目的 观察玻璃体腔注射不同浓度Mn2+对兔眼视网膜的毒性,从而筛选出合理的玻璃体腔注射浓度,为临床应用和实验研究提供依据.方法 36只青紫兰兔,随机分为9组,其中8个实验组分别于单眼玻璃体内注入不同浓度MnCl2溶液(0.5、1、2、5、10、15、20、40mmol·L-1)25μL,对照组单眼注射同容积生理盐水,均于注药7d后取材,光学显微镜、电子显微镜观察评价Mn2对眼视网膜组织结构的毒性作用.结果 1)玻璃体腔注入0.5 ～ 15mmol·L-1 MnCl2 7d后,视网膜外节盘膜完整,排列规则,各级神经元之间的排列正常,细胞核染色质分布均匀,超微结构未发现明显异常；2)当浓度＞ 20 mmol·L-1病理损伤渐明显.结论 注射剂量25 μL,浓度＜15mmol·L-1的MnCl2溶液是青紫兰兔玻璃体腔注射的安全剂量.%Objective To investigate the toxic effect of 0.5 -40 mmol/L Mn2+ on rabbit retina after intravit-real injection, and to verify the safe dose of intravitreal injecting MnCl2. Methods Thirty - six pigment rabbits were divided at random into 9 groups. A single dose of MnCl2 (25 μL) with the concentrations of 0. 5 , 1, 2,5, 10, 15, 20, 40 mmol·L-1 were intravitreally injected separately in 8 groups, and the normal rabbits were used as control group. Retinal toxicity was examined by light microscope and transmission electron microscopy (TEM) on the seventh day after injection. Results Histological examinations showed that the the morphology of retina was normal in 0. 5 , 1, 2, 5 , 10 mmol·L-1 MnCl2 group on the seventh day after injection. No obvious cellular degeneration was seen in various layers of retina in 20 mmol·L-1 MnCl2 group on the seventh day after injection,however, in 40 mmol·L-1 MnCl2 group, the disorder of retinal structure, disappearance of outer plexiform layer, inordinance of cells arrangement in internal granular layer were seen under the light microscope. TEM examination revealed mild RPE cells abnormality in 20 mmol·L-1 MnCl2 group, but pyknosis of RPE cells, loss of disc membrane, nonintact of outer limiting membrane were exhibited in 40 mmol·L-1 MnCl2 group under the TEM on the seventh day after injection. Conclusion This study indicate that the safe dose of MnCl2 as a tracer of optical pathway via intravitreal injection is < 15 mmol·L-1.
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