活体双光子成像观察小鼠脑血管CO_2反应性及其机制

A study of in vivo two-photon imaging of cerebravascular CO_2 reactivity in mice

目的活体观察脑血管CO2反应性及初步探讨其反应机制。方法利用双光子成像技术,在磨薄的颅窗下观察5只雄性C57小鼠脑皮层动脉、穿支动脉、皮层静脉及毛细血管共4种脑血管对吸入CO2的反应,分别使用一氧化氮合酶抑制剂L-NAME及前列腺素合成抑制剂吲哚美辛阻断血管扩张通路,观察血管反应性变化。结果吸入1 min 5%CO2后4种脑血管分别出现不同程度的扩张,其中穿支动脉扩张最显著(45.01%±4.45%);使用L-NAME后4种脑血管对CO2反应性较使用前显著下降(P<0.05);使用吲哚美辛后动脉CO2反应性较使用前及使用L-NAME后显著下降(P<0.05),但毛细血管CO2反应性较使用前无下降(P>0.05)。结论 4种脑血管在吸入CO2后出现不同程度的扩张反应,前列腺素类及NO参与介导反应。本实验方法有较好的应用价值。

Objective To examine cerebrovascular reactivity to CO2 inhalation in mice. Methods In vivo Two-Pho-ton imaging technique was used to record the reaction of cerebral cortical vessels including penetrating artery, surface vein and capillary in 5 male C57 mice after CO2 inhalation under a thinned-skull cranial window. Nitric oxide syntheses inhibitor L-NAME and Prostaglandin syntheses inhibitor Indomethacin were used to block different vasodilator pathways, respectively. Results Different mouse cortical vessels displayed different degrees of dilation to 1-minute 5%CO2 inhala-tion. The penetrating artery exhibited the most obvious dilation （45.01%±4.45%）. L-NAME intervention significantly di-minished cerebravascular CO2 reactivity（P〈0.05）. Indomethacin significantly attenuated the dilation of artery but not capillary comparing with L-NAME intervention（P〈0.05）. Conclusions Different vessels react differently to CO2 inhala-tion in which postaglandins and NO signal pathways are involved.