针刺促进大鼠脑缺血后亚急性期侧枝循环建立的USPIO-DSC MRI研究

USPIO-DSC MRI study on acupuncture promoting collateral circulation of subacute-stage cerebral ischemia in rats

目的应用超微超顺磁性氧化铁(USPIO)动态磁敏感加权增强(DSC)MRI评估针刺对永久性大脑中动脉栓塞(pMCAO)大鼠亚急性期缺血脑区侧枝循环建立的有效性。方法建立36只SD大鼠pMCAO模型和假手术组模型:假手术组9只(A组)、无针刺对照组13只(B组)、电针组14只(C组)。每组再分为72h、5天、7天3个亚组。每只大鼠均在相应时间点在1.5T MRI行USPIO-DSC MRI扫描。测量模型鼠缺血区域的相对脑血容量(rCBV)、相对脑血流量(rCBF)、平均通过时间(MTT)和达峰时间(TTP),获得对侧镜像区域参数值,计算比值(rrCBV、rrCBF、rMTT和rTTP)。观察各个时间点各组间的各参数比值有无统计学差异。评估B组加C组模型鼠rrCBV、rrCBF值与抗CD31染色阳性血管面积百分比(%VA)、微血管计数(MVD)以及血清血管内皮生长因子(VEGF)是否相关。结果C组5天和7天亚组大鼠的rrCBV分别明显高于B组(P<0.05);C组5天亚组的rrTTP明显低于B组(P<0.05)。B组加C组pMCAO模型鼠5天、7天的rrCBV和rrCBF分别与%VA、MVD以及VEGF显著正相关(P<0.05)。结论通过USPIO-DSC MRI,发现针刺通过促进缺血脑区侧枝循环微血管数目和容量的增加来改善永久性大鼠局灶性脑缺血亚急性期缺血脑区的血供。

Objective To evaluate the effectiveness of acupuncture on improving collateral circulation during subacute-stage after permanent middle cerebral artery occlusion(pMCAO)in rats on dynamic susceptibility contrast(DSC)MRI with ultrasmall superparamagnetic particles of iron oxides(USPIO).Methods Thirty-six SD rat models were established,including sham-operation group(group A,n=9),pMCAO group without acupuncture(group B,n=13),pMCAO group with electroacupuncture(group C,n=14).Each group was further divided into 3 subgroups on 72 h,5 days and 7days.USPIO-DSC was performed of every rat on a 1.5 T MR scanner.The values of the relative cerebral blood volume(rCBV),relative cerebral blood flow(rCBF),mean transit time(MTT)and time to peak(TTP)on regions of ischemia and contralateral in mirror were measured.The ratios(ischemia/contralateral)as rrCBV,rrCBF,rMTT and rTTP were calculated.These ratios were compared on three time points among three groups.The correlations between the ratios of Group B plus C and values of vascular endothelial growth factor(VEGF)and histopathologic results including percentage of vessels area quantified on anti-CD31-stained microvessels(%VA)and microvessel density(MVD)were analyzed.Results The values of rrCBV were significantly higher in group C than those in group B on 5th and 7th day(P<0.05).The values of rrTTP were significantly lower in group C than those in group B on 5th day(P<0.05).The values of rrCBV and rrCBF of group B plus C were significantly correlated with the values of%VA,MVD and VEGF on 5th and 7th day,respectively(P<0.05).Conclusion By undergoing USPIO-DSC MRI,we found acupuncture improved the blood supply with regions of ischemia on subacute-stage in pMCAO rats by promoting the increase in the numbers and volume of collateral circulation microvessels.