Erythropoietin with retrobulbar administration protects retinal ganglion cells from acute elevated intraocular pressure in rats.
OBJECTIVE
The aim of this study was to clarify whether erythropoietin (EPO) with a retrobulbar administration could protect retinal ganglion cells (RGCs) from acute elevated intraocular pressure (IOP).


METHODS
The anterior chamber of the right eye was cannulated, and the IOP was raised to 70 mm Hg for a duration of up to 60 min. One thousand (1000) units of recombinant erythropoietin (rhEPO) or vehicle solution was administered a retrobulbar injection immediately after the onset of the acute elevated IOP. After 1 week, RGCs were labeled with a commercially available retrograde tracer applied to the superior colliculi. Densities of surviving RGCs were estimated by counting retrograde-tracer-labeled cells in whole-mounted retinas. The ultrastructural changes of RGCs were observed by transmission electron microscope. Immunocytochemistry was used to detect EPO and erythropoietin receptor (EPOR) expression in the RGCs layer.


RESULTS
The acute elevated IOP could result in the loss of RGCs. The number of surviving RGCs per square millimeter in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group was significantly higher than that in the eyes of the acute elevated IOP and acute elevated IOP + vehicle solution retrobulbar injection groups (P < 0.05). The number of the organelles in the RGCs plasm decreased, but some intact mitochondrian still existed in the RGCs plasm in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group. The densities of EPO and EPOR expression of the RGCs layer in the eyes of the acute elevated IOP + rhEPO retrobulbar injection group were significantly higher than that in the eyes of the acute elevated IOP and acute elevated IOP + vehicle solution retrobulbar injection groups (P < 0.01).


CONCLUSIONS
EPO with a retrobulbar administration could protect RGCs from acute elevated IOP.
Zhong
Yi-Sheng
YS
Department of Ophthalmology, Ruijin Hospital Affiliated Shanghai Jiaotong University, Shanghai, China.
Liu
Xiao-Hong
XH
Cheng
Yu
Y
Min
Ying-Jun
YJ
D000208:Acute Disease; D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004921:Erythropoietin / Q000008:administration & dosage / Q000494:pharmacology*; D007150:Immunohistochemistry; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D046529:Microscopy, Electron, Transmission; D018696:Neuroprotective Agents / Q000008:administration & dosage / Q000494:pharmacology*; D009798:Ocular Hypertension / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control; D051381:Rats; D017207:Rats, Sprague-Dawley; D017467:Receptors, Erythropoietin / Q000378:metabolism; D011994:Recombinant Proteins; D012165:Retinal Ganglion Cells / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
D018696:Neuroprotective Agents; D017467:Receptors, Erythropoietin; D011994:Recombinant Proteins; D004921:Erythropoietin