Endothelin-1 (ET-1) is increased in rat retina after crushing optic nerve.
OBJECTIVE
To determine the alterations in the expression of endothelin-1 (ET-1) and its specific receptors in the sensory retina after optic nerve injury.


METHODS
The optic nerve of the right eye of Wistar rats was crushed. The sensory retinas were removed 1, 2, 4, 7, and 14 days after the surgery, and the amount of ET-1 in the retinas was measured by radioimmunoassay, and the mRNA levels of ET(A) and ET(B) receptors were determined by real-time PCR.


RESULTS
The ET-1 levels in the sensory retinas following the optic nerve crush were 8.83 +/- 2.23 and 9.99 +/- 4.83 pg/mg protein on days 7 and 14 after the injury, while those in the sham controls were 4.55 +/- 1.36 and 4.85 +/- 1.57 pg/mg protein, respectively. The increase was significant on day 7 (p = 0.003, ANOVA followed by t- test), but not on day 14 (p = 0.054). The mRNA levels of the ET(A) and ET(B) receptors in the retina after the optic nerve crush was significantly increased on day 7. A two-fold increase was recognized in ET(B) receptors. Immunohistochemical analyses revealed that the ET-1 expression was increased mainly in the inner retinal layers, including the nerve fiber layer and ganglion cell layer (GCL). The increased immunoreactivity of the ET(B) receptor was seen in the GCL cells and also in the outer nuclear layer.


CONCLUSIONS
An increase in the intraretinal ET-1 may be involved in the retinal remodeling after the optic nerve is crushed.
Oku
Hidehiro
H
Department of Ophthalmology, Osaka Medical College, Osaka, Japan. hidehirooku@aol.com
Fukuhara
Masayuki
M
Kurimoto
Takuji
T
Okuno
Takashi
T
Sugiyama
Tetsuya
T
Ikeda
Tsunehiko
T
D000818:Animals; D002452:Cell Count; D019332:Endothelin-1 / Q000378:metabolism*; D007124:Immunoenzyme Techniques; D008297:Male; D020221:Optic Nerve Injuries / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D017208:Rats, Wistar; D044022:Receptor, Endothelin A / Q000235:genetics; D044023:Receptor, Endothelin B / Q000235:genetics; D012160:Retina / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D019332:Endothelin-1; D012333:RNA, Messenger; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B