Neuro-protective effects and mechanism of Terminalia chebula extract HZ4 on cerebral infarction models / 中国中药杂志

To study the effect and possible molecular mechanisms of Terminalia chebula extract HZ4 on focal cerebral infarction in rats, 90 healthy male SD rats were randomly divided into sham-operation group, model group, T. chebula extract HZ4 high dose, middle dose and low dose groups (80, 40, 20 mg•kg ⁻¹•d ⁻¹, ig) and positive control group (Panax notoginseng saponins, PNS 30 mg•kg ⁻¹•d ⁻¹, ig). The focal cerebral infarction models were established by photochemical method. After the rats were administered for 7 consecutive days, neurogenic behavior rating of these rats was done by balance beam test and foot fault test. The cells morphological changes of penumbra in focal cerebral infarction were investigated by HE staining method; the infarct volume was detected by TTC staining. The expression levels of β-catenin and cyclin D1, the key node genes in Wnt signaling pathway of the focal penumbra tissues were detected via RT-PCR. The results showed that, as compared with the model group, behavioural indicators were improved significantly in the rats of administration groups, and the infarct volume and pathological changes of penumbra tissues were also improved at the same time. Compared with the model group, the expression levels of β-catenin and cyclin D1 in Wnt signaling pathway were significantly up-regulated in administration groups(P<0.01). This study first confirmed that T. chebula extract HZ4 can decrease infarct volume, improve the sport ability score, and promote rehabilitation of model animals. In addition, it could significant up-regulated the expression levels of β-catenin and cyclin D1, and the mechanism may be associated with Wnt signaling pathway. The study is innovative to a certain extent.

Activation of Matrix Metalloproteinases-9 after Photothrombotic Spinal Cord Injury Model in Rats

OBJECTIVE: Matrix metalloproteinases (MMPs), especially MMP-2 and MMP-9 have been known to play an important role in secondary inflammatory reaction after spinal cord injury (SCI). The aim of this study was to investigate the expression and activity of MMP-2 and MMP-9 and to determine their relationship with disruption of endothelial blood-barrier after photochemically induced SCI in rats. METHODS: Female Sprague-Dawley rats, weighing between 250 and 300 g (aged 8 weeks) received focal spinal cord ischemia by photothrombosis using Rose Bengal. Expressions and activities of MMP-2 and MMP-9 were assessed by Western blot and gelatin zymography at various times from 6 h to 7 days. Endothelial blood-barrier integrity was assessed indirectly using spinal cord water content. RESULTS: Zymography and Western blot analysis demonstrated rapid up-regulation of MMP-9 protein levels in spinal cord after ischemic onset. Expressions and activities of MMP-9 showed a significant increased at 6 h after the photothrombotic ischemic event, and reached a maximum level at 24 h after the insult. By contrast, activated MMP-2 was not detected at any time point in either the experimental or the control groups. When compared with the control group, a significant increase in spinal cord water content was detected in rats at 24 h after photothrombotic SCI. CONCLUSION: Early up-regulation of MMP-9 might be correlated with increased water content in the spinal cord at 24 h after SCI in rats. Results of this study suggest that MMP-9 is the key factor involved in disruption of the endothelial blood-barrier of the spinal cord and subsequent secondary damage after photothrombotic SCI in rats.

Photochemically Induced Cerebral Ischemia in a Mouse Model

OBJECTIVE: Middle cerebral artery occlusion(MCAO) has widely been used to produce ischemic brain lesions. The lesions induced by MCAO tend to be variable in size because of the variance in the collateral blood supply found in the mouse brain. To establish a less invasive and reproducible focal ischemia model in mice, we modified the technique used for rat photothrombosis model. METHODS: Male C57BL/6 mice were subjected to focal cerebral ischemia by photothrombosis of cortical microvessels. Cerebral infarction was produced by intraperitoneal injection of Rose Bengal, a photosensitive dye and by focal illumination through the skull. Motor impairment was assessed by the accelerating rotarod and staircase tests. The brain was perfusion-fixed for histological determination of infarct volume four weeks after stroke. RESULTS: The lesion was located in the frontal and parietal cortex and the underlying white matter was partly affected. A relatively constant infarct volume was achieved one month after photothrombosis. The presence of the photothrombotic lesion was associated with severe impairment of the motor performance measured by the rotarod and staircase tests. CONCLUSION: Photothrombotic infarction in mice is highly reproducible in size and location. This procedure can provide a simple method to produce cerebral infarction in a unilateral motor cortex lesion. In addition, it can provide a suitable model for study of potential neuroprotective and therapeutic agents in human stroke.

Chronological Changes in Cerebral Infarction of Photochemical Thrombosis Model: Magnetic Resonance Imaging and Histopathological Correlation

OBJECTIVE: Authors investigated magnetic resonance imaging (MRI) and histological characteristics of photothrombotic infraction rat model (PIRM) on long term basis to provide a basis for further research. METHOD: Photothrombotic ischemia was induced in male Sprague-Dawley rats using Rose-bengal dye (20 mg/kg) and cold light. MRI was performed 1, 6, 12, 24 hours, 3, 7 days, 2, 3, 4, 6, and 8 weeks after photothrombosis and obtained T1- & T2-weighted and contrast-enhanced images. Also, T2* images were obtained after superparamagnetic iron oxide injection. After MRI, animals were sacrificed and the brain sections were stained for routine immunohistopathology. RESULTS: MRI and histological analysis revealed well induced lesion in the cortex and showed biological course of infarction. However, PIRM showed rapid development of infarction lacking collateral circulation. Infarction size reached maximum 12 hours after induction, progressively decreasing over 4 weeks. Interstitial and cytotoxic edema were evident at 6, 12, 24 hours, but decreasing afterwards. Neurogenic inflammation appeared on 3rd day and reached maximum on 5~7th day. Arachnoid membrane was characteristically invaded with inflammatory cells and later thickened with fibrosis. CONCLUSION: This study showed PIRM is ideal model to study subacute and chronic stages of cerebral infarction.