Neuroprotective Effect of 4-Methylcyclopentadecanone on Focal Cerebral Ischemia/Reperfusion Injury in Rats

Moschus exerted protective activity against H2O2-induced cell injury in PC12 cells through regulating Nrf-2/ARE signaling pathways

The pivotal characteristics of Alzheimer's disease (AD) are irreversible memory loss and progressive cognitive decline, eventually causing death from brain failure. In the various proposed hypotheses of AD, oxidative stress is also regarded as a symbolic pathophysiologic cascade contributing to brain diseases. Using Chinese herbal medicine may be beneficial for treating and preventing AD. As a rare and valuable animal medicine, Moschus possesses antioxidant and antiapoptotic efficacy and is extensively applied for treating unconsciousness, stroke, coma, and cerebrovascular diseases. We aim to evaluate whether Moschus protects PC12 cells from hydrogen peroxide (H₂O₂)-induced cellular injury. The chemical constituents of Moschus are analyzed by GC-MS assay. The cell viability, reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP) levels, oxidative stress-related indicators, and apoptotic proteins are determined. Through GC-MS analysis, nineteen active contents were identified. The cell viability loss, lactate dehydrogenase releases, MMP levels, ROS productions, and Malondialdehyde (MDA) activities decreased, and BAX, Caspase-3, and Kelch-like ECH-associated protein 1 expression also significantly down-regulated and heme oxygenase 1, nuclear factor erythroid-2-related factor 2 (Nrf-2), and quinine oxidoreductase 1 expression upregulated after pretreatment of Moschus. The result indicated Moschus has neuroprotective activity in relieving H₂O₂-induced cellular damage, and the potential mechanism might be associated with regulating the Nrf-2/ARE signaling pathway. A more in-depth and comprehensive understanding of Moschus in the pathogenesis of AD will provide a fundamental basis for in vivo AD animal model research, which may be able to provide further insights and new targets for AD therapy.

microRNA-1906 protects cerebral ischemic injury through activating Janus kinase 2/signal transducer and activator of transcription 3 pathway in rats

This study aimed to investigate the effects of miR-1906 on cerebral ischemic injury and its underlying mechanisms. After 24 h of reperfusion, neurological deficit scores, brain water content and infarct volume were measured. Neuronal apoptosis was detected by using terminal dexynucleotidyl transferase-mediated dUTP nick end labeling assay. Hematoxylin-eosin staining was used to evaluate the histopathological damage of neurons. The expression of miR-1906 was detected by qRT-PCR. And the expressions of Bax, Bcl-2, caspase-3, Janus kinase 2 (JAK2), p-JAK2, signal transducer and activator of transcription 3 (STAT3) and p-STAT3 were measured by western blot. Furthermore, the levels of tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and IL-6 were measured by ELISA. We found that miR-1906 expression was significantly decreased in the cerebral ischemia injury rats. miR-1906 decreased neurological score, infarct volume, brain water content, neuronal apoptosis and inflammatory factors (TNF-α, IL-6 and IL-1β) expression. In addition, miR-1906 promoted the phosphorylation of JAK2 and STAT3. After treating with JAK2/STAT3 pathway inhibitor AG490, the phosphorylation of JAK2 and STAT3 was inhibited and the effects of miR-1906 on neurological score, infarct volume, brain water content, neuronal apoptosis and inflammatory factors were reversed. miR-1906 could protect cerebral ischemic injury through activating the JAK2/STAT3 pathway in rats.

Ginsenoside compound K attenuates cognitive deficits in vascular dementia rats by reducing the Aβ deposition

Ginsenoside compound K (CK) is the main metabolite of protopanaxadiol-type ginsenosides and has been demonstrated to exert neuroprotective and cognition-enhancing effects. The effects of CK on cognitive function in vascular dementia (VD) has not been elucidated. Therefore, the present study aims to elucidate the effects of CK on memory function as well as its potential mechanism in VD rats. Sprague-Dawley rats were subjected to Chronic Cerebral Hypoperfusion (CCH) by permanent bilateral common carotid artery occlusion (2VO). CCH induced neuronal damage and aggravated the aggregation of Amyloid-β_1-42 peptides (Aβ_1-42), which plays a critical role in the neurotoxicity and cognitive impairment. CK treatment attenuated CCH-induced Aβ_1-42 deposition and ameliorated cognition impairment. Furthermore, CK enhanced the activity of the pSer9-Glycogen synthase kinase 3β (pSer9-GSK3β) and the insulin degrading enzyme (IDE), which mainly involved the production and clearance of Aβ_1-42. Moreover, CK treatment enhanced the activity of protein kinase B (PKB/Akt), a key kinase in phosphatidylinositol 3 kinase (PI3K)/Akt pathway that can regulate the activity of GSK-3β and IDE. In short, our findings provide the first evidence that CK might attenuate cognitive deficits and Aβ_1-42 deposition in the hippocampus via enhancing the expression of pSer9-GSK-3β and IDE.

Anti-inflammatory effect of 4-methylcyclopentadecanone in rats submitted to ischemic stroke

This study aimed to investigate the anti-inflammatory effect of 4-methylcyclopentadecanone (4-MCPC) in rats suffering from a cerebral ischemia/reperfusion (I/R) injury. In this study, the focal cerebral ischemia in rats was induced by middle cerebral artery occlusion (MCAO) for 2 h, and the rats were treated with 4-MCPC (8 mg/kg) just 0.5 h before reperfusion. The ischemic infarct volume was recorded 24 h after the MCAO. In addition, myeloperoxidase (MPO) activity and TNF-α and IL-1β levels in the ischemic cerebral cortex were determined by ELISA, while nuclear translocation of NF-κB p65 subunit and expression of p-IκBα were investigated by Western blotting. Our results showed that 4-MCPC treatment decreased infarct volume significantly, compared with I/R group (16.8%±7.5% vs. 39.7%±10.9%); it reduced MPO activity (0.43 ± 0.10 vs. 1.00 ± 0.51 U/g) and expression levels of TNF-α (18.90 ± 3.65 vs. 35.87 ± 4.87 ng/g) and IL-1β (1.68 ± 0.23 vs. 2.67 ± 0.38 ng/g) in ischemic brain tissues of rats. Further study revealed that 4-MCPC treatment markedly reduced nuclear translocation of NF-κB p65 subunit and expression of p-IκBα in ischemic cerebral cortex. Taken together, our results suggest that 4-MCPC protects against cerebral I/R injury and displays anti-inflammatory actions through inhibition of the NF-κB signal pathway.

Transient Cerebral Ischemia Alters GSK-3β and p-GSK-3β Immunoreactivity in Pyramidal Neurons and Induces p-GSK-3β Expression in Astrocytes in the Gerbil Hippocampal CA1 Area

Glycogen synthase kinase 3β (GSK-3β) is a key downstream protein in the PI3K/Akt pathway. Phosphorylation of serine 9 of GSK-3β (GSK-3β activity inhibition) promotes cell survival. In this study, we examined changes in expressions of GSK-3β and phosphorylation of GSK-3β (p-GSK-3β) in the gerbil hippocampal CA1 area after 5 min of transient cerebral ischemia. GSK-3β immunoreactivity in the CA1 area was increased in pyramidal cells at 6 h after ischemia-reperfusion. It was decreased in CA1 pyramidal cells from 12 h after ischemia-reperfusion, and hardly detected in the CA1 pyramidal cells at 5 days after ischemia-reperfusion. p-GSK-3β immunoreactivity was slightly decreased in CA1 pyramidal cells at 6 and 12 h after ischemia-reperfusion. It was significantly increased in these cells at 1 and 2 days after ischemia-reperfusion. Five days after ischemia-reperfusion, p-GSK-3β immunoreactivity was hardly found in CA1 pyramidal cells. However, p-GSK-3β immunoreactivity was strongly expressed in astrocytes primarily distributed in strata oriens and radiatum. In conclusion, GSK-3β and p-GSK-3β were significantly changed in pyramidal cells and/or astrocytes in the gerbil hippocampal CA1 area following 5 min of transient cerebral ischemia. This finding indicates that GSK-3β and p-GSK-3β are closely related to delayed neuronal death.

Polyphenol-rich fraction of Parquetina nigrescens mitigates dichlorvos-induced neurotoxicity and apoptosis

BACKGROUND

Parquetina nigrescens (Afzel.) Bullock of the family Asclepiadaceae is known for its antioxidant effects with wide range of uses in Southwestern Nigeria especially in traditional medicine. This study was undertaken to explore if polyphenol-rich fraction (prf) from P. nigrescens will ameliorate dichlorvos-induced neurotoxicity and apoptosis. The exploration utilized evaluation of markers of oxidative stress, apoptosis and serum acetylcholinesterase (AchE) levels.

METHODS

Forty Wistar rats randomly placed in four groups were utilized for the study. Animals in Group A received corn oil, group B- dichlorvos (16 mg/kg), groups C and D- dichlorvos + 100 and 200 mg/kg prf of P. nigrescens respectively. Markers of oxidative stress, antioxidants and apoptosis were assessed in the serum and brain tissues using biochemical assay and immunohistochemistry.

RESULTS

Exposure to dichlorvos caused significant decreases in AchE, catalase, superoxide dismutase, glutathione peroxidase (GPx) and increases in hydrogen peroxide (H2O2) generation and malondialdehyde levels. Histopathology and immunohistochemistry of the cerebellum and cerebrum of rats exposed to dichlorvos revealed greater neurotoxic effects in the cerebellum as well as decreased expressions of AchE with a concomitant increase in Bax (proapototic) compared to prf of P. nigrescens treated rats.

CONCLUSION

This study showed that dichlorvos caused cellular and tissue neurotoxicity by inhibiting AchE activity, induced oxidative stress and apoptosis in rats with prominent effects on the cerebellum than cerebrum. The prf of P. nigrescens showed amelioration of neurotoxicity by its antioxidative and antiapoptotic properties in rats exposed to dichlorvos.

Neuroprotective DAMPs member prothymosin alpha has additional beneficial actions against cerebral ischemia-induced vascular damages

Prothymosin alpha (ProTα) suppresses stress-induced necrosis of cultured cortical neurons. As neuroprotection alone could not explain the long-lasting protective actions against cerebral ischemia by ProTα, we further examined whether ProTα, in addition to neuroprotective effects, has other anti-ischemic activities. When recombinant mouse ProTα (rmProTα) at 0.3 mg/kg was intravenously (i.v.) given 2 h after the start of tMCAO, all mice survived for more than 14 days. In evaluation of CD31- and tomato lectin-labeling as well as IgG and Evans blue leakage, rmProTα treatment (0.1 mg/kg) largely blocked ischemia-induced vascular damages. Therefore, rmProTα has novel beneficial effects against ischemia-induced brain damage through vascular mechanisms.

Matrine attenuates focal cerebral ischemic injury by improving antioxidant activity and inhibiting apoptosis in mice

Matrine, an active constituent of the Chinese herb, Sophora flavescens Ait., and it is known for its antioxidant, anti-inflammatory and antitumor activities. It has been demonstrated that matrine exerts protective effects against heart failure by decreasing the expression of caspase-3 and Bax, and increasing Bcl-2 levels. In this study, we aimed to determine whether these protective effects of matrine can be applied to cerebral ischemia. Following 7 successive days of treatment with matrine (7.5, 15 and 30 mg/kg) and nimodipine (1 mg/kg) by intraperitoneal injection, male Institute of Cancer Research (ICR) mice were subjected to middle cerebral artery occlusion (MCAO). Following reperfusion, the neurobehavioral score and brain infarct volume were estimated, and morphological changes were analyzed by hematoxylin and eosin (H&E) staining and electron microscopy. The percentage of apoptotic neurons was determined by flow cytometry. The levels of oxidative stress were assessed by measuring the levels of malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), and the total antioxidant capacity (T-AOC). Western blot analysis and immunofluorescence staining were used to examine the expression of the apoptosis-related proteins, caspase-3, Bax and Bcl-2. Our results revealed that pre-treatment with matrine significantly decreased the infarct volume and improved the neurological scores. Matrine also reduced the percentage of apoptotic neurons and relieved neuronal morphological damage. Furthermore, matrine markedly decreased the MDA levels, and increased SOD, GSH-Px and CAT activity, and T-AOC. Western blot analysis and immunofluorescence staining revealed a marked decrease in caspase-3 expression and an increase in the Bcl-2/Bax ratio in the group pre-treated with matrine (30 mg/kg) as compared with the vehicle-treated group. The findings of the present study demonstrate that matrine exerts neuroprotective effects against cerebral ischemic injury and that these effects are associated with its antioxidant and anti-apoptotic properties.