中风是可卡因滥用引起的最严重的医学风险。研究指出，可卡因的血管作用能破坏大脑血流（CBF），从而促使可卡因滥用者发生中风。因为对可卡因滥用性脑血管变化的基本机制缺乏认识，还没有发现此类中风的有效疗法。目前，神经影像学方法，包括磁共振成像和计算机断层扫描血管造影，对于卡因诱导性限制性大脑血流的基本机制可以揭示一些有限的线索。该研究报道的这种影像学方法是一种很有前途的方法，它能调查出中风可能牵连的大脑小神经血管网络的结构变化。
该研究通过这种新神经影像学技术，观察到：滥用者常用剂量的可卡因可影响大脑动脉、静脉和毛细血管，甚至最小的血管，使它们收缩，从而抑制不同时间内的大脑血液流量，在服用后短短的2-3分钟内大脑血流量明显减少，在某些血管中，脑血流量减少达到了70%，血管恢复时间各异。在一些动脉分支中，可卡因中断脑血流量超过45分钟，这种作用在重复使用可卡因后更为明显。这些变化对脑组织氧输送造成危害，使其更易局部缺血和神经死亡。
要指出的是，这些大脑模型中出现的可卡因诱导性微缺血性变化很可能就是神经毒性作用的诱因，它们可能隐含着可卡因滥用者常见的一些神经并发症，包括各种知觉改变、面瘫、麻木、半瘫或全瘫及不可逆瘫痪。(生物谷bioon.com)
doi:DOI: 10.1038/mp.2011.160
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Cocaine-induced cortical microischemia in the rodent brain: clinical implications.
H Ren, C Du, Z Yuan, K Park, N D Volkow, Y Pan
Cocaine-induced stroke is among the most serious medical complications associated with its abuse. However, the extent to which acute cocaine may induce silent microischemia predisposing the cerebral tissue to neurotoxicity has not been investigated; in part, because of limitations of current neuroimaging tools, that is, lack of high spatiotemporal resolution and sensitivity to simultaneously measure cerebral blood flow (CBF) in vessels of different calibers (including capillaries) quantitatively and over a large field of view. Here we combine ultrahigh-resolution optical coherence tomography to enable tracker-free three-dimensional (3D) microvascular angiography and a new phase-intensity-mapping algorithm to enhance the sensitivity of 3D optical Doppler tomography for simultaneous capillary CBF quantization. We apply the technique to study the responses of cerebral microvascular networks to single and repeated cocaine administration in the mouse somatosensory cortex. We show that within 2-3?min after cocaine administration CBF markedly decreased (for example, ~70%), but the magnitude and recovery differed for the various types of vessels; arterioles had the fastest recovery (~5?min), capillaries varied drastically (from 4-20?min) and venules showed relatively slower recovery (~12?min). More importantly, we showed that cocaine interrupted CBF in some arteriolar branches for over 45?min and this effect was exacerbated with repeated cocaine administration. These results provide evidence that cocaine doses within the range administered by drug abusers induces cerebral microischemia and that these effects are exacerbated with repeated use. Thus, cocaine-induced microischemia is likely to be a contributor to its neurotoxic effects.
