Proteomic analysis of optic nerve in the rat model of non-arteritic anterior ischemic optic neuropathy

Objective

To quantitatively analyze the protein expression changes of the optic nerve in an SD rat model of non-arteritic anterior ischemic optic neuropathy (NAION), and to make bioinformatics analysis of the differential proteins.

Methods

Ten 8-week-old SPF male SD rats with a body mass of 200-250 g were selected.The NAION model was established using the method of rose bengal and laser photodynamics.Four from the 8 rats with successful model were selected as the NAION model group.Another 4 body weight- and age-matched healthy SD rats without eye diseases were taken as the normal control group.The optic nerve was dissected on the 7th day after modeling.The samples were prepared by the enzyme digestion method, and the proteins were identified and quantitatively detected by isobaric tag for relative and absolute quantification labeling combined with liquid chromatography-tandem mass spectrometry.The proteins with expression fold greater than 1.5 times and significant differences between the two groups (P<0.05) were defined as differentially expressed proteins and analyzed by bioinformatics.The use and care of animals complied with Regulations for the Administration of Affair Concerning Experimental Animals by the State Science and Technology Commission of China.The study protocol was approved by an Animal Ethical and Welfare Committee of Tianjin Medical University Eye Hospital (No.TJYY2021041029).

Results

Three days after modeling, the optic disc of rats was swollen and fluorescein leakage in the optic disc was detected in fluorescein fundus angiography images in the NAION model group, which indicated the model was established successfully. A total of 1 291 quantifiable proteins including 80 differentially expressed proteins were identified.Compared with the normal control group, there were 5 up-regulated proteins and 75 down-regulated proteins.The expression levels of collagen alpha-1(V) chain (Col5A1), cAMP-dependent protein kinase catalytic subunit beta (Prkacb) and disks large homolog 1(Dlg1) were increased, and the expression levels of neurofilament medium polypeptide (Nefm), microtubule-associated protein 1B (Map1b), Ras-related protein Ral-A (Rala), serine/threonine-protein kinase N2 (Pkn2) and platelet-activating factor acetylhydrolase IB subunit beta (Pafah1b1) were decreased.Differentially expressed proteins were mainly involved in the biological processes, including regulation of the cytoskeleton, cellular response to hypoxia, axon production and extension, regulation of synapse, regulation of neuron apoptosis and axo-dendritic transport, etc.KEGG pathway enrichment analysis showed that differentially expressed proteins were mainly involved in metabolic pathways, synaptic vesicle circulation and platelet activation.

Conclusions

The expression of proteins related to signal pathways such as nerve growth, energy metabolism, axo-dendritic transport and apoptosis is involved in the apoptosis of neurons in NAION.