β-Estradiol Protects Against Acidosis-Mediated and Ischemic Neuronal Injury by Promoting ASIC1a (Acid-Sensing Ion Channel 1a) Protein Degradation

The Role of Zinc in Modulating Acid-Sensing Ion Channel Function

Acid-sensing ion channels (ASICs) are proton-gated, voltage-independent sodium channels widely expressed throughout the central and peripheral nervous systems. They are involved in synaptic plasticity, learning/memory, fear conditioning and pain. Zinc, an important trace metal in the body, contributes to numerous physiological functions, with neurotransmission being of note. Zinc has been implicated in the modulation of ASICs by binding to specific sites on these channels and exerting either stimulatory or inhibitory effects depending on the ASIC subtype. ASICs have been linked to several neurological and psychological disorders, such as Alzheimer's disease, Parkinson's disease, ischemic stroke, epilepsy and cocaine addiction. Different ASIC isoforms contribute to the persistence of each of these neurological and psychological disorders. It is critical to understand how various zinc concentrations can modulate specific ASIC subtypes and how zinc regulation of ASICs can contribute to neurological and psychological diseases. This review elucidates zinc's structural interactions with ASICs and discusses the potential therapeutic implications zinc may have on neurological and psychological diseases through targeting ASICs.

Modulators of ASIC1a and its potential as a therapeutic target for age-related diseases

Age-related diseases have become more common with the advancing age of the worldwide population. Such diseases involve multiple organs, with tissue degeneration and cellular apoptosis. To date, there is a general lack of effective drugs for treatment of most age-related diseases and there is therefore an urgent need to identify novel drug targets for improved treatment. Acid-sensing ion channel 1a (ASIC1a) is a degenerin/epithelial sodium channel family member, which is activated in an acidic environment to regulate pathophysiological processes such as acidosis, inflammation, hypoxia, and ischemia. A large body of evidence suggests that ASIC1a plays an important role in the development of age-related diseases (e.g., stroke, rheumatoid arthritis, Huntington's disease, and Parkinson's disease.). Herein we present: 1) a review of ASIC1a channel properties, distribution, and physiological function; 2) a summary of the pharmacological properties of ASIC1a; 3) and a consideration of ASIC1a as a potential therapeutic target for treatment of age-related disease.

Neuroprotective Mechanism of Icariin on Hypoxic Ischemic Brain Damage in Neonatal Mice

Objective. Our previous results showed that icariin (ICA) could inhibit apoptosis and provide neuroprotection against hypoxic-ischemic brain damage (HIBD) in neonatal mice, but the specific mechanism of its neuroprotective effect remains unknown. This study aims at exploring whether ICA plays a neuroprotective role in apoptosis inhibition by regulating autophagy through the estrogen receptor α (ERα)/estrogen receptor β (ERβ) pathway in neonatal mice with HIBD. Methods. A neonatal mouse model of HIBD was constructed in vivo, and an oxygen and glucose deprivation (OGD) model in HT22 cells from the hippocampal neuronal system was constructed in vitro. The effects of ICA pretreatment on autophagy and the expression of ERα and ERβ were detected in vitro and in vivo, respectively. ICA pretreatment was also supplemented with the autophagy inhibitor 3-methyladenine (3-MA), ERα inhibitor methylpiperidino pyrazole (MPP), and ERβ inhibitor 4-(2-phenyl-5,7-bis (trifluoromethyl) pyrazolo [1,5-a] pyramidin-3-yl) phenol (PHTPP) to further detect whether ICA pretreatment can activate the ERα/ERβ pathway to promote autophagy and reduce HIBD-induced apoptosis to play a neuroprotective role against HIBD in neonatal mice. Results. ICA pretreatment significantly promoted autophagy in HIBD mice. Treatment with 3-MA significantly inhibited the increase in autophagy induced by ICA pretreatment, reversed the neuroprotective effect of ICA pretreatment, and promoted apoptosis. Moreover, ICA pretreatment significantly increased the expression levels of the ERα and ERβ proteins in HIBD newborn mice. Both MPP and PHTPP administration significantly inhibited the expression levels of the ERα and ERβ proteins activated by ICA pretreatment, reversed the neuroprotective effects of ICA pretreatment, inhibited the increase in autophagy induced by ICA pretreatment, and promoted apoptosis. Conclusion. ICA pretreatment may promote autophagy by activating the ERα and ERβ pathways, thus reducing the apoptosis induced by HIBD and exerting a neuroprotective effect on neonatal mice with HIBD.

Ferroptosis promotes T-cell activation-induced neurodegeneration in multiple sclerosis

While many drugs are effective at reducing the relapse frequency of multiple sclerosis (MS), there is an unmet need for treatments that slow neurodegeneration resulting from secondary disease progression. The mechanism of neurodegeneration in MS has not yet been established. Here, we discovered a potential pathogenetic role of ferroptosis, an iron-dependent regulated cell death mechanism, in MS. We found that critical ferroptosis proteins (acyl-CoA synthetase long-chain family member 4, ACSL4) were altered in an existing genomic database of MS patients, and biochemical features of ferroptosis, including lipid reactive oxygen species (ROS) accumulation and mitochondrial shrinkage, were observed in the experimental autoimmune encephalitis (EAE) mouse model. Targeting ferroptosis with ferroptosis inhibitors or reducing ACSL4 expression improved the behavioral phenotypes of EAE mice, reduced neuroinflammation, and prevented neuronal death. We found that ferroptosis was an early event in EAE, which may promote T-cell activation through T-cell receptor (TCR) signaling in vitro and in vivo. These data indicate that ferroptosis may be a potential target for treating MS.

Exploring Active Compounds and Mechanisms of Angong Niuhuang Wan on Ischemic Stroke Based on Network Pharmacology and Molecular Docking

Methods

The chemical ingredients of ANW were retrieved from TCMSP, TCMID, and literature. We predicted the potential targets of active ingredients by PubChem, Swiss Target Prediction, and STITCH databases. The targets related to ischemic stroke were retrieved using GeneCards, DisGeNET, DrugBank, TTD, and GEO databases. Subsequently, Venn diagrams were used to identify common targets of active ingredients and ischemic stroke. Protein-protein interaction (PPI) network was structured with STRING platform and Cytoscape 3.8.2. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses of key targets were performed in the Metascape database. Finally, molecular docking was conducted by AutoDock Tools and PyMOL software.

Results

A total of 2391 targets were identified for 230 active ingredients of ANW, and 1386 of them overlapped with ischemic stroke targets. The key active ingredients were mainly quercetin, β-estradiol, berberine, wogonin, and β-sitosterol, and the key targets were also identified, including IL-6, AKT1, MAPK3, PIK3CA, and TNF. The biological process (BP) results indicated that ANW may have therapeutic effects through response oxidative stress, inflammatory response, cellular response to lipid, and response to nutrient levels. Furthermore, the ingredients of ANW were predicted to have therapeutic effects on ischemic stroke via the HIF-1 signaling pathway, FoxO signaling pathway, chemokine signaling pathway, fluid shear stress and atherosclerosis, and neurotrophin signaling pathway. The molecular docking results all showed that the core ingredients were strong binding activity with the core targets.

Conclusion

In conclusion, the bioinformatics and pharmacological results reveal that counteracting oxidative stress, suppressing inflammation, inhibiting the development of AS, and even protecting neurological function are critical pathways for ANW in the treatment of ischemic stroke. These results may help to elucidate the mechanism of ANW on ischemic stroke for experimental studies and clinical applications.

Acid-Sensing Ion Channel 1/Calpain1 Activation Impedes Macrophage ATP-Binding Cassette Protein A1-Mediated Cholesterol Efflux Induced by Extracellular Acidification

Background

Extracellular acidification is a common feature of atherosclerotic lesions, and such an acidic microenvironment impedes ATP-binding cassette transporter A1 (ABCA1)-mediated cholesterol efflux and promotes atherogenesis. However, the underlying mechanism is still unclear. Acid-sensing ion channel 1 (ASIC1) is a critical H⁺ receptor, which is responsible for the perception and transduction of extracellular acidification signals.

Aim

In this study, we explored whether or how ASIC1 influences extracellular acidification-induced ABCA1-mediated cholesterol efflux from macrophage-derived foam cells.

Methods

RAW 264.7 macrophages were cultured in an acidic medium (pH 6.5) to generate foam cells. Then the intracellular lipid deposition, cholesterol efflux, and ASIC1/calpain1/ABCA1 expressions were evaluated.

Results

We showed that extracellular acidification enhanced ASIC1 expression and translocation, promoted calpain1 expression and lipid accumulation, and decreased ABCA1 protein expression as well as ABCA1-mediated cholesterol efflux. Of note, inhibiting ASIC1 activation with amiloride or Psalmotoxin 1 (PcTx-1) not only lowered calpain1 protein level and lipid accumulation but also enhanced ABCA1 protein levels and ABCA1-mediated cholesterol efflux of macrophages under extracellular acidification conditions. Furthermore, similar results were observed in macrophages treated with calpain1 inhibitor PD150606.

Conclusion

Extracellular acidification declines cholesterol efflux via activating ASIC1 to promote calpain1-mediated ABCA1 degradation. Thus, ASIC1 may be a novel therapeutic target for atherosclerosis.

Insight into Crosstalk between Ferroptosis and Necroptosis: Novel Therapeutics in Ischemic Stroke

Ferroptosis is a nonapoptotic form of cell death characterized by iron-dependent accumulation of lipid hydroperoxides to lethal levels. Necroptosis, an alternative form of programmed necrosis, is regulated by receptor-interacting protein (RIP) 1 activation and by RIP3 and mixed-lineage kinase domain-like (MLKL) phosphorylation. Ferroptosis and necroptosis both play important roles in the pathological progress in ischemic stroke, which is a complex brain disease regulated by several cell death pathways. In the past few years, increasing evidence has suggested that the crosstalk occurs between necroptosis and ferroptosis in ischemic stroke. However, the potential links between ferroptosis and necroptosis in ischemic stroke have not been elucidated yet. Hence, in this review, we overview and analyze the mechanism underlying the crosstalk between necroptosis and ferroptosis in ischemic stroke. And we find that iron overload, one mechanism of ferroptosis, leads to mitochondrial permeability transition pore (MPTP) opening, which aggravates RIP1 phosphorylation and contributes to necroptosis. In addition, heat shock protein 90 (HSP90) induces necroptosis and ferroptosis by promoting RIP1 phosphorylation and suppressing glutathione peroxidase 4 (GPX4) activation. In this work, we try to deliver a new perspective in the exploration of novel therapeutic targets for the treatment of ischemic stroke.

Melatonin Protects Against Ischemic Brain Injury by Modulating PI3K/AKT Signaling Pathway via Suppression of PTEN Activity

Stroke is one of the leading causes of death and disability worldwide with limited therapeutic options. Melatonin can attenuate ischemic brain damage with improved functional outcomes. However, the cellular mechanisms of melatonin-driven neuroprotection against post-stroke neuronal death remain unknown. Here, distal middle cerebral artery occlusion (dMCAO) was performed in C57BL/6j mice to develop an ischemic stroke in vivo model. Melatonin was injected intraperitoneally immediately after ischemia, and 24 and 48 hours later. Melatonin treatment, with 5 to 20 mg/kg, elicited a dose-dependent decrease in infarct volume and concomitant increase in sensorimotor function. At the molecular level, phosphorylation of PTEN and Akt were increased, whereas PTEN activity was decreased in melatonin treated animals 72 hours after dMCAO. At the cellular level, oxygenglucose deprivation (OGD) challenge of neuronal cell line Neuro-2a (N2a) and primary neurons supported melatonin’s direct protection against neuronal cell death. Melatonin treatment reduced LDH release and neuronal apoptosis at various time points, markedly increased Akt phosphorylation in neuronal membrane, but significantly suppressed it in the cytoplasm of post-OGD neurons. Mechanistically, melatonin-induced Akt phosphorylation and neuronal survival was blocked by Wortmannin, a potent PIP3 inhibitor, exposing increased PI3K/Akt activation as a central player in melatonin-driven neuroprotection. Finally, PTEN knock-down through siRNA significantly inhibited PI3K/Akt activation and cell survival following melatonin treatment, suggesting that melatonin protection against ischemic brain damage, is at least partially, dependent on modulation of the PTEN/PI3K/Akt signaling axis.

Mechanisms of neuronal cell death in ischemic stroke and their therapeutic implications

Ischemic stroke caused by arterial occlusion is the most common type of stroke, which is among the most frequent causes of disability and death worldwide. Current treatment approaches involve achieving rapid reperfusion either pharmacologically or surgically, both of which are time-sensitive; moreover, blood flow recanalization often causes ischemia/reperfusion injury. However, even though neuroprotective intervention is urgently needed in the event of stroke, the exact mechanisms of neuronal death during ischemic stroke are still unclear, and consequently, the capacity for drug development has remained limited. Multiple cell death pathways are implicated in the pathogenesis of ischemic stroke. Here, we have reviewed these potential neuronal death pathways, including intrinsic and extrinsic apoptosis, necroptosis, autophagy, ferroptosis, parthanatos, phagoptosis, and pyroptosis. We have also reviewed the latest results of pharmacological studies on ischemic stroke and summarized emerging drug targets with a focus on clinical trials. These observations may help to further understand the pathological events in ischemic stroke and bridge the gap between basic and translational research to reveal novel neuroprotective interventions.

Acid-Sensing Ion Channels and Mechanosensation

Acid-sensing ion channels (ASICs) are mainly proton-gated cation channels that are activated by pH drops and nonproton ligands. They are part of the degenerin/epithelial sodium channel superfamily due to their sodium permeability. Predominantly expressed in the central nervous system, ASICs are involved in synaptic plasticity, learning/memory, and fear conditioning. These channels have also been implicated in multiple disease conditions, including ischemic brain injury, multiple sclerosis, Alzheimer’s disease, and drug addiction. Recent research has illustrated the involvement of ASICs in mechanosensation. Mechanosensation is a form of signal transduction in which mechanical forces are converted into neuronal signals. Specific mechanosensitive functions have been elucidated in functional ASIC1a, ASIC1b, ASIC2a, and ASIC3. The implications of mechanosensation in ASICs indicate their subsequent involvement in functions such as maintaining blood pressure, modulating the gastrointestinal function, and bladder micturition, and contributing to nociception. The underlying mechanism of ASIC mechanosensation is the tether-gate model, which uses a gating-spring mechanism to activate ASIC responses. Further understanding of the mechanism of ASICs will help in treatments for ASIC-related pathologies. Along with the well-known chemosensitive functions of ASICs, emerging evidence has revealed that mechanosensitive functions of ASICs are important for maintaining homeostasis and contribute to various disease conditions.

Acidosis induces synovial fibroblasts to release vascular endothelial growth factor via acid-sensitive ion channel 1a

Acid-sensitive ion channel 1a (ASIC1a) is a member of the extracellular H+ activated cation channel family. Studies have shown that tissue acidification contributes to the formation of microvessels in rheumatoid arthritis (RA) synovial tissue, but its underlying mechanisms remain unclear. The purpose of this study was to investigate the role of tissue acidification in microvascular formation of arthritic synovial tissue and the effect of ASIC1a on vascular endothelial growth factor (VEGF) release from arthritic synovial tissue. Our results indicate that ASIC1a expression, VEGF expression, and microvessel density (MVD) are elevated in RA synovial tissue and adjuvant arthritis (AA) rat synovial tissue. When AA rats were treated with ASIC1a-specific blocker psalmotoxin-1 (PcTx-1), the expression of ASIC1a, VEGF expression, and MVD were all reduced. Acidification of RA synovial fibroblasts (RASF) can promote the release of VEGF. PcTx-1 and ASIC1a-short hairpin RNA can inhibit acid-induced release of VEGF. In addition, the ASIC1a overexpression vector can promote acid-induced VEGF release. This indicates that extracellular acidification induces the release of VEGF by RASF via ASIC1a. These findings suggest that blocking ASIC1a mediates the release of VEGF from synoviocytes may provide a potential therapeutic strategy for RA therapy.

Acid-sensing ion channel 1 (ASIC1) mediates weak acid-induced migration of human malignant glioma cells

Glioblastoma is the most aggressive and lethal tumor in the central nervous system in adult and has poor prognosis due to strong proliferation and aggressive invasion capacity. Acidic microenvironment is commonly observed in tumor tissues but the exact role of acidosis in the pathophysiology of glioblastoma and underlying mechanisms remain unclear. Acid-sensing ion channels (ASICs) are proton-gated cation channels activated by low extracellular pH. Recent studies have suggested that ASICs are involved in the pathogenesis of some tumors, such as lung cancer and breast cancer. But the effect of acidosis and activation of ASICs on malignant glioma of the central nervous system has not been reported. In this study, we investigated the expression of ASIC1 in human glioma cell lines (U87MG and A172) and its possible effect on the proliferation and migration of these cells. The results demonstrated that ASIC1 is functionally expressed in U87MG and A172 cells. Treatment with extracellular weak acid (pH 7.0) has no effect on the proliferation but increases the migration of the two cell lines. Application of PcTX1, a specific inhibitor of ASIC1a and ASIC1a/2b channels, or knocking down ASIC1 by siRNA, can abolish the effect of weak acid-induced cell migration. Together, our results indicate that ASIC1 mediates extracellular weak acid induced migration of human malignant glioma cells and may therefore serve as a therapeutic target for malignant glioma in human.

Acid-Sensing Ion Channel-1a in Articular Chondrocytes and Synovial Fibroblasts: A Novel Therapeutic Target for Rheumatoid Arthritis

Acid-sensing ion channel 1a (ASIC1a) is a member of the extracellular H⁺-activated cation channel family. Emerging evidence has suggested that ASIC1a plays a crucial role in the pathogenesis of rheumatoid arthritis (RA). Specifically, ASIC1a could promote inflammation, synovial hyperplasia, articular cartilage, and bone destruction; these lead to the progression of RA, a chronic autoimmune disease characterized by chronic synovial inflammation and extra-articular lesions. In this review, we provided a brief overview of the molecular properties of ASIC1a, including the basic biological characteristics, tissue and cell distribution, channel blocker, and factors influencing the expression and function, and focused on the potential therapeutic targets of ASIC1a in RA and possible mechanisms of blocking ASIC1a to improve RA symptoms, such as regulation of apoptosis, autophagy, pyroptosis, and necroptosis of articular cartilage, and synovial inflammation and invasion of fibroblast-like cells in synovial tissue.

The interaction of ASIC1a and ERS mediates nerve cell apoptosis induced by insulin deficiency

Diabetes-related brain complications are the most serious complications of terminal diabetes. The increasing evidence have showed that the predisposing factor is not only hyperglycemia, but also insulin deficiency. In this study, we demonstrated that insulin deficiency was involved in the apoptosis of nerve cells, and it was related to the interaction between acid-sensitive ion channel 1a (ASIC1a) and endoplasmic reticulum stress (ERS). By silencing C/EBP homologous protein (CHOP) and ASIC1a, the pro-apoptotic effect of insulin deficiency on NS20y cells was relieved. Further research found that the binding of CHOP and C/EBPα was increased in the nucleus of cells cultured without insulin, and C/EBPα was competitively inhibited as a negative regulator of ASIC1a, which further increased the ERS and lead to neuronal apoptosis. In summary, ERS and ASIC1a play an important role in neurological damage caused by insulin deficiency. Our finding may lead to new ideas and treatment of diabetes-related brain complications.

Novel insights into ferroptosis: Implications for age-related diseases

Rapid increase in aging populations is an urgent problem because older adults are more likely to suffer from disabilities and age-related diseases (ARDs), burdening healthcare systems and society in general. ARDs are characterized by the progressive deterioration of tissues and organs over time, eventually leading to tissue and organ failure. To date, there are no effective interventions to prevent the progression of ARDs. Hence, there is an urgent need for new treatment strategies. Ferroptosis, an iron-dependent cell death, is linked to normal development and homeostasis. Accumulating evidence, however, has highlighted crucial roles for ferroptosis in ARDs, including neurodegenerative and cardiovascular diseases. In this review, we a) summarize initiation, regulatory mechanisms, and molecular signaling pathways involved in ferroptosis, b) discuss the direct and indirect involvement of the activation and/or inhibition of ferroptosis in the pathogenesis of some important diseases, and c) highlight therapeutic targets relevant for ARDs.

Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a

Acid-sensing ion channels (ASICs) are members of the degenerin/epithelial sodium channel superfamily. They are extracellular pH sensors that are activated by protons. Among all ASICs, ASIC1a is one of the most intensively studied isoforms because of its unique ability to be permeable to Ca²⁺. In addition, it is considered to contribute to various pathophysiological conditions. As a membrane proton receptor, the number of ASIC1a present on the cell surface determines its physiological and pathological functions, and this number partially depends on protein synthesis, degradation, and membrane trafficking processes. Recently, several studies have shown that various factors affect these processes. Therefore, this review elucidated the major factors and underlying molecular mechanisms affecting ASIC1a protein expression and membrane trafficking.

Antagonistic Effects of Tetramethylpyrazine on Hypoxic Respiratory Depression in Rats

Objective

Tetramethylpyrazine (TMP) is an alkaloid extracted from the root and stem of the traditional Chinese herbal medicine called Chuanxiong. The present study aims to study the effects of TMP on hypoxic respiratory depression in rats. Materials and methods. The effects of TMP on respiratory responses of rats induced by hypoxia were observed by diaphragm electromyogram (EMG) recording. The effects of TMP on the protein expression of FOS and acid sensing ion channel_1a (ASIC_1a) in the brainstem induced by hypoxia were investigated by immunohistochemistry.

Results

The respiration of rats was first excited and then depressed during hypoxia treatment, while TMP pretreatment could significantly antagonize the respiratory depression induced by hypoxia (P < 0.01). Hypoxia obviously induced the protein expression of FOS (P < 0.01) and ASIC_1a(P < 0.05) in the brainstem, which can be also significantly inhibited by TMP pretreatment.

Conclusions

TMP has protective effects on hypoxic respiratory depression, and the mechanisms might be concerned with its downregulation of FOS and ASIC_1a in the brainstem induced by hypoxia.

Histidine Residues Are Responsible for Bidirectional Effects of Zinc on Acid-Sensing Ion Channel 1a/3 Heteromeric Channels

Acid-sensing ion channel (ASIC) subunits 1a and 3 are highly expressed in central and peripheral sensory neurons, respectively. Endogenous biomolecule zinc plays a critical role in physiological and pathophysiological conditions. Here, we found that currents recorded from heterologously expressed ASIC1a/3 channels using the whole-cell patch-clamp technique were regulated by zinc with dual effects. Co-application of zinc dose-dependently potentiated both peak amplitude and the sustained component of heteromeric ASIC1a/3 currents; pretreatment with zinc between 3 to 100 µM exerted the same potentiation as co-application. However, pretreatment with zinc induced a significant inhibition of heteromeric ASIC1a/3 channels when zinc concentrations were over 250 µM. The potentiation of heteromeric ASIC1a/3 channels by zinc was pH dependent, as zinc shifted the pH dependence of ASIC1a/3 currents from a pH₅₀ of 6.54 to 6.77; whereas the inhibition of ASIC1a/3 currents by zinc was also pH dependent. Furthermore, we systematically mutated histidine residues in the extracellular domain of ASIC1a or ASIC3 and found that histidine residues 72 and 73 in both ASIC1a and ASIC3, and histidine residue 83 in the ASIC3 were responsible for bidirectional effects on heteromeric ASIC1a/3 channels by zinc. These findings suggest that histidine residues in the extracellular domain of heteromeric ASIC1a/3 channels are critical for zinc-mediated effects.

Sexual dimorphism following in vitro ischemia in the response to neurosteroids and mechanisms of injury

Background

Cerebral ischemic stroke is a significant cause of morbidity and mortality. Sex differences exist following stroke in terms of incidence, symptoms, outcomes and response to some treatments. Importantly, molecular mechanisms of injury, activated following ischemia may differ between the sexes and if so may account, at least in part, for sex differences seen in treatment response. Here we aimed to determine, using single-sex organotypic hippocampal slice cultures, whether the effectiveness of a potential treatment option, i.e. sex steroids, exhibited any sexual dimorphism and whether sex affected the mechanisms of apoptosis activated following ischemia.

Results

Following exposure to ischemia, male-derived tissue exhibited higher levels of cell death than female-derived tissue. Various sex steroid hormones, i.e. progesterone, allopregnanolone, and estradiol, were protective in terms of reducing the amount of cell death in male- and female-derived tissue whereas medoxyprogesterone acetate (MPA) was only protective in female-derived tissue. The protective effect of progesterone was abolished in the presence of finasteride, a 5α-reductase inhibitor, suggesting it was largely mediated via its conversion to allopregnanolone. To test the hypothesis that sex differences exist in the activation of specific elements of the apoptotic pathway activated following ischemia we administered Q-VD-OPH, a caspase inhibitor, or PJ34, an inhibitor of poly (ADP ribose) polymerase (PARP). Caspase inhibition was only effective, in terms of reducing cell death, in female-derived tissue, whereas PARP inhibition was only protective in male-derived tissue. However, in both sexes, the protective effects of progesterone and estradiol were not observed in the presence of either caspase or PARP inhibition.

Conclusions

Sex differences exist in both the amount of cell death produced and those elements of the cell death pathway activated following an ischemic insult. There are also some sex differences in the effectiveness of steroid hormones to provide neuroprotection following an ischemic insult—namely MPA was only protective in female-derived tissue. This adds further support to the notion sex is an important factor to consider when investigating future drug targets for CNS disorders, such as ischemic stroke.