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Alterations of the synapse of the inner retinal layers after chronic intraocular pressure elevation in glaucoma animal model.
Mol Brain. 2014 Aug 13; 7:53.MB

Abstract

BACKGROUND

Dendrites of retinal ganglion cells (RGCs) synapse with axon terminals of bipolar cells in the inner plexiform layer (IPL). Changes in RGC dendrites and synapses between bipolar cells in the inner retinal layer may critically alter the function of RGCs in glaucoma. Recently, synaptic plasticity has been observed in the adult central nervous system, including the outer retinal layers. However, few studies have focused on changes in the synapses between RGCs and bipolar cells in glaucoma. In the present study, we used a rat model of ocular hypertension induced by episcleral vein cauterization to investigate changes in synaptic structure and protein expression in the inner retinal layer at various time points after moderate intraocular pressure (IOP) elevation.

RESULTS

Synaptophysin, a presynaptic vesicle protein, increased throughout the IPL, outer plexiform layer, and outer nuclear layer after IOP elevation. Increased synaptophysin after IOP elevation was expressed in bipolar cells in the innermost IPL. The RGC marker, SMI-32, co-localized with synaptophysin in RGC dendrites and were significantly increased at 1 week and 4 weeks after IOP elevation. Both synaptophysin and postsynaptic vesicle protein, PSD-95, were increased after IOP elevation by western blot analysis. Ribbon synapses in the IPL were quantified and structurally evaluated in retinal sections by transmission electron microscopy. After IOP elevation the total number of ribbon synapses decreased. There were increases in synapse diameter and synaptic vesicle number and decreases in active zone length and the number of docked vesicles after IOP elevation.

CONCLUSIONS

Although the total number of synapses decreased as RGCs were lost after IOP elevation, there are attempts to increase synaptic vesicle proteins and immature synapse formation between RGCs and bipolar cells in the inner retinal layers after glaucoma induction.

Authors+Show Affiliations

No affiliation info availableNo affiliation info availableDepartment of Ophthalmology and Visual Science, Seoul St, Mary's Hospital, College of Medicine, The Catholic University of Korea, #505 Banpo-dong, Seocho-gu, Seoul 137-701, Korea. ckpark@catholic.ac.kr.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

25116810

Citation

Park, Hae-Young Lopilly, et al. "Alterations of the Synapse of the Inner Retinal Layers After Chronic Intraocular Pressure Elevation in Glaucoma Animal Model." Molecular Brain, vol. 7, 2014, p. 53.
Park HY, Kim JH, Park CK. Alterations of the synapse of the inner retinal layers after chronic intraocular pressure elevation in glaucoma animal model. Mol Brain. 2014;7:53.
Park, H. Y., Kim, J. H., & Park, C. K. (2014). Alterations of the synapse of the inner retinal layers after chronic intraocular pressure elevation in glaucoma animal model. Molecular Brain, 7, 53. https://doi.org/10.1186/s13041-014-0053-2
Park HY, Kim JH, Park CK. Alterations of the Synapse of the Inner Retinal Layers After Chronic Intraocular Pressure Elevation in Glaucoma Animal Model. Mol Brain. 2014 Aug 13;7:53. PubMed PMID: 25116810.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Alterations of the synapse of the inner retinal layers after chronic intraocular pressure elevation in glaucoma animal model. AU - Park,Hae-Young Lopilly, AU - Kim,Jie Hyun, AU - Park,Chan Kee, Y1 - 2014/08/13/ PY - 2014/01/06/received PY - 2014/07/23/accepted PY - 2014/8/14/entrez PY - 2014/8/15/pubmed PY - 2015/4/16/medline SP - 53 EP - 53 JF - Molecular brain JO - Mol Brain VL - 7 N2 - BACKGROUND: Dendrites of retinal ganglion cells (RGCs) synapse with axon terminals of bipolar cells in the inner plexiform layer (IPL). Changes in RGC dendrites and synapses between bipolar cells in the inner retinal layer may critically alter the function of RGCs in glaucoma. Recently, synaptic plasticity has been observed in the adult central nervous system, including the outer retinal layers. However, few studies have focused on changes in the synapses between RGCs and bipolar cells in glaucoma. In the present study, we used a rat model of ocular hypertension induced by episcleral vein cauterization to investigate changes in synaptic structure and protein expression in the inner retinal layer at various time points after moderate intraocular pressure (IOP) elevation. RESULTS: Synaptophysin, a presynaptic vesicle protein, increased throughout the IPL, outer plexiform layer, and outer nuclear layer after IOP elevation. Increased synaptophysin after IOP elevation was expressed in bipolar cells in the innermost IPL. The RGC marker, SMI-32, co-localized with synaptophysin in RGC dendrites and were significantly increased at 1 week and 4 weeks after IOP elevation. Both synaptophysin and postsynaptic vesicle protein, PSD-95, were increased after IOP elevation by western blot analysis. Ribbon synapses in the IPL were quantified and structurally evaluated in retinal sections by transmission electron microscopy. After IOP elevation the total number of ribbon synapses decreased. There were increases in synapse diameter and synaptic vesicle number and decreases in active zone length and the number of docked vesicles after IOP elevation. CONCLUSIONS: Although the total number of synapses decreased as RGCs were lost after IOP elevation, there are attempts to increase synaptic vesicle proteins and immature synapse formation between RGCs and bipolar cells in the inner retinal layers after glaucoma induction. SN - 1756-6606 UR - https://www.unboundmedicine.com/medline/citation/25116810/Alterations_of_the_synapse_of_the_inner_retinal_layers_after_chronic_intraocular_pressure_elevation_in_glaucoma_animal_model_ L2 - https://molecularbrain.biomedcentral.com/articles/10.1186/s13041-014-0053-2 DB - PRIME DP - Unbound Medicine ER -