Inhibition of Prostaglandin E2 Receptor EP3 Attenuates Oxidative Stress and Neuronal Apoptosis Partially by Modulating p38MAPK/FOXO3/Mul1/Mfn2 Pathway after Subarachnoid Hemorrhage in Rats

Paeoniflorin Attenuates Oxidative Stress and Inflammation in Parkinson's Disease by Activating the HSF1-NRF1 Axis

This study is to explore the effects of paeoniflorin (PF) on oxidative stress (OS) and inflammation in Parkinson's disease (PD) via the HSF1-NRF1 axis. SH-SY5Y cells were pretreated with PF and induced with α-synuclein preformed fibrils (PFF), followed by gain- and loss-of-function assays. Afterward, detection was conducted on cell viability, mitochondrial membrane potential ([Formula: see text]m), and reactive oxygen species (ROS), cyclooxygenase (COX)-2, and inducible nitric oxide synthase (iNOS) levels. The binding of HSF1 to NRF1 promoter was evaluated. HSF1 and NRF1 expression was examined. Lastly, PD mouse models were established, followed by observation of the behavioral features of mice. Apoptosis; cleaved-Caspase 3, cleaved-Caspase 8, repulsive guidance molecule A (RGMa), GAP-43, and brain-derived neurotrophic factor (BDNF) expression; and superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), catalase (CAT), tumor necrosis factor (TNF)-α, interleukin (IL)-2, IL-6, and IL-10 levels were determined in mice and cells. HSF1 and NRF1 were downregulated, and HSF1 promoted NRF1 transcription and PF dose-dependently augmented HSF1 and NRF1 expression. PF dose-dependently reduced RGMa expression, ROS, MDA, TNF-α, IL-2, and IL-6 levels; mitigated apoptosis; and lowered cleaved-Caspase 3, cleaved-Caspase 8, COX-2, and iNOS expression while improving cell viability; increasing [Formula: see text]m, GAP-43, and BDNF expression; and raising SOD, GSH-Px, CAT, and IL-10 levels in PFF-induced SH-SY5Y cells. These effects were neutralized by HSF1 knockdown. In conclusion, PF dose-dependently activated the HSF1-NRF1 axis and alleviated OS and inflammation in PFF-treated mice, thereby impeding PD progression in mice.

Mitochondrial dysfunction and quality control lie at the heart of subarachnoid hemorrhage

The dramatic increase in intracranial pressure after subarachnoid hemorrhage leads to a decrease in cerebral perfusion pressure and a reduction in cerebral blood flow. Mitochondria are directly affected by direct factors such as ischemia, hypoxia, excitotoxicity, and toxicity of free hemoglobin and its degradation products, which trigger mitochondrial dysfunction. Dysfunctional mitochondria release large amounts of reactive oxygen species, inflammatory mediators, and apoptotic proteins that activate apoptotic pathways, further damaging cells. In response to this array of damage, cells have adopted multiple mitochondrial quality control mechanisms through evolution, including mitochondrial protein quality control, mitochondrial dynamics, mitophagy, mitochondrial biogenesis, and intercellular mitochondrial transfer, to maintain mitochondrial homeostasis under pathological conditions. Specific interventions targeting mitochondrial quality control mechanisms have emerged as promising therapeutic strategies for subarachnoid hemorrhage. This review provides an overview of recent research advances in mitochondrial pathophysiological processes after subarachnoid hemorrhage, particularly mitochondrial quality control mechanisms. It also presents potential therapeutic strategies to target mitochondrial quality control in subarachnoid hemorrhage.

Neuroprotection and Beyond: The Central Role of CB1 and CB2 Receptors in Stroke Recovery

The endocannabinoid system, with its intricate presence in numerous cells, tissues, and organs, offers a compelling avenue for therapeutic interventions. Central to this system are the cannabinoid receptors 1 and 2 (CB1R and CB2R), whose ubiquity can introduce complexities in targeted treatments due to their wide-ranging physiological influence. Injuries to the central nervous system (CNS), including strokes and traumatic brain injuries, induce localized pro-inflammatory immune responses, termed neuroinflammation. Research has shown that compensatory immunodepression usually follows, and these mechanisms might influence immunity, potentially affecting infection risks in patients. As traditional preventive treatments like antibiotics face challenges, the exploration of immunomodulatory therapies offers a promising alternative. This review delves into the potential neuroprotective roles of the cannabinoid receptors: CB1R's involvement in mitigating excitotoxicity and CB2R's dual role in promoting cell survival and anti-inflammatory responses. However, the potential of cannabinoids to reduce neuroinflammation must be weighed against the risk of exacerbating immunodepression. Though the endocannabinoid system promises numerous therapeutic benefits, understanding its multifaceted signaling mechanisms and outcomes remains a challenge.

RU.521 mitigates subarachnoid hemorrhage-induced brain injury via regulating microglial polarization and neuroinflammation mediated by the cGAS/STING/NF-κB pathway

BACKGROUND

The poor prognosis of subarachnoid hemorrhage (SAH) is often attributed to neuroinflammation. The cGAS-STING axis, a cytoplasmic pathway responsible for detecting dsDNA, plays a significant role in mediating neuroinflammation in neurological diseases. However, the effects of inhibiting cGAS with the selective small molecule inhibitor RU.521 on brain injury and the underlying mechanisms after SAH are still unclear.

METHODS

The expression and microglial localization of cGAS following SAH were investigated with western blot analysis and immunofluorescent double-staining, respectively. RU.521 was administered after SAH. 2'3'-cGAMP, a second messenger converted by activated cGAS, was used to activate cGAS-STING. The assessments were carried out by adopting various techniques including neurological function scores, brain water content, blood-brain barrier permeability, western blot analysis, TUNEL staining, Nissl staining, immunofluorescence, morphological analysis, Morris water maze test, Golgi staining, CCK8, flow cytometry in the in vivo and in vitro settings.

RESULTS

Following SAH, there was an observed increase in the expression levels of cGAS in rat brain tissue, with peak levels observed at 24 h post-SAH. RU.521 resulted in a reduction of brain water content and blood-brain barrier permeability, leading to an improvement in neurological deficits after SAH. RU.521 had beneficial effects on neuronal apoptosis and microglia activation, as well as improvements in microglial morphology. Additionally, RU.521 prompted a shift in microglial phenotype from M1 to M2. We also noted a decrease in the production of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6, and an increase in the level of the anti-inflammatory cytokine IL-10. Finally, RU.521 treatment was associated with improvements in cognitive function and an increase in the number of dendritic spines in the hippocampus. The therapeutic effects were mediated by the cGAS/STING/NF-κB pathway and were found to be abolished by 2'3'-cGAMP. In vitro, RU.521 significantly reduced apoptosis and neuroinflammation.

CONCLUSION

The study showed that SAH leads to neuroinflammation caused by microglial activation, which contributes to early brain injury. RU.521 improved neurological outcomes and reduced neuroinflammation by regulating microglial polarization through the cGAS/STING/NF-κB pathway in early brain injury after SAH. RU.521 may be a promising candidate for the treatment of neuroinflammatory pathology after SAH. Video Abstract.

Inhibition of lysophosphatidic acid receptor 1 relieves PMN recruitment in CNS via LPA1/TSP1/CXCR2 pathway and alleviates disruption on blood-brain barrier following intracerebral haemorrhage in mice

BACKGROUD

The frequencies of morbidity and impairment associated with spontaneous intracerebral haemorrhage (ICH) are comparatively high. Blood-brain barrier (BBB) integrity was compromised due to subsequent brain injury induced by ICH, which is crucial for a poor prognosis. Polymorphonuclear leukocyte (PMN) strongly modulate the disruption of BBB in the central nervous system (CNS). The lysophosphatidic acid receptor 1 (LPA1) mediated thrombospondin-1 (TSP1) regulation in astrocytes, which induce macrophage inflammatory protein 2(MIP2) secretion. MIP2 enhance PMN recruitment through CXC chemokine type 2 (CXCR2) activation. The purpose of this study was to investigate whether the LPA1-mediated inhibition of PMN recruitment and BBB protection after ICH is regulated by TSP1 and CXCR2 networks.

METHODS

ICH induction was performed in CD1 mice using collagenase administration. AM966, a targeted LPA1 antagonist, was orally administered 1 and 12 h following ICH. further identify possible LPA1-mediated BBB protection mechanisms, we intracerebroventricularly (ICV) administered a CXCR2 ligand MIP2, as well as TSP1 CRISPR activation (ACT) with AM966. Consequently, we performed neurobehavioral, brain water content (BWC), Evans blue staining (EBS), immunofluorescence (IF), and western blot (WB) analyses.

RESULTS

After ICH, astrocytes showed signs of LPA1, which peaked after 24 h, while PMN\ displayed evidence of CXCR2. The AM966-mediated LPA1 suppression relieved PMN recruitment, diminished brain oedema, demonstrated extravasation (as evidenced by EBS), protected BBB integrity, and enhanced neurologic activity following ICH. AM966 treatment strongly reduced TSP1, CXCR2, Occludin, and Claudin-5 expressions and PMN recruitment following ICH, and their expressions were restored by MIP2 and TSP1 CRISPR (ACT).

CONCLUSIONS

This study shows that LAP1 suppression reduced PMN recruitment after ICH in mice via TSP1/CXCR2 signalling, which minimized BBB disruption and improved the CNS's neurobehavioral functioning. Hence, LPA1 is a strong candidate for therapy to reduce PMN recruitment and offer protection of BBB integrity after ICH.

The Cannabinoid Ligand Arachidonyl-2'-Chloroethylamide (ACEA) Ameliorates Depressive and Overactive Bladder Symptoms in a Corticosterone-Induced Female Wistar Rat Model

There is growing need to increase the knowledge on the cannabinoid ligands in the treatment of overactive bladder. Among potential candidates, arachidonyl-2'-chloroethylamide (ACEA), a selective cannabinoid CB1 receptor agonist is proposed. The aim of this paper was to determine if ACEA, a selective cannabinoid CB1 receptor agonist, could reverse the effects of corticosterone (CORT), characteristic of depressive and bladder overactivity potential. The animals (48 female rats) were divided into four groups: I-control, II-received CORT, III-received ACEA, and IV-received the combination of CORT and ACEA. The conscious cystometry, forced swim test (FST), and locomotor activity measurements were performed 3 days after the last dose of ACEA, followed by ELISA measurements. In group IV, ACEA restored urodynamic parameters that were altered by CORT. CORT prolonged the immobility time in FST and the values were lowered by ACEA. ACEA normalized the expression of c-Fos in all the analyzed central micturition centers (group IV vs. group II). ACEA restored the CORT-induced changes in the biomarkers in urine (BDNF, NGF), bladder detrusor (VAChT, Rho kinase), bladder urothelium (CGRP, ATP, CRF, OCT-3, TRPV1), and hippocampus (TNF-α, IL-1β and Il-6, CRF, IL-10, BDNF, NGF). In conclusion, ACEA was proven to reverse CORT-induced changes in both cystometric and biochemical parameters that are determinants of OAB/depression, which represents an example of an existing link between OAB and depression via cannabinoid receptors.

ASK1 inhibitor NQDI‑1 decreases oxidative stress and neuroapoptosis via the ASK1/p38 and JNK signaling pathway in early brain injury after subarachnoid hemorrhage in rats

Oxidative stress and neuroapoptosis are key pathological processes after subarachnoid hemorrhage (SAH). The present study evaluated the anti‑oxidation and anti‑apoptotic neuroprotective effects of the apoptosis signal‑regulating kinase 1 (ASK1) inhibitor ethyl‑2,7‑dioxo‑2,7‑dihydro‑3H‑naphtho(1,2,3‑de)quinoline‑1‑carboxylate (NQDI‑1) in early brain injury (EBI) following SAH in a rat model. A total of 191 rats were used and the SAH model was induced using monofilament perforation. Western blotting was subsequently used to detect the endogenous expression levels of proteins. Immunofluorescence was then used to confirm the nerve cellular localization of ASK1. Short‑term neurological function was assessed using the modified Garcia scores and the beam balance test 24 h after SAH, whereas long‑term neurological function was assessed using the rotarod test and the Morris water maze test. Apoptosis of neurons was assessed by TUNEL staining and oxidative stress was assessed by dihydroethidium staining 24 h after SAH. The protein expression levels of phosphorylated (p‑)ASK1 and ASK1 rose following SAH. NQDI‑1 was intracerebroventricularly injected 1 h after SAH and demonstrated significant improvements in both short and long‑term neurological function and significantly reduced oxidative stress and neuronal apoptosis. Injection of NQDI‑1 caused a significant decrease in protein expression levels of p‑ASK1, p‑p38, p‑JNK, 4 hydroxynonenal, and Bax and significantly increased the protein expression levels of heme oxygenase 1 and Bcl‑2. The use of the p38 inhibitor BMS‑582949 or the JNK inhibitor SP600125 led to significant decreases in the protein expression levels of p‑p38 or p‑JNK, respectively, and a significant reduction in oxidative stress and neuronal apoptosis; however, these inhibitors did not demonstrate an effect on p‑ASK1 or ASK1 protein expression levels. In conclusion, treatment with NQDI‑1 improved neurological function and decreased oxidative stress and neuronal apoptosis in EBI following SAH in rats, possibly via inhibition of ASK1 phosphorylation and the ASK1/p38 and JNK signaling pathway. NQDI‑1 may be considered a potential agent for the treatment of patients with SAH.