Akt activation improves microregional oxygen supply/consumption balance after cerebral ischemia-reperfusion

The Protective Role of Transcript-Induced in Spermiogenesis 40 in Cerebral Ischemia-Reperfusion Injury

Prompt reperfusion after cerebral ischemia is important to maintain neuronal survival and reduce permanent disability and death. However, the resupply of blood can induce oxidative stress, inflammatory response and apoptosis, further leading to tissue damage. Here, we report the versatile biological roles of transcript-induced in spermiogenesis 40 (Tisp40) in ischemic stroke. We found that the expression of Tisp40 was upregulated in ischemia/reperfusion-induced brain tissues and oxygen glucose deprivation/returned -stimulated neurons. Tisp40 deficiency increased the infarct size and neurological deficit score, and promoted inflammation and apoptosis. Tisp40 overexpression played the opposite role. In vitro, the oxygen glucose deprivation/returned model was established in Tisp40 knockdown and overexpression primary cultured cortical neurons. Tisp40 knockdown can aggravate the process of inflammation and apoptosis, and Tisp40 overexpression ameliorated the aforementioned processes. Mechanistically, Tisp40 protected against ischemic stroke via activating the AKT signaling pathway. Tisp40 may be a new therapeutic target in brain ischemia/reperfusion injury.

Investigation of the underlying mechanism of Buyang Huanwu decoction in ischemic stroke by integrating systems pharmacology-proteomics and in vivo experiments

Buyang Huanwu Decoction (BHD) has been effective in treating ischemic stroke (IS). However, its mechanism of action remains unclear. The study intended to explore the potential mechanism of BHD against IS using systems pharmacology, proteomics, and animal experiments. The active components of BHD were identified from UPLC-Q-TOF-MS and literature mining. Systems pharmacology and proteomics were employed to investigate the underlying mechanism of BHD against IS. The AutoDock tool was used for molecular docking. A middle cerebral artery occlusion (MCAO) model rat was utilized to explore the therapeutic benefits of BHD. The rats were divided into sham, model, BHD (5, 10, 20 g/kg, ig) groups. The neurological scores, pathological section characteristics, brain infarct volumes, inflammatory cytokines, and signaling pathways were investigated in vivo experiments. The results of systems pharmacology showed that 13 active compounds and 112 common targets were screened in BHD. The docking results suggested that the active compounds in BHD had a high affinity for the key targets. In vivo experiments demonstrated that BHD exhibited neuroprotective benefits by lowering the neurological score, the volume of the cerebral infarct, the release of inflammatory cytokines, and reducing neuroinflammatory damage in MCAO rats. Furthermore, BHD decreased TNF-α and CD38 levels while increasing ATP2B2, PDE1A, CaMK4, p-PI3K, and p-AKT. Combined with systems pharmacology and proteomic studies, we confirmed that PI3K-Akt and calcium signaling pathways are the key mechanisms for BHD against IS. Furthermore, this study demonstrated the feasibility of combining proteomics with systems pharmacology to study the mechanism of herbal medicine.

The mTORC2 signaling network: targets and cross-talks

The mechanistic target of rapamycin, mTOR, controls cell metabolism in response to growth signals and stress stimuli. The cellular functions of mTOR are mediated by two distinct protein complexes, mTOR complex 1 (mTORC1) and mTORC2. Rapamycin and its analogs are currently used in the clinic to treat a variety of diseases and have been instrumental in delineating the functions of its direct target, mTORC1. Despite the lack of a specific mTORC2 inhibitor, genetic studies that disrupt mTORC2 expression unravel the functions of this more elusive mTOR complex. Like mTORC1 which responds to growth signals, mTORC2 is also activated by anabolic signals but is additionally triggered by stress. mTORC2 mediates signals from growth factor receptors and G-protein coupled receptors. How stress conditions such as nutrient limitation modulate mTORC2 activation to allow metabolic reprogramming and ensure cell survival remains poorly understood. A variety of downstream effectors of mTORC2 have been identified but the most well-characterized mTORC2 substrates include Akt, PKC, and SGK, which are members of the AGC protein kinase family. Here, we review how mTORC2 is regulated by cellular stimuli including how compartmentalization and modulation of complex components affect mTORC2 signaling. We elaborate on how phosphorylation of its substrates, particularly the AGC kinases, mediates its diverse functions in growth, proliferation, survival, and differentiation. We discuss other signaling and metabolic components that cross-talk with mTORC2 and the cellular output of these signals. Lastly, we consider how to more effectively target the mTORC2 pathway to treat diseases that have deregulated mTOR signaling.

Leucine Reduced Blood-Brain Barrier Disruption and Infarct Size in Early Cerebral Ischemia-Reperfusion

A disruption of the blood-brain barrier (BBB) is a crucial pathophysiological change that can impact the outcome of a stroke. Ribosomal protein S6 (S6) and protein kinase B (Akt) play significant roles in early cerebral ischemia-reperfusion injury. Studies have suggested that branched-chain amino acids (BCAAs) may have neuroprotective properties for spinal cord or brain injuries. Therefore, we conducted research to investigate if leucine, one of the BCAAs, could offer neuroprotection and alter BBB disruption, along with its effects on the phosphorylation of S6 and Akt during the early phase of cerebral ischemia-reperfusion, specifically within the thrombolytic therapy time window. In rats, ten min after left middle cerebral artery occlusion (MCAO), 5 µL of 20 mM L-leucine or normal saline was injected into the left lateral ventricle. After two hours of reperfusion following one hour of MCAO, we determined the transfer coefficient (Ki) of 14C-α-aminoisobutyric acid to assess the BBB disruption, infarct size, and phosphorylation of S6 and Akt. Ischemia-reperfusion increased the Ki (+143%, p < 0.001) and the intra-cerebroventricular injection of leucine lowered the Ki in the ischemic-reperfused cortex (-34%, p < 0.001). Leucine reduced the percentage of cortical infarct (-42%, p < 0.0001) out of the total cortical area. Ischemia-reperfusion alone significantly increased the phosphorylation of both S6 and Akt (p < 0.05). However, the administration of leucine had no further effect on the phosphorylation of S6 or Akt in the ischemic-reperfused cortex. This study suggests that an acute increase in leucine levels in the brain during early ischemia-reperfusion within a few hours of stroke may offer neuroprotection, possibly due to reduced BBB disruption being one of the major contributing factors. Leucine did not further increase the already elevated phosphorylation of S6 or Akt by ischemia-reperfusion under the current experimental conditions. Our data warrant further studies on the effects of leucine on neuronal survival and its mechanisms in the later stages of cerebral ischemia-reperfusion.

Histone methyltransferase enzyme enhancer of zeste homolog 2 counteracts ischemic brain injury via H3K27me3-mediated regulation of PI3K/AKT/mTOR signaling pathway

BACKGROUND

Epigenetic histone methylation plays a crucial role in cerebral ischemic injury, particularly in the context of ischemic stroke. However, the complete understanding of regulators involved in histone methylation, such as Enhancer of Zeste Homolog 2 (EZH2), along with their functional effects and underlying mechanisms, remains incomplete.

METHODS

Here, we employed a rat model of MCAO (Middle cerebral artery occlusion) and an OGD (Oxygen-Glucose Deprivation) model of primary cortical neurons to study the role of EZH2 and H3K27me3 in cerebral ischemia-reperfusion injury. The infarct volume was measured through TTC staining, while cell apoptosis was detected using TUNEL staining. The mRNA expression levels were quantified through quantitative real-time polymerase chain reaction (qPCR), whereas protein expressions were evaluated via western blotting and immunofluorescence experiments.

RESULTS

The expression levels of EZH2 and H3K27me3 were upregulated in OGD; these expression levels were further enhanced by GSK-J4 but reduced by EPZ-6438 and AKT inhibitor (LY294002) under OGD conditions. Similar trends were observed for mTOR, AKT, and PI3K while contrasting results were noted for UTX and JMJD3. The phosphorylation levels of mTOR, AKT, and PI3K were activated by OGD, further stimulated by GSK-J4, but inhibited by EPZ-6438 and AKT inhibitor. Inhibition of EZH2 or AKT effectively counteracted OGD-/MCAO-induced cell apoptosis. Additionally, inhibition of EZH2 or AKT mitigated MCAO-induced infarct size and neurological deficit in vivo.

CONCLUSIONS

Collectively, our results demonstrate that EZH2 inhibition exerts a protective effect against ischemic brain injury by modulating the H3K27me3/PI3K/AKT/mTOR signaling pathway. The results provide novel insights into potential therapeutic mechanisms for stroke treatment.

Vitexin Improves Cerebral ischemia‑reperfusion Injury by Attenuating Oxidative Injury and Ferroptosis via Keap1/Nrf2/HO-1signaling

Cerebral ischemia/reperfusion involves multiple pathological processes and ferroptosis played a crucial role in the disease progression. Nevertheless, whether Vitexin could ameliorate ischemia/reperfusion injury via meditate the ferroptosis still remains unknown. In this study, we established the oxygen-glucose deprivation and reoxygenation (OGD/R) neuron cell and middle cerebral artery occlusion/reperfusion (MCAO/R) rat model. The cell viability, cell apoptosis and reactive oxygen species (ROS) levels were tested by CCK-8 assay and Flow cytometry, respectively. Hematoxylin-eosin staining, TTC, TEM, immunofluorescence analysis and western blot were used to investigate the effects of Vitexin. The results demonstrated that Vitexin could enhanced the cell viability and decreased the cell apoptosis in OGD/R cell model. Meanwhile, incubation with Vitexin maintained the neuroprotective effects in OGD/R induced generation of lipid ROS and neuronal cell ferroptosis via regulated the expressions of Keap1/Nrf2/HO-1 relative protein levels. Moreover, treatment with Vitexin reversed brain infracted volume, the normal histopathology and mitochondrial function in MCAO/R rat model. Vitexin significantly decreased the Nrf2 transfer ration from nuclear to cytosol and regulated the expression of Keap1/Nrf2/HO-1 signaling both in vitro and in vivo. Nevertheless, the protective effects of Vitexin were blocked with the Nrf2 inhibitor ML385. Vitexin could protect the neuron cell and brain related with the Keap1/Nrf2/HO-1 signaling pathway. Vitexin was a useful candidate for stroke therapy and our research may provide an attractive therapeutic target for the treatment of stroke.

Integrating network pharmacology and pharmacological evaluation to explore the protective mechanism of Ershiwuwei Zhenzhu pill in ischemic stroke

ETHNOPHARMACOLOGICAL RELEVANCE

Ershiwuwei Zhenzhu Pill (EZP), a representative and classic formula in Tibetan medicine, is commonly used in the treatment of various cerebrovascular diseases, including ischemic stroke (IS). Nevertheless, their efficacy and potential mechanism in treating IS have yet to be investigated.

AIM OF THE STUDY

This study aimed to investigate the potential mechanisms of EZP in the treatment of IS based on network pharmacology and experimental verification.

MATERIALS AND METHODS

The chemical profile of EZP was characterized using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The targets related to the compounds in EZP were predicted by the Swiss Target Prediction and Target Net platform, and targets of IS were collected from the Gene Cards and OMIM databases. Subsequently, a protein-protein interaction (PPI) network of targets was constructed and analyzed by the STRING database and Cytoscape software, version 3.7.1. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed, and an ingredient-target-pathway network was constructed. Ultimately, the middle cerebral artery occlusion (MCAO) model was established to evaluate the anti-IS effects of EZP by detecting the neurological deficit score, HE, Nissl and TCC staining, and inflammatory factors, and the expression of key protein targets was detected by western blotting.

RESULTS

A total of 129 components were identified in EZP. Network pharmacology revealed 3136 compound targets and 2826 disease-related targets, and 412 overlapping proteins were obtained as potential therapeutic targets. The PPI network results showed that 6 key targets (AKT1, SRC, VEGFA, TP53, TNF and EGFR) were core targets of EZP in the treatment of IS. Western blotting demonstrated that the expression levels of AKT1, VEGFA, TP53, SRC, TNF and EGFR in the brain tissue of MCAO rats were significantly changed after treatment with EZP compared to the model group.

CONCLUSIONS

EZP ameliorated IS in MCAO rats. The underlying mechanism might be associated with inhibiting inflammation and apoptosis, promoting angiogenesis and protecting neurons by regulating multiple targets and pathways.

Systems pharmacology, proteomics and in vivo studies identification of mechanisms of cerebral ischemia injury amelioration by Huanglian Jiedu Decoction

ETHNOPHARMACOLOGICAL RELEVANCE

Huanglian Jiedu Decoction (HLJDD) has the effect of clearing heat and detoxifying, and has been considered as an effective prescription for cerebral ischemia (CI) for thousands of years in traditional Chinese medicine (TCM). It can improve the quality of life of patients with ischemic stroke, but its pharmacological mechanism remains unclear.

AIM OF THE STUDY

The study aimed to explore the pharmacological action and potential mechanism of HLJDD against CI by systems pharmacology, proteomics and in vivo experiments.

MATERIALS AND METHODS

In this study, databases such as TCMIP V2.0 and Genecards were used to predict compounds, targets and CI related targets, and network topology criteria of protein-protein interaction (PPI) network was used to screen core targets. The Database for Annotation, Visualization and Integrated Discovery database (DAVID) was used to discover biological processes and pathways. In addition, molecular docking was performed between the screened core biological active compounds and targets to verify the binding activity. Finally, proteomics and Western blot were performed on cerebral cortex tissues of middle cerebral artery occlusion (MCAO) model rats with HLJDD intervention to further verify the predicted results.

RESULTS

77 compounds and 308 targets of HLJDD were identified, 54 of which were predicted to be associated with cerebral ischemia. PPI network and enrichment results showed that 8 targets, including AKT1, PTGS2 and TLR4, were core targets of HLJDD in CI. And 19 signaling pathways, including Rap1 signaling pathway, cAMP signaling pathway and arachidonic acid metabolism, were identified as key pathways to the therapeutic activity of HLJDD in CI. Combined with proteomics studies, we identified that Rap1 signaling pathway and upstream and downstream targets were the key mechanisms. Molecular biology experiments showed that RAP1A and AKT expression levels were significantly up-regulated in middle cerebral artery occlusion (MCAO) rats treated with HLJDD (P < 0.0001), GRIN1 expression level was significantly down-regulated (P < 0.0001). However, ACTB expression level was slightly down-regulated (P > 0.05), which may be related to the biological function.

CONCLUSION

This study confirms the pharmacological effect of HLJDD on cerebral ischemia. These results indicate that HLJDD mediates various pathways such as inhibition of apoptosis, regulation of oxygen balance, inhibition of excitatory toxicity and maintenance of basic cell functions to improve CI by regulating Rap1 signaling pathway.

Adhesion molecule L1 inhibition increases infarct size in cerebral ischemia-reperfusion without change in blood-brain barrier disruption

OBJECTIVE

Neural cell adhesion molecule L1CAM (L1) is involved in neuroprotection. To investigate a possible neuroprotective effect of L1 during ischemia, we determined whether blocking L1 with an antagonistic antibody would worsen the outcome of focal cerebral ischemia-reperfusion and increase blood-brain barrier (BBB) disruption.

METHODS

Transient middle cerebral artery occlusion (MCAO) was performed in anesthetized rats. Five µg of antagonistic mouse IgG monoclonal L1 antibody 324 or non-immune control mouse IgG was applied on the ischemic-reperfused cortex during one hour of MCAO and two hours of reperfusion. At two hours of reperfusion, BBB permeability, size of infarct using tetrazolium staining, number of TUNEL-labeled apoptotic cells, and immunohistochemistry for expression of PTEN and p53 were studied.

RESULTS

The antagonistic L1 antibody 324 increased the percentage of cortical infarct area (+36%), but did not affect BBB permeability in the ischemic-reperfused cortex. The antagonistic L1 antibody increased number of apoptotic neurons and p53 expression, but decreased PTEN expression.

CONCLUSION

Functional antagonism of L1 increases infarct size by increasing numbers of apoptotic neurons without affecting BBB permeability during the early stage of cerebral ischemia-reperfusion. Our data suggest that L1 affects primarily the brain parenchyma rather than BBB during early stages of cerebral ischemia-reperfusion and that endogenous brain L1 may be neuroprotective.

Advancement in research on the role of the transient receptor potential vanilloid channel in cerebral ischemic injury (Review)

Stroke is a common critical disease occurring in middle-aged and elderly individuals, and is characterized by high morbidity, lethality and mortality. As such, it is of great concern to medical professionals. The aim of the present review was to investigate the effects of transient receptor potential vanilloid (TRPV) subtypes during cerebral ischemia in ischemia-reperfusion animal models, oxygen glucose deprivation and in other administration cell models in vitro to explore new avenues for stroke research and clinical treatments. TRPV1, TRPV2 and TRPV4 employ different methodologies by which they confer protection against cerebral ischemic injury. TRPV1 and TRPV4 are likely related to the inhibition of inflammatory reactions, neurotoxicity and cell apoptosis, thus promoting nerve growth and regulation of intracellular calcium ions (Ca2+). The mechanisms of neuroprotection of TRPV1 are the JNK pathway, N-methyl-D-aspartate (NMDA) receptor and therapeutic hypothermia. The mechanisms of neuroprotection of TRPV4 are the PI3K/Akt pathways, NMDA receptor and p38 MAPK pathway, amongst others. The mechanisms by which TRPV2 confers its protective effects are predominantly connected with the regulation of nerve growth factor, MAPK and JNK pathways, as well as JNK-dependent pathways. Thus, TRPVs have the potential for improving outcomes associated with cerebral ischemic or reperfusion injuries. The protection conferred by TRPV1 and TRPV4 is closely related to cellular Ca2+ influx, while TRPV2 has a different target and mode of action, possibly due to its expression sites. However, in light of certain contradictory research conclusions, further experimentation is required to clarify the mechanisms and specific pathways by which TRPVs act to alleviate nerve injuries.

Inhibition of serum and glucocorticoid regulated kinases by GSK650394 reduced infarct size in early cerebral ischemia-reperfusion with decreased BBB disruption

Blood-brain barrier (BBB) disruption is one of the most important pathological changes following cerebral ischemia-reperfusion. We tested whether inhibition of the serum and glucocorticoid regulated kinase 1 (SGK1) would decrease BBB disruption and contribute to decreasing infarct size in the first few hours of cerebral ischemia-reperfusion within the thrombolysis therapy time window. After transient middle cerebral artery occlusion (MCAO), an SGK1 inhibitor GSK650394, or vehicle was administered into the lateral ventricle of rats. After one hour of MCAO and two hours of reperfusion, we determined BBB disruption using the transfer coefficient (K_i) of ¹⁴C-α-aminoisobutyric acid, and also determined infarct size, phosphorylation of NDRG1, and MMP2 protein level. Ischemia-reperfusion increased (+34%, p < 0.05) and GSK650394 decreased (-25%, p < 0.05) the K_i in the ischemic-reperfused cortex. GSK650394 decreased the percentage of cortical infarct (-31%, p < 0.001). At the same time GSK650394 reduced NDRG1 phosphorylation and MMP2 protein level in the ischemic-reperfused cortex suggesting that SGK1 was inhibited by GSK650394 and that lower MMP2 could be one of the mechanisms of decreased BBB disruption. Collectively our data suggest that GSK650394 could be neuroprotective and one of the mechanisms of the neuroprotection could be decreased BBB disruption. SGK1 inhibition within the thrombolysis therapy time window might reduce cerebral ischemia-reperfusion injury.

Rapalink-1 Increased Infarct Size in Early Cerebral Ischemia-Reperfusion With Increased Blood-Brain Barrier Disruption

It has been reported that the mechanistic target of rapamycin (mTOR) pathway is involved in cerebral ischemia–reperfusion injury. One of the important pathological changes during reperfusion after cerebral ischemia is disruption of blood–brain barrier (BBB). Rapamycin, a first-generation mTOR inhibitor, produces divergent effects on neuronal survival and alteration in BBB disruption. In this study, we investigated how Rapalink-1, a third-generation mTOR inhibitor, would affect neuronal survival and BBB disruption in the very early stage of cerebral ischemia–reperfusion that is within the time window of thrombolysis therapy. The middle cerebral artery occlusion (MCAO) was performed in rats under isoflurane anesthesia with controlled ventilation. Of note, 2 mg/kg of Rapalink-1 or vehicle was administered intraperitoneally 10 min after MCAO. After 1 h of MCAO and 2 h of reperfusion, the transfer coefficient (K_i) of ¹⁴C-α-aminoisobutyric acid (104 Da) and the volume of ³H-dextran (70,000 Da) distribution were determined to assess the degree of BBB disruption. At the same time points, phosphorylated S6 (Ser240/244) and Akt (Ser473) as well as matrix metalloproteinase-2 (MMP2) protein level were determined by Western blot along with the infarct size using tetrazolium stain. Rapalink-1 increased the K_i in the ischemic-reperfused cortex (IR-C, +23%, p < 0.05) without a significant change in the volume of dextran distribution. Rapalink-1 increased the percentage of cortical infarct out of the total cortical area (+41%, p < 0.005). Rapalink-1 significantly decreased phosphorylated S6 and Akt to half the level of the control rats in the IR-C, which suggests that both of the mechanistic target of rapamycin complex 1 and 2 (mTORC1 and mTORC2) were inhibited. The MMP2 level was increased suggesting that BBB disruption could be aggravated by Rapalink-1. Taken together, our data suggest that inhibiting both mTORC1 and mTORC2 by Rapalink-1 could worsen the neuronal damage in the early stage of cerebral ischemia–reperfusion and that the aggravation of BBB disruption could be one of the contributing factors.

Melatonin protects against focal cerebral ischemia-reperfusion injury in diabetic mice by ameliorating mitochondrial impairments: involvement of the Akt-SIRT3-SOD2 signaling pathway

Diabetic patients are more vulnerable to cerebral ischemia-reperfusion (CIR) injury and have a worse prognosis and higher mortality after ischemic stroke than non-diabetic counterparts. Melatonin can exert neuroprotective effects against CIR injury in nondiabetic animal models. However, its effects on diabetic CIR injury and the underlying mechanisms remain unclarified. Herein, we found that melatonin administration improved neurological deficit, cerebral infarct volume, brain edema, and cell viability, reduced mitochondrial swelling, reactive oxygen species generation, and cytoplasmic cytochrome C release, and increased mitochondrial antioxidant enzymes activities, adenosine triphosphate production, and mitochondrial membrane potential in both streptozotocin-induced diabetic mice and high glucose-treated HT22 cells. Importantly, melatonin also activated protein kinase B (Akt) and sirtuin 3 (SIRT3)/superoxide dismutase 2 (SOD2) signaling and upregulated mitochondrial biogenesis-related transcription factors. However, these effects were largely attenuated by LY294002 (a specific Akt signaling blocker) administration. Additionally, 3-TYP (a selective SIRT3 inhibitor) and SIRT3 siRNA inhibited the above protective effects of melatonin as well as the upregulation of SIRT3 and the decrease of SOD2 acetylation but did not affect the p-Akt/Akt ratio. Overall, we demonstrate that melatonin can alleviate CIR injury in diabetic mice by activating Akt-SIRT3-SOD2 signaling and subsequently improving mitochondrial damage.

Brain-Specific Serine-47 Modification of Cytochrome c Regulates Cytochrome c Oxidase Activity Attenuating ROS Production and Cell Death: Implications for Ischemia/Reperfusion Injury and Akt Signaling

We previously reported that serine-47 (S47) phosphorylation of cytochrome c (Cytc) in the brain results in lower cytochrome c oxidase (COX) activity and caspase-3 activity in vitro. We here analyze the effect of S47 modification in fibroblast cell lines stably expressing S47E phosphomimetic Cytc, unphosphorylated WT, or S47A Cytc. Our results show that S47E Cytc results in partial inhibition of mitochondrial respiration corresponding with lower mitochondrial membrane potentials (ΔΨm) and reduced reactive oxygen species (ROS) production. When exposed to an oxygen-glucose deprivation/reoxygenation (OGD/R) model simulating ischemia/reperfusion injury, the Cytc S47E phosphomimetic cell line showed minimal ROS generation compared to the unphosphorylated WT Cytc cell line that generated high levels of ROS upon reoxygenation. Consequently, the S47E Cytc cell line also resulted in significantly lower cell death upon exposure to OGD/R, confirming the cytoprotective role of S47 phosphorylation of Cytc. S47E Cytc also resulted in lower cell death upon H2O2 treatment. Finally, we propose that pro-survival kinase Akt (protein kinase B) is a likely mediator of the S47 phosphorylation of Cytc in the brain. Akt inhibitor wortmannin abolished S47 phosphorylation of Cytc, while the Akt activator SC79 maintained S47 phosphorylation of Cytc. Overall, our results suggest that loss of S47 phosphorylation of Cytc during brain ischemia drives reperfusion injury through maximal electron transport chain flux, ΔΨm hyperpolarization, and ROS-triggered cell death.

A Network Pharmacology Approach to Investigate the Active Compounds and Mechanisms of Musk for Ischemic Stroke

Objectives

This study aims to study the material basis and effective mechanism of musk for ischemic stroke (IS) based on the network pharmacology approach.

Methods

We collected the chemical components and target gene of musk from the BATMAN-TCM analytical platform and identified ischemic stroke-related targets from the following databases: DisGeNET, NCBI-Gene, HPO, OMIM, DrugBank, and TTD. The targets of musk and IS were uploaded to the String database to construct the protein-protein interaction (PPI) network, and then, the key targets were analyzed by topological methods. At last, the function biological process and signaling pathways of key targets were carried out by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and cluster analysis by using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) server and Metascape platform.

Results

A total of 29 active compounds involving 1081 predicted targets were identified in musk and there were 1104 IS-related targets. And 88 key targets of musk for IS were obtained including AKT1, MAPK1/3, TP53, TNF, SRC, FOS, CASP3, JUN, NOS3, and IL1B. The GO and KEGG enrichment analysis suggested that these key targets are mainly involved in multiple pathways which participated in TNF signaling pathway, estrogen signaling pathway, prolactin signaling pathway, neurotrophin signaling pathway, T-cell receptor signaling pathway, cAMP signaling pathway, FoxO signaling pathway, and HIF1 signaling pathway.

Conclusion

This study revealed that the effective mechanisms of musk against IS would be associated with the regulation of apoptosis, inflammatory response, and gene transcription.

Lysophosphatidic Acid Reduces Microregional Oxygen Supply/Consumption Balance after Cerebral Ischemia-Reperfusion

BACKGROUND

Lysophosphatidic acid (LPA) is a small phospholipid-signaling molecule, which can alter responses to stress in the central nervous system.

OBJECTIVE

We hypothesized that exogenous LPA would increase the size of infarct and reduce microregional O2 supply/consumption balance after cerebral ischemia-reperfusion.

METHODS

This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without LPA (1 mg/kg, at 30, 60, and 90 min after reperfusion). Regional cerebral blood flow was determined using a C14-iodoantipyrine autoradiographic technique. Regional small-vessel (20-60 µm in diameter) arterial and venous oxygen saturations were determined microspectrophotometrically.

RESULTS

There were no significant hemodynamic or arterial blood gas differences between groups. The control ischemic-reperfused cortex had a similar O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex with many areas of low O2 saturation (43 of 80 veins with O2 saturation below 50%). LPA did not significantly alter cerebral blood flow, but it did significantly increase O2 extraction and consumption of the ischemic-reperfused region. It also significantly increased the number of small veins with low O2 saturations in the reperfused region (76 of 80 veins with O2 saturation below 50%). This was associated with a significantly increased cortical infarct size after LPA administration (11.4 ± 0.5% control vs. 16.4 ± 0.6% LPA).

CONCLUSION

This suggests that LPA reduces cell survival and that it is associated with an increase in the number of small microregions with reduced local oxygen balance after cerebral ischemia-reperfusion.

Application of P(jv-a) CO2 in monitoring cerebral oxygen supply-demand balance in injured brain

Transcranial Doppler sonography (TCD) assayed cerebral blood flow (CBF) may vary between different intracranial pathologies. Blood gas analysis of the jugular bulb provides a novel way to estimate the global relationship between CBF and oxygen metabolism. In this study, 25 patients with brain trauma, spontaneous intracerebral hemorrhage, and acute cerebral infarction were recruited. Jugular venous oxygen saturation (SjvO₂) increased significantly at different time points after hyperventilation (p < 0.05). A negative correlation between the partial pressure of CO₂ between jugular venous bulb and radial artery blood (P(jv-a)CO₂) and CBF could be observed in acute brain injury and spontaneous intracerebral hemorrhage groups, while P(jv-a)CO₂ and CBF show positive correlation in acute cerebral infarction group. Our results suggest that serial P(jv-a)CO₂ analysis combing with SjvO₂ can be utilized to monitor the change of CBF for patients undergoing craniocerebral surgery.

Activation of Akt by SC79 decreased cerebral infarct in early cerebral ischemia-reperfusion despite increased BBB disruption

Activation of Akt has been suggested to produce neuronal protection in cerebral ischemia. Decreasing blood-brain barrier (BBB) disruption has been associated with a better neuronal outcome in cerebral ischemia. We hypothesized that activation of Akt would decrease BBB disruption and contribute to decreasing the size of infarct in the early stage of cerebral ischemia-reperfusion within the therapeutic window. Transient middle cerebral artery occlusion (MCAO) was performed in rats under isoflurane anesthesia with controlled ventilation. Rats were treated with SC79 (a selective Akt activator which is cell and BBB permeable) 0.05 mg/kg × 3 i.p. or vehicle i.p. perioperatively. After one hour of MCAO and two hours of reperfusion, the transfer coefficient (K_i) of ¹⁴C-α-aminoisobutyric acid (¹⁴C-AIB, molecular weight 104 Da) and the volume of ³H-dextran (molecular weight 70,000 Da) distribution were determined to measure the degree of BBB disruption. At the same time point, the size of infarction was determined using tetrazolium staining. In an additional group of rats, a higher dose of SC79 (0.5 mg/kg × 3) was administered to determine the size of infarct. Administration of SC79 increased the K_i in the ischemic-reperfused cortex (IR-C, +32%, p < 0.05) as well as in the contralateral cortex (CC, +35%, p < 0.05) when compared with the untreated animals with MCAO/reperfusion. The volume of dextran distribution was not significantly changed by SC79. SC79 treatment significantly produced a decrease in the percentage of cortical infarct out of total cortical area (12.7 ± 1.7% vs 6.9 ± 0.9%, p < 0.001). Increasing the dose of SC79 by ten times did not significantly affect the size of cortical infarct. Contrary to our hypothesis, our data demonstrated that SC79 decreased the size of the infarct in the ischemic-reperfused cortex despite an increase in BBB disruption. Our data suggest the importance of activation of Akt for neuronal survival in the early stage of cerebral ischemia-reperfusion within the therapeutic window and that the mechanism of neuroprotection may not be related to the BBB effects of SC79.