Purchase this article with an account.
Alena Z. Minton, Nitasha R. Phatak, Hai-Ying Ma, Dorota L. Stankowska, Shaoqing He, Brett H. Mueller, Raghu R. Krishnamoorthy; Endothelin B Receptors Contribute to Neurodegeneration in a Rodent Model of Glaucoma. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5387.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
ETB receptors have gained increased attention for their neurodegenerative role in glaucoma. The present study was aimed at investigating changes in the expression of ETB receptors in vivo in a rodent model of glaucoma and whether neurodegenerative changes following IOP elevation are attenuated in ETB-deficient transgenic rats.
In one set of Brown Norway rats, IOP was elevated in one eye using the Morrison’s method (injection of hypertonic saline through episcleral veins), while the corresponding contralateral eye served as control. After 2 or 4 weeks of IOP elevation, animals were sacrificed. Retinal sections were obtained and stained for ETB receptor expression by immunohistochemistry. Colocalization of ETB receptor immunostaining was performed using an antibody to neuritin, a selective marker of RGCs. In the second set of Brown Norway rats, retinal ganglion cells were retrogradely labeled with Fluoro-gold following which IOP was elevated in one eye using Morrison’s method, while the contralateral eye served as control. After 2 weeks of IOP elevation, animals were sacrificed. Retinas were sectioned and stained for ETB receptor expression by immunohistochemistry. In a separate study, adult wild type and ETB- deficient transgenic Wistar rats were used for retrograde labeling of retinal ganglion cells (RGCs) with Fluoro-gold. Following labeling, IOP was elevated in one eye using the Morrison’s method, while the contralateral eye served as control. After IOP was elevated, rats were maintained for 4 weeks and sacrificed. Fluoro-gold labeled retinas were isolated, flat-mounted, imaged in a Zeiss LSM-510 confocal microscope, and labeled RGCs were counted. Optic nerves were sectioned and stained with p-phenylenediamine (PPD).
Immunohistochemical analysis showed that IOP elevation for both 2 and 4 weeks produced increased expression of ETB receptors in retinal ganglion cells. After retrograde labeling and IOP elevation in Brown Norway rats, increased colocalization of ETB immunostaining with Fluoro-gold was observed in retinal ganglion cells. IOP elevation for 4 weeks in wild type transgenic rats caused significant loss of RGCs and degeneration of axons in the optic nerve, whereas significant neuroprotection of RGCs and optic nerve axons were observed in ETB-deficient transgenic rats.
Increased intraocular pressure caused increased ETB receptor expression possibly through pressure-related mechanism. ETB receptors appear to play a causative role in retinal ganglion cell death in the Morrison’s rodent model of glaucoma.
This PDF is available to Subscribers Only