关键词: 黄芩茎叶总黄酮, 脑缺血再灌注, 海马, 水通道蛋白4, 血脑屏障, 单宁酸-氯化铁媒染法, 大鼠

Abstract:

Objective To explore the preventive protective effects on ischemia reperfusion injury of microvessels and blood brain barrier(BBB) in cerebral hippocampus with scutellaria baicalensis stem leaf total flavonoids (SSTF). Methods Ninety SD rats were assigned randomly into sham operation, ischemia reperfusion, and SSTF pretreated groups. The SSTF group rats were administrated with SSTF intragastrically one week before animal model-making. Low, medium and high dose groups were administrated with 50, 100, 200 mg/(kg ·d), respectively, for 7 days. The model group and SSTF group animals were remodelled into focal ischemia reperfusion models. Changes of neurological defects were evaluated. Postoperatively, water contents and microvascular permeability in brain tissue were detected with wet weight methods and Evans blue (EB) methods. The microvessel density (MVD) and microvessel area ratio(MVA) were observed with tannic acid-ferric chloride mordant dyeing methods (TA-Fe). The change of aquaporin 4(AQP4) mRNA expression was assessed by Real-Time PCR. The ultrastructural integrity of the blood brain barrier was observed under an electron microscope. Results The neurological function defect scale, water content in brain tissue and microvascular permeability in each SSTF group were significantly reduced compared with IR groups（P＜0.01，P＜0.05. The MVD and MVA were obviously increased (P＜0.01), the expression of AQP4 was reduced significantly (P＜0.01), the BBB injuries were alleviated in various degrees, the endothelial cells swelling gradually disappeared, the unloosed tight junction also gradually reclosed and recovered into a normal status, the basal membrane gradually returned into continuous and clear, and the gliacyte cytoplasm dissolving in pedal plate was alleviated and gradually turned close to normal status. While the above alleviate improvements in SSTF M and SSTF H groups were more conspicuous than that in SSTF L group (P<0.01), there was no significant difference between SSTF M and H groups (P>0.05). Conclusion Cerebral ischemia reperfusion can lead the hippocampus microvessel and blood brain barrier to be injured, and SSTF intervention can exert preventive protective effects on cerebral hippocampus tissue. The functional mechanism may carry out effectively by increasing the number of microvascular recanalization, by maintaining the microvessel and brain blood barrier to be in intact status and in normal function, as well as by relieving cerebral edema. It is proved that the optimal effective prevention dose of SSTF is 100mg/(kg·d).

Key words: Scutellaria baicalensis stem-leaf total flavonoid, Cerebral ischemia reperfusion(CIR), Hippocampus, Aquaporin 4, Brain blood barrier, TA-Fe mordant dyeing method, Rat