Ginsenoside-Rg1 mitigates cardiac arrest-induced cognitive damage by modulating neuroinflammation and hippocampal plasticity

Blood-brain barrier disruption and neuroinflammation in the hippocampus of a cardiac arrest porcine model: Single-cell RNA sequencing analysis

JOURNAL/nrgr/04.03/01300535-202602000-00043/figure1/v/2025-05-05T160104Z/r/image-tiff Global brain ischemia and neurological deficit are consequences of cardiac arrest that lead to high mortality. Despite advancements in resuscitation science, our limited understanding of the cellular and molecular mechanisms underlying post-cardiac arrest brain injury have hindered the development of effective neuroprotective strategies. Previous studies primarily focused on neuronal death, potentially overlooking the contributions of non-neuronal cells and intercellular communication to the pathophysiology of cardiac arrest-induced brain injury. To address these gaps, we hypothesized that single-cell transcriptomic analysis could uncover previously unidentified cellular subpopulations, altered cell communication networks, and novel molecular mechanisms involved in post-cardiac arrest brain injury. In this study, we performed a single-cell transcriptomic analysis of the hippocampus from pigs with ventricular fibrillation-induced cardiac arrest at 6 and 24 hours following the return of spontaneous circulation, and from sham control pigs. Sequencing results revealed changes in the proportions of different cell types, suggesting post-arrest disruption in the blood-brain barrier and infiltration of neutrophils. These results were validated through western blotting, quantitative reverse transcription-polymerase chain reaction, and immunofluorescence staining. We also identified and validated a unique subcluster of activated microglia with high expression of S100A8, which increased over time following cardiac arrest. This subcluster simultaneously exhibited significant M1/M2 polarization and expressed key functional genes related to chemokines and interleukins. Additionally, we revealed the post-cardiac arrest dysfunction of oligodendrocytes and the differentiation of oligodendrocyte precursor cells into oligodendrocytes. Cell communication analysis identified enhanced post-cardiac arrest communication between neutrophils and microglia that was mediated by neutrophil-derived resistin, driving pro-inflammatory microglial polarization. Our findings provide a comprehensive single-cell map of the post-cardiac arrest hippocampus, offering potential novel targets for neuroprotection and repair following cardiac arrest.

Disorder of neuroplasticity aggravates cognitive impairment via neuroinflammation associated with intestinal flora dysbiosis in chronic heart failure

BACKGROUND

Chronic heart failure (CHF) impairs cognitive function, yet its effects on brain structure and underlying mechanisms remain elusive. This study aims to explore the mechanisms behind cognitive impairment.

METHODS

CHF models in rats were induced by ligation of the left anterior descending coronary artery. Cardiac function was analyzed by cardiac ultrasound and hemodynamics. ELISA, immunofluorescence, Western blot, Golgi staining and transmission electron microscopy were performed on hippocampal tissues. The alterations of intestinal flora under the morbid state were investigated via 16S rRNA sequencing. The connection between neuroinflammation and synapses is confirmed by a co-culture system of BV2 microglia and HT22 cells in vitro. Results: CHF rats exhibited deteriorated cognitive behaviors. CHF induced neuronal structural disruption, loss of Nissl bodies, and synaptic damage, exhibiting alterations in multiple parameters. CHF rats showed increased hippocampal levels of inflammatory cytokines and activated microglia and astrocytes. Furthermore, the study highlights dysregulated PDE4-dependent cAMP signaling and intestinal flora dysbiosis, closely associated with neuroinflammation, and altered synaptic proteins. In vitro, microglial neuroinflammation impaired synaptic plasticity via PDE4-dependent cAMP signaling.

CONCLUSIONS

Neuroinflammation worsens CHF-related cognitive impairment through neuroplasticity disorder, tied to intestinal flora dysbiosis. PDE4 emerges as a potential therapeutic target. These findings provide insightful perspectives on the heart-gut-brain axis.

Neuroprotective Approaches for Brain Injury After Cardiac Arrest: Current Trends and Prospective Avenues

With the implementation of improved bystander cardiopulmonary resuscitation techniques and public-access defibrillation, survival after out-of-hospital cardiac arrest (OHCA) has increased significantly over the years. Nevertheless, OHCA survivors have residual anoxia/reperfusion brain damage and associated neurological impairment resulting in poor quality of life. Extracorporeal membrane oxygenation or targeted temperature management has proven effective in improving post-cardiac arrest (CA) neurological outcomes, yet considering the substantial healthcare costs and resources involved, there is an urgent need for alternative treatment strategies that are crucial to alleviate brain injury and promote recovery of neurological function after CA. In this review, we searched PubMed for the latest preclinical or clinical studies (2016-2023) utilizing gas-mediated, pharmacological, or stem cell-based neuroprotective approaches after CA. Preclinical studies utilizing various gases (nitric oxide, hydrogen, hydrogen sulfide, carbon monoxide, argon, and xenon), pharmacological agents targeting specific CA-related pathophysiology, and stem cells have shown promising results in rodent and porcine models of CA. Although inhaled gases and several pharmacological agents have entered clinical trials, most have failed to demonstrate therapeutic effects in CA patients. To date, stem cell therapies have not been reported in clinical trials for CA. A relatively small number of preclinical stem-cell studies with subtle therapeutic benefits and unelucidated mechanistic explanations warrant the need for further preclinical studies including the improvement of their therapeutic potential. The current state of the field is discussed and the exciting potential of stem-cell therapy to abate neurological dysfunction following CA is highlighted.

Advancements in research on the effects of panax notoginseng saponin constituents in ameliorating learning and memory disorders

Learning and memory disorder is a cluster of symptoms caused by neuronal aging and other diseases of the central nervous system (CNS). Panax notoginseng saponins (PNS) are a series of saponins derived from the natural active ingredients of traditional Chinese medicine (TCM) that have neuroprotective effects on the central nervous system. In this paper, we review the ameliorative effects and mechanisms of Panax notoginseng saponin-like components on learning and memory disorders to provide valuable references and insights for the development of new drugs for the treatment of learning and memory disorders. Our summary results suggest that Panax ginseng saponins have significant effects on improving learning and memory disorders, and these effects and potential mechanisms are mediated by their anti-inflammatory, anti-apoptotic, antioxidant, β-amyloid lowering, mitochondrial homeostasis in vivo, neuronal structure and function improving, neurogenesis promoting, neurotransmitter release regulating, and probiotic homeostasis in vivo activities. These findings suggest the potential of Panax notoginseng saponin-like constituents as drug candidates for improving learning and memory disorders.

Ginsenoside Rg1 ameliorates depressive-like behavior by inhibiting NLRP3 inflammasome activation in mice exposed to chronic stress

Microglia-mediated inflammatory process is recognized as a target in the treatment of depression. Ginsenoside Rg1 (GRg1), the active ingredient of traditional ginseng, regulates microglial phenotypes to resist stress-induced inflammatory responses. Here we used a mouse model of stress-induced depression to investigate the involvement of microglial Nod-like receptor protein 3 (NLRP3) in the antidepressant effects of GRg1. Male C57BL/6J mice were exposed to chronic mild stress (CMS) for three weeks, followed by intraperitoneal injection of GRg1 (20 mg/kg) or the antidepressant imipramine (20 mg/kg) for another three weeks. Depressive-like behaviors were assessed by sucrose preference test, forced swimming test, and tail suspension test. Microglial phenotypes were assessed in terms of morphological features and cytokine profiles; inflammasome activity, in terms of levels of complexes containing NLRP3, apoptosis-associated speck-like protein containing CARD (ASC) and caspase-1; and neurogenesis, in terms of numbers of proliferating, differentiating, and mature neurons identified by immunostaining. GRg1 reduced abnormal animal behaviors caused by CMS, such as anhedonia and desperate behaviors, without affecting locomotor behaviors. GRg1 also reduced the number of ASC-specks, implying inhibition of inflammasome activation, which was associated with weaker activation of pro-inflammatory microglia. At the same time, GRg1 rescued impairment of hippocampal neurogenesis in vivo and in vitro, which correlated with modulation of microglial phenotypes. GRg1 exert antidepressant effects by preventing stress from activating the NLRP3 inflammasome in microglia, promoting a proneurogenic phenotype and allowing adult hippocampal neurogenesis.

Modulation of PI3K/Akt/GSK3β signaling cascade through G protein-coupled receptor 55 (GPR55) activation: Prenatal lysophosphatidylinositol attenuates valproic acid-induced synaptic abnormalities and mitochondrial dysfunction

AIMS

Dysregulation of PI3K/Akt/GSK3β signaling has been implicated in various neurological disorders, including autism spectrum disorder (ASD). G protein-coupled receptor 55 (GPR55) has recently emerged as a potential regulator of this signaling cascade. This study explores the intricate modulation of the PI3K/Akt/GSK3β signaling cascade via GPR55 activation and its potential therapeutic implications in the context of autism-associated neuronal impairments.

MAIN METHODS

Valproic acid (VPA) was administered on embryonic day 12 (E12) to induce ASD, and lysophosphatidylinositol (LPI), a GPR55 agonist, was used prenatally to modulate the receptor activity. Golgi-cox staining was performed to observe neuronal morphology, and Hematoxylin and eosin (H and E) staining was carried out to quantify damaged neurons. Enzyme-linked immunosorbent assay (ELISA) was implemented to identify molecular mediators involved in neuroprotection.

KEY FINDINGS

Prenatal VPA exposure resulted in significant abnormalities in synaptic development, which were further evidenced by impairments in social interaction and cognitive function. When LPI was administered, most of the synaptic abnormalities were alleviated, as reflected by higher neuron and dendritic spine count. LPI treatment also reduced cytoplasmic cytochrome c concentration and related neuronal cell death. Mechanistically, GPR55 activation by LPI increases the expression of phospho-Akt and phospho-GSK3β, leading to the activation of this signaling in the process of rescuing synaptic abnormalities and mitochondria-mediated neuronal apoptosis.

SIGNIFICANCE

The observed therapeutic effects of GPR55 activation shed light on its significance as a prospective target for ameliorating mitochondrial dysfunction and dendritic spine loss, offering novel prospects for developing targeted interventions to alleviate the neuropathological causes of ASD.