Treatment of Acute Ischemic Stroke

Phosphodiesterase-5 Inhibitor Attenuates Anxious Phenotypes and Movement Disorder Induced by Mild Ischemic Stroke in Rats

Objective

Patients with mild ischemic stroke experience various sequela and residual symptoms, such as anxious behavior and deficits in movement. Few approaches have been proved to be effective and safe therapeutic approaches for patients with mild ischemic stroke by acute stroke. Sildenafil (SIL), a phosphodiesterase-5 inhibitor (PDE5i), is a known remedy for neurodegenerative disorders and vascular dementia through its angiogenesis and neurogenesis effects. In this study, we investigated the efficacy of PDE5i in the emotional and behavioral abnormalities in rats with mild ischemic stroke.

Methods

We divided the rats into four groups as follows (n=20, respectively) : group 1, naïve; group 2, middle cerebral artery occlusion (MCAo30); group 3, MCAo30+SIL-pre; and group 4, MCAo30+SIL-post. In the case of drug administration groups, single dose of PDE5i (sildenafil citrate, 20 mg/kg) was given at 30-minute before and after reperfusion of MCAo in rats. After surgery, we investigated and confirmed the therapeutic effect of sildenafil on histology, immunofluorescence, behavioral assays and neural oscillations.

Results

Sildenafil alleviated a neuronal loss and reduced the infarction volume. And results of behavior task and immunofluorescence shown possibility that anti-inflammation process and improve motor deficits sildenafil treatment after mild ischemic stroke. Furthermore, sildenafil treatment attenuated the alteration of theta-frequency rhythm in the CA1 region of the hippocampus, a known neural oscillatory marker for anxiety disorder in rodents, induced by mild ischemic stroke.

Conclusion

PDE5i as effective therapeutic agents for anxiety and movement disorders and provide robust preclinical evidence to support the development and use of PDE5i for the treatment of mild ischemic stroke residual disorders.

Novel Treatments for Transient Ischemic Attack and Acute Ischemic Stroke

The treatment of acute ischemic stroke is one of the most rapidly evolving areas in medicine. Like all ischemic vascular emergencies, the priority is reperfusion before irreversible infarction. The central nervous system is sensitive to brief periods of hypoperfusion, making stroke a golden hour diagnosis. Although the phrase "time is brain" is relevant today, emerging treatment strategies use more specific markers for consideration of reperfusion than time alone. Innovations in early stroke detection and individualized patient selection for reperfusion therapies have equipped the emergency medicine clinician with more opportunities to help stroke patients and minimize the impact of this disease.

The Dichotomous Role of Inflammation in the CNS: A Mitochondrial Point of View

Innate immune response is one of our primary defenses against pathogens infection, although, if dysregulated, it represents the leading cause of chronic tissue inflammation. This dualism is even more present in the central nervous system, where neuroinflammation is both important for the activation of reparatory mechanisms and, at the same time, leads to the release of detrimental factors that induce neurons loss. Key players in modulating the neuroinflammatory response are mitochondria. Indeed, they are responsible for a variety of cell mechanisms that control tissue homeostasis, such as autophagy, apoptosis, energy production, and also inflammation. Accordingly, it is widely recognized that mitochondria exert a pivotal role in the development of neurodegenerative diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, as well as in acute brain damage, such in ischemic stroke and epileptic seizures. In this review, we will describe the role of mitochondria molecular signaling in regulating neuroinflammation in central nervous system (CNS) diseases, by focusing on pattern recognition receptors (PRRs) signaling, reactive oxygen species (ROS) production, and mitophagy, giving a hint on the possible therapeutic approaches targeting mitochondrial pathways involved in inflammation.

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.

Ischemic stroke and mitochondria: mechanisms and targets

Stroke is one of the main causes of mortality and disability in most countries of the world. The only way of managing patients with ischemic stroke is the use of intravenous tissue plasminogen activator and endovascular thrombectomy. However, very few patients receive these treatments as the therapeutic time window is narrow after an ischemic stroke. The paucity of stroke management approaches can only be addressed by identifying new possible therapeutic targets. Mitochondria have been a rare target in the clinical management of stroke. Previous studies have only investigated the bioenergetics and apoptotic roles of this organelle; however, the mitochondrion is now considered as a key organelle that participates in many cellular and molecular functions. This review discusses the mitochondrial mechanisms in cerebral ischemia such as its role in reactive oxygen species (ROS) generation, apoptosis, and electron transport chain dysfunction. Understanding the mechanisms of mitochondria in neural cell death during ischemic stroke might help to design new therapeutic targets for ischemic stroke as well as other neurological diseases.

Possible involvement of PI3K/AKT/mTOR signaling pathway in the protective effect of selegiline (deprenyl) against memory impairment following ischemia reperfusion in rat

Short-term cerebral ischemia led to memory dysfunction. There is a pressing need to introduce effective agents to reduce complications of the ischemia. Involvement of PI3K/AKT/mTOR signaling pathway has been determined in the neuroprotective effect of various agents. Selegiline (deprenyl) possessed neuroprotective properties. In this study global ischemia/reperfusion was established in rats. Selegiline (5 mg/kg for 7 consecutive days) administrated via intraperitoneal route. Possible involvement of PI3K/AKT/mTOR signaling pathway was evaluated using qRT-PCR, immunohistochemistry and histophatologic evaluations in the hippocampus. Spatial memory was evaluated by morris water maze (MWM). Results showed that ischemia impaired the memory and ischemic rats spent more time to find hidden platform in the MWM. Ischemia significantly decreased levels of PI3K, AKT and mTOR in the hippocampus. Histopathologic assessment revealed that the percent of dark neurons significantly increased in the CA1 area of the hippocampus of ischemic rats. Selegiline improved the memory as ischemic rats spent fewer time to find hidden platform in the MWM. Findings showed that selegiline increased the level and expression of PI3K, AKT and mTOR as well as decreased the proportion of dark neurons in the CA1 area of the pyramidal layer of the hippocampus. We concluded that selegiline, partially at least, through increases the expression of PI3K, AKT and mTOR as well as decreases the percent of dark neurons in the hippocampus could improve the memory impairment following the ischemia in rats.

Diallyl Trisulfide Protects Rat Brain Tissue against the Damage Induced by Ischemia-Reperfusion through the Nrf2 Pathway

Stroke is a public health problem due to its high mortality and disability rates; despite these, the pharmacological treatments are limited. Oxidative stress plays an important role in cerebral damage in stroke and the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) confers protection against oxidative stress. Different compounds, such as diallyl trisulfide (DATS), have the ability to activate Nrf2. DATS protects against the damage induced in oxygen-glucose deprivation in neuronal cells; however, in in vivo models of cerebral ischemia, DATS has not been evaluated. Male Wistar rats were subjected to 1 h of ischemia and seven days of reperfusion and the protective effect of DATS was evaluated. DATS administration (IR + DATS) decreased the infarct area and brain damage in the striatum and cortex; improved neurological function; decreased malondialdehyde and metalloproteinase-9 levels; increased Nrf2 activation in the cortex and the expression of superoxide dismutase 1 (SOD1) in the nucleus, SOD2 and glutathione S-transferase (GST) in the striatum and cortex; and increased the activity of catalase (CAT) in the striatum and glutathione peroxidase (GPx) in the cortex. Our results demonstrate the protective effect of DATS in an in vivo model of cerebral ischemia that involves Nrf2 activation.

Silencing of SNHG12 Enhanced the Effectiveness of MSCs in Alleviating Ischemia/Reperfusion Injuries via the PI3K/AKT/mTOR Signaling Pathway

Previous studies have reported that the long non-coding RNA SNHG12 (lncRNA SNHG12) plays a critical role in regulating the function of mesenchymal stem cells (MSCs); however, the effect of lncRNA SNHG12 on MSCs in injured brain tissue has rarely been reported. We studied the effect and mechanism of lncRNA SNHG12-modified mesenchymal stem cells (MSCs) in treating brain injuries caused by ischemia/reperfusion (I/R). I/R treated rat brain microvascular endothelial cells (BMECs) were co-cultured with MSCs or I/R pretreated MSCs. Next, BMEC proliferation was detected by using CCK-8 and EdU assays, and cell apoptosis was determined by using flow cytometry and the Hoechst staining method. Autophagy of BMECs was determined using immunofluorescence and expression of associated pathway proteins were measured by western blotting. Moreover, BMEC proliferation, apoptosis, and autophagy were also determined after the BMECs had been co-cultured with shSNHG12-MSCs. In addition, a rat model of middle cerebral artery occlusion (MCAO) was used to further confirm the findings obtained with cells. I/R treatment significantly decreased the proliferation of BMECs, but increased their levels of SNHG12 expression, apoptosis, and autophagy. However, co-culturing of BMECs with MSCs markedly alleviated the reduction in BMEC proliferation and the increases in BMEC apoptosis and autophagy, as well as the phosphorylation of PI3K, AKT, and mTOR proteins in BMECs that had been induced by I/R. Furthermore, shSNHG12 remarkably enhanced the effects of MSCs. In addition, an injection MSCs reduced the infarct areas and rates of cell apoptosis in MACO rats, and reduced the phosphorylation of PI3K, AKT, and mTOR proteins. Moreover, shSNHG12 enhanced the ameliorative effect of MSCs in treating brain injuries in the MACO rats. In conclusion, silencing of SNHG12 enhanced the effects of MSCs in reducing apoptosis and autophagy of BMECs by activating the PI3K/AKT/mTOR signaling pathway.

Hemicraniectomy for Malignant Middle Cerebral Artery Syndrome: A Review of Functional Outcomes in Two High-Volume Stroke Centers

BACKGROUND AND PURPOSE

Despite recent landmark randomized controlled trials showing significant benefits for hemicraniectomy (HCT) compared with medical therapy (MT) in patients with malignant middle cerebral artery infarction (MMCAI), HCT rates have not substantially increased in the United States. We sought to evaluate early outcomes in patients with MMCAI who were treated with HCT (cases) in comparison to patients treated with MT due to the perception of procedural futility by families (controls).

METHODS

We retrospectively evaluated consecutive patients with acute MMCAI treated in 2 tertiary care centers during a 7-year period. Pretreatment National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) at 3 months were documented. Functional independence (FI) and survival without severe disability (SWSD) were defined as mRS of 0-2 and 0-4, respectively.

RESULTS

A total of 66 patients (37 cases and 29 controls) fulfilled the study inclusion criteria (mean age 59 ± 15 years, 52% men, median admission NIHSS score: 19 points [interquartile range {IQR}: 16-22]). Cases were younger (51 ± 11 versus 68 ± 13 years; P < .001) and tended to have lower median admission NIHSS than controls (18 [IQR:16-20] versus 20 [IQR:18-23]; P = .072). The rates of FI and SWSD at 3 months were higher in cases than controls (16% versus 0% [P = .031] and 62% versus 0% [P < .001]), while 3-month mortality was lower (24% versus 77%; P < .001). Multivariable Cox regression analyses adjusting for potential confounders identified HCT as the most important predictor of lower risk of 3-month mortality (hazard ratio: .02, 95% confidence interval: .01-0.10; P < .001).

CONCLUSIONS

HCT is a critical and effective therapy for patients with MMCAI but cannot provide a guarantee of functional recovery.

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

There have been reports that activation of Akt may provide neuroprotection after cerebral ischemia-reperfusion. We tested the hypothesis that activation of Akt would decrease infarct size and improve microregional O₂ supply/consumption balance after cerebral ischemia-reperfusion. This hypothesis was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1 h and reperfusion for 2 h with or without SC-79 (Akt activator, 0.05 mg/kg, three doses). Regional cerebral blood flow was determined using a C¹⁴-iodoantipyrine autoradiographic technique. Regional small vessel (20-60 μm diameter) arterial and venous oxygen saturations were determined microspectrophotometrically. Akt phosphorylation was determined by Western blot. There were no significant hemodynamic or blood gas differences between groups. The control ischemic-reperfused cortex had a similar O₂ consumption, but lower blood flow and higher O₂ extraction compared 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 (42 of 80 veins with O₂ saturation below 50%). SC-79 did not significantly affect cerebral O₂ consumption, but significantly improved O₂ supply/consumption balance in the reperfused area (18 of 80 veins with O₂ saturation below 50%). This was associated with a reduced cortical infarct size (13.3 ± 0.5% control vs 6.7 ± 0.3% SC-79). In control, Akt phosphorylation was elevated at 2 h after ischemia. With SC-79, Akt was activated at 15 min but not at 2 h in the ischemic reperfused area. These results suggest that early Akt activation is important for not only cell survival, but also for the control of local oxygen balance after cerebral ischemia-reperfusion.