Changes and Significance of SYP and GAP-43 Expression in the Hippocampus of CIH Rats

Disruption of Dopamine Homeostasis Associated with Alteration of Proteins in Synaptic Vesicles: A Putative Central Mechanism of Parkinson's Disease Pathogenesis

Vestigial dopaminergic cells in PD have selectivity for a sub-class of hypersensitive neurons with the nigrostriatal dopamine (DA) tract. DA is modulated in pre-synaptic nerve terminals to remain stable. To be specific, proteins at DA release sites that have a function of synthesizing and packing DA in cytoplasm, modulating release and reingestion, and changing excitability of neurons, display regional discrepancies that uncover relevancy of the observed sensitivity to neurodegenerative changes. Although the reasons of a majority of PD cases are still indistinct, heredity and environment are known to us to make significant influences. For decades, genetic analysis of PD patients with heredity in family have promoted our comprehension of pathogenesis to a great extent, which reveals correlative mechanisms including oxidative stress, abnormal protein homeostasis and mitochondrial dysfunction. In this review, we review the constitution of presynaptic vesicle related to DA homeostasis and describe the genetic and environmental evidence of presynaptic dysfunction that increase risky possibility of PD concerning intracellular vesicle transmission and their functional outcomes. We summarize alterations in synaptic vesicular proteins with great involvement in the reasons of some DA neurons highly vulnerable to neurodegenerative changes. We generalize different potential targets and therapeutic strategies for different pathogenic mechanisms, providing a reference for further studies of PD treatment in the future. But it remains to be further researched on this recently discovered and converging mechanism of vesicular dynamics and PD, which will provide a more profound comprehension and put up with new therapeutic tactics for PD patients.

Volatile oil of Angelica sinensis Radix improves cognitive function by inhibiting miR-301a-3p targeting Ppp2ca in cerebral ischemia mice

ETHNOPHARMACOLOGICAL RELEVANCE

Angelica Sinensis Radix (ASR) is a commonly used Chinese medicine known for its effects on tonifying blood, promoting blood circulation, and alleviating pain associated with menstrual regulation. Additionally, it has been used in the treatment of vascular cognitive impairment (VCI). The primary pharmacodynamic agent within ASR is volatile oil of Angelica Sinensis Radix (VOASR), which has demonstrated efficacy in combating cognitive impairment, although its mechanism remains unclear.

OBJECTIVE

This study aimed to elucidate the potential molecular mechanisms underlying VOASR's improvement of cognitive function in cerebral ischemic mice.

METHODS

A model of cerebral ischemic mice was established through unilateral common carotid artery occlusion (UCCAO) surgery, followed by intervention with VOASR. Cognitive function was assessed using the Morris water maze (MWM) test, while RT-qPCR was utilized to measure the differential expression of miR-301a-3p in the hippocampus. To evaluate cognitive function and hippocampal protein differences, wild-type mice and miR-301a-3p knockout mice were subjected to the MWM test and iTRAQ protein profiling. The relationship between miR-301a-3p and potential target genes was validated through a Dual-Luciferase Reporter experiment. RT-qPCR and Western blot were employed to determine the differential expression of Ppp2ca and synaptic plasticity-related proteins in the mouse hippocampus.

RESULTS

Intervention with VOASR significantly improved cognitive impairment in cerebral ischemic mice and reduced the expression of miR-301a-3p in the hippocampus. Our findings suggest that miR-301a-3p may regulate cognitive function by targeting Ppp2ca. Furthermore, VOASR intervention led to an increase in the expression of Ppp2ca and synaptic plasticity-related proteins.

CONCLUSION

Our study indicates that VOASR may be involved in regulating cognitive function by inhibiting miR-301a-3p, consequently increasing the expression of Ppp2ca and synaptic plasticity proteins. These results provide a new target and direction for the treatment of cognitive dysfunction.

Identification of IGF-1 Effects on White Adipose Tissue and Hippocampus in Alzheimer's Disease Mice via Transcriptomic and Cellular Analysis

Alzheimer's disease (AD) stands as the most prevalent neurodegenerative disorder, characterized by a multitude of pathological manifestations, prominently marked by the aggregation of amyloid beta. Recent investigations have revealed a compelling association between excessive adiposity and glial activation, further correlating with cognitive impairments. Additionally, alterations in levels of insulin-like growth factor 1 (IGF-1) have been reported in individuals with metabolic conditions accompanied by memory dysfunction. Hence, our research endeavors to comprehensively explore the impact of IGF-1 on the hippocampus and adipose tissue in the context of Alzheimer's disease. To address this, we have conducted an in-depth analysis utilizing APP/PS2 transgenic mice, recognized as a well-established mouse model for Alzheimer's disease. Upon administering IGF-1 injections to the APP/PS2 mice, we observed notable alterations in their behavioral patterns, prompting us to undertake a comprehensive transcriptomic analysis of both the hippocampal and adipose tissues. Our data unveiled significant modifications in the functional profiles of these tissues. Specifically, in the hippocampus, we identified changes associated with synaptic activity and neuroinflammation. Concurrently, the adipose tissue displayed shifts in processes related to fat browning and cell death signaling. In addition to these findings, our analysis enabled the identification of a collection of long non-coding RNAs and circular RNAs that exhibited significant changes in expression subsequent to the administration of IGF-1 injections. Furthermore, we endeavored to predict the potential roles of these identified RNA molecules within the context of our study. In summary, our study offers valuable transcriptome data for hippocampal and adipose tissues within an Alzheimer's disease model and posits a significant role for IGF-1 within both the hippocampus and adipose tissue.

Quantitative proteomic and phosphoproteomic analyses of the hippocampus reveal the involvement of NMDAR1 signaling in repetitive mild traumatic brain injury

The cumulative damage caused by repetitive mild traumatic brain injury can cause long-term neurodegeneration leading to cognitive impairment. This cognitive impairment is thought to result specifically from damage to the hippocampus. In this study, we detected cognitive impairment in mice 6 weeks after repetitive mild traumatic brain injury using the novel object recognition test and the Morris water maze test. Immunofluorescence staining showed that p-tau expression was increased in the hippocampus after repetitive mild traumatic brain injury. Golgi staining showed a significant decrease in the total density of neuronal dendritic spines in the hippocampus, as well as in the density of mature dendritic spines. To investigate the specific molecular mechanisms underlying cognitive impairment due to hippocampal damage, we performed proteomic and phosphoproteomic analyses of the hippocampus with and without repetitive mild traumatic brain injury. The differentially expressed proteins were mainly enriched in inflammation, immunity, and coagulation, suggesting that non-neuronal cells are involved in the pathological changes that occur in the hippocampus in the chronic stage after repetitive mild traumatic brain injury. In contrast, differentially expressed phosphorylated proteins were mainly enriched in pathways related to neuronal function and structure, which is more consistent with neurodegeneration. We identified N-methyl-D-aspartate receptor 1 as a hub molecule involved in the response to repetitive mild traumatic brain injury , and western blotting showed that, while N-methyl-D-aspartate receptor 1 expression was not altered in the hippocampus after repetitive mild traumatic brain injury, its phosphorylation level was significantly increased, which is consistent with the omics results. Administration of GRP78608, an N-methyl-D-aspartate receptor 1 antagonist, to the hippocampus markedly improved repetitive mild traumatic brain injury-induced cognitive impairment. In conclusion, our findings suggest that N-methyl-D-aspartate receptor 1 signaling in the hippocampus is involved in cognitive impairment in the chronic stage after repetitive mild traumatic brain injury and may be a potential target for intervention and treatment.

Simultaneous Pericytes and M2 Microglia Transplantation Improve Cognitive Function in Mice Model of mPFC Ischemia

Cerebral ischemia is one of the major problems threatening global health. Many of the cerebral ischemia survivors would suffer from the physical and cognitive disabilities for their whole lifetime. Cell based-therapies have been introduced as a therapeutic approach for alleviating ischemia-enforced limitations. Photothrombotic stroke model was applied on the left medial prefrontal cortex (mPFC) of adult male BALB/c mice. Then, pericytes isolated from brain microvessels of adult male BALB/c mice, microglia isolated from brain cortices of the neonatal male BALB/c mice, and M2 phenotype shifted microglia by IL-4 treatment were used for transplantation into the injured area after 24 h of ischemia induction. The behavioural outcomes evaluated by social interaction and Barnes tests and the levels of growth associated protein (GAP)-43 and inflammatory cytokine interleukin (IL)-1 protein were assessed by western blotting 7 days after cell transplantation. Animals in both of the microglia + pericytes and microglia M2 + pericytes transplanted groups showed better performance in social memory as well as enhanced spatial learning and memory compared to ischemic controls. Also, improved escape latency was only observed in microglia M2 + pericytes (p < 0.01) group compared to ischemic controls. GAP-43 showed significant protein expression in microglia + pericytes and microglia M2 + pericytes groups compared to the control group. Conversely, IL-1 levels diminished in all of the pericytes microglia + pericytes, and microglia M2 + pericytes groups compared to the ischemic controls. Current study highlights efficiency of M2 microglia and pericytes combinatory transplantation therapeutic role on relieving ischemic stroke outcomes.

Dysfunction of inhibitory interneurons contributes to synaptic plasticity via GABABR-pNR2B signaling in a chronic migraine rat model

Background

According to our previous study, the loss of inhibitory interneuron function contributes to central sensitization in chronic migraine (CM). Synaptic plasticity is a vital basis for the occurrence of central sensitization. However, whether the decline in interneuron-mediated inhibition promotes central sensitization by regulating synaptic plasticity in CM remains unclear. Therefore, this study aims to explore the role of interneuron-mediated inhibition in the development of synaptic plasticity in CM.

Methods

A CM model was established in rats by repeated dural infusion of inflammatory soup (IS) for 7 days, and the function of inhibitory interneurons was then evaluated. After intraventricular injection of baclofen [a gamma-aminobutyric acid type B receptor (GABABR) agonist] or H89 [a protein kinase A (PKA) inhibitor), behavioral tests were performed. The changes in synaptic plasticity were investigated by determining the levels of the synapse-associated proteins postsynaptic density protein 95 (PSD95), synaptophysin (Syp) and synaptophysin-1(Syt-1)]; evaluating the synaptic ultrastructure by transmission electron microscopy (TEM); and determining the density of synaptic spines via Golgi-Cox staining. Central sensitization was evaluated by measuring calcitonin gene-related peptide (CGRP), brain-derived neurotrophic factor (BDNF), c-Fos and substance P (SP) levels. Finally, the PKA/Fyn kinase (Fyn)/tyrosine-phosphorylated NR2B (pNR2B) pathway and downstream calcium-calmodulin-dependent kinase II (CaMKII)/c-AMP-responsive element binding protein (pCREB) signaling were assessed.

Results

We observed dysfunction of inhibitory interneurons, and found that activation of GABABR ameliorated CM-induced hyperalgesia, repressed the CM-evoked elevation of synapse-associated protein levels and enhancement of synaptic transmission, alleviated the CM-triggered increases in the levels of central sensitization-related proteins, and inhibited CaMKII/pCREB signaling via the PKA/Fyn/pNR2B pathway. The inhibition of PKA suppressed the CM-induced activation of Fyn/pNR2B signaling.

Conclusion

These data reveal that the dysfunction of inhibitory interneurons contributes to central sensitization by regulating synaptic plasticity through the GABABR/PKA/Fyn/pNR2B pathway in the periaqueductal gray (PAG) of CM rats. Blockade of GABABR-pNR2B signaling might have a positive influence on the effects of CM therapy by modulating synaptic plasticity in central sensitization.

Effect of prenatal stress and extremely low-frequency electromagnetic fields on anxiety-like behavior in female rats: With an emphasis on prefrontal cortex and hippocampus

OBJECTIVE

Prenatal stress (PS) is a problematic situation resulting in psychological implications such as social anxiety. Ubiquitous extremely low-frequency electromagnetic fields (ELF-EMF) have been confirmed as a potential physiological stressor; however, useful neuroregenerative effect of these types of electromagnetic fields has also frequently been reported. The aim of the present study was to survey the interaction of PS and ELF-EMF on anxiety-like behavior.

METHOD

A total of 24 female rats 40 days of age were distributed into four groups of 6 rats each: control, stress (their mothers were exposed to stress), EMF (their mothers underwent to ELF-EMF), and EMF/stress (their mothers concurrently underwent to stress and ELF-EMF). The rats were assayed using elevated plus-maze and open field tests.

RESULTS

Expressions of the hippocampus GAP-43, BDNF, and caspase-3 (cas-3) were detected by immunohistochemistry in Cornu Ammonis 1 (CA1) and dentate gyrus (DG) of the hippocampus and prefrontal cortex (PFC). Anxiety-like behavior increased in all treatment groups. Rats in the EMF/stress group presented more serious anxiety-like behavior. In all treatment groups, upregulated expression of cas-3 was seen in PFC, DG, and CA1 and downregulated expression of BDNF and GAP-43 was seen in PFC and DG and the CA1. Histomorphological study showed vast neurodegenerative changes in the hippocampus and PFC.

CONCLUSION

The results showed ,female rats that underwent PS or/and EMF exhibited critical anxiety-like behavior and this process may be attributed to neurodegeneration in PFC and DG of the hippocampus and possibly decreased synaptic plasticity so-called areas.

Copper Induces Cognitive Impairment in Mice via Modulation of Cuproptosis and CREB Signaling

It has been reported that disordered Cu metabolism is associated with several neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanism is still unclear. In this study, 4-week-old male mice were exposed to Cu by free-drinking water for three months. Then, the effects of Cu on cognitive functions in mice were tested by Morris water maze tests, and the potential mechanisms were investigated by the ELISA, immunochemistry, TUNEL, and Western blot tests. It was found that Cu exacerbates learning and memory impairment, and leads to Cu-overload in the brain and urine of mice. The results showed that Cu induces neuronal degeneration and oxidative damage, promotes the expression of apoptosis-related protein Bax, cuproptosis-related proteins FDX1 and DLAT and the proteotoxic stress marker HSP70, and decreases Fe-S cluster proteins. In addition, Cu affects the pre-synaptic and post-synaptic regulatory mechanisms through inhibiting the expression of PSD-95 and SYP. Cu also suppresses phosphorylation levels in CREB and decreases the expression of BDNF and TrkB in the mouse hippocampus. In conclusion, Cu might mediate cuproptosis, damage synaptic plasticity and inhibit the CREB/BDNF pathway to cause cognitive dysfunction in mice.

Exploring the mechanism of Chaihujia Longgu Muli decoction in the treatment of epilepsy in rats based on the RhoA/ROCK signaling pathway

BACKGROUND

The Chinese herbal formula Chaihujia Longgu Muli Decoction (CD) has a good antiepileptic effect, but its mechanisms remain unclear. Therefore, in this study we explored the molecular mechanisms of CD against epilepsy.

METHODS

Twelve-day-old SD rats were randomly divided into a normal group, model group, valproic acid group, and CD high, medium, and low groups. Except for the normal group, the other groups were given an intraperitoneal injection of pentylenetetrazol (PTZ) to establish epilepsy models, and the Racine score was applied for model judgment. After 14 consecutive days of dosing, the Morris water maze test was performed. Then, hippocampal Nissl staining and immunofluorescence staining were performed, and synaptic ultrastructure was observed by transmission electron microscopy (TEM). RhoA/ROCK signaling pathway proteins were detected.

RESULTS

In PTZ model rats, the passing times were reduced, and the escape latency was prolonged in the Morris water maze test. Nissl staining showed that some hippocampal neurons swelled and ruptured, Nissl bodies in the cytoplasm were significantly reduced, and neurons were lost. Immunofluorescence detection revealed that the expression of PSD95 and SYP was significantly reduced. Electron microscopy results revealed that the number of synapses in hippocampal neurons was significantly reduced and the postsynaptic membrane length was significantly reduced. Western blot analysis showed that the RhoA/ROCK signaling pathway was activated, while SYP, SPD95, and PTEN expression was significantly decreased. After treatment with CD, neurobehavioral abnormalities and neuronal damage caused by epileptic seizures were improved.

CONCLUSION

CD exerted an antiepileptic effect by inhibiting the activation of the RhoA/ROCK signaling pathway.

Prediction Model for Sensory Perception Abnormality in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by heterogeneous clinical phenotypes. Patients often experience abnormal sensory perception, which may further affect the ASD core phenotype, significantly and adversely affecting their quality of life. However, biomarkers for the diagnosis of ASD sensory perception abnormality are currently elusive. We sought to identify potential biomarkers related to ASD sensory perception abnormality to construct a prediction model that could facilitate the early identification of and screening for ASD. Differentially expressed genes in ASD were obtained from the Gene Expression Omnibus database and were screened for genes related to sensory perception abnormality. After enrichment analysis, the random forest method was used to identify disease-characteristic genes. A prediction model was constructed with an artificial neural network. Finally, the results were validated using data from the dorsal root ganglion, cerebral cortex, and striatum of the BTBR T+ Itpr3tf/J (BTBR) ASD mouse model. A total of 1869 differentially expressed genes in ASD were screened, among which 16 genes related to sensory perception abnormality were identified. According to enrichment analysis, these 16 genes were mainly related to actin, cholesterol metabolism, and tight junctions. Using random forest, 15 disease-characteristic genes were screened for model construction. The area under the curve of the training set validation result was 0.999, and for the model function validation, the result was 0.711, indicating high accuracy. The validation of BTBR mice confirmed the reliability of using these disease-characteristic genes for prediction of ASD. In conclusion, we developed a highly accurate model for predicting ASD sensory perception abnormality from 15 disease-characteristic genes. This model provides a new method for the early identification and diagnosis of ASD sensory perception abnormality.

Evaluation of the concentration of growth associated protein-43 and glial cell-derived neurotrophic factor in degenerated intervertebral discs of the lumbosacral region of the spine

Important neurotrophic factors that are potentially involved in degenerative intervertebral disc (IVD) disease of the spine's lumbosacral (L/S) region include glial cell-derived neurotrophic factor (GDNF) and growth associated protein 43 (GAP-43). The aim of this study was to determine and compare the concentrations of GAP-43 and GDNF in degenerated and healthy IVDs and to quantify and compare the GAP-43-positive and GDNF-positive nerve fibers. The study group consisted of 113 Caucasian patients with symptomatic lumbosacral discopathy (confirmed by a specialist surgeon), an indication for surgical treatment. The control group included 81 people who underwent postmortem examination. GAP-43 and GDNF concentrations were significantly higher in IVD samples from the study group compared with the control group, and the highest concentrations were observed in the degenerated IVDs that were graded 4 on the Pfirrmann scale. In the case of GAP-43, it was found that as the degree of IVD degeneration increased, the number of GAP-43-positive nerve fibers decreased. In the case of GDNF, the greatest number of fibers per mm² of surface area was found in the IVD samples graded 3 on the Pfirrmann scale, and the number was found to be lower in samples graded 4 and 5. Hence, GAP-43 and GDNF are promising targets for analgesic treatment of degenerative IVD disease of the lumbosacral region of the spine.

The regulatory role of NAAG-mGluR3 signaling on cortical synaptic plasticity after hypoxic ischemia

Background

Synapses can adapt to changes in the intracerebral microenvironment by regulation of presynaptic neurotransmitter release and postsynaptic neurotransmitter receptor expression following hypoxic ischemia (HI) injury. The peptide neurotransmitter N-acetylaspartylglutamate (NAAG) exerts a protective effect on neurons after HI and may be involved in maintaining the function of synaptic networks. In this study, we investigated the changes in the expression of NAAG, glutamic acid (Glu) and metabotropic glutamate receptors (mGluRs), as well as the dynamic regulation of neurotransmitters in the brain after HI, and assessed their effects on synaptic plasticity of the cerebral cortex.

Methods

Thirty-six Yorkshire newborn pigs (3-day-old, males, 1.0–1.5 kg) were selected and randomly divided into normal saline (NS) group (n = 18) and glutamate carboxypeptidase II inhibition group (n = 18), both groups were divided into control group, 0–6 h, 6–12 h, 12–24 h, 24–48 h and 48–72 h groups (all n = 3) according to different post-HI time. The content of Glu and NAAG after HI injury were detected by 1H-MRS scanning, immunofluorescence staining of mGluRs, synaptophysin (syph) along with postsynaptic density protein-95 (PSD95) and transmission electron microscopy were performed. ANOVA, Tukey and LSD test were used to compare the differences in metabolite and protein expression levels among subgroups. Correlation analysis was performed using Pearson analysis with a significance level of α = 0.05.

Results

We observed that the NAAG and mGluR3 expression levels in the brain increased and then decreased after HI and was significantly higher in the 12–24 h (P < 0.05, Tukey test). There was a significant positive correlation between Glu content and the expression of mGluR1/mGluR5 after HI with r = 0.521 (P = 0.027) and r = 0.477 (P = 0.045), respectively. NAAG content was significantly and positively correlated with the level of mGluR3 expression (r = 0.472, P = 0.048). When hydrolysis of NAAG was inhibited, the expression of synaptic protein PSD95 and syph decreased significantly.

Conclusions

After 12–24 h of HI injury, there was a one-time elevation in NAAG levels, which was consistent with the corresponding mGluR3 receptor expression trend; the NAAG maintains cortical synaptic plasticity and neurotransmitter homeostasis by inhibiting presynaptic glutamate vesicle release, regulating postsynaptic density proteins and postsynaptic receptor expression after pathway activation.

Inhibition of ERK1/2 regulates cognitive function by decreasing expression levels of PSD-95 in the Hippocampus of CIH Rats

Obstructive sleep apnea syndrome (OSAS) is a potentially severe sleep disorder characterized by intermittent hypoxia, and there is growing evidence that OSAS can lead to cognitive decline. Extracellular signal-regulated protein kinase 1/2 (ERK1/2) plays a key role in synaptic plasticity. We established CIH model in male SD rats and examined their expression of p-ERK1/2 and PSD-95, as well as in CIH group, the effect of SL327 on the expression of p-ERK1/2 and PSD-95 in hippocampus of CIH model rats was observed by pretreating the experimental rats with SL327 during peak time of p-ERK1/2 expression. Mean oxygen saturation in the tail artery was lower in the CIH group. In the CIH groups exhibited increased escape latencies in the navigation test and decreased numbers of platform crossings in the space exploration test. Reduced volume, irregular structure, deepened cytoplasmic eosinophilic staining in the cytoplasm, and decreased nuclear size were found in hippocampal neurons in the 28-d CIH 、28-d CIH + SL327 group. The hippocampus of CIH rats^, p-ERK expressions gradually increased with prolonged CIH exposure but decreased after SL327 treatment. Moreover, PSD-95 expressions gradually reduced in the 14-d CIH, 21-d CIH, and 28-d CIH groups but increased in the SL327-treated group. The SL327 intervention decreased p-ERK1/2 expression, increased PSD-95 expression, and improved cognitive function in CIH rats. The present findings provide some insights into the mechanisms underlying OSAS-associated cognitive impairment.

Sexual experience in female mice involves synaptophysin-related plasticity in the accessory olfactory bulb

Sexually naïve female mice do not display high levels of sexual receptivity in their first sexual experience; they require around 4-5 sexual encounters to display the full receptive response, assessed by the lordosis reflex. In this study, we evaluated if repeated sexual stimulation with the same male is associated with changes in synaptic remodeling evaluated by synaptophysin (SYP) in brain structures involved in the control of sexual behavior such as the main and accessory olfactory bulbs (MOB and AOB, respectively), medial preoptic area (MPOA), ventromedial hypothalamus (VMH), and amygdala (AMG). Female mice were ovariectomized and hormonally primed to induce sexual receptivity. They were randomly distributed into three groups: a) sexually naïve (SN), with no prior sexual stimulation; b) sexually inexperienced (SI), with one prior mating session; and c) sexually experienced (SE), with six mating sessions. The SI group showed a significant decrease in SYP in the glomerular, mitral and granular layers of the AOB in comparison to SN and SE females. SYP expression increased in the SE group in comparison to SN and SI females in the glomerular and mitral cell layers of the AOB. No significant differences between groups were found in the other brain regions (MOB, MPOA, VMH or AMG). These changes in SYP expression in the AOB suggest that plastic modifications in this brain region can be associated with receptivity increase in sexual experience in female mice.

NEP1‑40 promotes myelin regeneration via upregulation of GAP‑43 and MAP‑2 expression after focal cerebral ischemia in rats

Axon regeneration after lesions to the central nervous system (CNS) is largely limited by the presence of growth inhibitory molecules expressed in myelin. Nogo‑A is a principal inhibitor of neurite outgrowth, and blocking the activity of Nogo‑A can induce axonal sprouting and functional recovery. However, there are limited data on the expression of Nogo‑A after CNS lesions, and the mechanism underlying its influences on myelin growth remains unknown. The aim of the present study was to observe the time course of Nogo‑A after cerebral ischemia/reperfusion in rats using immunohistochemistry and western blot techniques, and to test the effect of its inhibitor Nogo extracellular peptide 1‑40 (NEP1‑40) on neural plasticity proteins, growth‑associated binding protein 43 (GAP‑43) and microtubule associated protein 2 (MAP‑2), as a possible mechanism underlying myelin suppression. A classic model of middle cerebral artery occlusion (MCAO) was established in Sprague‑Dawley rats, which were divided into three groups: i) MCAO model group; ii) MCAO + saline group; and iii) MCAO + NEP1‑40 group. Rats of each group were divided into five subgroups by time points as follows: days 1, 3, 7, 14 and 28. Animals that only received sham operation were used as controls. The Nogo‑A immunoreactivity was located primarily in the cytoplasm of oligodendrocytes. The number of Nogo‑A immunoreactive cells significantly increased from day 1 to day 3 after MCAO, nearly returning to the control level at day 7, increased again at day 14 and decreased at day 28. Myelin basic protein (MBP) immunoreactivity in the ipsilateral striatum gradually decreased from day 1 to day 28 after ischemia, indicating myelin loss appeared at early time points and continuously advanced during ischemia. Then, intracerebroventricular infusion of NEP1‑40, which is a Nogo‑66 receptor antagonist peptide, was administered at days 1, 3 and 14 after MCAO. It was observed that GAP‑43 considerably increased from day 1 to day 7 and then decreased to a baseline level at day 28 compared with the control. MAP‑2 expression across days 1‑28 significantly decreased after MCAO. Administration of NEP1‑40 attenuated the reduction of MBP, and upregulated GAP‑43 and MAP‑2 expression at the corresponding time points after MCAO compared with the MCAO + saline group. The present results indicated that NEP1‑40 ameliorated myelin damage and promoted regeneration by upregulating the expression of GAP‑43 and MAP‑2 related to neuronal and axonal plasticity, which may aid with the identification of a novel molecular mechanism of restriction in CNS regeneration mediated by Nogo‑A after ischemia in rats.

Effect of regulation of the NRG1/ErbB4 signaling pathway on the visual cortex synaptic plasticity of amblyopic adult rats

This study aimed to investigate the effect of the neuregulin-1/epidermal growth factor 4 (NRG1/ErbB4) signaling pathway on visual cortex synaptic plasticity in adult amblyopic rats with monocular deprivation (MD). Compared with the control group, the P wave latency and amplitude of the MD group were prolonged and low, respectively, with reduced synaptic plasticity-related protein expression, lower number of visual cortex neurons, and increased apoptosis of visual cortex neurons. Recombinant neuregulin-1 (rNRG1) administration activated the NRG1/ErbB4 signaling pathway and improved the visual cortex synaptic plasticity in MD amblyopic rats. However, the effects of rNRG1 were reversed by AG1478 (ErbB4 receptor blockers). The NRG1/ErbB4 signaling pathway in the parvalbumin neurons from MD rats was also inactivated. Amblyopic rats had significantly low cell activity and downregulated expression of synaptic plasticity-related proteins. Thus, exogenous administration of NRG1 can activate ErbB4 signal transduction and improve the damaged synaptic plasticity of the visual cortex among amblyopic rats. Further studies are warranted to explore the potential for clinical management of amblyopia.

Shashen-Maidong Decoction improved chronic intermittent hypoxia-induced cognitive impairment through regulating glutamatergic signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Obstructive sleep apnea (OSA) is characterized by chronic intermittent hypoxia (CIH), which is associated with cognitive impairment. Previous study suggested CIH exposure could induce similar symptoms and signs to the clinical features of Deficiency of both Qi and Yin Syndrome (DQYS) in Traditional Chinese Medicine (TCM). Shashen-Maidong Decoction (SMD) has been applied clinically for DQYS for hundred years. However, SMD treatment could be beneficial to CIH induced cognitive impairment is still unclear.

AIM OF THE STUDY

Therefore, the aim of this study was to investigate the effect of SMD treatment on CIH induced cognitive impairment, and to explore the related neuroprotective mechanism.

MATERIALS AND METHODS

Mice were exposed to CIH for 5 weeks (8 h/day) and were orally treated with either vehicle or SMD (5.265 g/kg/day) 30 min before CIH exposure. Spatial memory was evaluated by Morris Water Maze and Y-Maze test. Synaptic morphology in hippocampus was observed by Golgi-Cox staining and Electron microscope, and NR2B-ERK signaling pathway were detected by western blotting.

RESULTS

Our results showed that SMD treatment improved performance in either Morris Water Maze or Y-Maze test in mice exposed to CIH, increased spine density and postsynaptic density (PSD) thickness in hippocampus. SMD treatment suppressed the over-activation of NR2B/CaMKII/SynGAP induced by CIH exposure, enhanced ERK/CREB phosphorylation and increased PSD-95 and BDNF expression.

CONCLUSION

SMD attenuates the CIH-induced cognitive impairment through regulating NR2B-ERK signaling pathway. Additionally, our findings provided that DQYS may be the potential therapeutic target for neurocognitive diseases in patients with OSA.

Exploring the Key Genes and Identification of Potential Diagnosis Biomarkers in Alzheimer's Disease Using Bioinformatics Analysis

Background

Alzheimer’s disease (AD) is one of the major threats of the twenty-first century and lacks available therapy. Identification of novel molecular markers for diagnosis and treatment of AD is urgently demanded, and genetic biomarkers show potential prospects.

Method

We identify and intersected differentially expressed genes (DEGs) from five microarray datasets to detect consensus DEGs. Based on these DEGs, we conducted Gene Ontology (GO), performed the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, constructed a protein—protein interaction (PPI) network, and utilized Cytoscape to identify hub genes. The least absolute shrinkage and selection operator (LASSO) logistic regression was applied to identify potential diagnostic biomarkers. Gene set enrichment analysis (GSEA) was performed to investigate the biological functions of the key genes.

Result

We identified 608 consensus DEGs, several dysregulated pathways, and 18 hub genes. Sixteen hub genes dysregulated as AD progressed. The diagnostic model of 35 genes was constructed, which has a high area under the curve (AUC) value in both the validation dataset and combined dataset (AUC = 0.992 and AUC = 0.985, respectively). The model can also differentiate mild cognitive impairment and AD patients from controls in two blood datasets. Brain-derived neurotrophic factor (BDNF) and WW domain-containing transcription regulator protein 1 (WWTR1), which are associated with the Braak stage, Aβ 42 levels, and β-secretase activity, were identified as critical genes of AD.

Conclusion

Our study identified 16 hub genes correlated to the neuropathological stage and 35 potential biomarkers for the diagnosis of AD. WWTR1 were identified as candidate genes for future studies. This study deepens our understanding of the transcriptomic and functional features and provides new potential diagnostic biomarkers and therapeutic targets for AD.

Anti-Cognitive Decline by Yinxing-Mihuan-Oral-Liquid via Activating CREB/BDNF Signaling and Inhibiting Neuroinflammatory Process

BACKGROUND: Cognitive decline in the normal aging process is one of the most common and prominent problems. Delaying and alleviating cognitive impairment is an important strategy of anti-aging. This study is to aim at investigating the effects of Yinxing-Mihuan-Oral-Liquid(GMOL) on the CREB/BDNF signaling in the normal aging process.METHODS: SD rats were randomly divided into GMOL group and control group. The Morris water maze (MWM) was introduced for behavioral test. Immunohistochemistry and immunofluorescence were used for cAMP response element binding protein 1(CREB1), p-CREB(Ser133), brain-derived neurotrophic factor(BDNF), synaptophysin(SYP) and glial fibrillary acidic protein(GFAP). Western blot was conducted for investigating the levels of CREB1 and p-CREB(Ser133), BDNF, SYP, GFAP and interleukin 6(IL-6). RESULTS:  Our data showed that compared with the control group, GMOL group had higher expression of memory-related proteins, decreased inflammatory factors, and enhanced spatial learning and memory ability.CONCLUSION: The study results show that GMOL ameliorates cognitive impairment of the normal aged SD rats via enhancing the expression of memory biomarkers and inhibiting inflammatory process. The potential neuroprotective role of GMOL in the process of aging may be related to mitigating cognitive decline via activating CREB/BDNF signaling and inhibiting inflammatory process.

Metabotropic glutamate receptor 5 regulates synaptic plasticity in a chronic migraine rat model through the PKC/NR2B signal

Background

The mechanism of chronic migraine (CM) is complex, central sensitization is considered as one of the pathological mechanism. Synaptic plasticity is the basis of central sensitization. Metabotropic glutamate receptor 5 (mGluR5) plays a vital role in the synaptic plasticity of the central nervous system. However, whether mGluR5 can promote the central sensitization by regulating synaptic plasticity in CM is unknown.

Methods

Male Wistar rats were used to establish a CM rat model, and the expression of mGluR5 mRNA and protein were detected by qRT-PCR and western blot. The allodynia was assessed by mechanical and thermal thresholds, and central sensitization was assessed by expression of the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) at Serine 133(pCREB-S133) and c-Fos. The synaptic-associated protein postsynaptic density protein 95 (PSD), synaptophysin (Syp), and synaptophysin-1(Syt-1), synaptic ultrastructure, and dendritic spines were detected to explore synaptic plasticity. The expression of PKC, total NR2B(tNR2B), and phosphorylation of NR2B at Tyr1472(pNR2B-Y1472) were detected by western blot.

Results

We found that the expression of mGluR5 was upregulated in CM rats. Downregulated the mGluR5 with MPEP alleviated the allodynia and reduced the expression of CGRP, pCREB-S133, c-Fos, PSD, Syp and Syt-1 and synaptic transmission. Moreover, the administration of MPEP inhibited the upregulation of PKC and pNR2B-Y1472.

Conclusions

These results indicate that mGluR5 contributes to central sensitization by regulating synaptic plasticity in CM through the PKC/NR2B signal, which suggests that mGluR5 may be a potential therapeutic candidate for CM.

Pre- and early postnatal enriched environmental experiences prevent neonatal hypoxia-ischemia late neurodegeneration via metabolic and neuroplastic mechanisms

Prenatal and early postnatal periods are important for brain development and neural function. Neonatal insults such as hypoxia-ischemia (HI) causes prolonged neural and metabolic dysregulation, affecting central nervous system maturation. There is evidence that brain hypometabolism could increase the risk of adult-onset neurodegenerative diseases. However, the impact of non-pharmacologic strategies to attenuate HI-induced brain glucose dysfunction is still underexplored. This study investigated the long-term effects of early environmental enrichment in metabolic, cell, and functional responses after neonatal HI. Thereby, male Wistar rats were divided according to surgical procedure, sham, and HI (performed at postnatal day 3), and the allocation to standard (SC) or enriched condition (EC) during gestation and lactation periods. In-vivo cerebral metabolism was assessed by means of [¹⁸ F]-FDG micro-positron emission tomography, and cognitive, biochemical, and histological analyses were performed in adulthood. Our findings reveal that HI causes a reduction in glucose metabolism and glucose transporter levels as well as hyposynchronicity in metabolic brain networks. However, EC during prenatal or early postnatal period attenuated these metabolic disturbances. A positive correlation was observed between [¹⁸ F]-FDG values and volume ratios in adulthood, indicating that preserved tissue by EC is metabolically active. EC promotes better cognitive scores, as well as down-regulation of amyloid precursor protein in the parietal cortex and hippocampus of HI animals. Furthermore, growth-associated protein 43 was up-regulated in the cortex of EC animals. Altogether, results presented support that EC during gestation and lactation period can reduce HI-induced impairments that may contribute to functional decline and progressive late neurodegeneration.

Differential changes in GAP-43 or synaptophysin during appetitive and aversive taste memory formation

Association between events in time and space is a major mechanism for all animals, including humans, which allows them to learn about the world and potentially change their behavior in the future to adapt to different environments. Conditioning taste aversion (CTA) is a single-trial learning paradigm where animals are trained to avoid a novel flavor which is associated with malaise. Many variables can be analyzed with this model and the circuits involved are well described. Thus, the amygdala and the gustatory cortex (GC) are some of the most relevant structures involved in CTA. In the present study we focused in plastic changes that occur during appetitive and/or aversive taste memory formation. Previous studies have demonstrated that memory consolidation, in hippocampal dependent paradigms, induces plastic changes like increase in the concentration of proteins considered as markers of neuronal plasticity, such as the growth associated protein 43 (GAP-43) and synaptophysin (SYN). In the present experiment in male rats we evaluated changes in GAP-43 and SYN expression, using immunofluorescence, induce by the formation of aversive and appetitive taste memory. We found that taste aversive memory formation can induce an increase in GAP-43 in the granular layer of the GC. Furthermore, we also found an increase in SYN expression in both layers of the GC, the basolateral amygdala (BLA) and the central amygdala (CeA). These results suggest that aversive memory representation induces a new circuitry (inferred from an increase in GAP 43). On the other hand, an appetitive taste learning increased SYN expression in the GC (both layers), the BLA and the CeA without any changes in GAP 43. Together these results indicate that aversive memory formation induces structural and synaptic changes, while appetitive memory formation induces synaptic changes; suggesting that aversive and appetitive memories require a different set of cortical and amygdala plastic changes.

Nelumbo nucifera Gaertn Stems (Hegeng) Improved Depression Behavior in CUMS Mice by Regulating NCAM and GAP-43 Expression

Background

Nelumbo nucifera Gaertn stem (Hegeng [HG]) is a traditional Chinese medicine that is used to treat mental symptoms in East Asia. However, scientific evidence is generally lacking to support this traditional claim. Aim of the Study. This study's aim is to investigate the antidepression effect of HG and to further explore the possible molecular mechanisms that are involved in its actions. Materials and Methods. HG aqueous extract was administered intragastrically for 21 days after the chronic unpredictable mild stress (CUMS) procedure, and its effect on memory, learning, and emotion was assessed using animal behavioral tests. HG aqueous extract was characterized using HPLC. Immunofluorescence was used to measure the neural cell-adhesion molecule (NCAM) and growth-associated protein-43 (GAP-43) expression.

Results

Depression-like behaviors increased in the CUMS group compared with the control (CON) group, while they were reduced in the high-dose HG (H-HG) and fluoxetine (FLU) groups (p < 0.05). Additionally, NCAM and GAP-43 expression was reduced in the CUMS group compared with the CON group, but it increased in the H-HG and FLU groups (p < 0.05).

Conclusions

These findings show the potential antidepressant effects of HG through mechanisms involving regulation of NCAM and GAP-43. This provides a new theoretical basis for its potential application as an antidepressant-like agent.

Brain-Region Specific Metabolic Abnormalities in Parkinson's Disease and Levodopa-Induced Dyskinesia

Several lines of evidence point to alteration in brain metabolic homeostasis in Parkinson’s disease (PD) and levodopa-induced dyskinesia (LID), yet the metabolic mechanism in different brain regions underlying PD and LID remains largely unknown. The present study aimed to uncover the metabolic pathways across anatomical regions in the brain of PD and LID. Using an NMR-based metabolomic approach, we generated the metabolomics profiling data from six different brain regions of PD rats and following the onset of LIDs. The diversity of metabolite patterns across the brain and its relation to PD and LID were further investigated through principal component analysis (PCA) and multivariate general linear model. Compared with control rats, dopamine loss in PD rats produced a marked and persistent metabolic disturbance in neurotransmitter metabolism and energy pathway, resulting in a metabolic imbalance among different brain regions. In LID rats, levodopa replacement did not restore the midbrain-striatum metabolic crosstalk and metabolic disturbance throughout the brain was involved in levodopa related involuntary movements. Most notably, the midbrain and right cortex were identified as the primary regions of metabolic abnormalities in PD and LID rats. Neurochemical differences in metabolic phenotypes were mainly defined by various neurotransmitters including glutamate, glutamine and aspartate. Accordingly, we found that the PD and LID rats exhibited lower levels of synaptophysin (SYP), a marker for synaptic plasticity, compared with control rats. These findings provide key insights into the metabolic mechanism underlying PD and LID by defining brain-region specific metabolic phenotype, with implications for developing targeted therapies.

Early-Life Stress Induces Depression-Like Behavior and Synaptic-Plasticity Changes in a Maternal Separation Rat Model: Gender Difference and Metabolomics Study

More than 300 million people suffer from depressive disorders globally. People under early-life stress (ELS) are reportedly vulnerable to depression in their adulthood, and synaptic plasticity can be the molecular mechanism underlying such depression. Herein, we simulated ELS by using a maternal separation (MS) model and evaluated the behavior of Sprague-Dawley (SD) rats in adulthood through behavioral examination, including sucrose preference, forced swimming, and open-field tests. The behavior tests showed that SD rats in the MS group were more susceptible to depression- and anxiety-like behaviors than did the non-MS (NMS) group. Nissl staining analysis indicated a significant reduction in the number of neurons at the prefrontal cortex and hippocampus, including the CA1, CA2, CA3, and DG regions of SD rats in the MS group. Immunohistochemistry results showed that the percentages of synaptophysin-positive area in the prefrontal cortex and hippocampus (including the CA1, CA2, CA3, and DG regions) slice of the MS group significantly decreased compared with those of the NMS group. Western blot analysis was used to assess synaptic-plasticity protein markers, including postsynaptic density 95, synaptophysin, and growth-associated binding protein 43 protein expression in the cortex and hippocampus. Results showed that the expression levels of these three proteins in the MS group were significantly lower than those in the NMS group. LC-MS/MS analysis revealed no significant differences in the peak areas of sex hormones and their metabolites, including estradiol, testosterone, androstenedione, estrone, estriol, and 5β-dihydrotestosterone. Through the application of nontargeted metabolomics to the overall analysis of differential metabolites, pathway-enrichment results showed the importance of arginine and proline metabolism; pantothenate and CoA biosyntheses; glutathione metabolism; and the phenylalanine, tyrosine, and tryptophan biosynthesis pathways. In summary, the MS model caused adult SD rats to be susceptible to depression, which may regulate synaptic plasticity through arginine and proline metabolism; pantothenate and CoA biosyntheses; glutathione metabolism; and phenylalanine, tyrosine, and tryptophan biosyntheses.