Administration of 17beta-estradiol attenuates retinal ischemia-reperfusion injury in rats.
OBJECTIVE
Accumulating evidence has suggested that 17beta-estradiol exerts protective effects against ischemic damage in various organs. In addition, leukocytes that accumulate in postischemic tissues are thought to play a central role in ischemia-reperfusion injury. This study was designed to evaluate quantitatively the inhibitory effects of 17beta-estradiol on leukocyte accumulation during ischemia-reperfusion injury and on subsequent retinal damage after transient retinal ischemia.


METHODS
Transient (60 minutes) retinal ischemia was induced in male rats by temporary ligation of the optic nerve. Thirty minutes before induction of ischemia, 17beta-estradiol (0.1 mg/kg) was administered intraperitoneally. At 6, 12, 24, and 48 hours after reperfusion, leukocyte accumulation in the retina was evaluated in vivo by means of acridine orange digital fluorography. Histologic and electroretinographic (ERG) studies were carried out to evaluate retinal damage.


RESULTS
Treatment with 17beta-estradiol significantly inhibited postischemic leukocyte accumulation; the maximum number of accumulating leukocytes was reduced by 35.7% at 24 hours after reperfusion (P = 0.01). Histologic examination showed that administration of 17beta-estradiol significantly reduced retinal damage, which was most obvious in the inner retina, 168 hours after reperfusion (P = 0.0001). ERG studies at 12 and 168 hours after reperfusion showed that recovery of the b-wave amplitude was significantly improved with treatment of 17beta-estradiol (P = 0.023).


CONCLUSIONS
The present study demonstrated the inhibitory effects of 17beta-estradiol on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.
Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Japan.
A
A
Nonaka
J
J
Kiryu
A
A
Tsujikawa
K
K
Yamashiro
K
K
Miyamoto
H
H
Nishiwaki
M
M
Mandai
Y
Y
Honda
Y
Y
Ogura
D000165:Acridine Orange; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D004596:Electroretinography; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology*; D015590:Fluorophotometry; D007274:Injections, Intraperitoneal; D007958:Leukocyte Count; D007962:Leukocytes / Q000502:physiology; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans; D015427:Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D012164:Retinal Diseases / Q000378:metabolism / Q000517:prevention & control*; D012171:Retinal Vessels / Q000166:cytology / Q000502:physiology
D004958:Estradiol; D000165:Acridine Orange