单眼致盲后大鼠视觉通路锰增强磁共振成像的实验研究

Manganese-enhanced MR imaging(MEMRI) in the Study of the Visual Pathway in Experimental Rat models with Monocular Blindness

目的:探讨单眼盲大鼠视觉通路锰增强磁共振成像(ME MRI)的形态学改变,并与病理结果相对照,探寻是否建立新的视觉代偿通路及视觉与听觉中枢是否有神经纤维联系。方法:14只健康新生雄性Sprague-Dawley(SD)大鼠随机分为双眼盲组(Group A)与正常组(Group B)(每组n=7),采用右眼视神经离断法使大鼠致盲,盲后4个月分别经两组大鼠的左侧玻璃体内注入0.2M MnCl_2,24h后比较MEMRI表现,并与病理结果相对照,以帮助确定视觉代偿通路的产生。结果:MEMRI显示单眼盲大鼠左侧视觉通路代表结构(视神经、视束、外侧膝状体、上丘及视皮层)的对比度(CNR)明显高于右侧(P<0.001),而比正常大鼠的左眼的视觉通路信号稍差(P<0.05)。MEMRI表现与病理结果具有较好一致性。结论:新生大鼠单眼致盲4个月后,ME MRI改变结合病理结果,提示双侧视觉通路有功能重组。

Purpose： To investigate the changes of visual pathway of rats with grown blind eye by MEMRI, and to verify the changes by pathology results. Methods： The operation of optic nerve transection was performed to obtain monocular blindness （right eye） models in 14 newborn normal rats. Four months later （critical period）, 0.2M MnCI2 was intravitreally injected into the left eyes, 24h later, MEMRI of visual pathway of right and left eyes were acquired and compared. We aimed to find if there was new visual compensatory pathway by comparing the MEMRI findings of visual pathway in the normal rats and pathology results in monocular blindness rats. Results： Four months after the blindness model was built, MEMRI demonstrated the CNR of visual pathway of the non-blind eye was much higher than that of blind eye （P〈0.001）, the CNR of visual pathway of the non-blind eye was slightly lower than that of left eye in normal rat（P〈0.05）, the CNR of the non-blind eye was slightly higher than that of right eye accompanied with atrophy in normal rat. The results of MEMRI of visual pathway were confirmed by the pathology results. ConcLusion： Four months after the blindness model was built in new born rats, MEMRI and pathology results demonstrated that bilateral different structures of visual pathway of both blind and non-blind eyes were reorganized.