rats were randomly divided into a control group (n =10) and an experimental group (n =20).The pregnant rats in experimental group were treated with LPS (66 μg/kg,intraperitoneally),and the pregnant rats in control group were intraperitoneally injected with same volume of saline on gestational day 10.On postnatal day 48,Morris water maze was used to estimate the ability of learning and memory;the brain tissues of offspring were taken and paraffin sections were stained with hematoxylin eosin (HE) for histological observation of CA1 region of the dorsal hippocampus;frozen sections were treated with indirect immunofluorescence to observe the expression of MR in CA1 region of the dorsal hippocampus;Golgi-Cox method was used to observe the density of dendritic spines of CA1 region.Results In Morris water maze test,from the third day the time of escape latency in experimental group [the 3rd day:(42.603 ± 9.837) s;the 4th day:(30.222 ± 9.789) s;the 5th day:(28.808 ± 12.526) s] was significantly higher than that of the control group [the 3rd day:(28.078±14.088) s;the 4th day:(20.692±13.099) s;the 5th day:(14.632 ±11.624) s] (the 3rd day:t =-3.274,P＜0.01;the 4th day:t =-2.257,P ＜0.05;the 5th day:t =-3.213,P＜0.01);the swimming time in the target quadrant [(14.660 ± 7.337) times] and the number of crossing platform [(0.933 ± 0.704) times] in experi mental group were significantly decreased compared with those of the control group [time:(23.820 ± 6.321) s;num bers:(2.000 ± 0.756) times] (t =3.663,4.000,all P ＜ 0.01).Hematoxylin eosin staining showed that the nerve cells of the hippocampus in the control group distributed in order,nucleuses were round or oval,nucleoli were obvious,and chromatins were homogeneous;but the cells in the experimental group distributed in disorder and pathological changes were detected,such as cellular swelling,necrosis and obvious nuclear pyknosis.By immunofluorescence staining,the average optical density (AOD) of MR in CA1 region decreased significantly in the experimental group (0.067 ± 0.017) compared with that of the control group (0.083 ± 0.009) (t =2.644,P ＜ 0.05).In Golgi-Cox method,the density of dendritic spines in experimental group [(7.705 ± 0.791)/10 μm] was below that of the control group [(9.655 ± 1.391)/10 μm] (t =3.852,P ＜ 0.01).Conclusions LPS-mediated infection during pregnancy might lead to hippocampus-dependent learning and memory dysfunction which might be associated with the reduced expression of MR and the low density of dendritic spines in CA1 region of the dorsal hippocampus.

Influence of pregnant rats' prenatal chronic stress on hippocampal dendritic spines and the function of learning and memory in their offsprings / 中华实用儿科临床杂志

Objective To study the influence of pregnant rats' prenatal chronic stress (PS) on learning and memory of their offspring rats and its possible molecular mechanisms.Methods Pregnant females were individually restrained for 45 min 3 times a day during pregnancy from day 14 to day 21.Control pregnant females were left undisturbed in their home cages.The rat offsprings were randomly assigned to PS group or control group.Males and females were kept for the study separately.The learning and memory of the developing rat offspring in the Morris water maze were examined.The basal levels of corticosterone (COR) and adreno-cortico-tropic-hormone (ACTH) were analyzed by using radioimmunoassay.The Golgi-Cox impregnation technique was used to compare density and morphology of the CA1 hippocampal dendritic spines.Results The escape latency (EL) to find the platform in the control group was significantly less than that in the PS group in female rat offspring (F =4.533,P ＜ 0.05),and the difference was statistically significant on the 5th day (t =2.788,P ＜ 0.01).EL to find the platform in the control group was significantly less than that in the PS group in male rat offspring (F =6.101,P ＜0.05),and the difference was statistically significant on the second day (t =3.051,P ＜ 0.01).In the space exploration experiments of the water maze,the retention time observed for the control group and the PS group in the goal quadrant was similar(P ＞ 0.05).The basal levels of the serum COR in the PS group were higher than those in the control group of female rat offspring(t =3.658,P ＜ 0.01) and the basal levels of the serum ACTH in the PS group were higher than those in the control group of male rat offsprings(t =2.319,P ＜ 0.05).A simplified pattern was observed in the CA1 hippocampal dendritic spines in the PS group,showing a less extent of dendritic arborization and the density was significantly lower than that in the control group(t =-3.072,P ＜ 0.01).Conclusions Altered function of the hypothalamic-pituitary-adrenal axis in the offspring mediates the cognitive alterations observed following prenatal stress should to be associated with the lower density and simplified pattern of CA1 dendritic spines.

Effects ofZi-Bu Pi-YinRecipe on Dendritic Spines in Spleen-YinDeficiency Dementia Model Rats / 世界科学技术-中医药现代化

This study was aimed to observe the changes of dendritic spine density in different regions of brain among spleen-yindeficiency dementia (SYDD) model rats, in order to investigate the effects ofZi-Bu Pi-Yin Recipe (ZBPYR) on dendritic spines. Spleen-yindeficiency (SYD) rats were modeled by classical method. And incubatedβ-Amyloid 1-40 (Aβ1-40) was injected into the hippocampus of each rat to make SYDD model, which received the administration of ZBPYR. Golgi staining was used to stain dendritic spine in different regions of brain in rat model for the observation of the amount and shape. The results showed that dendritic spine density in different regions of hippocampus and cortex in SYDD group was reduced than that of the SYD group. Compared with the dementia group and the SYDD group, the dendritic spine density in different regions of hippocampus and cortex of the SYDD + ZBPYR group was increased. Compared with the blank control group, the dendritic spine density in different regions of hippocampus and cortex in rats from the dementia group was reduced. It was concluded that there were different degrees of reducing in the dendritic spine density of different brain regions in SYDD group. ZBPYR improved the learning and memory impairment, which might be related to the maintenance of dendritic spine density in different brain regions.

High-fat diet induces learning and memory impairments and hippocampal dendritic spine density in rats / 中华行为医学与脑科学杂志

Objective To explore the influence of high fat diet on learning and memory,as well as the alteration of the number of neurons and morphology of dendritic spines in rat hippocampi.Methods 24 male adult SD rats were randomly assigned to high fat diet group or control group.The rats were fed with high-fat diet or standaM laboratory rodent chow diet for 12 weeks.Learning and memory were tested by Morris water maze and object recognition tests, and mood and motor ability were tested by open field tests.Golgi staining detected dendritic spine density of hippocampal neurons, and Nissl staining was used to observe the number of hippocampal neurons and pathological changes.Results High-fat diet induced rat spatial learning deficits, which was demonstrated by the prolonged escape latency ((38.50±9.70) s, (20.08±7.35) s, (19.96± 10.56) s, (22.75± 12.51) s, (14.56±4.82) s) compared with the control ((33.61±12.41) s, (14.25±7.89) s, (15.06±7.59) s, (5.53±2.81) s, (4.7± 1.58) s).The spatial memory deficits demonstrated that the latency reaching platform ((30.46± 21.43) s) was prolonged compared with control ((5.18± 1.33)s).The working memory was impaired, which was demonstrated by the prolonged escape latency compared with control group (P＜ 0.05).Discrimination index lowered than control group ((0.67±0.12) vs (0.81±0.08)), and the difference was significant (P=0.038), but no anxiety behaviors were observed(P=0.461).The neuron number of hippocampal neurons and dendritic spine density were significantly lowered than those in the control group((209.73±24.29) vs (262.2±18.94), (17.9±2.84) vs (21.93±2.56) ,respectively) (P＜0.05).Conclusion Intake of high-fat diet can impair learning and memory in rats, as well as decrease the number of neurons and the density of dendritic spines in the hippocampus.

Developmental bisphenol-A exposure affects hippocampal dentate gyrus area spine formation through Wnt/β-catenin signaling / 中国药理学与毒理学杂志

OBJECTIVE To investigate the effects and its underlying mechanis m of bisphenol-A (BPA)exposure on spine and synapse formation in detate gyrus (DG)area of hippoca mpus during criti-cal develop mental period.METHODS Sprague-Dawley(SD)rats were injected intraperitoneally with BPA (50,250 and 500 μg·kg -1·d -1 )fro m postnatal day 7 (PND7)to PND14.Dendritic spine morphol-ogy in DG area was exa mined using Golgi-Cox staining method and determined with I mage J software. Western blotting method was e mployed to test the Wnt related proteins.RESULTS The spine density and the average spine head size in BPA exposed groups significantly decreased in a dose-dependent manner when co mpared to control group(P<0.05).Meanwhile,Wnt related proteins were affected dur-ing BPA exposure.Specifically,the percentage of phosphorylated β-catenin increased following BPA ex-posure (P<0.05),whereas Wnt7a expression level was significantly decreased and Wnt5a expression level increased (P<0.05).CONCLUSION Wnt signaling pathway plays an i mportant role in BPA-in-duced i mpairments in spine and synapse formation.

Depressed nNOS expression during spine transition in the developing hippocampus of FMR1 KO mice

Nitric oxide (NO), synthesized as needed by NO synthase (NOS), is involved in spinogenesis and synaptogenesis. Immature spine morphology is characteristic of fragile X syndrome (FXS). The objective of this research was to investigate and compare changes of postnatal neuronal NOS (nNOS) expression in the hippocampus of male fragile X mental retardation 1 gene knockout mice (FMR1 KO mice, the animal model of FXS) and male wild-type mice (WT) at postnatal day 7 (P7), P14, P21, and P28. nNOS mRNA levels were analyzed by real-time quantitative PCR (N = 4-7) and nNOS protein was estimated by Western blot (N = 3) and immunohistochemistry (N = 1). In the PCR assessment, primers 5’-GTGGCCATCGTGTCCTACCATAC-3’ and 5’-GTTTCGAGGCAGGTGGAAGCTA-3’ were used for the detection of nNOS and primers 5’-CCGTTTCTCCTGGCTCAGTTTA-3’ and 5’-CCCCAATACCACATCATCCAT-3’ were used for the detection of β-actin. Compared to the WT group, nNOS mRNA expression was significantly decreased in FMR1 KO mice at P21 (KO: 0.2857 ± 0.0150, WT: 0.5646 ± 0.0657; P < 0.05). Consistently, nNOS immunoreactivity also revealed reduced staining intensity at P21 in the FMR1 KO group. Western blot analysis validated the immunostaining results by demonstrating a significant reduction in nNOS protein levels in the FMR1 KO group compared to the WT group at P21 (KO: 0.3015 ± 0.0897, WT: 1.7542 ± 0.5455; P < 0.05). These results suggest that nNOS was involved in the postnatal development of the hippocampus in FXS and impaired NO production may retard spine maturation in FXS.

Expressions of Drebrins and lcam-5 in mouse cerebral cortex with Fmr-1 gene knockout and their significance in fragile X syndrome / 中华神经医学杂志

[Objective]To investigate and compare the changes of Drebrin A,Drebrin E and lcam-5 mRNA levels in the cerebral cortex of Frr-1 gene knockout mouse during brain development periods.[Methods]Fmr-1 gene knockout (KO) male mice and their wild type (WT) counterparts were chosen in our experiment (4≤n≤ 10);the levels of target mRNAs were detected by real time quantitative PCR;check points were set on the 7th,14th,21th and 28rh postnatal d.[Results] The mRNA level of Drebrin A in the KO group was significantly lower than that in the WT group on the 14th postnatal d,while that of Drebrin E was significantly higher than that in the WT group (P＜0.05).The mRNA level of lcam-5 in the KO group was significantly higher than that in the WT group on the 14th and 21th postnatal d (P＜0.05).[Conclusion] The delayed shift of Drebrin A to Drebrin E and transitional over-expression of lcam-5 in developmental cerebral cortex are the reasons for mental retardation in Fragile X Syndrome.

Protein and mRNA expressions of LIMK1 in the cerebral cortex of mice with fragile X syndrome / 中华神经医学杂志

Objective To observe the mRNA and protein expressions of LIMK1 in the cerebral cortex of mice with FMR1 gene knockout, and explore the roles of LIMK1 mRNA and LIMK1 protein inthe pathogenic mechanism of fragile X syndrome (FXS). Methods FVB strain male mice with FMR1 gene knockout (KO, n=36, experimental group) and their wild type (WT, n=36, control group) were equally divided into 8 counterpart subgroups (WT0d, WT2W, WT4W, WT6W, KO0d, KO2W, KO4W and KO6W),respectively, according to different ages. LIMK1 mRNA expression in the left sides of the cerebral cortex were analyzed with RT-qPCR and protein expression of LIMK1 in another side with Western blotting.Results No significant differences of LIMK1 mRNA expression in the cerebral cortex of KO0d, KO2Wand KO4W subgroups were noted as compared with that of respective age-matched WT mice (P>0.05);but that of KO6W subgroup was significantly increased as compared with that of WT6W subgroup, and KO0d,KO2W and KO4W subgroups (P<0.05);the level of LIMK1 mRNA in WT0d subgroup was obviously higher than that of WT2W, WT4W and WT6W subgroups (P<0.05). No statistic differences of LIMK1 protein between the same-age KO and WT mice were noted (P>0.05);significantly lower level of LIMK1 protein in KO0d subgroup was found as compared with that of KO2W, KO4W and KO6W subgroups (P<0.05);that of WT0d subgroup was lower than that of WT2W, WT4W and WT6W subgroups (P<0.05). Conclusion The translation process of LIMK1 protein is significantly inhibited at 6 weeks and LIMK1 mRNA expression increased sharply based on the feedback adjustment of LIMK1 protein expression declining;once this translation process is inhibited or interrupted, it will affect the dendritic spines skeleton protein reconstruct and lead to the dendritic spines function deficient;the inhabitation of translation process might probably play an important role in the process of dendritic spines maturation and should be an important pathogenic mechanism of FXS.

Differential regulation of Purkinje cell dendritic spines in rolling mouse Nagoya (tg(rol)/tg(rol)), P/Q type calcium channel (alpha1(A)/Ca(v)2.1) mutant / 대한해부학회지

Voltage dependent calcium channels (VDCC) participate in regulation of neuronal Ca2+. The Rolling mouse Nagoya (Cacna1a(tg-rol) ) is a spontaneous P/Q type VDCC mutant, which has been suggested as an animal model for some human neurological diseases such as autosomal dominant cerebellar ataxia (SCA6), familial hemiplegic migraine and episodic ataxia type-2. Morphology of Purkinje cell (PC) dendritic spine is suggested to be regulated by signal molecules such as Ca2+ and by interactions with afferent inputs. The amplitude of excitatory postsynaptic current was decreased in parallel fiber (PF) to PC synapses, whereas apparently increased in climbing fiber (CF) to PC synapses in rolling mice Nagoya. We have studied synaptic morphology changes in cerebella of this mutant strain. We previously found altered synapses between PF varicosity and PC dendritic spines. To study dendritic spine plasticity of PC in the condition of insufficient P/Q type VDCC function, we used high voltage electron microscopy (HVEM). We measured the density and length of PC dendritic spines at tertiary braches. We observed statistically a significant decrease in spine density as well as shorter spine length in rolling mice compared to wild type mice at tertiary dendritic braches. In proximal PC dendrites, however, there were more numerous dendritic spines in rolling mice Nagoya. The differential regulation of rolling PC spines at tertiary and proximal dendrites in rolling mice Nagoya suggests that two major excitatory afferent systems may be regulated reciprocally in the cerebellum of rolling mouse Nagoya.