A circRNA ceRNA network involved in cognitive dysfunction after chronic cerebral hypoperfusion.

Chronic Cerebral Hypoperfusion (CCH) is associated with cognitive dysfunction, the underlying mechanisms of which remain elusive, hindering the development of effective therapeutic approaches. In this study, we employed an established CCH animal model to delve into neuropathological alterations like oxidative stress, inflammation, neurotransmitter synthesis deficits, and other morphological alterations. Our findings revealed that while the number of neurons remained unchanged, there was a significant reduction in neuronal fibers post-CCH, as evidenced by microtubule-associated protein 2 (MAP2) staining. Moreover, myelin basic protein (MBP) staining showed exacerbated demyelination of neuronal fibers. Furthermore, we observed increased neuroinflammation, proliferation, and activation of astrocytes and microglia, as well as synaptic loss and microglial-mediated synapse engulfment post-CCH. Utilizing RNA sequencing, differential expression analysis displayed alterations in both mRNAs and circRNAs. Following gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, both showed significant enrichment in immunological and inflammation-related terms and pathways. Importantly, the differentially expressed circular RNAs (DE circRNAs) exhibited a notable coexpression pattern with DE mRNAs. The ternary circRNA-miRNA-mRNA competing endogenous RNAs (ceRNA) network was constructed, and subsequent analysis reiterated the significance of neuroimmunological and neuroinflammatory dysfunction in CCH-induced neuropathological changes and cognitive dysfunction. This study underscores the potential role of circRNAs in these processes, suggesting them as promising therapeutic targets to mitigate the detrimental effects of CCH.

Alteration of Cognitive Function in Aging and Alzheimer's Disease Mice Is Related to Dysfunction of the Neuroimmune System.

BACKGROUND: Both Alzheimer's disease (AD) and aging have aging-related cognitive dysfunction with a high incidence. These neurological diseases cause serious cognitive problems in patients' daily life. But the cognitive dysfunction mechanism in-depth of aging is far less known than that of AD. OBJECTIVE: To reveal the different mechanisms of AD and aging-related cognitive dysfunction, we compared the mechanisms of aging and AD through analysis of differentially expressed genes. METHODS: Mice were divided into four groups (3-month C57BL, 16-month C57BL, 3-month 3xTg AD mice, and 16-month 3xTg AD mice) according to genotype and age. The Morris water maze was employed to investigate the spatial cognition of mice. Differential expressions of genes of AD and aging were analyzed through RNA sequencing and GO, KEGG, Reactome analysis, and the dynamic change trend analysis. Microglia was stained with immunofluorescence and its numbers were counted for analysis. RESULTS: The cognitive function of elderly mice were worse through testing with the Morris water maze. The cognitive function of 16-month 3xTg AD mice were worse than 16-month C57BL mice. The alteration tendencies of DE genes were uncovered, and microglia numbers increased during aging and AD progression through immunofluorescence. CONCLUSION: These results suggest that immune-related pathways might play a critical role in aging and AD-related cognitive dysfunction. Our research will help to provide some new potential targets for treating cognitive dysfunction in aging and AD.

Upregulation of RasGRF1 ameliorates spatial cognitive dysfunction in mice after chronic cerebral hypoperfusion.

Chronic cerebral hypoperfusion (CCH)-mediated cognitive impairment is a serious problem worldwide. However, given its complexity, the underlying mechanisms by which CCH induces cognitive dysfunction remain unclear, resulting in a lack of effective treatments. In this study, we aimed to determine whether changes in the expression of RasGRF1, an important protein associated with cognition and synaptic plasticity, underlie the associated impairments in cognition after CCH. We found that RasGRF1 levels markedly decreased following CCH. Through prediction and validation studies, we observed that miRNA-323-3p was upregulated after CCH and could bind to the 3'-untranslated region of Rasgrf1 mRNA and regulate its expression in vitro. Moreover, the inhibition of miRNA-323-3p upregulated Rasgrf1 expression in the hippocampus after CCH, which was reversed by Rasgrf1 siRNA. This suggests that miRNA-323-3p is an important regulator of Rasgrf1. The Morris water maze and Y maze tests showed that miRNA-323-3p inhibition and Rasgrf1 upregulation improved spatial learning and memory, and electrophysiological measurements revealed deficits in long-term potentiation after CCH that were reversed by Rasgrf1 upregulation. Dendritic spine density and mature mushroom spine density were also improved after miRNA-323-3p inhibition and Rasgrf1 upregulation. Furthermore, Rasgrf1 upregulation by miRNA-323-3p inhibition improved dendritic spine density and mature mushroom spine density and ameliorated the deterioration of synapses and postsynaptic density. Overall, RasGRF1 regulation attenuated cognitive impairment, helped maintain structural and functional synaptic plasticity, and prevented synapse deterioration after CCH. These results suggest that Rasgrf1 downregulation by miRNA-323-3p plays an important role in cognitive impairment after CCH. Thus, RasGRF1 and miRNA-323-3p may represent potential therapeutic targets for cognitive impairment after CCH.

EGB761 ameliorates chronic cerebral hypoperfusion-induced cognitive dysfunction and synaptic plasticity impairment.

Chronic cerebral hypoperfusion (CCH) may lead to the cognitive dysfunction, but the underlying mechanisms are unclear. EGB761, extracted from Ginkgo biloba and as a phytomedicine widely used in the world, has been showed to have various neuroprotective roles and mechanisms, and therapeutic effects in Alzheimer's disease and other cognitive dysfunctions. However, improvements in cognitive function after CCH, following treatment with EGB761, have not been ascertained yet. In this study, we used the behavior test, electrophysiology, neurobiochemistry, and immunohistochemistry to investigate the EGB761's effect on CCH-induced cognitive dysfunction and identify its underlying mechanisms. The results showed that EGB761 ameliorates spatial cognitive dysfunction occurring after CCH. It may also improve impairment of the long-term potentiation, field excitable potential, synaptic transmission, and the transmission synchronization of neural circuit signals between the entorhinal cortex and hippocampal CA1. EGB761 may also reverse the inhibition of neural activity and the degeneration of dendritic spines and synaptic structure after CCH; it also prevents the downregulation of synaptic proteins molecules and pathways related to the formation and stability of dendritic spines structures. EGB761 may inhibit axon demyelination and ameliorate the inhibition of the mTOR signaling pathway after CCH to improve protein synthesis. In conclusion, EGB761 treatment after CCH may improve spatial cognitive function by ameliorating synaptic plasticity impairment, synapse degeneration, and axon demyelination by rectifying the inhibition of the mTOR signaling pathway.

Identification of a hippocampal lncRNA-regulating network in cognitive dysfunction caused by chronic cerebral hypoperfusion.

Cognitive dysfunction caused by chronic cerebral hypoperfusion is a common underlying cause of many cognition-related neurodegenerative diseases. The mechanisms of cognitive dysfunction caused by CCH are not clear. Long non-coding RNA is involved in synaptic plasticity and cognitive function, but whether lncRNA is involved in cognitive dysfunction caused by CCH has not yet been reported. In the present study, we identified the altered lncRNAs and mRNAs by deep RNA sequencing. A total of 128 mRNAs and 91 lncRNAs were up-regulated, and 108 mRNAs and 98 lncRNAs were down-regulated. Real-time reverse transcription-polymerase chain reaction verified the reliability of the lncRNA and mRNA sequencing. Gene Ontology and KEGG pathway analyses showed that differentially-expressed mRNAs were related to peptide antigen binding, the extracellular space, the monocarboxylic acid transport, and tryptophan metabolism. The co-expression analysis showed that 161 differentially expressed lncRNAs were correlated with DE mRNAs. By predicting the miRNA in which both DE lncRNAs and DE mRNAs bind together, we constructed a competitive endogenous RNA network. In this lncRNAs-miRNAs-mRNAs network, 559 lncRNA-miRNA-mRNA targeted pairs were identified, including 83 lncRNAs, 67 miRNAs, and 108 mRNAs. Through GO and KEGG pathway analysis, we further analyzed and predicted the regulatory function and potential mechanism of ceRNA network regulation. Our results are helpful for understanding the pathogenesis of cognitive dysfunction caused by CCH and provide direction for further research.

Tripchlorolide May Improve Spatial Cognition Dysfunction and Synaptic Plasticity after Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological mechanism that underlies cognitive decline and degenerative processes in dementia and other neurodegenerative diseases. Low cerebral blood flow (CBF) during CCH leads to disturbances in the homeostasis of hemodynamics and energy metabolism, which in turn results in oxidative stress, astroglia overactivation, and synaptic protein downregulation. These events contribute to synaptic plasticity and cognitive dysfunction after CCH. Tripchlorolide (TRC) is an herbal compound with potent neuroprotective effects. The potential of TRC to improve CCH-induced cognitive impairment has not yet been determined. In the current study, we employed behavioral techniques, electrophysiology, Western blotting, immunofluorescence, and Golgi staining to investigate the effect of TRC on spatial learning and memory impairment and on synaptic plasticity changes in rats after CCH. Our findings showed that TRC could rescue CCH-induced spatial learning and memory dysfunction and improve long-term potentiation (LTP) disorders. We also found that TRC could prevent CCH-induced reductions in N-methyl-D-aspartic acid receptor 2B, synapsin I, and postsynaptic density protein 95 levels. Moreover, TRC upregulated cAMP-response element binding protein, which is an important transcription factor for synaptic proteins. TRC also prevented the reduction in dendritic spine density that is caused by CCH. However, sham rats treated with TRC did not show any improvement in cognition. Because CCH causes disturbances in brain energy homeostasis, TRC therapy may resolve this instability by correcting a variety of cognitive-related signaling pathways. However, for the normal brain, TRC treatment led to neither disturbance nor improvement in neural plasticity. Additionally, this treatment neither impaired nor further improved cognition. In conclusion, we found that TRC can improve spatial learning and memory, enhance synaptic plasticity, upregulate the expression of some synaptic proteins, and increase the density of dendritic spines. Our findings suggest that TRC may be beneficial in the treatment of cognitive impairment induced by CCH.

Glucagon-Like Peptide-2 Receptor is Involved in Spatial Cognitive Dysfunction in Rats After Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) affects the aging population and especially patients with neurodegenerative diseases, such as Alzheimer's disease or Parkinson's disease. CCH is closely related to the cognitive dysfunction in these diseases. Glucagon-like peptide-2 receptor (GLP2R) mRNA and protein are highly expressed in the gut and in hippocampal neurons. This receptor is involved in the regulation of food intake and the control of energy balance and glucose homeostasis. The present study employed behavioral techniques, electrophysiology, western blotting, immunohistochemistry, quantitative real time polymerase chain reaction (qRT-PCR), and Golgi staining to investigate whether the expression of GLP2R changes after CCH and whether GLP2R is involved in cognitive impairment caused by CCH. Our findings show that CCH significantly decreased hippocampal GLP2R mRNA and protein levels. GLP2R upregulation could prevent CCH-induced cognitive impairment. It also improved the CCH-induced impairment of long-term potentiation and long-term depression. Additionally, GLP2R modulated after CCH the AKT-mTOR-p70S6K pathway in the hippocampus. Moreover, an upregulation of the GLP2R increased the neurogenesis in the dentate gyrus, neuronal activity, and density of dendritic spines and mushroom spines in hippocampal neurons. Our findings reveal the involvement of GLP2R via a modulation of the AKT-mTOR-p70S6K pathway in the mechanisms underlying CCH-induced impairments of spatial learning and memory. We suggest that the GLP2R and the AKT-mTOR-p70S6K pathway in the hippocampus are promising targets to treat cognition deficits in CCH.

Luteolin Could Improve Cognitive Dysfunction by Inhibiting Neuroinflammation.

Neuroinflammation and oxidative stress play an important role in cognition deficit following chronic cerebral hypoperfusion (CCH). Luteolin, a natural flavonoid found in many plants, is known for a variety of pharmacological activities, such as its anti-inflammatory, anti-allergy, urate, anti-tumor, antibacterial, and antiviral effects. To assess whether luteolin could prevent CCH-induced cognitive dysfunction, through its anti-inflammatory and anti-oxidative-stress effects, we used enzyme-linked immunosorbent assays, enzyme activity assays, behavioral methods, immunohistochemistry, and electrophysiology to detect neuroinflammation and oxidative stress, cognition alterations, and long-term potential (LTP), in a bilateral common carotid arteries ligation (2VO) rat model. We demonstrated that CCH increased tumor necrosis factor α (TNF-α), interleukin 1ß (IL-1ß), interleukin 6 (IL-6), and malondialdehyde (MDA), and decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) levels. Further, it caused microglia over-activation and astrogliosis, learning and short-term memory dysfunction, and an LTP deficit. Luteolin treatment reversed CCH-induced changes. Specifically, luteolin prevented the increase of TNF-α and IL-1ß, IL-6, and MDA, improved the activity of SOD and GPx, inhibited microglia over-activation and astrogliosis (particularly in the hippocampus and cortex), and ameliorated learning and short-term memory dysfunction, and LTP deficit. Thus, our study suggested that luteolin could be a preferable anti-inflammatory agent to protect cognitive function and synaptic plasticity following CCH. Luteolin could also be putative therapeutic candidate for other inflammation-related brain diseases.

miR-132 Down-regulates Methyl CpG Binding Protein 2 (MeCP2) During Cognitive Dysfunction Following Chronic Cerebral Hypoperfusion.

BACKGROUND: Chronic Cerebral Hypoperfusion (CCH) is an important vascular risk factor for vascular-related dementia cognitive impairment and there are no effective measures for the prevention and treatment of cognitive deficit by CCH and the underlying mechanisms are still poorly understood. Methyl cytidine-phosphate-guanosine (CpG) binding protein 2 (MeCP2), regulated by microRNA 132 (miR-132), is as a transcriptional repressor in high concentrations in the brain, which regulates the expression of synaptic proteins and neuroplasticity, and may be involved in the cognitive deficit after CCH. But no relevant studies have been reported. The aim of this study is to investigate the status of MeCP2 expression after CCH and explore whether MeCP2 changes is associated with cognitive deficits after CCH. METHODS: We investigated MeCP2 expression after CCH using Western blotting, quantitative Real- Time Polymerase Chain Reaction (qRT-PCR) analysis and immunofluorescence technique in a rat model of permanent bilateral common carotid artery occlusion (2VO) to mimic CCH. We determined the effect of MeCP2 expression on cognitive deficits and neuroplasticity after CCH through lenti-virus stereotaxic injection, the Morris water maze and electrophysiology. RESULTS: CCH contributed to the down-regulation of MeCP2 and mecp2 expressions in the hippocampus and cortex. miR-132 up-regulated by 2VO was distinctly negatively correlated with MeCP2 down-regulation by miR-132 inhibitors. MeCP2 over-expression improved learning and memory impairment, as well as neuroplasticity after 2VO. Brain-Derived Neurotrophic Factor (BDNF) and the activities of its downstream pathways moleculars, tropomyosin receptor kinase B (TrkB) and the cAMP Response Element Binding Protein (CREB) were down-regulated by 2VO and rescued by MeCP2 over-expression. CONCLUSION: Our study found that miR-132 may participate in the down-regulation of MeCP2 after CCH and MeCP2 down-regulation was possibly involved in the cognitive deficit through regulation of BDNF and its downstream pathways after 2VO. Our findings expounded the underlying mechanisms of cognition deficit after CCH, which contributes to understanding the mechanisms of vascular dementia.

Oxiracetam can improve cognitive impairment after chronic cerebral hypoperfusion in rats.

Chronic cerebral hypoperfusion (CCH) induces cognitive deficits. Although CCH can be improved, cognitive impairment is not improved accordingly. To date, many studies have focused on investigating the pathophysiological mechanisms of CCH; however, the treatment of the induced cognitive impairment remains ineffective. Thus, the mechanisms underlying cognitive impairment after CCH and potential agents for treating this impairment need to be explored further. Oxiracetam is a nootropic drug that improves clinical outcomes for some central nervous system (CNS) disorders. Whether it can improve cognitive impairment after CCH is unknown. In this study, we used behavioural methods, electrophysiology, biochemistry, histopathological staining and transmission electron microscope to investigate rat's cognitive impairment by CCH, and found that Oxiracetam could improve CCH-induced cognitive impairment and prevent deficits of neural plasticity, white matter lesions, and synaptic ultrastructure. These results suggest that Oxiracetam may be effective as a potential agent against CCH-induced cognitive impairment.

PBA regulates neurogenesis and cognition dysfunction after repeated electroconvulsive shock in a rat model.

Electroconvulsive therapy (ECT) was widely used to treat the refractory depression. But ECT led to the cognitive deficits plaguing the depression patients. The underlying mechanisms of the cognitive deficits remain elusive. Repeated electroconvulsive shock (rECS) was used to simulate ECT and explore the mechanisms of ECT during the animal studies. Previous studies showed rECS could lead to neurogenesis and cognitive impairment. But it was well known that neurogenesis could improve the cognition. So these suggested that the mechanism of the cognitive deficit after rECS was very complex. In present study, we explored the probable mechanisms of the cognitive deficit after rECS from neurogenesis aspect. We found the cognitive deficit was reversible and neurogenesis could bring a long-term beneficial effect on cognition. Astrogliosis and NR1 down-regulation probably participated in the reversible cognitive deficits after rECS. Phenylbutyric acid (PBA), generally as an agent to investigate the roles of histone acetylation, could prevent the reversible cognitive dysfunction, but PBA could diminish the long-term effect of enhanced cognition by rECS. These suggested that ECT could possibly bring the long-term beneficial cognitive effect by regulating neurogenesis.

Phenylbutyric acid protects against spatial memory deficits in a model of repeated electroconvulsive therapy.

Repeated electroconvulsive therapy (rECT) is widely applied in the treatment of refractory depression. Among the side effects of rECT, memory impairment is noticeable and needs effective protection. In this study, by employing a recognized repeated electroconvulsive shock (rECS) rat model, we found that rECS induced the significant spatial memory retention deficits with the simultaneous decreases in long-term potential (LTP), enhanced excitable postsynaptic potentials (EPSP), population spike (PS) and input/output curve in perforant pathway-dentate gyrus (PP-DG), but had no obvious neuron loss or dentritic spine loss in the brain by Nissle or Golgi stainings. Furthermore, the increased synaptic proteins of NR2A/B, PSD93, PSD95, the immediate early gene c-Fos and CREB protein were detected in hippocampus of rECS rats. rECS was also found to cause enhanced axon reorganization in DG region of hippocampus by Timm staining. Intraperitoneal injection of phenylbutyric acid (PBA), an aromatic short chain fatty acid acting as a molecule chaperon, could prevent rats from the rECS-induced memory deficits and synaptic potential enhancement by decreasing the levels of the abnormally increased memory-associated proteins and enhanced axon reorganization in hippocampus. Our data suggested that PBA might be potentially used to attenuate the rECS-induced memory impairment.

Enriched environment prevents cognitive impairment and tau hyperphosphorylation after chronic cerebral hypoperfusion.

Chronic cerebral hypoperfusion (CCH) has been gradually prevalent in the patients over middle age, especially the old over 60 years. It has been proved that CCH is highly related with cognitive impairment. CCH emerges not only in vascular dementia (VaD), but also in Alzheimer's disease (AD), which regarded as a critical causative for cognitive impairment in these diseases. Nevertheless, the mechanisms underlying cognitive deficit remain elusive. Moreover, there are no dramatically effective preventions. In the present study, by employing a recognized CCH rat model, we found that CCH induced spatial learning/memory deficits with simultaneously increasing tau hyperphosphorylation at multiple Alzheimer-related phosphorylation sites with activation of glycogen synthase kinase-3ß (GSK-3ß), Cyclin-dependent kinase (Cdk5), Calcium/calmodulin-dependent protein kinase II (CaMKII), and protein kinase B (Akt), and inhibition of protein phosphatase (PP) 2A (PP-2A). Interestingly, enriched environment (EE) treatment, an effect environment stimuli filled with various novel objects, could prevent rats from the EE-induced memory deficits and alterations of tau hyperphosphorylation. Our data suggested that EE might be potentially used for attenuating the detrimental cognition induced by CCH through regulating tau hyperphosphorylation.