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Liu Yang, Xiaoling Jiao, Yuan Peng; Neuroprotective effect of minocycline on mouse retinal ganglion cells in the early stage after optic nerve crush. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2441.
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© ARVO (1962-2015); The Authors (2016-present)
To observe the effect of minocycline on retinal ganglion cells in the early stage after optic nerve crush in mice, and to explore the neuroprotective mechanism.
One hundred and thirty-six C57BL/6J mice were randomly divided into three groups: control group, saline group and minocycline group. The optic nerve crush injury model was induced in the left eyes of saline and minocycline group by a cross-action forceps for 3 seconds. Minocycline was injected intraperitoneally in minocycline group, first with 45mg/kg, after 24h, with 22.5mg/kg per day, and the same dose of normal saline was injected in saline group. The mice was euthanized at 4d, 7d, 11d, 14d postoperatively and the eyeball was collected. Retinal flat mounts and DAPI staining was used to observe RGC loss. RGC apoptosis were assessed by TdT-mediated dUTP nick end labeling(TUNEL). Real-time reverse transcription-polymerase chain reaction (RT-PCR ) was used to measure the mRNA of retinal microglial CD11b. Electron microscopy was used to observe autophagosomes, and the conversion of microtubule-associated protein 1 light chain3 (LC3-I) to LC3-II was detected in western blot.
DAPI staining in retinal flat mounts showed that, the average cell number of RGC layer was lower in saline group than in minocycline group at 4d, 7d (P<0.01),but did not vary significantly at 11d, 14d (P=0.708) .The number of apoptotic RGCs in minocycline group was reduced significantly at 4 d, 7d (P<0.05), and apoptotic cells were absent in both groups at 11d, 14d. RT-PCR showed that the expression of CD11b were higher in saline group than minocycline group at 4d, 7d (P<0.01), but did not vary significantly at 11d, 14d (P=0.055). EM revealed autophagosomes appearances within first hour after lesion in saline group. While in minocycline group, the autopahgosomes showed in 7d.And the results of western blot confirmed that the increase of LC3-II was delayed in minocycline group.
Minocycline inhibits microglia activation and RGCs apoptosis, thus delays the loss of RGCs in the early stage after optic nerve crush in mice. Minocycline also appears to protect RGCs after ONC in mice by delaying autophagy activation.
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