Ischemia can cause decreased cerebral neurovascular coupling, leading to a failure in the autoregulation of cerebral blood flow. This study aims to investigate the effect of varying degrees of ischemia on cerebral hemodynamic reactivity using in vivo real-time optical imaging. We utilized direct cortical stimulation to elicit hyper-excitable neuronal activation, which leads to induced hemodynamic changes in both the normal and middle cerebral artery occlusion (MCAO) ischemic stroke groups. Hemodynamic measurements from optical imaging accurately predict the severity of occlusion in mild and severe MCAO animals. There is neither an increase in cerebral blood volume nor in vessel reactivity in the ipsilateral hemisphere (I.H) of animals with severe MCAO. The pial artery in the contralateral hemisphere (C.H) of the severe MCAO group reacted more slowly than both hemispheres in the normal and mild MCAO groups. In addition, the arterial reactivity of the I.H in the mild MCAO animals was faster than the normal animals. Furthermore, artery reactivity is tightly correlated with histological and behavioral results in the MCAO ischemic group. Thus, in vivo optical imaging may offer a simple and useful tool to assess the degree of ischemia and to understand how cerebral hemodynamics and vascular reactivity are affected by ischemia.

中文翻译：

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在轻度和重度缺血性啮齿动物中脑动脉闭塞性中风模型中的脑血流动力学和血管反应性。

缺血可导致脑神经血管耦合减少，导致脑血流自动调节功能失败。本研究旨在利用体内实时光学成像技术研究不同程度的局部缺血对脑血流动力学反应的影响。我们利用直接的皮层刺激来引起高兴奋性神经元激活，从而导致正常和中脑动脉闭塞（MCAO）缺血性中风组的血流动力学改变。光学成像的血流动力学测量值可以准确预测轻度和重度MCAO动物的阻塞严重程度。患有严重MCAO的动物的同侧半球（IH）的脑血容量和血管反应性均未增加。对侧半球的颈动脉（C. 重度MCAO组的H）反应比正常和轻度MCAO组的两个半球反应都要慢。此外，在温和的MCAO动物中，IH的动脉反应性比正常动物快。此外，在MCAO缺血组中，动脉反应性与组织学和行为结果紧密相关。因此，体内光学成像可以提供一种简单而有用的工具来评估缺血程度并了解缺血如何影响脑血流动力学和血管反应性。