1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) Urea Exerts Neuro-Protective Effects Against Ischemic Injury via Suppressing JNK/p38 MAPK-Mediated Mitochondrial Apoptosis Pathway

Inhibition of soluble epoxide hydrolase as a therapeutic approach for blood-brain barrier dysfunction

The blood-brain barrier (BBB) is a protective semi-permeable structure that regulates the exchange of biomolecules between the peripheral blood and the central nervous system (CNS). Due to its specialized tight junctions and low vesicle trafficking, the BBB strictly limits the paracellular passage and transcellular transport of molecules to maintain the physiological condition of brain tissues. BBB breakdown is associated with many CNS disorders. Soluble epoxide hydrolase (sEH) is a hydrolase enzyme that converts epoxy-fatty acids (EpFAs) to their corresponding diols and is involved in the onset and progression of multiple diseases. EpFAs play a protective role in the central nervous system via preventing neuroinflammation, making sEH a potential therapeutic target for CNS diseases. Recent studies showed that sEH inhibition prevented BBB impairment caused by stroke, hemorrhage, traumatic brain injury, hyperglycemia and sepsis via regulating the expression of tight junctions. In this review, the protective actions of sEH inhibition on BBB and potential mechanisms are summarized, and some important questions that remain to be resolved are also addressed.

DUSP10 alleviates ischemic stroke-induced neuronal damage by restricting p38/JNK pathway

Neuronal apoptosis is considered one of the hallmarks of ischemic stroke. Dual specificity phosphatase 10 (DUSP10), a member of the dual-specificity phosphatase family, which is involved in the regulation of apoptosis process. This study aimed to investigate the effect of on apoptosis in primary cortical neurons exposed to oxygen-glucose deprivation and reoxygenation (OGD/R) and mice suffered from transient middle cerebral artery occlusion and reperfusion (MCAO/R). The results showed that DUSP10 overexpression improved survival and reduced apoptosis in neurons subjected to OGD/R, which was manifested by decreased apoptotic proteins (cleaved caspase 3 and bax) and TUNEL+ cells, as well as increased the anti-apoptotic protein (bcl-2). DUSP10 overexpression inhibited the p38/JNK signaling pathway after OGD/R treatment, whilst DUSP10 knockdown had opposite effects. In addition, the p38 inhibitor SB203580 or JNK inhibitor SP600125 attenuated the increased apoptosis of OGD/R-stimulated neurons treated with DUSP10 silencing. Consistently, DUSP10 knockdown exacerbated infarct volume in MCAO/R injury. The data of Nissl staining and TUNEL-NeuN double staining revealed that DUSP10 interference aggravated neuronal damage in the ischemic penumbra of mice. Furthermore, DUSP10 inhibition activated the p38/JNK axis accompanied by enhanced phosphorylation of p38 and JNK in vivo. In summary, DUSP10 is a neuroprotective agent against ischemic stroke-induced neuronal damage via suppressing the p38/JNK signaling pathway.

Guhong injection mitigates myocardial ischemia/reperfusion injury by activating GST P to inhibit ASK1-JNK/p38 pathway

BACKGROUND

Guhong injection (GHI), a novel compound preparation that is composed of a chemical drug, namely aceglutamide, and the aqueous extract of safflower (Carthamus tinctorius L.), exhibits extreme antioxidative, antiapoptotic, anti-inflammatory, and neuroprotective effects. Since oxidative stress, apoptosis, and inflammatory response are all the dominant mechanisms of myocardial ischemia/reperfusion (MI/R) injury, we probe into the protective mechanism of GHI on MI/R injury for the first time.

METHODS

In this research, we first employed molecular docking to determine whether three active ingredients in GHI, acetylglutamine (NAG), hydroxysafflor yellow A (HSYA), and syringin, possessed the potential activity to modulate the protein, glutathione S-transferase P (GST P). We further identified the protective effect of GHI on myocardial tissue with TTC staining, HE staining, TUNEL staining, and ELISA, and on H9c2 with flow cytometry and ELISA. We next explored whether the cardioprotective effect of GHI on left anterior descending ligation-reperfusion in rats and hypoxia/reoxygenation (H/R) in H9c2 cells was related to activate GST P to inhibit ASK1-JNK/p38 pathway via approaches of qRT-PCR and Western blot.

RESULTS

Results of molecular docking indicated that all three compounds spontaneously docked to GST P, among them the binding affinities of both HSYA and syringin to GST P were higher than NAG. In vivo, GHI reduced myocardial infarction size and mitigated myocardial pathological injury. In vitro, GHI enhanced cell viability and extenuated depolarization of mitochondrial membrane potential. In addition, the results of in vivo and in vitro studies demonstrated that the cardioprotection of GHI was associated with improving the mRNA and protein expression levels of GST P to modulate oxidative stress, and inhibiting the levels of mRNA expression and protein phosphorylation of ASK1, JNK, and p38. However, the suppressed effect of GHI on ASK1-JNK/p38 pathway was reversed by ethacrynic acid (EA, a GST inhibitor), indicating that the regulation of GHI on ASK1-JNK/p38 was related to the activity of GST P. Besides, the in vitro results of qRT-PCR and western-blot also certified that the inhibited JNK and p38 further reduced Bax expression and elevated Bcl-2 expression to reduce the expression of caspase-3 to exert anti-apoptosis effects.

CONCLUSION

Taken together, the cardioprotection of GHI mainly incarnated in activating GST P to relieve oxidation properties, thereby inhibiting ASK1-JNK/p38 pathway to suppress apoptosis.

Maizediterpene D from the roots of Zea mays L. alleviates hydrogen peroxide induced oxidative stress and improves cell survival by activation of TrkB/IGF-1R crosstalk pathways

The ent-kaurane diterpenoid enriched fraction (EDEF) of maize root was isolated and purified, and 10 compounds, including 4 ent-kaurane diterpenoids, were isolated and identified. We evaluated their neuroprotective properties in vitro for the first time using an H₂O₂-induced oxidative damage model in SH-SY5Y cells. The results showed that pretreatment with maizediterpene D, a new ent-kaurane diterpenoid isolated from the EDEF, significantly attenuated H₂O₂-induced apoptosis by improving cell survival, reducing ROS production and increasing mitochondrial membrane potential. Mechanistically, the neuroprotective effect of maizediterpene D was confirmed to be related to the dual activation of IGF-1R and BDNF/TrkB crosstalk pathways. Our findings suggest that the EDEF and its active constituent maizediterpene D had good neuroprotective properties and could serve as potential candidates for the development of therapeutic drugs for oxidative stress-related diseases.

Delavatine A attenuates OGD/R-caused PC12 cell injury and apoptosis through suppressing the MKK7/JNK signaling pathway

Delavatine A (DA) is an unusual isoquinoline alkaloid with a novel skeleton isolated from Chinese folk medicine Incarvillea delavayi. Studies conducted in our lab have demonstrated that DA has potential anti-inflammatory activity in LPS-treated BV-2 cells. DA, however, has not been studied for its protective effect on neuronal cells yet. Thus, to explore whether DA can protect neurons, oxygen and glucose deprivation/reperfusion (OGD/R)-injured PC12 cell and middle cerebral artery occlusion/reperfusion (MCAO/R) rat model were used to assess the protective efficacy of DA against OGD/R damaged PC12 cells and MCAO/R injured rats. Our results demonstrated that DA pretreatment (0.31-2.5 μM) dose-dependently increased cell survival and mitochondrial membrane potential (MMP), whereas it lowered the leakage of lactate dehydrogenase (LDH), intracellular cumulation of Ca²⁺, and overproduction of reactive oxygen species (ROS), and inhibited the apoptosis rate in OGD/R-injured PC12 cells. Western blot demonstrated that DA pretreatment lowered the expression of apoptotic proteins and repressed the activation of the MKK7/JNK pathway. It was also found that the neuroprotective efficacy of DA was significantly reversed by co-treatment with the JNK agonist anisomycin, suggesting that DA reduced PC12 cell injury and apoptosis by suppressing the MKK7/JNK pathway. Furthermore, DA oral administration greatly alleviated the neurological dysfunction and reduced the infarct volume of MCAO/R rats. Taken together, DA could ameliorate OGD/R-caused PC12 cell injury and improve brain ischemia/reperfusion (I/R) damage in MCAO/R rats, and its neuroprotection might be attributed to suppressing the MKK7/JNK signaling pathway.

TPPU Downregulates Oxidative Stress Damage and Induces BDNF Expression in PC-12 Cells

Objective

Ischemia-reperfusion is an ongoing clinical challenge that can lead to a series of pathological changes including oxidative stress. The inhibition of soluble epoxide hydrolase inhibitor (sEH) by 1-(1-propanoylpiperidin-4-yl)-3-[4-(trifluoromethoxy)phenyl]urea (TPPU) results in an anti-inflammatory, cardioprotective, and blood vessel growth-promoting effects. Therefore, this study focused on the protective effect of TPPU on a rat pheochromocytoma (PC-12) cell oxidative stress model induced by H2O2.

Methods

CCK-8 and Hoechst 33342 were used to evaluate cell apoptosis and western blot to detect the apoptotic proteins and brain-derived neurotrophic factor (BDNF) expression.

Result

The incubation with 100 μM, 50 μM, and 25 μM TPPU significantly increased PC-12 cell viability. Epoxyeicosatrienoic acid (EET) pretreatment also protected PC-12 cells from oxidative stress. In addition, TPPU reduced caspase-3 and Bax expression and induced Bcl-2 expression, and EETs exerted the same effect on caspase-3 expression as TPPU. A positive relationship was found between TPPU or EET incubation and BDNF expression.

Conclusion

These results revealed that TPPU reduced PC-12 cell oxidative stress injury induced by H2O2 and promoted BDNF expression.