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Reduced expression of aquaporin-9 in rat optic nerve head and retina following elevated intraocular pressure.
Invest Ophthalmol Vis Sci. 2010 Sep; 51(9):4618-26.IO

Abstract

PURPOSE

To investigate the effect of chronically elevated intraocular pressure (IOP) on the expression of water channel aquaporins (AQPs) 1, 4, and 9 in the optic nerve and retina in rats.

METHODS

Three episcleral veins were cauterized to elevate IOP in the left eyes of Sprague-Dawley rats. IOPs were monitored with a rebound tonometer. At 2 and 4 weeks after surgery, eyeballs with the attached optic nerve were enucleated for cryosectioning with immunohistochemistry, or dissected retinas and desheathed optic nerves were subjected to gene expression analyses.

RESULTS

IOP was significantly increased after surgery up to 4 weeks (P=0.0008). In the control optic nerve, the unmyelinated portion showed only AQP9 immunoreactivity, whereas the myelinated portion expressed both AQP4 and AQP9 immunoreactivities colabeled for glial fibrillary acidic protein but not for neurofilament. In the control retina, AQP1 was expressed in the outer nuclear layer and photoreceptors, AQP4 was expressed in Müller cell endfeet, and AQP9 was expressed primarily in NeuN-positive cells in the ganglion cell layer (GCL). Elevated IOPs substantially reduced AQP9 expression in the optic nerve head (ONH) and the GCL and decreased the retinal gene expression, but not immunoreactivity, of AQP1.

CONCLUSIONS

AQP9 was the only water channel expressed in the unmyelinated portion of the ONH and in the GCL whose expression was reduced after IOP elevation. Given that AQP9 presumably acts as a channel for metabolites to pass from astrocytes to neurons, the reduced expression of AQP9 at these specific sites may be implicated in the pathogenesis of glaucomatous optic neuropathy.

Authors+Show Affiliations

Division of Ophthalmology, Department of Surgery, Kobe University Graduate School of Medicine, Kobe, Japan.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

20357197

Citation

Naka, Maiko, et al. "Reduced Expression of Aquaporin-9 in Rat Optic Nerve Head and Retina Following Elevated Intraocular Pressure." Investigative Ophthalmology & Visual Science, vol. 51, no. 9, 2010, pp. 4618-26.
Naka M, Kanamori A, Negi A, et al. Reduced expression of aquaporin-9 in rat optic nerve head and retina following elevated intraocular pressure. Invest Ophthalmol Vis Sci. 2010;51(9):4618-26.
Naka, M., Kanamori, A., Negi, A., & Nakamura, M. (2010). Reduced expression of aquaporin-9 in rat optic nerve head and retina following elevated intraocular pressure. Investigative Ophthalmology & Visual Science, 51(9), 4618-26. https://doi.org/10.1167/iovs.09-4712
Naka M, et al. Reduced Expression of Aquaporin-9 in Rat Optic Nerve Head and Retina Following Elevated Intraocular Pressure. Invest Ophthalmol Vis Sci. 2010;51(9):4618-26. PubMed PMID: 20357197.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Reduced expression of aquaporin-9 in rat optic nerve head and retina following elevated intraocular pressure. AU - Naka,Maiko, AU - Kanamori,Akiyasu, AU - Negi,Akira, AU - Nakamura,Makoto, Y1 - 2010/03/31/ PY - 2010/4/2/entrez PY - 2010/4/2/pubmed PY - 2010/10/5/medline SP - 4618 EP - 26 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 51 IS - 9 N2 - PURPOSE: To investigate the effect of chronically elevated intraocular pressure (IOP) on the expression of water channel aquaporins (AQPs) 1, 4, and 9 in the optic nerve and retina in rats. METHODS: Three episcleral veins were cauterized to elevate IOP in the left eyes of Sprague-Dawley rats. IOPs were monitored with a rebound tonometer. At 2 and 4 weeks after surgery, eyeballs with the attached optic nerve were enucleated for cryosectioning with immunohistochemistry, or dissected retinas and desheathed optic nerves were subjected to gene expression analyses. RESULTS: IOP was significantly increased after surgery up to 4 weeks (P=0.0008). In the control optic nerve, the unmyelinated portion showed only AQP9 immunoreactivity, whereas the myelinated portion expressed both AQP4 and AQP9 immunoreactivities colabeled for glial fibrillary acidic protein but not for neurofilament. In the control retina, AQP1 was expressed in the outer nuclear layer and photoreceptors, AQP4 was expressed in Müller cell endfeet, and AQP9 was expressed primarily in NeuN-positive cells in the ganglion cell layer (GCL). Elevated IOPs substantially reduced AQP9 expression in the optic nerve head (ONH) and the GCL and decreased the retinal gene expression, but not immunoreactivity, of AQP1. CONCLUSIONS: AQP9 was the only water channel expressed in the unmyelinated portion of the ONH and in the GCL whose expression was reduced after IOP elevation. Given that AQP9 presumably acts as a channel for metabolites to pass from astrocytes to neurons, the reduced expression of AQP9 at these specific sites may be implicated in the pathogenesis of glaucomatous optic neuropathy. SN - 1552-5783 UR - https://www.unboundmedicine.com/medline/citation/20357197/Reduced_expression_of_aquaporin_9_in_rat_optic_nerve_head_and_retina_following_elevated_intraocular_pressure_ L2 - https://iovs.arvojournals.org/article.aspx?doi=10.1167/iovs.09-4712 DB - PRIME DP - Unbound Medicine ER -