The Cannabinoid Receptor Agonist WIN55,212-2 Ameliorates Hippocampal Neuronal Damage After Chronic Cerebral Hypoperfusion Possibly Through Inhibiting Oxidative Stress and ASK1-p38 Signaling

Inhibition of Endoplasmic Reticulum Stress Improves Chronic Ischemic Hippocampal Damage Associated with Suppression of IRE1α/TRAF2/ASK1/JNK-Dependent Apoptosis

Chronic cerebral ischemia is a complex form of stress, of which the most common hemodynamic characteristic is chronic cerebral hypoperfusion (CCH). Lasting endoplasmic reticulum (ER) stress can drive neurological disorders. Targeting ER stress shows potential neuroprotective effects against stroke. However, the role of ER stress in CCH pathological processes and the effects of targeting ER stress on brain ischemia are unclear. Here, a CCH rat model was established by bilateral common carotid artery occlusion. Rats were treated with 4-PBA, URB597, or both for 4 weeks. Neuronal morphological damage was detected using hematoxylin-eosin staining. The expression levels of the ER stress-ASK1 cascade-related proteins GRP78, IRE1α, TRAF2, CHOP, Caspase-12, ASK1, p-ASK1, JNK, and p-JNK were assessed by Western blot. The mRNA levels of TNF-α, IL-1β, and iNOS were assessed by RT-PCR. For oxygen-glucose deprivation experiments, mouse hippocampal HT22 neurons were used. Apoptosis of the hippocampus and HT22 cells was detected by TUNEL staining and Annexin V-FITC analysis, respectively. CCH evoked ER stress with increased expression of GRP78, IRE1α, TRAF2, CHOP, and Caspase-12. Co-immunoprecipitation experiments confirmed the interaction between TRAF2 and ASK1. ASK1/JNK signaling, inflammatory cytokines, and neuronal apoptosis were enhanced, accompanied by persistent ER stress; these were reversed by 4-PBA and URB597. Furthermore, the ASK1 inhibitor GS4997 and 4-PBA displayed synergistic anti-apoptotic effects in cells with oxygen-glucose deprivation. In summary, ER stress-induced apoptosis in CCH is associated with the IRE1α/TRAF2/ASK1/JNK signaling pathway. Targeting the ER stress-ASK1 cascade could be a novel therapeutic approach for ischemic cerebrovascular diseases.

Alleviating CB2-Dependent ER Stress and Mitochondrial Dysfunction Improves Chronic Cerebral Hypoperfusion-Induced Cognitive Impairment

Augmentation of endoplasmic reticulum (ER) stress may trigger excessive oxidative stress, which induces mitochondrial dysfunction. The fatty acid amide hydrolase inhibitor, URB597, shows anti-oxidation characteristics in multiple neurological disorders. The present study aimed to determine whether inhibition of ER stress was involved in the protective effects of URB597 against chronic cerebral hypoperfusion (CCH)-induced cognitive impairment. Hippocampal HT-22 cells were exposed to oxygen-glucose deprivation. The cell viability, apoptosis, ER stress, mitochondrial ATP, and oxidative stress levels were assessed following treatment with URB597, benzenebutyric acid (4-PBA), and thapsigargin (TG). Furthermore, the effects of URB597 on ER stress and related pathways were investigated in the CCH animal model, including Morris water maze testing of cognition, western blotting analysis of ER stress signaling, and transmission electron microscopy of mitochondrial and ER ultrastructure changes. The results suggested that cerebral ischemia caused ER stress with upregulation of ER stress signaling-related proteins, mitochondrial dysfunction, neuronal apoptosis, ultrastructural injuries of mitochondria-associated ER membranes, and cognitive decline. Co-immunoprecipitation experiments confirmed the interaction between CB2 and β-Arrestin1. Inhibiting ER stress by URB597 improved these changes by activating CB2/β-Arrestin1 signaling, which was reversed by the CB2 antagonist, AM630. Together, the results identified a novel mechanism of URB597, involving CCH-induced cognitive impairment alleviation of CB2-dependent ER stress and mitochondrial dysfunction. Furthermore, this study identified CB2 as a potential target for therapy of ischemic cerebrovascular diseases.

VEGF-A ameliorates ischemia hippocampal neural injury via regulating autophagy and Akt/CREB signaling in a rat model of chronic cerebral hypoperfusion

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) can cause a series of pathophysiological processes, including neuronal autophagy and apoptosis. VEGF-A has been reported to affect angiogenesis and neurogenesis in many CNS diseases. However, its effects on neuronal autophagy and apoptosis, as well as the underlying mechanisms in CCH remain unclear.

METHODS

To address these issues, the CCH model was established by permanent bilateral common carotid artery occlusion (2VO). Rats were sacrificed at different stages of CCH. Hippocampal morphological and ultrastructural changes were detected using HE staining and electron microscopy. The immunoreactivities of microtubule-associated protein 1 light chain 3 (LC3) and phospho-cAMP response element binding protein (p-CREB) were examined by immunofluorescence staining. The neuronal apoptosis was detected via TUNEL staining. The levels of LC3-II, Beclin-1, Akt, p-Akt, CREB, p-CREB, Caspase-3, and Bad were accessed by Western blotting. Furthermore, mouse hippocampal HT22 neurons received the oxygen and glucose deprivation (OGD) treatment, VEGF-A treatment, and GSK690693 (an Akt inhibitor) treatment, respectively.

RESULTS

LC3-II protein started to increase at 3 days of CCH, peaked at 4 weeks of CCH, then decreased. CCH increased the levels of LC3-II, Caspase-3, and Bad, and decreased the levels of p-Akt, CREB, and p-CREB, which were reversed by VEGF-A treatment. VEGF-A also improved CCH-induced neuronal ultrastructural injuries and apoptosis in the hippocampus in vitro. In HT22, the anti-apoptosis and pro-phosphorylation of VEGF-A were reversed by GSK690693.

CONCLUSION

Present results provide a novel neuroprotective effect of VEGF-A in CCH that is related to the inhibition of neuronal autophagy and activation of the Akt/CREB signaling, suggesting a potential therapeutic strategy for ischemic brain damage.

Dimethyl fumarate improves cognitive deficits in chronic cerebral hypoperfusion rats by alleviating inflammation, oxidative stress, and ferroptosis via NRF2/ARE/NF-κB signal pathway

Cerebrovascular disease and its risk factors cause persistent decrease of cerebral blood flow, chronic cerebral hypoperfusion (CCH) is the major foundation of vascular cognitive impairment (VCI). The hippocampus is extremely vulnerable to cerebral ischemia and hypoxia. Oxidative stress and neuroinflammation injury are important pathophysiological mechanisms of this process, which is closely related to hippocampal neurons damage and loss. Dimethyl fumarate (DMF), an FDA-approved therapeutic for multiple sclerosis (MS), plays a protective role in multiple neurological disorders. Studies have shown that DMF exerts anti-inflammatory and antioxidant effects via the NRF2/ARE/NF-κB signaling pathway. Thus, this study aimed to evaluate the neuroprotective effect of DMF in the CCH rat model. Ferroptosis, a novel defined iron-dependent cell death form, were found to be strongly associated with the pathophysiology of CCH. Emerging evidences have shown that inhibition of ferroptosis by targeting NRF2 exerted neuroprotective effect in neurodegeneration diseases. We also investigated whether DMF can alleviate cognitive deficits through inhibition of ferroptosis by the NRF2 signaling pathway in this study. DMF was intragastric for consecutive five weeks (100 mg/kg/day). Then behavior test and histological, molecular, and biochemical analysis were performed. We found that DMF treatment significantly improved cognitive deficits and partially reversed hippocampus neuronal damage and loss caused by CCH. And DMF treatment decreased hippocampus IL-1β, TNF-α, and IL-6 pro-inflammatory cytokines concentration, and mediated the NF-κB signaling pathway. And DMF also alleviated hippocampus oxidative stress through reducing MDA, and increasing GSH and SOD levels, which are also closely associated with ferroptosis. Besides, DMF treatment reduced the expression of PTGS2, and increased the expression of FTH1 and xCT, and the iron content is also reduced, which were the important features related to ferroptosis. Furthermore, DMF activated the NRF2/ARE signaling pathway and upregulated the expression of HO-1, NQO1 and GPX4. These outcomes indicated that DMF can improve cognitive impairment in rats with CCH, possibly through alleviating neuroinflammation, oxidative stress damage and inhibiting ferroptosis of hippocampal neurons. Overall, our results provide new evidence for the neuroprotective role of DMF.

Cannabinoid WIN 55,212-2 Inhibits Human Glioma Cell Growth by Triggering ROS-Mediated Signal Pathways

Glioblastoma is a highly invasive primary malignant tumor of the central nervous system. Cannabinoid analogue WIN 55,212-2 (WIN) exhibited a novel anticancer effect against human tumors. However, the anticancer potential and underlying mechanism of WIN against human glioma remain unclear. Herein, the anticancer efficiency and mechanism of WIN in U251 human glioma cells were investigated. The results showed that WIN dose-dependently inhibited U251 cell proliferation, migration, and invasion in vitro. WIN treatment also effectively suppressed U251 tumor spheroids growth ex vivo. Further studies found that WIN induced significant apoptosis as convinced by the caspase-3 activation and release of cytochrome C. Mechanism investigation revealed that WIN triggered ROS-mediated DNA damage and caused dysfunction of VEGF-AKT/FAK signal axis. However, ROS inhibition effectively attenuated WIN-induced DNA damage and dysfunction of VEGF-AKT/FAK signal axis and eventually improved U251 cell proliferation, migration, and invasion. Taken together, our findings validated that WIN had the potential to inhibit U251 cell proliferation, migration, and invasion and induce apoptosis by triggering ROS-dependent DNA damage and dysfunction of VEGF-AKT/FAK signal axis.

Pharmacological Treatment of Vascular Dementia: A Molecular Mechanism Perspective

Vascular dementia (VaD) is a neurodegenerative disease, with cognitive dysfunction attributable to cerebrovascular factors. At present, it is the second most frequently occurring type of dementia in older adults (after Alzheimer's disease). The underlying etiology of VaD has not been completely elucidated, which limits its management. Currently, there are no approved standard treatments for VaD. The drugs used in VaD are only suitable for symptomatic treatment and cannot prevent or reduce the occurrence and progression of VaD. This review summarizes the current status of pharmacological treatment for VaD, from the perspective of the molecular mechanisms specified in various pathogenic hypotheses, including oxidative stress, the central cholinergic system, neuroinflammation, neuronal apoptosis, and synaptic plasticity. As VaD is a chronic cerebrovascular disease with multifactorial etiology, combined therapy, targeting multiple pathophysiological factors, may be the future trend in VaD.

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.

[Choice of neuroprotective therapy regimens in patients with chronic cerebral ischemia, taking into account the synergy of drug interactions]

OBJECTIVE

Optimization of the choice of neuroprotective treatment regimens in patients with chronic cerebral ischemia that takes into account the synergy of drug interactions gives the doctor an opportunity for personalized approach that increases the effectiveness of treatment.

MATERIAL AND METHODS

Differential chemoreactomic analysis of the synergism of ethyl methyl hydroxypyridine succinate (EMHPS) and a number of monocomponent neuroprotective agents (piracetam, vinpocetine, citicoline, choline alfoscerate); proteomic analysis of polypeptide neuroprotectors (cerebrolysin, etc.); an expert analysis of multicomponent neuroprotector Cytoflavin.

RESULTS

Piracetam, citicoline (Neupilept) and choline alfoscerate (Cereton) effectively enhance the pharmacological properties of EMHPS and vice versa. Expert assessments of the synergism between the properties of EMHPS, polypeptide neuroprotectors (cerebrolysin) and other multicomponent drugs (cytoflavin), which are also used in adjuvant therapy with EMHPS, are presented.

CONCLUSION

In real clinical practice, of particular interest is the objectification of the appointment of combined therapy regimens. This study indicates that EMHPS can provide a favorable background for maximizing the effectiveness of therapy when used with other drugs.

Tat-Cannabinoid Receptor Interacting Protein Reduces Ischemia-Induced Neuronal Damage and Its Possible Relationship with 14-3-3η

Cannabinoid receptor-interacting protein 1a (CRIP1a) binds to the C-terminal domain of cannabinoid 1 receptor (CB1R) and regulates CB1R activities. In this study, we made Tat-CRIP1a fusion proteins to enhance CRIP1a penetration into neurons and brain and to evaluate the function of CRIP1a in neuroprotection following oxidative stress in HT22 hippocampal cells and transient forebrain ischemia in gerbils. Purified exogenous Tat-CRIP1a was penetrated into HT22 cells in a time and concentration-dependent manner and prevented H₂O₂-induced reactive oxygen species formation, DNA fragmentation, and cell damage. Tat-CRIP1a fusion protein also ameliorated the reduction of 14-3-3η expression by H₂O₂ treatment in HT22 cells. Ischemia–reperfusion damage caused motor hyperactivity in the open field test of gerbils; however, the treatment of Tat-CRIP1a significantly reduced hyperactivity 1 day after ischemia. Four days after ischemia, the administration of Tat-CRIP1a restored the loss of pyramidal neurons and decreased reactive astrocytosis and microgliosis induced by ischemic damage in the hippocampal cornu Ammonis (CA)1 region. Ischemic damage decreased 14-3-3η expression in all hippocampal sub-regions 4 days after ischemia; however, the treatment of Tat-CRIP1 ameliorated the reduction of 14-3-3η expression. These results suggest that Tat-CRIP1a attenuates neuronal damage and hyperactivity induced by ischemic damage, and it restores normal expression levels of 14-3-3η protein in the hippocampus.