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Updated: May 26, 2026

An Engulfment Assay: A Protocol to Assess Interactions Between CNS Phagocytes and Neurons
Published on: June 8, 2014
Enhanced engulfment by microglia and oligodendrocyte precursor cells contributes to synapse loss in the primary
Qinyuan Hu1, Deling Li2, Yixiao Fu1
1State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, Guangdong, China.
Aims:
To investigate the alterations of glial cells and synapses as well as their interactions in the primary visual cortex (V1) following optic nerve injury.
Methods:
Bilateral V1 tissues of mice were collected 4 weeks after unilateral optic nerve crush (ONC) or sham surgery. Synaptic changes were examined by transmission electron microscopy (TEM), immunofluorescence and western blot. Immunofluorescence assessed the quantity of glial cells and their engulfment of vGluT2. Quantitative real-time polymerase chain reaction (qPCR) and immunofluorescence evaluated the expression of phagocytic genes.
Results:
In the contralateral V1 of ONC mice, presynaptic vesicles and PSD length decreased, synaptic puncta of SYP in L2/3, L4, and L6, as well as PSD95 and vGluT2 puncta in L4 reduced. Microglia, astrocytes, and oligodendrocyte precursor cells (OPCs) increased and phagocytosis analysis revealed enhanced vGluT2 engulfment by microglia and OPCs, but not astrocytes in the contralateral V1 of ONC mice. The number of vGluT2 puncta tagged by C1q, and the colocalization of microglia or OPCs with MERTK, were both elevated in the ONC-contra group.
Conclusions:
Optic nerve injury leads to synaptic impairment and glial cells alterations in the contralateral V1. Enhanced synaptic engulfment by microglia and OPCs contributes to synapse loss in the V1 after optic nerve injury.
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