Abstract
BackgroundPrevious neuroimaging studies have shown the hemodynamic effect of either preconditioning or postconditioning anesthesia in ischemic stroke model. However, the anesthetic effect in hemodynamics during and immediately after the stroke modeling surgery remains unknown due to the lack of appropriate anesthesia-free stroke model and intraoperative imaging technology. In the present study, we utilized our recently developed photothrombotic model of focal cerebral ischemia in conscious and freely moving rats, and investigated transient hemodynamic changes with or without isoflurane administration. Laser speckle imaging was applied to acquire real-time two-dimensional full-field cerebral blood flow (CBF) information throughout the surgical operations and early after.ResultsSignificantly larger CBF reduction area was observed in conscious rats from 8 min immediately after the onset of stroke modeling, compared with anesthetized rats. Stroke rats without isoflurane administration also showed larger lesion volume identified by magnetic resonance imaging 3 h post occlusion (58.9%), higher neurological severity score 24 h post occlusion (28.3%), and larger infarct volume from 2,3,5-triphenyltetrazolium chloride staining 24 h post occlusion (46.9%).ConclusionsOur results demonstrated that the hemodynamic features were affected by anesthetics at as early as during the stroke induction. Also, our findings about the neuroprotection of intraoperative anesthetics administration bring additional insights into understanding the translational difficulty in stroke research.
Highlights
Previous neuroimaging studies have shown the hemodynamic effect of either preconditioning or postconditioning anesthesia in ischemic stroke model
The procedures were identical to those in the conscious group, except that the rats were anesthetized with isoflurane (5% initial and 1.0–1.5% for maintenance) starting from 30 min prior to stroke modeling till the end of illumination
Real‐time cerebral blood flow monitoring Since we focused on the intraoperative anesthetic influence on CBF, only up to 25 min post-occlusion CBF data were recorded
Summary
Cerebral blood flow information The CBF results confirmed that MCAs of all rats in both groups were completely occluded by an intraluminal thrombus formed after 15 min 532 nm laser illumination (regional CBF with over 85% decrease, compared with baseline values obtained before stroke modeling). To address the impact of the anesthetics administered during MRI scanning on the measurement conducted 24 h following stroke, we performed an extra experiment with conscious (n = 3) and anesthetic (n = 3) rats going through all the protocol except for MRI scanning Both NSS and infarct volume showed no significant difference in comparison with the groups from the original protocol (Fig. 4). Discussions In this study, we compared the CBF changes throughout the photothrombotic stroke modeling of focal cerebral ischemia in conscious and isoflurane anesthetized rats, respectively. The dilation of arterioles in the ischemic penumbra [35] could be neuroprotective It is in line with the present study that the CBF reduction area in the isoflurane anesthetized group was more constrained than that in the conscious group, which might contribute to the less brain injury after stroke. Author details 1 School of Biomedical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China. 2 Med‐X Research Institute, Shanghai Jiao Tong University, 1954 Huashan Road, Shanghai 200030, China
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