Baptiste D C, Powell K J, Jollimore C A B, Hamilton C, LeVatte T L, Archibald M L, Chauhan B C, Robertson G S, Kelly M E M
Laboratory for Retina and Optic Nerve Research, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4H7.
Neuroscience. 2005;134(2):575-82. doi: 10.1016/j.neuroscience.2005.04.011.
In the present study, we compared the in vivo neuroprotective efficacy of intraperitoneally administered tetracycline and minocycline to enhance the survival of retinal ganglion cells (RGCs) following unilateral axotomy of the adult rat optic nerve. We also examined the effects of the tetracycline drugs on the activation of retinal microglia. RGCs in retinal whole-mounts were visualized by retrograde labeling with fluorogold. The presence of activated microglia was confirmed immunohistochemically using OX-42 monoclonal antibodies. Optic nerve axotomy produced RGC death and increased activation of microglia. No significant RGC loss was seen prior to 5 days and approximately 50% and 80-90% cell loss occurred at 7 and 14 days, respectively. Examination of the effects of tetracycline and minocycline on RGC survival at 7 days post-axotomy, revealed increased numbers of RGCs in minocycline-treated animals (75% of non-axotomized control) compared with vehicle-only (52% of control) and tetracycline-treated (58% of control) animals. The densities of RGCs (RGCs/mm2+/-S.D.) for control, vehicle-, tetracycline- and minocycline-treated axotomized animals were 1996+/-81, 1029+/-186, 1158+/-190 and 1497+/-312, respectively. The neuroprotective effect of minocycline seen at 7 days was transient, since RGCs present in minocycline-treated animals at 14 days post-axotomy (281+/-43, 14% of control) were not significantly different to vehicle-treated animals (225+/-47, 11% of control). OX-42 staining of activated retinal microglia was reduced in tetracycline- and minocycline-treated axotomized animals compared with axotomized animals receiving vehicle-only. These results demonstrate that systemic administration of the second-generation tetracycline derivative, minocycline, delays the death of axotomized RGCs by a mechanism that may be associated with inhibition of microglia activation. The neuroprotective efficacy of minocycline following optic nerve axotomy was superior to that of tetracycline.
在本研究中，我们比较了腹腔注射四环素和米诺环素对成年大鼠视神经单侧切断后提高视网膜神经节细胞（RGCs）存活率的体内神经保护效果。我们还研究了四环素类药物对视网膜小胶质细胞激活的影响。通过用荧光金逆行标记对视网膜铺片中的RGCs进行可视化。使用OX - 42单克隆抗体通过免疫组织化学法确认活化小胶质细胞的存在。视神经切断导致RGCs死亡并增加小胶质细胞的激活。在5天之前未观察到明显的RGCs丢失，在7天和14天时分别发生约50%和80 - 90%的细胞丢失。在视神经切断后7天检查四环素和米诺环素对RGCs存活的影响，发现与仅接受载体处理（对照组的52%）和四环素处理（对照组的58%）的动物相比，米诺环素处理的动物中RGCs数量增加（非切断对照组的75%）。对照组、载体处理组、四环素处理组和米诺环素处理组的切断动物的RGCs密度（RGCs/mm²±标准差）分别为1996±81、1029±186、1158±190和1497±312。米诺环素在7天时观察到的神经保护作用是短暂的，因为在视神经切断后14天米诺环素处理的动物中存在的RGCs（281±43，对照组的14%）与载体处理的动物（225±47，对照组的11%）没有显著差异。与仅接受载体处理的切断动物相比，四环素和米诺环素处理的切断动物中活化视网膜小胶质细胞的OX - 42染色减少。这些结果表明，第二代四环素衍生物米诺环素的全身给药通过一种可能与抑制小胶质细胞激活相关的机制延迟了切断的RGCs的死亡。视神经切断后米诺环素的神经保护效果优于四环素。
