Evaluation of neurovascular function in mouse cortex using multispectral optical imaging after ischemic stroke

Objective To acquire the signal of neuron excitability and blood oxygen in mouse cortex after ischemic stroke, and to clarify the relationship between the change of neurovascular function and the degree of cerebral infarction. Methods The male C57BL/6 mouse(n=20) about 6-8 weeks and 20 g weight were produced the embolic stroke modal by photochemical injury. The mouse cortex was scanned by the multispectral optical imaging while using electric stimulation in 1, 3 and 7 d after operation. Then several data around the infarction were acquired including neuron excitability, the total hemoglobin concentration and deoxygenated hemoglobin concentration. The ischemic cerebral infarction size was analyzed by TTC staining. Plasma TNF-α concentration was measured by enzyme-linked immunosorbent assay(ELISA). And modified neurological severity score (mNSS) was recorded after ischemic stroke(n=30). Then correlativity analysis was used between the optical signals and three indicators of cerebral infarction degree. Results The changes of neuron excitability signals were 1.15%±0.28%, 2.84%±1.06%, 2.21%±0.55%. The total hemoglobin concentration signals were 3.71%±2.76%,3.19%±2.70%,4.27%±3.05%. The deoxygenated hemoglobin concentration signals were 2.93%±2.33%, 3.60%±1.74%, 2.08%±1.28%. The neural signal was correlated to cerebral infarction size, plasma TNF-α concentration and mNSS(r=-0.441, -0.449,-0.404, all P<0.05), and mNSS had a great effect on neuron excitability(β=-0.169,P<0.05). Meanwhile, the total hemoglobin concentration was correlated to cerebral infarction size(r=0.440,P<0.05). Conclusion The signal of neuron and blood oxygen is able to represent the change of neurovascular function and evaluate the progression of ischemic stroke. Key words: Stroke; Tomography, optical; Blood vessels