PLPP/CIN-mediated NF2 S10 dephosphorylation distinctly regulates kainate-induced seizure susceptibility and neuronal death through PAK1-NF-κB-COX-2-PTGES2 signaling pathway

Neuronal PLPP/CIN exaggerates the immune response of hippocampal microglia to LPS challenge dependent on PAK1-NF-κB-COX-2 signaling pathway

Recently, we have reported that pyridoxal-5'-phosphate phosphatase/chronophin (PLPP/CIN) selectively dephosphorylates neurofibromin 2 (NF2, also known as merlin) at serine (S) 10 site. Since NF2 inhibits p21-activated kinase 1 (PAK1)-mediated nuclear factor-κB (NF-κB) activation, in the present study, we investigated the role of PLPP/CIN-mediated NF2 S10 dephosphorylation in lipopolysaccharide (LPS)-induced neuroinflammation and explored its related signaling pathways in the mouse hippocampus. PLPP/CIN overexpression increased NF2 S10 dephosphorylation and PAK1 S204 autophosphorylation under physiological condition, which were reversed by PLPP/CIN deletion. Following LPS injection, PLPP/CIN overexpression exacerbated microglial activation, although microglial PLPP/CIN expression was undetectable. In addition, PLPP/CIN overexpression enhanced PAK1 and NF-κB phosphorylations, and upregulated cyclooxygenase-2 (COX-2) and prostaglandin E synthase 2 (PTGES2) expressions in CA1 neurons. PLPP/CIN overexpression also augmented microglial interleukin-1β induction. PLPP/CIN ablation and 1,1'-dithiodi-2-naphthtol (IPA-3, a PAK1 inhibitor) pretreatment ameliorated these LPS-induced neuroinflammatory responses. These findings indicate that PLPP/CIN-mediated NF2 S10 dephosphorylation may facilitate PAK1-NF-κB-COX-2-PTGES2 signaling pathway in CA1 neurons, which would subsequently exaggerate immune response of microglia following LPS treatment. Therefore, our findings suggest that this PLPP/CIN-mediated neuron-microglia interaction may play an important role in the pathogenesis of inflammation-related neurological diseases.

Safranal alleviates pentetrazole-induced epileptic seizures in mice by inhibiting the NF-κB signaling pathway and mitochondrial-dependent apoptosis through GSK-3β inactivation

ETHNOPHARMACOLOGICAL RELEVANCE

Saffron, a traditional Chinese medicine, is derived from Crocus sativus L. stigmas and has been reported to possess neuroprotective properties and potentially contribute to the inhibition of apoptosis and inflammation. Safranal, a potent monothyral aldehyde, is a main component of saffron that has been reported to have antiepileptic activity. However, the specific mechanism by which safranal suppresses epileptic seizures via its antiapoptotic and anti-inflammatory properties is unclear.

AIM

To evaluate the effect of safranal on seizure severity, inflammation, and postictal neuronal apoptosis in a mouse model of pentetrazole (PTZ)-induced seizures and explore the underlying mechanism involved.

MATERIALS AND METHODS

The seizure stage and latency of stage 2 and 4 were quantified to assess the efficacy of safranal in mitigating PTZ-induced epileptic seizures in mice. Electroencephalography (EEG) was employed to monitor epileptiform afterdischarges in each experimental group. The cognitive abilities and motor functions of the mice were evaluated using the novel object recognition test and the open field test, respectively. Neurons were quantified using hematoxylin and eosin staining. Additionally, bioinformatics tools were utilized to predict the interactions between safranal and specific target proteins. Glycogen synthase kinase-3β (GSK-3β), mitochondrial apoptosis-related proteins, and inflammatory factor levels were analyzed through western blotting. Tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) concentrations in brain tissue were assessed by ELISA.

RESULTS

Safranal decreased the average seizure stage and increased the lantency of stage 2 and 4 seizures in PTZ-induced epileptic mice. Additionally, safranal exhibited neuroprotective effects on hippocampal CA1 and CA3 neurons and reduced hyperactivity caused by postictal hyperexcitability. Bioinformatics analysis revealed that safranal can bind to five specific proteins, including GSK-3β. By promoting Ser9 phosphorylation and inhibiting GSK-3β activity, safranal effectively suppressed the NF-κB signaling pathway. Moreover, the findings indicate that safranal treatment can decrease TNF-α and IL-1β levels in the cerebral tissues of epileptic mice and downregulate mitochondrial apoptosis-related proteins, including Bcl-2, Bax, Bak, Caspase 9, and Caspase 3.

CONCLUSION

Safranal can suppress the NF-κB signaling pathway and mitochondrial-dependent apoptosis through GSK-3β inactivation, suggesting that it is a promising therapeutic agent for epilepsy treatment.

Ipomoea carnea mitigates ethanol-induced ulcers in irradiated rats via Nrf2/HO-1 pathway: an in vivo and in silico study

The aim of this study was to investigate the potential of Ipomoea carnea flower methanolic extract (ICME) as a natural gastroprotective therapy against ethanol-induced gastric ulcers, particularly in individuals exposed to ionizing radiation (IR). The study focused on the Nrf2/HO-1 signaling pathway, which plays a crucial role in protecting the gastrointestinal mucosa from oxidative stress and inflammation. Male Wistar rats were divided into nine groups, the control group received distilled water orally for one week, while other groups were treated with ethanol to induce stomach ulcers, IR exposure, omeprazole, and different doses of ICME in combination with ethanol and/or IR. The study conducted comprehensive analyses, including LC-HRESI-MS/MS, to characterize the phenolic contents of ICME. Additionally, the Nrf2/HO-1 pathway, oxidative stress parameters, gastric pH, and histopathological changes were examined. The results showed that rats treated with IR and/or ethanol exhibited histopathological alterations, increased lipid peroxidation, decreased antioxidant enzyme activity, and reduced expression levels of Nrf2 and HO-1. However, pretreatment with ICME significantly improved these parameters. Phytochemical analysis identified 39 compounds in ICME, with flavonoids, hydroxybenzoic acids, and fatty acids as the predominant compounds. Virtual screening and molecular dynamics simulations suggested that ICME may protect against gastric ulceration by inhibiting oxidative stress and inflammatory mediators. In conclusion, this study demonstrates the potential of ICME as a natural gastroprotective therapy for preventing gastric ulcers. These findings contribute to the development of novel interventions for gastrointestinal disorders using natural plant extracts particularly in individuals with a history of radiation exposure.