Effect of cornel iridoid glycoside on microglia activation through suppression of the JAK/STAT signalling pathway.

The effect of cornel iridoid glycoside (CIG), main component extracted from Cornus officinalis, on microglia activation has not been elucidated so far. We induced a mouse model of multiple sclerosis (MS), namely, the experimental autoimmune encephalomyelitis (EAE) model by immunization subcutaneously with the MOG35-55 peptide, which causes neuroinflammation and microglia activation. Our data demonstrated that CIG delayed the onset of the EAE, ameliorated the severity of the symptoms and inhibited the activation of microglia in different brain regions. In addition, we also found that CIG has therapeutic potential by modulating microglia polarization by reducing the expression and release of proinflammatory cytokines, chemokines and inhibiting phosphorylation in the JAK/STAT cell signalling pathway. Based on our findings, CIG might be a promising candidate for the prevention of neurological disorders such as multiple sclerosis (MS).

Increased central dopaminergic activity might be involved in the behavioral abnormality of cuprizone exposure mice.

The neurotoxican cuprizone (CPZ, a copper chelator) has been used extensively to create a mouse model of demyelination. However, the effects on behavior of CPZ treatment have not been reported in C57BL/6 mice given a diet containing 0.4% CPZ within 3weeks. Behavioral abnormalities were assessed using a range of test: Y-maze, spontaneous locomotor activity, rota-rod test, novel object recognition, climbing. Mice exposed to CPZ displayed more arm entrance, locomotor movements, and climbing behavior, suggesting an increase in central nervous system activity. However, no significant differences either in spontaneous alternation or latency to fall from the rotating drum were observed, demonstrating that spatial working memory or motor coordination and balance didn't impair by CPZ short-term exposure. In addition, they showed higher dopamine levels and dopamine transporter expression in the cortex. Our findings indicate that increased central dopaminergic activity may relate to the behavioral abnormality in mice, and this CPZ short-term exposure with higher dose may offer a model to study some aspects of biology relevant to schizophrenia and other related disorders.

EphB4 Regulates Self-Renewal, Proliferation and Neuronal Differentiation of Human Embryonic Neural Stem Cells in Vitro.

BACKGROUND/AIMS: EphB4 belongs to the largest family of Eph receptor tyrosine kinases. It contributes to a variety of pathological progresses of cancer malignancy. However, little is known about its role in neural stem cells (NSCs). This study examined whether EphB4 is required for proliferation and differentiation of human embryonic neural stem cells (hNSCs) in vitro. METHODS: We up- and down-regulated EphB4 expression in hNSCs using lentiviral over-expression and shRNA knockdown constructs and then investigated the influence of EphB4 on the properties of hNSCs. RESULTS: Our results show that shRNA-mediated EphB4 reduction profoundly impaired hNSCs self-renewal and proliferation. Furthermore, detection of differentiation revealed that knockdown of EphB4 inhibited hNSCs differentiation towards a neuronal lineage and promoted hNSCs differentiation to glial cells. In contrast, EphB4 overexpression promoted hNSCs self-renewal and proliferation, further induced hNSCs differentiation towards a neuronal lineage and inhibited hNSCs differentiation to glial cells. Moreover, we found that EphB4 regulates cell proliferation mediated by the Abl-CyclinD1 pathway. CONCLUSION: These studies provide strong evidence that fine tuning of EphB4 expression is crucial for the proliferation and neuronal differentiation of hNSCs, suggesting that EphB4 might be an interesting target for overcoming some of the therapeutic limitations of neuronal loss in brain diseases.

Morroniside promotes angiogenesis and further improves microvascular circulation after focal cerebral ischemia/reperfusion.

Preservation of cerebral microvascular functional integrity is crucial for protecting and repairing the brain after stroke. Our previous study demonstrated that morroniside promoted angiogenesis 7days after stroke. The current study aimed to further evaluate the long-term effects of morroniside on angiogenesis and to examine whether angiogenesis induced by morroniside could improve blood flow velocity. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO), and morroniside was then administered once per day at a dose of 270mg/kg. New vessel formation and the expression of ephrinB2/VEGFR2 signaling pathway components were examined 14days after MCAO to examine angiogenesis and the associated mechanisms. The dynamics of regional cerebral blood flow (rCBF) and the number of vessels of the leptomeningeal anastomoses were analyzed to characterize microvascular circulation 3days after MCAO. We demonstrated that morroniside promoted angiogenesis by regulating the ephrinB2/VEGFR2 signaling pathway 14days post-ischemia. By 3days post-ischemia, morroniside improved rCBF and increased the number of vessels of the leptomeningeal anastomoses. Moreover, morroniside decreased the infarct volume and improved neurological function 14days after MCAO. Our findings suggest that morroniside promoted long-term angiogenesis, thereby improving microvascular circulation and neurological function. It suggested that the angiogenic mechanism of morroniside might be mediated by the ephrinB2/VEGFR2 signaling pathway.

Morroniside improves microvascular functional integrity of the neurovascular unit after cerebral ischemia.

Treating the vascular elements within the neurovascular unit is essential for protecting and repairing the brain after stroke. Acute injury on endothelial systems results in the disruption of blood-brain barrier (BBB), while post-ischemic angiogenesis plays an important role in delayed functional recovery. Here, we considered alterations in microvessel integrity to be targets for brain recovery, and tested the natural compound morroniside as a therapeutic approach to restore the vascular elements of injured tissue in a rat model of focal cerebral ischemia. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) model, and morroniside was then administered intragastrically once a day at doses of 30, 90, and 270 mg/kg. BBB integrity and associated factors were analyzed to identify cerebrovascular permeability 3 days after MCAO. The recruitment of endothelial progenitor cells (EPCs), the expression of angiogenic factors and the new vessel formation in the peri-infarct cortex of rats were examined 7 days after MCAO to identify the angiogenesis. We demonstrated that at 3 days post-ischemia, morroniside preserved neurovascular unit function by ameliorating BBB injury. By 7 days post-ischemia, morroniside amplified angiogenesis, in part by enhancing endothelial progenitor cell proliferation and expression of angiogenic factors. Morever, the increase in the amount of vWF+ vessels induced by ischemia could be extended to 28 days after administration of morroniside, indicating the crucial role of morroniside in angiogenesis during the chronic phase. Taken together, our findings suggested that morroniside might offer a novel therapeutic approach for promoting microvascular integrity recovery and provide a thoroughly new direction for stroke therapy.

Promoting neurogenesis via Wnt/ß-catenin signaling pathway accounts for the neurorestorative effects of morroniside against cerebral ischemia injury.

Ischemic stroke is a leading cause of mortality and permanent disability in adults worldwide. Neurogenesis triggered by ischemia in the adult mammalian brain may provide insights into stroke treatment. Morroniside is an active component of sarcocarp of C. officinalis that have shown neuroprotective effects. The aim of the present study is to test whether morroniside promotes neurogenesis via Wnt/ß-catenin signaling pathway for brain recovery in a rat model of focal cerebral ischemia. Morroniside was administered intragastrically once daily at the concentrations of 30, 90 and 270 mg/kg for 7 days post-ischemia. Neurological functions were detected by Ludmila Belayev score tests. Endogenous neural stem cells responses were investigated with immunofluorescence staining of Ki-67 and Nestin to identify the neurogenesis in the subventricular zone (SVZ). The expression of proteins involved in and related to Wnt/ß-catenin signaling pathway was detected by western blotting analysis. Morroniside significantly promoted neurogenesis for brain recovery 7 days post-ischemia. Increased expression of Wnt 3a, ß-catenin and T-cell transcription factor-4 (Tcf-4), along with activation of downstream transcription factors Pax6 and neurogenin2 (Ngn2), indicated that the neurorestorative effects of morroniside may be associated with Wnt/ß-catenin signaling pathway. These data provide support for understanding the mechanisms of morroniside in neurorestorative effects and suggest a potential new strategy for ischemic stroke treatment.

[Effects of icariin on beta-amyloid and neurotrophic factors in brain of mitochondrial deficiency model rats].

The purpose of the present study was to investigate the effects of icariin (ICA) on the content of beta-amyloid (Abeta) and the expression of neurotrophic factors in the brain of mitochondrial deficiency model rats. SD rats were infused subcutaneously with sodium azide, which is an inhibitor of mitochondrial respiratory chain complex IV, via a minipump (0. 5 mg . kg-1 h-1) for 28 days to establish the mitochondrial deficiency animal model. The activity of mitochondrial respiratory chain complex IV (i. e. cytochrome C oxidase, COX) in hippocampus was measured by biochemical methods. ELISA method was used to detect the content of Abeta in the brain. The expression of neurotrophic factors was detected by Western blot and immunohistochemistry methods. Image analysis was performed by Image-pro software. The results showed that chronic infusion of sodium azide by minipump induced a significant decrease in the activity of mitochondrial cytochrome C oxidase, an obvious increase in the content of Abeta, and a marked decline in the expression of nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and its receptor TrkB in the brain of rats. Intragastrical administration of ICA (12 or 36 mg . kg-l) significantly ameliorated all these abnormalities in the model rats. In conclusion, ICA can increase mitochondrial activity, inhibit Abeta production, and enhance the expression of neurotrophic factors in the brain of model rats induced by sodium azide. The results suggested that ICA may have beneficial prospect for the treatment of Alzheimer's disease.

Neuroprotective effect of morroniside on focal cerebral ischemia in rats.

Cornus officinalis Sieb. et Zucc., known as Shan-zhu-yu in Chinese, has been used to treat cerebrovascular disease and diabetes in Traditional Chinese Medicine for a long time and morroniside is the main component of Shan-zhu-yu. In this study, we examined whether morroniside could protect ischemia/reperfusion-induced brain injury by minimizing oxidative stress and anti-apoptosis. Morroniside was intragastrically administered to rats in doses of 30, 90 and 270mg/kg/day, starting 3h after the onset of middle cerebral artery occlusion. The behavioral test was performed by using the Zea-Longa scores, Prehensile Traction score and Ludmila Belayer score. Rats were sacrificed 3 days after ischemia occurred. The infarction volume of brain was assessed in the brain slices stained with 2,3,5-triphenyl tetrazolium chloride. Cortex tissues were also used for determination of malondialdehyde levels, glutathione levels and superoxide dismutase. The treatment with morroniside significantly improved Zea-Longa scores and Prehensile Traction score at the doses of 30, 90 and 270mg/kg, increased Ludmila Belayer score and reduced the infarction volume at the doses of 90 and 270mg/kg. Morroniside (30, 90 and 270mg/kg) treatment significantly decreased the level of malondialdehyde and caspase-3 activity by colorimetric analysis in ischemic cortex tissues. Morroniside (270mg/kg) treatment significantly increased the content of glutathione, enhanced the activity of superoxide dismutase, but decreased the caspase-3 expression by Western-blot analysis in ischemic cortex tissues. These findings demonstrated that morroniside could notably protect the brain from damage induced by focal cerebral ischemia which might be related to morroniside antioxidant and anti-apoptotic properties in the brain.

Morroniside protects human neuroblastoma SH-SY5Y cells against hydrogen peroxide-induced cytotoxicity.

Oxidative stress-induced cell damage has been implicated in a variety of neurodegenerative disorders. Morroniside, an iridorid glycoside isolated from Cornus officinalis Sieb. Et Zucc., has shown potent antioxidant properties. The present study investigated the protective actions of morroniside against the cytotoxicity produced by exposure to H(2)O(2) (300-500 microM) in SH-SY5Y cells. Intracellular accumulation of Ca(2+), and decreases in mitochondrial membrane potential (MMP) caused by added H(2)O(2) were reduced by morroniside. Incubation of cells with H(2)O(2) caused a marked decrease in superoxide dismutase (SOD) activity; this decrease was significantly inhibited by morroniside. In addition, the percentage of cells undergoing H(2)O(2)-induced apoptosis was decreased, dose dependently, in the presence of morroniside. These results suggest that morroniside has protective effects against oxidative stress-induced neurotoxic processes.

[Morroniside inhibits H2O2-induced apoptosis in cultured nerve cells].

OBJECTIVE: To investigate the effects of morroniside on H2O2-induced apoptosis in nerve cells. METHOD: Human neuroblastoma cell line SH-SY5Y cells were pre-incubaed with morroniside (1, 10, and 100 micromol x L(-1)) for 24 h prior to exposure to H2O2 (500 micromol x L(-1)) for 18 h. The activity of reactive SOD was measured by a biochemical assay. The expression of caspase-3, caspase-9, Bcl-2 and Bax was determined by Wastern blotting method. RESULT: Pretreatment of the cells with morroniside (10 and 100 micromol x L(-1)) increasd SOD activity by 14% (P<0.01) and 11% (P<0.05) in comparison with cells exposed only to H2O2. Morroniside (1, 10, 100 micromol x L(-1)) lowered caspase-3 level by 31% (P<0.01), 103% (P<0.001) and 95% (P<0.001), decreased caspase-9 content by 71% (P<0.001), 132% (P<0.001) and 37% (P<0.05), and increasd Bcl-1 level by 88% (P<0.01), 121% (P<0.001) and 60% (P<0.01) respectively but no significant change occurred in Bax level in comparison with cells exposed only to H2O2. CONCLUSION: Morroniside has neuroprotection effect against H2O2-induced oxidation injury in nerve cell.

Morroniside prevents peroxide-induced apoptosis by induction of endogenous glutathione in human neuroblastoma cells.

(1) Morroniside belongs to an extensive group of natural iridorid glycosides. In the present study, using human neuroblastoma SH-SY5Y cells, we have investigated the protective effects of this compound on modifications in endogenous reduced glutathione (GSH), intracellular oxygen species (ROS) and apoptotic death on H(2)O(2)-mediated cytoxicity. (2) Incubation of cells with morroniside led to a significant dose-dependent elevation of cellular GSH accompanied by a marked protection against H(2)O(2)-mediated toxicity. Morroniside at 1-100 microM inhibited the formation of ROS and the activation of caspase-3 and 9, and the upregulation of Bcl-2, whereas no significant change occurred in Bax levels. (3) The results indicated that the anti-oxidative and anti-apoptotic properties render this natural compound potentially protective against H(2)O(2)-induced cytotoxicity. (4) This study suggested that intracellular GSH appeared to be an important factor in morroniside-mediated cytoprotection against H(2)O(2)-toxicity in SH-SY5Y cells.

Learning-memory deficit with aging in APP transgenic mice of Alzheimer's disease and intervention by using tetrahydroxystilbene glucoside.

OBJECTIVE: To investigate learning-memory deficit in different ages of AD-like APP transgenic mice and to observe the protective effects of 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glucoside (TSG), which is the main component of Polygonum multiflorum, on learning-memory abilities. METHODS: PDAPPV717I transgenic (Tg) mice were randomly divided into 3 model groups (4, 10 and 16 months old mice) and TSG treated (at doses 120 and 240 micromol/kg/d) groups. TSG was administered to some Tg mice with an age range 4-10 months. In untreated 10 months old Tg mice, the TSG was administrated to those falling in the age range 10-16 months. For the control group we adopted the same age and background C57BL/6J mice. The learning-memory ability was measured by applying Morris water maze (MWM) and object recognition test (ORT). RESULTS: In the 4 months old PDAPPV717I Tg mice, the learning-memory deficit was detected. The escape latency in MWM was prolonged, and the discrimination index decreased in ORT. In the 10 months old Tg mice, the learning-memory deficit was aggravated. TSG improved all spatial learning-memory impairment in MWM as well as the object recognition impairment in ORT. In the 16 months old Tg mice, the learning-memory deficit remained to exist but abated a lot. TSG showed significant improvement in learning-memory ability in both MWM and ORT. CONCLUSION: PDAPPV717I transgenic mice with an age range 4-16 months revealed the existence of learning-memory deficit compared with the control group. Tetrahydroxystilbene glucoside not only prevents, i.e. at an early stage, the learning-memory deficit in AD-like model, but also can reverse the learning-memory deficit in the late stage of AD-like model. Thus, TSG could be considered among the future therapeutic drugs indicated for the treatment of AD.

Behavioural study of the D-galactose induced aging model in C57BL/6J mice.

Rodent chronically injected with D-galactose (D-gal) has been used as an animal aging model for brain aging or anti-aging pharmacology research. However, the dosage of D-gal used to establish this model in mice has been reported in a wide range. To study the dose-dependent effect of D-gal on rodent behaviour, we investigated the learning and memory ability of C57BL/6J (C57) mice after 8-week subcutaneous injection of D-gal at different doses by Morris water maze (MWM) and object recognition test (ORT). In addition, locomotor activity test (LAT) was also performed to examine the neuromuscular function. In comparison of vehicle (0.9% saline)-treated mice, D-gal-treated mice at dose of high (200 mg/kg per day) and middle (100 mg/kg per day) doses showed significant longer latency to platform and less target quadrant search time and distance in MWM In ORT, D-gal at high and middle doses reduced the discrimination index (DI) of mice more significantly than low dose (50 mg/kg per day), although all three doses of D-gal reduced the DI of mice significantly. Furthermore, D-gal at high and middle doses significantly decreased locomotor activity of the mice in LAT. Throughout three tests, D-gal induced behavioural impairments in C57 mice at high and middle doses tended to be in the same degree. These results indicate that d-gal can induce the behavioural impairment of C57 mice in a dose-dependent manner from 50 to 100 mg/kg, higher dose than 100 mg/kg cannot further deteriorate its behavioural performance.

[Effects of extract from Cornus officinalis on nitric oxide and NF-kappaB in cortex of cerebral infarction rat model].

OBJECTIVE: To observe the change of nitric oxide (NO) and expression of nuclear factor-kappa B (NF-kappaB) in the cortex of cerebral infarction rat induced by photochemical reaction, and study the effect of extract from Cornus officinalis (whose main ingredient is iridoid glycoside) in the course of disease. METHOD: After rats were fed with experimental drugs for 7 days, the model of cerebral infarction was induced. Spectrophotography and immunohistochemistry were used to detect the change of the content of NO, NOS and the expression of NF-kappaB in the cortex. RESULT: Compared with control group, distinct infarction was visible in the model group, and the content of NO, the activity of NOS and the positive cell number of NF-kappaB were increased obviously. Compared with model group, the extract of C. officeinalis decreased the area of infarction, the content of NO, the activity of NOS and the positive cell number of NF-kappaB. CONCLUSION: The iridoid glycoside of C. officinalis may have therapeutical effect on cerebral infarction through regulating the content of NO and NF-kappaB.