Xuesaitong Combined with Dexmedetomidine Improves Cerebral Ischemia-Reperfusion Injury in Rats by Activating Keap1/Nrf2 Signaling and Mitophagy in Hippocampal Tissue

Nuclear factor erythroid 2-related factor-mediated signaling alleviates ferroptosis during cerebral ischemia-reperfusion injury

Cardiac arrest (CA) is a significant challenge for emergency physicians worldwide and leads to increased morbidity and mortality rates. The poor prognosis of CA primarily stems from the complexity and irreversibility of cerebral ischemia-reperfusion injury (CIRI). Ferroptosis, a form of programmed cell death characterized by iron overload and lipid peroxidation, plays a crucial role in the progression and treatment of CIRI. In this review, we highlight the mechanisms of ferroptosis within the context of CIRI, focusing on its role as a key contributor to neuronal damage and dysfunction post-CA. We explore the crucial involvement of the nuclear factor erythroid 2-related factor (Nrf2)-mediated signaling pathway in modulating ferroptosis-associated processes during CIRI. Through comprehensive analysis of the regulatory role of Nrf2 in the cellular responses to oxidative stress, we highlight its potential as a therapeutic target for mitigating ferroptotic cell death and improving the neurological prognosis of patients experiencing CA. Furthermore, we discuss interventions targeting the Kelch-like ECH-associated protein 1/Nrf2/antioxidant response element pathway, including the use of traditional Chinese medicine and Western medicine, which demonstrate potential for attenuating ferroptosis and preserving neuronal function in CIRI. Owing to the limitations in the safety, specificity, and effectiveness of Nrf2-targeted drugs, as well as the technical difficulties and ethical constraints in obtaining the results related to the brain pathological examination of patients, most of the studies focusing on Nrf2-related regulation of ferroptosis in CIRI are still in the basic research stage. Overall, this review aims to provide a comprehensive understanding of the mechanisms underlying ferroptosis in CIRI, offering insights into novel therapeutics aimed at enhancing the clinical outcomes of patients with CA.

Progress on the Mechanisms and Neuroprotective Benefits of Dexmedetomidine in Brain Diseases

INTRODUCTION

Dexmedetomidine, a highly specific α2 agonist, has been extensively utilized in clinical sedation and surgical anesthesia since its introduction in 2000 due to its excellent sympatholytic, sedative, and analgesic effects. This review aimed to identify new approaches for the treatment of patients with brain disorders by thoroughly describing the mechanism of action of dexmedetomidine and examining its neuroprotective effects from the standpoints of basic and clinical research.

METHODS

The PubMed and Web of Science databases were searched using the keywords dexmedetomidine and related brain diseases, although relevant articles from the last decade were included for detailed summarization and analysis.

RESULTS

Dexmedetomidine has shown strong neuroprotective effects, such as protection of the blood-brain barrier, decreased neuronal death, maintained hemodynamic stability, and reduced postoperative agitation and cognitive dysfunction. Furthermore, dexmedetomidine has been shown to exert various neuroprotective effects, including anti-inflammatory and antioxidative stress effects, modulation of autophagy, and reduction of apoptosis in cerebral diseases.

CONCLUSIONS

Dexmedetomidine acts as a neuroprotective agent against brain diseases during all phases of treatment. However, clinical trials with larger sample sizes are required to optimize dosage and dosing strategies.

Targeting MAD2B as a strategy for ischemic stroke therapy

INTRODUCTION

Post-stroke cognitive impairment is one of the major causes of disability due to cerebral ischemia. MAD2B is an inhibitor of Cdh1/APC, and loss of Cdh1/APC function in mature neurons increases ROCK2 activity, leading to changes in synaptic plasticity and memory loss in mouse neurons. Whether MAD2B regulates learning memory capacity through ROCK2 in cerebral ischemia is not known.

OBJECTIVES

We investigated the role and mechanism of MAD2B in cerebral ischemia-induced cognitive dysfunction.

METHODS

The expression of MAD2B and its downstream related molecules was detected by immunoblotting and intervened with neuroprotectants after middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation/reoxygenation (OGD/R). We constructed MAD2B-cKO-specific knockout mice, knocked down and overexpressed MAD2B in mouse hippocampus by lentiviral injection in brain stereotaxis, modeled cerebral ischemia by using MCAO, and explored the role of MAD2B in post-stroke cognitive impairment (PSCI) by animal behaviors such as Y-maze and Novel object recognition test. Then the expression of MAD2B/ROCK2, downstream molecules and apoptosis-related molecules was detected. Finally, ROCK2 expression was intervened using its inhibitor and shRNA-ROCK2 lentivirus.

RESULTS

The expression of MAD2B and its downstream molecules increased after MCAO and OGD/R. Nonetheless, this expression underwent a decline post-therapy with neuroprotective agents. Deletion of MAD2B in the hippocampus ameliorated memory and learning deficits and improved motor coordination in MCAO mice. Conversely, the overexpression of MAD2B in the hippocampus exacerbated learning and memory deficits. Deletion of MAD2B resulted in the downregulation of ROCK2/LIMK1/cofilin. It effectively reduced ischemia-induced upregulation of BAX and cleaved caspase-3, which could be reversed by MAD2B overexpression. Inhibition or knockdown of ROCK2 expression in primary cultured neurons led to the downregulation of LIMK1/cofilin expression and reduced the expression of apoptosis-associated molecules induced by ischemia.

CONCLUSIONS

Our findings suggest that MAD2B affects neuronal apoptosis via Rock2, which affects neurological function and cerebral infarction.

THSG alleviates cerebral ischemia/reperfusion injury via the GluN2B-CaMKII-ERK1/2 pathway

BACKGROUND

The potential therapeutic targeting of PINK1-PARK2-mediated mitophagy against cerebral ischemia/reperfusion (CI/R) injury involves the pathophysiological processes of neurovascular unit (NVU) and is closely associated with N-methyl-D-aspartate receptors (NMDARs) commonly expressed in NVU. 2,3,5,4'-Tetrahydroxy-stilbene-2-O-β-D-glucoside (THSG), a compound derived from the traditional Chinese medicine Polygonum multiflorum Thunb., has demonstrated notable neuroprotective properties against CI/R injury. However, it remains unclear whether THSG exerts its protective effects through GluN2B related PINK1/ PARK2 pathway.

PURPOSE

This study aims to explore the pharmacological effects of THSG on alleviating CI/R injury via the GluN2B-CaMKII-ERK1/2 pathway.

METHODS

THSG neuroprotection against CI/R injury was studied in transient middle cerebral artery occlusion/reversion (tMCAO/R) model rats and in oxygen and glucose deprivation/ reoxygenation (OGD/R) induced neurons. PINK1-PARK2-mediated mitophagy involvement in the protective effect of THSG was investigated in tMCAO/R rats and OGD/R-induced neurons via THSG and 3-methyladenine (3-MA) treatment. Furthermore, the beneficial role of GluN2B in reperfusion and its contribution to the THSG effect via CaMKII-ERK1/2 and PINK1-PARK2-mediated mitophagy was explored using the GluN2B-selective antagonist Ro 25-6981 both in vivo and in vitro. Finally, the interaction between THSG and GluN2B was evaluated using molecular docking.

RESULTS

THSG significantly reduced infarct volume, neurological deficits, penumbral neuron structure, and functional damage, upregulated the inhibitory apoptotic marker Bcl-2, and suppressed the increase of pro-apoptotic proteins including cleaved caspase-3 and Bax in tMCAO/R rats. THSG (1 μM) markedly improved the neuronal survival under OGD/R conditions. Furthermore, THSG promoted PINK1 and PARK2 expression and increased mitophagosome numbers and LC3-II-LC3-I ratio both in vivo and in vitro. The effects of THSG were considerably abrogated by the mitophagy inhibitor 3-MA in OGD/R-induced neurons. Inhibiting GluN2B profoundly decreased mitophagosome numbers and OGD/R-induced neuronal viability. Specifically, inhibiting GluN2B abolished the protection of THSG against CI/R injury and reversed the upregulation of PINK1-PARK2-mediated mitophagy by THSG. Inhibiting GluN2B eliminated THSG upregulation of ERK1/2 and CaMKII phosphorylation. The molecular docking analysis results demonstrated that THSG bound to GluN2B (binding energy: -5.2 ± 0.11 kcal/mol).

CONCLUSIONS

This study validates the premise that THSG alleviates CI/R injury by promoting GluN2B expression, activating CaMKII and ERK1/2, and subsequently enhancing PINK1-PARK2-mediated mitophagy. This work enlightens the potential of THSG as a promising candidate for novel therapeutic strategies for treating ischemic stroke.

The neuroprotective effect of Chinese herbal medicine for cerebral ischemia reperfusion injury through regulating mitophagy

The incidence of ischemic stroke has been increasing annually with an unfavorable prognosis. Cerebral ischemia reperfusion injury can exacerbate nerve damage. Effective mitochondrial quality control including mitochondrial fission, fusion and autophagy, is crucial for maintaining cellular homeostasis. Several studies have revealed the critical role of mitophagy in Cerebral ischemia reperfusion injury. Cerebral ischemia and hypoxia induce mitophagy, and mitophagy exhibits positive and negative effects in cerebral ischemia reperfusion injury. Studies have shown that Chinese herbal medicine can alleviate Cerebral ischemia reperfusion injury and serve as a neuroprotective agent by inhibiting or promoting mitophagy-mediated pathways. This review focuses on the mitochondrial dynamics and mitophagy-related pathways, as well as the role of mitophagy in ischemia reperfusion injury. Additionally, it discusses the therapeutic potential and benefits of Chinese herbal monomers and decoctions in the treatment of ischemic stroke.

Suppression of cerebral ischemia injury induced blood brain barrier breakdown by dexmedetomidine via promoting CCN1

BACKGROUND

Blood-brain barrier (BBB) could aggravate cerebral ischemia injury. Dexmedetomidine (Dex) has been believed to play a protective role in cerebral ischemia injury-induced BBB injury.

METHODS

Middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation (OGD) models were established to simulate cerebral ischemia injury. Animal experiments included 4 groups, Sham, MCAO, MCAO+Dex, MCAO+Dex+sh-CCN1. Generally applicable gene set enrichment analysis was performed to analyze gene expression difference. Total collagen content and Evans blue staining were performed to measure infarct ratio and BBB breakdown, respectively. The cell apoptosis, mRNA and protein expression were measured through flow cytometry, PCR, and western blotting, respectively. The levels of IL-1β, TNF-α, and IL-6 in serum were measured with commercial ELISA kits.

RESULTS

Dex greatly promoted the expression level of CCN1. Dex suppressed cerebral ischemia injury, increased tight junction protein expression, improved the memory ability and neurological function of MCAO rats through targeting CCN1. The significant increase of inflammatory factors in the serum of MCAO rats were suppressed by Dex. Dex suppressed OGD induced increase of HRP permeability and promoting tight junction protein expression in vitro through regulating CCN1. The neurological function evaluation was performed with Neurological Severity Score (NSS) and Longa Score Scale.

CONCLUSIONS

Dex could remarkably alleviate cerebral ischemia injury by inhibiting BBB breakdown, inflammatory response, and promoting neurological function and tight junction protein expression via up-regulating CCN1. This study might provide a novel therapeutic target for the prevention and treatment of cerebral ischemia injury-induced BBB.

The Protective Effect of (-)-Tetrahydroalstonine against OGD/R-Induced Neuronal Injury via Autophagy Regulation

Here, (-)-Tetrahydroalstonine (THA) was isolated from Alstonia scholaris and investigated for its neuroprotective effect towards oxygen-glucose deprivation/re-oxygenation (OGD/R)-induced neuronal damage. In this study, primary cortical neurons were pre-treated with THA and then subjected to OGD/R induction. The cell viability was tested by the MTT assay, and the states of the autophagy-lysosomal pathway and Akt/mTOR pathway were monitored by Western blot analysis. The findings suggested that THA administration increased the cell viability of OGD/R-induced cortical neurons. Autophagic activity and lysosomal dysfunction were found at the early stage of OGD/R, which were significantly ameliorated by THA treatment. Meanwhile, the protective effect of THA was significantly reversed by the lysosome inhibitor. Additionally, THA significantly activated the Akt/mTOR pathway, which was suppressed after OGD/R induction. In summary, THA exhibited promising protective effects against OGD/R-induced neuronal injury by autophagy regulation through the Akt/mTOR pathway.