Protective Effects And Mechanisms Of Scutellarin On Focal Cerebral Ischemia-Reperfusion Injury In Rats

OBJECTIVES Scutellarin is the most important compound in breviscapine. Breviscapine is a sort of compounds of flavones that was extracted from Chinese traditional medicine. This study were to investigate the protective effects and their possible mechanisms of scutellarin in a rat model of transient focal cerebral ischemia. In the past, the studies suggested that ischemic penumbra(IP) is the key of curing cerebral ischemic vascular disease(ICVD). This study investigates the effects of scutellarin on three characteristic of ischemia penumbra: cell apoptosis, overloard of calcium, the expression of heat shock protein 70, and to explore the protective mechanisms of scutellarin for cerebral ischemia vascular disease.METHODS 162 healthy male Wistar rats were randomly divided into 6 groups: group I (sham), anesthesia and NS intravenously (iv) only; group II (IR), ischemia-reperfusion and same volume of NS intrave-nously(iv); groupsIII~V ischemia-reperfusion and scutellarin 12.5,25, 50 mg . kg~-1 iv. groups VI ischemia-reperfusion and nimodipine 0.4mg.kg~-1 iv. Rats were prepared for models of focal cerebral ischemic injury by inserting a 0.25~0.3mm OD nylon thread into middle cerebral artery to make it occluded. One hour later, the thread was withdrown toresume perfusion. Drugs were administered at the beginning of ischemic injury and at the time of resumtion of perfusion.Twenty-four hours after reperfusion, Neurological grades were calculated, then rats were sacrificed by heads cutting and brains removing for the following studies.(1) TTC stain were used to estimate the infarct volume of brain ischemic damage. The sections of the optic chiasm brain were stained in TTC, then the infarct volume at the coronal level of the rostral edge of the optic chiasm was calculated by image analysis.(2) flow cytometry(FCM) were used for determination of apoptosis and intraneuron calcium.(3) HE stain detects the changes of pathological of ischemia hemisphere. At the same time, heat shock protein 70(HSP70) and Caspase-3 protein expression of the neurons were detected by immunohistochemistry. (4) Reverse transcription polymerase chain reaction(RT-PCR) was used to detect the expression of the mRNA level of heat shock protein 70 and Caspase-3 in CA1 reigon of hippocampus. RESULTS Compared with sham operation group, the neurological deficit and infarction volume were obvious in the group. The percentage of apoptosis and intracellrlar calcium content were obviously increased. Noticeable ischemic phenomenon was also seen in HE stain. The expression of Caspase-3 and Caspase-3mRNA were increased significantly, while expression of HSP70 and HSP70mRNA were mildly increased. On the contrary, comparing with group II, the neurological deficit was improved and the infarct volume of cerebral ischemia was decreased significantly in group HI~VI. The scutellarin can decrease the expression of Caspase-3 and Caspase-3mRNA, at the same time, increase the expression of HSP70 and HSP70mRNA. The reduction of apoptosis and intracellular calcium was observed in different dose of scutellarin groups.CONCLUSION Scutellarin can protect the brain from ischemia-reperfusion injury in rats by improving neurological deficit anddecreasing infarct volume. And the neuroprotections mechenism may be related to the inhibiting the neuronal apoptosis and the process of the neuronal apoptosis, for example, the inhibition of transcription of Caspase-3mRNA and reducing the expression of the protein, which can induce cell apoptosis. Also, the neuroprotections mechenism may be also related to inhibiting calcium overload of neuron and increasing the transcription of HSP70mRNA and the expression of the protein.