Neuroprotective effects of erythromycin on cerebral ischemia reperfusion-injury and cell viability after oxygen-glucose deprivation in cultured neuronal cells

Immunomodulatory Mechanism and Potential Therapies for Perinatal Hypoxic-Ischemic Brain Damage

Hypoxia-ischemia (HI) is one of the most common causes of death and disability in neonates. Currently, the only available licensed treatment for perinatal HI is hypothermia. However, it alone is not sufficient to prevent the brain injuries and/or neurological dysfunction related to HI. Perinatal HI can activate the immune system and trigger the peripheral and central responses which involve the immune cell activation, increase in production of immune mediators and release of reactive oxygen species. There is mounting evidence indicating that regulation of immune response can effectively rescue the outcomes of brain injury in experimental perinatal HI models such as Rice-Vannucci model of newborn hypoxic-ischemic brain damage (HIBD), local transient cerebral ischemia and reperfusion model, perinatal asphyxia model, and intrauterine hypoxia model. This review summarizes the many studies about immunomodulatory mechanisms and therapies for HI. It highlights the important actions of some widely documented therapeutic agents for effective intervening of HI related brain damage, namely, HIBD, such as EPO, FTY720, Minocycline, Gastrodin, Breviscapine, Milkvetch etc. In this connection, it has been reported that the ameboid microglial cells featured prominently in the perinatal brain represent the key immune cells involved in HIBD. To this end, drugs, chemical agents and herbal compounds which have the properties to suppress microglia activation have recently been extensively explored and identified as potential therapeutic agents or strategies for amelioration of neonatal HIBD.

Sodium Tanshinone IIA Silate Exerts Microcirculation Protective Effects against Spinal Cord Injury In Vitro and In Vivo

Spinal cord microcirculation involves functioning endothelial cells at the blood spinal cord barrier (BSCB) and maintains normal functioning of spinal cord neurons, axons, and glial cells. Protection of both the function and integrity of endothelial cells as well as the prevention of BSCB disruption may be a strong strategy for the treatment of spinal cord injury (SCI) cases. Sodium Tanshinone IIA silate (STS) is used for the treatment of coronary heart disease and improves microcirculation. Whether STS exhibits protective effects for SCI microcirculation is not yet clear. The purpose of this study is to investigate the protective effects of STS on oxygen-glucose deprivation- (OGD-) induced injury of spinal cord endothelial cells (SCMECs) in vitro and to explore effects on BSCB and neurovascular protection in vivo. SCMECs were treated with various concentrations of STS (1 μM, 3 μM, and 10 μM) for 24 h with or without OGD-induction. Cell viability, tube formation, migration, and expression of Notch signaling pathway components were evaluated. Histopathological evaluation (H&E), Nissl staining, BSCB permeability, and the expression levels of von Willebrand Factor (vWF), CD31, NeuN, and Notch signaling pathway components were analyzed. STS was found to improve SCMEC functions and reduce inflammatory mediators after OGD. STS also relieved histopathological damage, increased zonula occludens-1 (ZO-1), inhibited BSCB permeability, rescued microvessels, protected motor neuromas, and improved functional recovery in a SCI model. Moreover, we uncovered that the Notch signaling pathway plays an important role during these processes. These results indicated that STS protects microcirculation in SCI, which may be used as a therapeutic strategy for SCI in the future.

Ischemia/Reperfusion Injury Revisited: An Overview of the Latest Pharmacological Strategies

Ischemia/reperfusion injury (IRI) permeates a variety of diseases and is a ubiquitous concern in every transplantation proceeding, from whole organs to modest grafts. Given its significance, efforts to evade the damaging effects of both ischemia and reperfusion are abundant in the literature and they consist of several strategies, such as applying pre-ischemic conditioning protocols, improving protection from preservation solutions, thus providing extended cold ischemia time and so on. In this review, we describe many of the latest pharmacological approaches that have been proven effective against IRI, while also revisiting well-established concepts and presenting recent pathophysiological findings in this ever-expanding field. A plethora of promising protocols has emerged in the last few years. They have been showing exciting results regarding protection against IRI by employing drugs that engage several strategies, such as modulating cell-surviving pathways, evading oxidative damage, physically protecting cell membrane integrity, and enhancing cell energetics.

Upregulated microRNA-31 inhibits oxidative stress-induced neuronal injury through the JAK/STAT3 pathway by binding to PKD1 in mice with ischemic stroke

Ischemic stroke (IS), which is characterized by high morbidity, disability, and mortality, is recognized as a major cerebrovascular disease. MicroRNA-31 (miR-31) was reported to participate in the progression of brain disease. The present study was conducted in order to investigate the effect of miR-31 on oxidative stress-induced neuronal injury in IS mice with the involvement of protein kinase D1 (PKD1) and the JAK/STAT3 pathway. C57BL/6J mice were used to establish the middle cerebral artery occlusion (MCAO) model. Astrocytes were transfected with miR-31 mimic, miR-31 inhibitor, si-PKD1, or JAK-STAT3 pathway inhibitor. Following the establishment of an oxygen-glucose deprivation (OGD) model, the astrocytes were cocultured with neuronal OGD. Lower miR-31, higher PKD1 expressions, and activated JAK/STAT3 pathway were found in both the MCAO and OGD models. miR-31 could negatively target PKD1. In an MCAO model, overexpressing miR-31 and silencing PKD1 reduced neuronal injury, cerebral infarct volume, neuron loss, and oxidative stress injury, inhibited the activation of JAK/STAT3 pathway and the expressions of PKD1, interleukin (IL)-1β, IL-6, tumor necrosis factor-α, malondialdehyde, 4-HNE, 8-HOdG, caspase-3, and Bax, but increased the superoxide dismutase content. In the OGD model, overexpression of miR-31 and silencing of PKD1 attenuated oxidative stress-induced neuronal injury, and diminished the lactate dehydrogenase leakage and reactive oxygen species level, accompanied by elevated neuronal viability. These results indicate that miR-31 alleviates inflammatory response as well as an oxidative stress-induced neuronal injury in IS mice by downregulating PKD1 and JAK/STAT3 pathway.

Tangeretin protects human brain microvascular endothelial cells against oxygen-glucose deprivation-induced injury

Tangeretin, a citrus flavonoid extracted from the peel of citrus fruits, was reported to possess antiasthmatic, antioxidant, anti-inflammatory, and neuroprotective properties. However, the effect of tangeretin on human brain microvascular endothelial cells (HBMECs) has not been examined. This study was designed to investigate the protective effects of tangeretin on oxygen-glucose deprivation (OGD)-induced injury of HBMECs, and explore the underlying mechanisms. Our results showed that tangeretin improved HBMECs viability in response to OGD. In addition, tangeretin was able to increase the activity of superoxide dismutase and decrease the levels of reactive oxygen species and malondialdehyde (MDA), as well as ameliorate cell apoptosis in OGD-stimulated HBMECs. Mechanistic studies showed that tangeretin prevented the activation of JNK signaling pathway in OGD-stimulated HBMECs. Taken together, our current study demonstrated that tangeretin could ameliorate OGD-induced HBMECs injury through the JNK signaling pathway. Thus, tangeretin might be used as a therapeutic strategy for ischemia-reperfusion brain injury and related diseases.

Dexmedetomidine alleviates cerebral ischemia-reperfusion injury by inhibiting endoplasmic reticulum stress dependent apoptosis through the PERK-CHOP-Caspase-11 pathway

Dexmedetomidine (Dex) has the neuroprotective effect on cerebral ischemia-reperfusion injury (CIRI). But the mechanism is not yet clear. In this study, we established a model of middle cerebral artery occlusion (MCAO) and treated primary cortical neurons with oxygen glucose deprivation (OGD), followed by Dex treatment. Neurological protection of Dex was then assessed by neurological deficit score, brain edema, TTC staining, TUNEL assay, Western blot analysis, immunohistochemistry, and RT-PCR. The results showed that Dex significantly reduced the neurological deficit score, brain edema and cerebral infarction area due to CIRI. After Dex treatment, the expression levels of ER stress-related apoptosis pathway proteins (GRP78, p-PERK, CHOP and Cleaved-caspase-3) were significantly decreased and the apoptosis of brain cells was also significantly reduced. Immunohistochemistry showed that expression and nuclear localization of CHOP decreased significantly after the application of Dex. The downstream apoptotic protein caspase-11 mediated by PERK-CHOP was also markedly inhibited by Dex. In conclusion, our results suggested that Dex reduced ER stress-induced apoptosis after CIRI. Its protective mechanism may be related to PERK-CHOP-Caspase-11 dependent signaling pathway.

Pre-treatment with spermine for acute cerebral ischemia/reperfusion injuries

Acute cerebral ischemia/reperfusion injury (ACIR) rat model was used to investigate the effect of spermine on oxidative stress and apoptosis. Sixty healthy and clean male Sprague-Dawley rats were randomly divided into 3 groups: The sham-operated group (n=12), the model group (n=12) and the experiment group (n=36). The experiment group was further divided into 3 subgroups: The SPE-10 group (n=12), the SPE-25 group (n=12) and the SPE-50 group (n=12). Rats in the experimental sub-groups SPE-10, SPE-25 and SPE-50 were injected with 10, 25 and 50 mg/kg of spermine, respectively, one week before the establishment of rat models. Rats in the sham-operated and model groups were injected with 0.9% NaCl solution. We evaluated the effect of spermine on malondialdehyde (MDA) level and superoxide dismutase (SOD) activity using ELISA kits. Bax and Bcl-2 levels were measured using western blot analysis. Our results showed that after spermine injection, MDA levels markedly decreased, while SOD activity increased significantly. The variations in MDA levels and SOD activity were dose (spermine)-dependent. Bax protein levels increased significantly, while Bcl-2 levels decreased significantly after the onset of ACIR injuries. After spermine injection, there was a significant decrease in Bax levels. Bcl-2 levels in these rats markedly increased. The observed decline in Bax levels and the increase in Bcl-2 levels in the experimental groups were dose-dependent. We concluded that spermine protected nerve tissues in rats with ACIR by decreasing the MDA level, increasing SOD activity and modifying the balance between Bax and Bcl-2 proteins.

Investigation of 8-OHdG, CYP1A, HSP70 and transcriptional analyses of antioxidant defence system in liver tissues of rainbow trout exposed to eprinomectin

Eprinomectin (EPM), a member of avermectin family, is a semi-synthetic antibiotic. It has been known that avermectin family enters the aquatic environments and adversely affects the aquatic organisms. Effects of EPM is fully unknown in aquatic organisms especially fish, thus the aim of the present study was to investigate transcriptional changes (sod, cat, gpx) and activities of some antioxidant enzymes (superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase (CAT) and malondialdehyde (MDA) levels, oxidative DNA damage (8-hydroxy-2-deoxyguanosine (8-OHdG)) and transcriptional changes of heat shock protein 70 (HSP70), and cytochromes P4501A (CYP1A) in liver tissues of rainbow trout exposed to sublethal EPM concentration (0.001 μg/L, 0.002 μg/L, 0.01 μg/L, 0.05 μg/L) for 24 h, 48 h, 72 h and 96 h. The decrease in antioxidant enzyme (SOD, CAT and GPx) activity, transcriptional changes (sod, cat, gpx, HSP70 and CYP1A genes) and increase in MDA level and activity of 8-OHdG in a dose-time-dependent manner in the liver of rainbow trout were observed. The down-regulated of antioxidant (sod, cat and gpx), HSP70 and CYP1A obviously, the severity of which increased with the concentration of EPM and exposure time. The results imply that EPM could induce oxidative damage to the liver tissue of rainbow trout. The information presented in this study is helpful to understand the mechanism of veterinary pharmaceuticals-induced oxidative stress in fishes.

NaHS Protects against the Impairments Induced by Oxygen-Glucose Deprivation in Different Ages of Primary Hippocampal Neurons

Brain ischemia leads to poor oxygen supply, and is one of the leading causes of brain damage and/or death. Neuroprotective agents are thus in great need for treatment purpose. Using both young and aged primary cultured hippocampal neurons as in vitro models, we investigated the effect of sodium hydrosulfide (NaHS), an exogenous donor of hydrogen sulfide, on oxygen-glucose deprivation (OGD) damaged neurons that mimick focal cerebral ischemia/reperfusion (I/R) induced brain injury. NaHS treatment (250 μM) protected both young and aged hippocampal neurons, as indicated by restoring number of primary dendrites by 43.9 and 68.7%, number of dendritic end tips by 59.8 and 101.1%, neurite length by 36.8 and 66.7%, and spine density by 38.0 and 58.5% in the OGD-damaged young and aged neurons, respectively. NaHS treatment inhibited growth-associated protein 43 downregulation, oxidative stress in both young and aged hippocampal neurons following OGD damage. Further studies revealed that NaHS treatment could restore ERK1/2 activation, which was inhibited by OGD-induced protein phosphatase 2 (PP2A) upregulation. Our results demonstrated that NaHS has potent protective effects against neuron injury induced by OGD in both young and aged hippocampal neurons.

Neuroprotective effects of clarithromycin against neuronal damage in cerebral ischemia and in cultured neuronal cells after oxygen-glucose deprivation

AIMS

Rats subjected to transient focal ischemia and cultured neuronal cells subjected to oxygen-glucose deprivation (OGD) were treated with clarithromycin (CAM) to evaluate the effects of CAM in protecting against neuronal damage.

MAIN METHODS

Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 90min and then reperfused. Each animal was given an oral dose clarithromycin (CAM, 100mg/kg) or vehicle alone just after the ischemia was commenced. The infarct volume, edema index and neurological performance were assessed after 24 and 72h of reperfusion. The cerebral blood flow (CBF) was measured with an MRI system at 90min after MCAO. After 24 and 72h, oxidative stress (4-HNE, 8-OHdG) and inflammation (Iba-1, TNF-α) were assessed by immunohistochemical analyses and degenerative cells were assessed in the cortex by Fluoro-Jade C (FJC) labeling. The cultured neuronal cells were also used to examine the effects of CAM exposure on the viability of the cells after OGD.

KEY FINDINGS

CBF was unchanged between the two groups. Significant reductions of the infarct volume and edema index, an improved neurological deficit score, a significant suppression of 4-HNE and 8-OHdG expression, marked reductions of Iba-1 and TNF-α expression, and a significant reduction of FJC-positive cells were also observed in the CAM-treated animals at both time points. Treatment with 10μM and 100μM CAM in vitro significantly reduced cell death after OGD.

SIGNIFICANCE

CAM appears to provide antioxidant and anti-inflammatory effects and protect against neuronal damage after cerebral ischemia and OGD.

Neuroprotective effects of erythromycin on ischemic injury following permanent focal cerebral ischemia in rats

OBJECTIVE

This study aims to determine if erythromycin provides neuroprotective effects against ischemic injury following permanent focal cerebral ischemia.

METHODS

Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO). Each animal received a single subcutaneous injection of erythromycin lactobionate (EM, 50 mg/kg) or vehicle immediately after ischemia. The infarct volume, edema index and neurological performance were evaluated at 24 and 72 h after MCAO. The cerebral blood flow (CBF) was measured with an MRI system at 30 min after MCAO. TUNEL staining and immunohistochemical analyses for oxidative stress (4-HNE, 8-OHdG) and inflammation (Iba-1, TNF-α) in the cortex were conducted at 24 and 72 h after MCAO.

RESULTS

The CBF did not differ between the EM-treated and vehicle-treated groups. The EM treatment significantly reduced the infarct volume (p < 0.01) at 24 and 72 h after MCAO and significantly reduced the edema index (p < 0.01) at 24 h. The EM treatment significantly improved the neurological deficit scores (p < 0.05) at 24 and 72 h. EM also significantly suppressed the accumulation of 4-HNE (p < 0.01) and 8-OHdG (p < 0.01) and markedly reduced Iba-1 (p < 0.01) and TNF-α expression (p < 0.05) at both time points. The EM treatment significantly reduced TUNEL-positive cells (p < 0.01) at both time points.

CONCLUSION

These findings suggest that EM can protect against the neuronal damage caused by cerebral ischemia by alleviating inflammation and reducing oxidant stress.

Neuroprotective effects of pretreatment with macrolide antibiotics on cerebral ischemia reperfusion injury

OBJECTIVE

This study aims to determine if macrolide antibiotics have neuroprotective effects against transient cerebral ischemia.

METHODS

Sprague-Dawley rats were subjected to cerebral ischemia for 90 minutes followed by 24 or 72 hours of reperfusion. An oral suspension of roxithromycin (RXM), clarithromycin (CAM), erythromycin (EM), azithromycin (AZM), or kitasamycin (INN) was given at 10 or 100 mg/kg for 7 days before ischemia. The infarct volume, edema volume, and neurological performance were evaluated after 24 and 72 hours of reperfusion. The cerebral blood flow (CBF) was measured with a magnetic resonance imaging (MRI) system after 90 minutes of ischemia. Another experiment was conducted to investigate how the ischemic injury was affected by the interval from the antibiotic pretreatment to the ischemia in rats pretreated with CAM.

RESULTS

Roxithromycin, CAM, AZM, and INN significantly reduced the infarct volume in the high-dose group after 24 and 72 hours of reperfusion. All of the agents significantly decreased the edema in the high-dose groups at 24 and 72 hours, while only CAM and AZM significantly reduced the edema volume in the low-dose groups at 24 hours. All of the macrolide antibiotics at the high dose significantly improved neurological deficit scores at 24 and 72 hours. There were no differences in the CBF between the vehicle and respective antibiotic groups. In the experiment examining the interval, the 24-hour interval group exhibited the strongest neuroprotective effect.

DISCUSSION

These results demonstrate that the macrolide antibiotics RXM, CAM, EM, AZM, and INN may confer neuroprotective effects against ischemic damage following cerebral ischemia without affecting the CBF.