Expression pattern of erythropoietin and erythropoietin receptor in experimental model of retinal detachment.
OBJECTIVE
Erythropoietin (EPO), known for its role in erythroid cell differentiation, has been suggested to have a neuroprotective effect on retinal neurons. The aim of the current study was to investigate the expression pattern of EPO and erythropoietin receptor (EPOR) in the detached retina of a rat model of retinal detachment (RD).


METHODS
Forty-eight albino Sprague-Dawley rats were randomized into normal control group (n = 6) and RD model group (n = 42). The rat RD model was established by slow injection of 1.4% sodium hyaluronate into the upper half of the subretinal space, in which the upper half of the neurosensory retina was detached from the underlying retinal pigment epithelium (RPE). The expression of EPO and EPOR mRNA/protein was determined at 1, 3, 6, 12, 24, 48, and 72 hr after sodium hyaluronate injection by semiquantitative RT-PCR and Western blot analysis, respectively. Meanwhile, the distributions of EPO and EPOR were examined by immunohistochemistry.


RESULTS
EPO and EPOR mRNA levels increased gradually after sodium hyaluronate injection and peaked 48 hr later. EPO mRNA level became significantly higher than that in the normal control group at 12 hr after injection, and EPOR mRNA level became significantly higher at 6 hr (p < 0.05). Moreover, the protein levels of EPO and EPOR presented a similar tendency to the mRNA level and became significantly higher than those in normal control group at 3 hr after injection (p < 0.05). Immunohistochemical results showed that both EPO and EPOR were strongly expressed all over the neurosensory retina 48 hr after injection, but EPOR was not found in the rod outer segment. Only weak expression of EPO and EPOR was noticed in the retina of normal control group.


CONCLUSIONS
The levels of EPO and EPOR in detached retina increase with the duration of retinal detachment and reach their peaks at 48 hr; most layers of detached neurosensory retina can express EPO and EPOR. It is indicated that the EPO/EPOR system might play an important role in protection of retinal neurons during RD; supplementation with exogenous EPO might promote the survival of retinal neurons.
Xie
Zhenggao
Z
Department of Ophthalmology, The First Affiliated Hospital, Shanghai Jiao Tong University, Shanghai 200080, China. wxweye@hotmail.com
Wu
Xingwei
X
Qiu
Qinghua
Q
Gong
Yuanyuan
Y
Song
Yi
Y
Gu
Qing
Q
Li
Caihong
C
D000818:Animals; D015153:Blotting, Western; D004921:Erythropoietin / Q000235:genetics / Q000378:metabolism*; D006820:Hyaluronic Acid / Q000008:administration & dosage; D007150:Immunohistochemistry; D007267:Injections; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017467:Receptors, Erythropoietin / Q000235:genetics / Q000378:metabolism*; D012160:Retina / Q000378:metabolism; D012163:Retinal Detachment / Q000139:chemically induced / Q000378:metabolism*; D013997:Time Factors; D014018:Tissue Distribution
D012333:RNA, Messenger; D017467:Receptors, Erythropoietin; D004921:Erythropoietin; D006820:Hyaluronic Acid