Multi-Target Neuroprotection of Thiazolidinediones on Alzheimer's Disease via Neuroinflammation and Ferroptosis.

Alzheimer's disease (AD) is the main cause of dementia in older age. The prevalence of AD is growing worldwide, causing a tremendous burden to societies and families. Due to the complexity of its pathogenesis, the current treatment of AD is not satisfactory, and drugs acting on a single target may not prevent AD progression. This review summarizes the multi-target pharmacological effects of thiazolidinediones (TZDs) on AD. TZDs act as peroxisome proliferator-activated receptor gamma (PPARγ) agonists and long-chain acyl-CoA synthetase family member 4 (ACSL4) inhibitors. TZDs ameliorated neuroinflammation and ferroptosis in preclinical models of AD. Here, we discussed recent findings from clinical trials of pioglitazone in the treatment of AD, ischemic stroke, and atherosclerosis. We also dissected the major limitations in the clinical application of pioglitazone and explained the potential benefit of pioglitazone in AD. We recommend the use of pioglitazone to prevent cognitive decline and lower AD risk in a specific group of patients.

Neuroprotective Effects of Activin A against Cerebral Ischemia/Reperfusion Injury in Mice by Enhancing Nrf2 Expression to Attenuate Neuronal Ferroptosis.

Activin A (Act A) is a member of the transforming growth factor-ß (TGF-ß) superfamily and can protect against ischemic cerebral injury. Ferroptosis, a newly discovered type of programmed cell death, contributes to the pathogenesis of cerebral ischemia-reperfusion injury (CIRI). However, little is known on whether Act A can modulate neuronal ferroptosis to protect against CIRI in a mouse model of middle cerebral artery occlusion (MCAO) and an HT22 cell model of oxygen-glucose deprivation/reoxygenation (OGD/R). The results indicated that Act A treatment relieved CIRI by improving neurological deficits and reducing the infarct volume in mice. MCAO stimulated iron accumulation and malondialdehyde formation and upregulated ACSL4 expression but downregulated GPX4 expression, a hallmark of ferroptosis in the brain of mice. Treatment with Act A significantly mitigated MCAO-triggered ferroptosis in the brain of mice. Furthermore, Act A treatment enhanced the MCAO-upregulated nuclear factor erythroid-2-related factor 2 (Nrf2) expression in the brains of mice. Similar results were observed in HT22 cells following OGD/R and pretreatment with Act A. The neuronal protective effect of Act A in HT22 cells was attenuated by treatment with ML385, an Nrf2 inhibitor. To conclude, Act A attenuated CIRI by enhancing Nrf2 expression and inhibiting neuronal ferroptosis.

Enriched environment remedies cognitive dysfunctions and synaptic plasticity through NMDAR-Ca2+-Activin A circuit in chronic cerebral hypoperfusion rats.

Chronic cerebral ischemia (CCI) is one of the critical factors in the occurrence and development of vascular cognitive impairment (VCI). Apoptosis of nerve cells and changes in synaptic activity after CCI are the key factors to induce VCI. Synaptic stimulation up-regulates intraneuronal Ca2+ level through N-methyl-D-aspartic acid receptor (NMDAR) via induction of the activity-regulated inhibitor of death (AID) expression to produce active-dependent neuroprotection. Moreover, the regulation of synaptic plasticity could improve cognition and learning ability. Activin A (ActA), an exocrine protein of AID, can promote NMDAR phosphorylation and participate in the regulation of synaptic plasticity. We previously found that exogenous ActA can improve the cognitive function of rats with chronic cerebral ischemia and enhance the oxygenated glucose deprivation of intracellular Ca2+ level. In addition to NMDAR, the Wnt pathway is critical in the positive regulation of LTP through activation or inhibition. It plays an essential role in synaptic transmission and activity-dependent synaptic plasticity. The enriched environment can increase ActA expression during CCI injury. We speculated that the NMDAR-Ca2+-ActA signal pathway has a loop-acting mode, and the environmental enrichment could improve chronic cerebral ischemia cognitive impairment via NMDAR-Ca2+-ActA, Wnt/ß-catenin pathway is involved in this process. For the hypothesis verification, this study intends to establish chronic cerebral hypoperfusion (CCH) rat model, explore the improvement effect of enriched environment on VCI, detect the changes in plasticity of synaptic morphology and investigate the regulatory mechanism NMDAR-Ca2+-ActA-Wnt/ß-catenin signaling loop, providing a therapeutic method for the treatment of CCH.

Effects of Microglial Activation and Polarization on Brain Injury After Stroke.

Stroke is one of the most common causes of death worldwide. The subsequent development of neuroinflammation and brain edema dramatically increases the risks associated with stroke, leading to a substantial increase in mortality. Although considerable progress has been made in improving cerebral perfusion in the acute phase of stroke, effective treatment options for the subacute and chronic phases associated with cerebral infarction are limited. Microglia, the innate immune cells of the central nervous system (CNS), can be activated and polarized to take on different phenotypes in response to stimulations associated with stroke, including pro-inflammatory and anti-inflammatory phenotypes, which affect the prognosis of stroke. Therefore, investigation of the activation and polarizing mechanisms of microglia plays a critical role in treating stroke. The aim of this article was to investigate the significance of microglial phenotype regulation in stroke treatment by summarizing the activation, polarizing mechanisms, and general microglia characteristics.

Betulinic Acid Ameliorates Cerebral Injury in Middle Cerebral Artery Occlusion Rats through Regulating Autophagy.

Cerebral ischemic stroke (CIS) is an acute cerebrovascular disease that is caused by the sudden rupture of blood vessels inside the brain and the intervention of reperfusion to the brain, resulting in severe cerebral injury. Autophagy has been reported to be involved in the occurrence and progression of CIS. Betulinic acid (BA) is a pentacyclic triterpene acid mainly extracted from birch bark. Studies have shown the neuroprotective effects of BA. Here, the effect and mechanism of BA on ischemia-reperfusion induced cerebral injury was explored using a CIS model in vivo via 1 h middle cerebral artery occlusion (MCAO) and 24 h reperfusion in rats and in vitro via oxygen-glucose deprivation/reperfusion (OGD/R) of PC12 cells, respectively. We found that BA not only reduced cerebral injury by reducing oxidative stress but also activated the SIRT1/FoxO1 pathway to suppress autophagy and improve cerebral injury in MCAO rats. These results provide a basis for the potential clinical application of BA.

Resveratrol Treatment Is Associated with Lipid Regulation and Inhibition of Lipoprotein-Associated Phospholipase A2 (Lp-PLA2) in Rabbits Fed a High-Fat Diet.

The effects of resveratrol on various conditions have been widely studied previously. This paper aimed to investigate the influence of resveratrol on atherosclerosis (AS). Twenty-four New Zealand male rabbits were randomly and equally assigned to the normal diet group (NDG), fat diet group (FDG), and fat diet with resveratrol group (80 mg/kg/d, RFG). Biochemical indicators from blood samples were analyzed at baseline and 3 months to investigate the effects of resveratrol on blood lipid, lipoprotein-associated phospholipase A2 (Lp-PLA2), liver, and renal function. The indicators including alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatinine (CREA), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and Lp-PLA2. At 3 months, arteries were stained with hematoxylin and eosin to study the influence of resveratrol on the aortic intima, smooth muscle layer, and the intima/media ratio. Comparisons of weight, ALT, AST, CREA, TG, TC, HDL-C, LDL-C, and Lp-PLA2 among the three groups showed no significant difference at baseline. However, at the end of 3 months, significant differences were observed in AST, CREA, TC, HDL-C, LDL-C, and Lp-PLA2 between the three groups (P < 0.05). In pairwise comparison, CREA, TC, LDL-C, and Lp-PLA2 had significant differences between any two groups (P < 0.05). In addition, there were significant differences in the AST and HDL-C levels between RFG and NDG groups (P < 0.05). Meanwhile, the HDL-C levels were also significantly different between the FDG and NDG groups (P < 0.01). The histologic analysis also showed that the thickness of the aortic intima and the ratio of the intima and aortic tunica media (P < 0.05) significantly decreased in RFG compared to FDG. Resveratrol may have an antiatherosclerosis effect on a rabbit model of AS.

Comparison of the Diagnostic Performances of Ultrasound, High-Resolution Magnetic Resonance Imaging, and Positron Emission Tomography/Computed Tomography in a Rabbit Carotid Vulnerable Plaque Atherosclerosis Model.

OBJECTIVES: Our study aimed to evaluate the diagnostic performances of 3 routine examination methods for cerebrovascular disease in a rabbit carotid artery atherosclerosis model. METHODS: A total of 12 New Zealand rabbits were included: 4 in a control group and 8 in an experimental group. A clinically relevant atherosclerosis rabbit model was induced by left common carotid artery ligation and a 12-week high-fat diet. Atherosclerosis was further confirmed by a histopathologic analysis. Then carotid ultrasound (US) imaging, high-resolution magnetic resonance imaging (HRMRI), and positron emission tomography (PET)/computed tomography (CT) were performed on this model to evaluate the diagnostic performances. RESULTS: Carotid US showed plaque formation in the left common carotid artery and little plaque in the right common carotid artery in the experimental group. In addition, HRMRI showed stenosis formation in the left common carotid artery in the experimental group. At the horizontal level, plaques were found in the left common carotid artery, and no plaques were found in the right common carotid artery in the experimental group. Also, PET/CT showed local hypermetabolism and vulnerable plaques in the left common carotid artery of the experimental group, whereas no hypermetabolism was found in the right common carotid artery of the experimental group. Moreover, the soft plaques detected by carotid US were different from the vulnerable plaques detected by PET/CT. The unstable plaques on HRMRI were the same as the hypermetabolic vulnerable plaques on PET/CT. CONCLUSIONS: High-resolution MRI is recommended for the evaluation of neck and intracranial vascular stenosis and plaque properties in patients with stroke.

Serotonin-norepinephrine reuptake inhibitors for the prevention of migraine and vestibular migraine: a systematic review and meta-analysis.

BACKGROUND AND OBJECTIVES: The role of serotonin-norepinephrine reuptake inhibitors (SNRIs) in migraine prophylaxis has not been completely established. Current treatments for vestibular migraine (VM) are based on scarce evidence. We aimed to perform an updated review focusing on the efficacy and tolerability of SNRIs for migraine and VM prevention. METHODS: We searched the PubMed, Web of Science, and Cochrane Library databases for relevant studies. The primary outcome was migraine frequency. In the case of VM, the Dizziness Handicap Inventory (DHI) scores and Vertigo Severity Scores (VSSs) were extracted. RESULTS: Six randomized controlled trials involving 418 patients were analyzed. Patients receiving SNRIs had fewer migraine days than those receiving a placebo (standardized mean difference -0.38, 95% CI -0.76 to -0.01, p=0.04). The effects of SNRIs and other active drugs were comparable. In patients with VM, venlafaxine had a significant advantage over other active drugs in decreasing the VSS (weighted mean difference (MD) -1.45, 95% CI -2.11 to -0.78, p<0.0001) and the emotional domain score of the DHI (MD -2.64, 95% CI -4.97 to -0.31, p=0.03). We found no significant difference in the rate of withdrawals due to any reason or withdrawals due to side effects between SNRIs and active drugs and between SNRIs and a placebo. CONCLUSIONS: SNRIs were clinically safe and effective for migraine and VM prophylaxis, were better than a placebo, and not inferior to other active drugs. SNRIs may be a preferable choice for patients with VM with psychiatric disorders.

Mechanical Thrombectomy for Posterior Circulation Occlusion: A Comparison of Outcomes with the Anterior Circulation Occlusion - A Meta-Analysis.

AIM: There is no randomized controlled trial to compare the effectiveness and safety of mechanical thrombectomy (MT) to intravenous thrombolysis in patients with posterior circulation occlusion (PCO). Hence, we firstly performed a meta-analysis to investigate the outcomes of MT in PCO and then compared these outcomes to anterior circulation occlusion (ACO) to provide fundamental data to further studies. METHODS: We searched the PubMed, EMBASE, and Cochrane Library from dates of inception to June 2019 for relevant studies. Outcomes including functional independence at 90 days, successful recanalization, mortality, symptomatic intracranial hemorrhage (sICH), and futile recanalization were extracted. RESULTS: Seven studies involving 474 patients with PCO thrombectomy were analyzed. There was a lower rate of functional independence at 90 days and a higher rate of mortality after thrombectomy in PCO versus ACO (odds ratios (OR) 0.72; 95% confidence interval (CI) 0.57-0.90; OR 2.03; 95% CI 1.30-3.18). Recanalization rates were comparable (OR 1.01; 95% CI 0.62-1.65), but a higher futile recanalization rate was found in basilar artery occlusion (BAO) (OR 1.75; 95% CI 1.30-2.37). There was a lower rate of sICH in MT for patients with PCO versus ACO (OR 0.54; 95% CI 0.29-0.99). CONCLUSIONS: We found that the outcomes of MT for patients with PCO were poorer than with ACO. On the other hand, MT appears to have lower rates of sICH and to increase successful recanalization. Given the high recanalization rate, MT may serve as an adjunct to standard treatment. The key point to improve outcomes is recognizing reliable factors associated with futile recanalization and optimizing the results of MT. But in view of the different characteristics of posterior circulation stroke and anterior circulation stroke, the results are far from robust.

Prognostic utility of serum 25-hydroxyvitamin D in patients with stroke: a meta-analysis.

BACKGROUND: Conflicting findings have been reported on the prognostic significance of serum 25-hydroxyvitamin D level in patients with stroke. The objective of this meta-analysis was to evaluate the prognostic utility of serum 25-hydroxyvitamin D in stroke patients. METHODS: PubMed and Embase databases were systematically searched for potentially eligible studies until October 16, 2019. Observational studies investigating the association between serum 25-hydroxyvitamin D level and prognosis of patients with stroke were eligible. Multivariable adjusted risk ratios (RR) with 95% confidence intervals (CI) of poor functional outcome, all-cause mortality, and recurrence of stroke were pooled with the lowest versus the highest category of 25-hydroxyvitamin D level. RESULTS: Eleven articles (ten studies) involving 6845 stroke patients satisfied our predefined inclusion criteria. Lower serum 25-hydroxyvitamin D level was associated with an increased risk of poor functional outcome (RR 1.86; 95% CI 1.16-2.98), all-cause mortality (RR 3.56; 95% CI 1.54-8.25), and recurrence of stroke (RR 5.49; 95% CI 2.69-11.23). Sensitivity analysis further confirmed the above findings. CONCLUSIONS: Lower serum 25-hydroxyvitamin D level is significantly associated with poorer prognosis in stroke patients. Future prospective studies are warranted to verify the prognostic role and to examine the association in different subtypes of stroke.

Resveratrol Activates Autophagy via the AKT/mTOR Signaling Pathway to Improve Cognitive Dysfunction in Rats With Chronic Cerebral Hypoperfusion.

Chronic cerebral hypoperfusion (CCH) is a main cause of vascular dementia and is also an etiological factor of neurological diseases and mental disorders. However, few treatments are available for CCH, and new medications are needed. In the present study, we employed a rat model of CCH that was based on bilateral common carotid artery occlusion and investigated the therapeutic effects of resveratrol and its detailed mechanism of action. We evaluated neurological deficit scores and performed the Morris water maze test, hematoxylin and eosin staining, TUNEL staining, enzyme-linked immunosorbent assays, and Western blot. Resveratrol reduced neurological deficit scores in CCH rats and reduced pathological damage in the frontal cortex and hippocampus. Resveratrol activated autophagy and inhibited the expression of AKT/mechanistic target of rapamycin (mTOR) signaling pathway-related proteins. Treatment with a phosphoinositide-3 kinase inhibitor reversed the protective effect of resveratrol. These findings suggest that resveratrol improves cognitive function in a rat model of CCH and reduces oxidative stress-induced neuronal damage in the frontal cortex and hippocampus by activating autophagy and inhibiting neuronal apoptosis. These effects may be regulated by the AKT/mTOR signaling pathway.

Proteomic analyses identify a potential mechanism by which extracellular vesicles aggravate ischemic stroke.

AIMS: Extracellular vesicles (EVs) are vital for information exchange between donor and recipient cells. When cells are stressed (e.g., by oxygen glucose deprivation, OGD), the complex information carried by the EVs is altered by the donor cells. Here, we aimed to analyze the proteomic differences between EVs derived from OGD-damaged cells and EVs derived from undamaged cells to explore the potential mechanisms by which EVs aggravate ischemic stroke (IS). MAIN METHODS: EVs released by rat adrenal gland PC12 cells subjected to 0, 3, 6, or 12 h of OGD were isolated. The proteins from the EVs secreted by each of the OGD groups were profiled using liquid chromatography-tandem mass spectroscopy (LC-MS/MS). We predicted the functions, pathways, and interactions of the differentially expressed proteins using Gene Ontology (GO), KEGG pathways, and STRING. We used parallel reaction monitoring (PRM) to validate our results. KEY FINDINGS: We identified several differentially expressed proteins in the OGD groups as compared to the controls: 170 proteins in the 3 h OGD EVs, 44 proteins in the 6 h OGD EVs, and 77 proteins in the 12 h OGD EVs (fold-change ≥1.5; p ≤ 0.05). These proteins were associated with oxidative stress, carbohydrate metabolism, protein synthesis and degradation, and thrombosis. SIGNIFICANCE: We identified changes in protein expression in the EVs secreted by OGD-damaged cells, highlighting potential mechanisms by which EVs aggravate IS. Our results also suggested potential protein targets, which may be useful for the prevention and treatment of IS.

Knockdown of microRNA-17-5p Enhances the Neuroprotective Effect of Act A/Smads Signal Loop After Ischemic Injury.

Cerebral ischemic injury is a leading cause of human mortality and disability, seriously threatening human health in the world. Activin A (Act A), as a well-known neuroprotective factor, could alleviate ischemic brain injury mainly through Act A/Smads signaling. In our previous study, a noncanonical Act A/Smads signal loop with self-amplifying property was found, which strengthened the neuroprotective effect of Act A. However, this neuroprotective effect was limited due to the self-limiting behavior mediated by Smad anchor for receptor activation (SARA) protein. It was reported that microRNA-17-5p (miR-17-5p) could suppress the expression of SARA in esophageal squamous cell carcinoma. Thus we proposed that knockdown of miR-17-5p could strengthen the neuroprotective effect of Act A/Smads signal loop through SARA. To testify this hypothesis, oxygen-glucose deficiency (OGD) was introduced to highly differentiated rattus pheochromocytoma (PC12) cells. After the transfection of miR-17-5p mimic or inhibitor, the activity of Act A signal loop was quantified by the expression of phosphorylated Smad3. The results showed that suppression of miR-17-5p up-regulated the expression of SARA protein, which prolonged and strengthened the activity of Act A signaling through increased phosphorylation of downstream Smad3 and accumulation of Act A ligand. Further luciferase assay confirmed that SARA was a direct target gene of miR-17-5p. These practical discoveries will bring new insight on the endogenous neuroprotective effects of Act A signal loop by interfering a novel target: miR-17-5p.

Expression changes of the notch signaling pathway of PC12 cells after oxygen glucose deprivation.

Ischemic stroke is caused by obstructed blood supply to the brain. It is a common as well as a serious health problem worldwide, which is often linked to disability and mortality. Here we studied, under the conditions of oxygen glucose deprivation (OGD), the expression of Notch signaling pathway proteins in PC12 cells. PC12 cells were stimulated and converted into neuron-like cells by nerve growth factor. Exposure to OGD was used as an in vitro model of cerebral hypoxia-ischemia. Our findings demonstrate that, after 3 h of OGD exposure, the expression of Notch1, Hes1 and Hes5 significantly increased, on both mRNA and protein levels. This effect gradually reduced with continuous OGD treatment, but the expression levels of these three genes remained higher, compared to untreated controls, even after 24 h of OGD exposure. Our results suggest that OGD exposure up-regulates the expression of Notch1, Hes1 and Hes5, which are important participants in Notch signaling pathway. Since their regulatory roles appear to change dynamically with the extension of OGD, the activation of the Notch pathway may play an important role in cerebral ischemic injury.

Neuroprotective effects of Activin A on endoplasmic reticulum stress-mediated apoptotic and autophagic PC12 cell death.

Activin A, a member of the transforming growth factor-beta superfamily, plays a neuroprotective role in multiple neurological diseases. Endoplasmic reticulum (ER) stress-mediated apoptotic and autophagic cell death is implicated in a wide range of diseases, including cerebral ischemia and neurodegenerative diseases. Thapsigargin was used to induce PC12 cell death, and Activin A was used for intervention. Our results showed that Activin A significantly inhibited morphological changes in thapsigargin-induced apoptotic cells, and the expression of apoptosis-associated proteins [cleaved-caspase-12, C/EBP homologous protein (CHOP) and cleaved-caspase-3] and biomarkers of autophagy (Beclin-1 and light chain 3), and downregulated the expression of thapsigargin-induced ER stress-associated proteins [inositol requiring enzyme-1 (IRE1), tumor necrosis factor receptor-associated factor 2 (TRAF2), apoptosis signal-regulating kinase 1 (ASK1), c-Jun N-terminal kinase (JNK) and p38]. The inhibition of thapsigargin-induced cell death was concentration-dependent. These findings suggest that administration of Activin A protects PC12 cells against ER stress-mediated apoptotic and autophagic cell death by inhibiting the activation of the IRE1-TRAF2-ASK1-JNK/p38 cascade.

Activin A/Smads signaling pathway negatively regulates Oxygen Glucose Deprivation-induced autophagy via suppression of JNK and p38 MAPK pathways in neuronal PC12 cells.

Activin A (Act A), a member of the transforming growth factor-beta (TGF-ß), reduces neuronal apoptosis during cerebral ischemia through Act A/Smads signaling pathway. However, little is known about the effect of Act A/Smads pathway on autophagy in neurons. Here, we found that oxygen-glucose deprivation (OGD)-induced autophagy was suppressed by exogenous Act A in a concentration-dependent manner and enhanced by Act A/Smads pathway inhibitor (ActRIIA-Ab) in neuronal PC12 cells. These results indicate that Act A/Smads pathway negatively regulates autophagy in OGD-treated PC12 cells. In addition, we found that c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase pathways are involved in the OGD-induced autophagy. The activation of JNK and p38 MAPK pathways in OGD-treated PC12 cells was suppressed by exogenous Act A and enhanced by ActRIIA-Ab. Together, our results suggest that Act A/Smads signaling pathway negatively regulates OGD-induced autophagy via suppression of JNK and p38 MAPK pathways in neuronal PC12 cells.

Noncanonical Activin A Signaling in PC12 Cells: A Self-Limiting Feedback Loop.

Activin A (Act A), a member of transforming growth factor-ß superfamily, plays a neuroprotective role in multiple neurological diseases through Act A/Smads signal activation. Traditionally, the up-regulation of Act A gene and extracellular Act A accumulation show the signal activation as a linear pathway. However, one of our discoveries indicated that Act A could lead a loop signaling in ischemic injury. To clarify the characteristic of this loop signaling in a non-pathological state, we up-regulated the expression of Act A, monitored extracellular Act A accumulation and examined the activity of Act A signaling, which was quantified by the expression of phosphorylated Smad3 and the fluorescence intensity of Smad4 in nuclei. The results demonstrated a noncanonical Act A signal loop with self-amplifying property in PC12 cells. Further, it showed self-limiting behavior due to temporary activation and spontaneous attenuation. This periodic behavior of Act A signal loop was found to be regulated by the level of Smad anchor for receptor activation (SARA). Moreover, increased activity of Act A signal loop could promote PC12 cell proliferation and enhance the survival rate of cells to Oxygen-Glucose Deprivation. These practical discoveries will bring new insight on the functional outcome of Act A signaling in neurological diseases by the further understanding: loop signaling.

Effects of the combination of methylprednisolone with aminoguanidine on functional recovery in rats following spinal cord injury.

Methylprednisolone (MP), a synthetic glucocorticoid, has been widely used as a standard therapeutic agent for the treatment of spinal cord injury (SCI). The combination of MP and other pharmacological agents aimed at enhancing functional recovery is desirable as the beneficial effects of MP are controversial, due to a variety of side-effects. Aminoguanidine (AG), a small water-soluble compound, is potentially useful in the treatment of acute SCI. The aim of the present study was to determine the effects of MP and AG, administered in combination, following SCI in adult rats. In rats with SCI, the combination therapy group treated with AG (75 mg/kg) and MP (0.75 mg/kg) exhibited significantly reduced levels of cytokine expression and cell apoptosis compared with those in the control group. In addition, the data demonstrated that the combination therapy significantly enhanced the recovery of limb function. These data clearly suggest that treatment with a combination of MP and AG represents a promising strategy of clinically applicable pharmacological therapy for the rapid initiation of neuroprotection following SCI.

Endogenous protection derived from activin A/Smads transduction loop stimulated via ischemic injury in PC12 cells.

Activin A (ActA), a member of transforming growth factor-beta (TGF-b) super- family, affects many cellular processes, including ischemic stroke. Though the neuroprotective effects of exogenous ActA on oxygen-glucose deprivation (OGD) injury have already been reported by us, the endogenous role of ActA remains poorly understood. To further define the role and mechanism of endogenous ActA and its signaling in response to acute ischemic damage, we used an OGD model in PC12 cells to simulate ischemic injury on neurons in vitro. Cells were pre-treated by monoclonal antibody against activin receptor type IIA (ActRII-Ab). We found that ActRII-Ab augments ischemic injury in PC12 cells. Further, the extracellular secretion of ActA as well as phosphorylation of smad3 in PC12 cells was also up-regulated by OGD, but suppressed by ActRII-Ab. Taken together, our results show that ActRII-Ab may augment ischemic injury via blocking of transmembrane signal transduction of ActA, which confirmed the existence of endogenous neuroprotective effects derived from the ActA/Smads pathway. ActRIIA plays an important role in transferring neuronal protective signals inside. It is highly possible that ActA transmembrance signaling is a part of the positive feed-back loop for extracellular ActA secretion.