Administration of 17 beta-estradiol attenuates retinal ischemia-reperfusion injury in rats

PURPOSE. Accumulating evidence has suggested that 17 beta-estradiol exerts protective effects against ischemic damage in various organs. In addition, leukocytes that accumulate in postischemic tissues are thought to play a ce ntral role in ischemia-reperfusion injury. This study was designed to evalu ate quantitatively the inhibitory effects of 17 beta-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 b y temporary ligation of the optic nerve. Thirty minutes before induction of ischemia, 17 beta-estradiol (0.1 mg/kg) was administered intrapericoneally . At 6, 12, 24, and 48 hours after reperfusion, leukocyte accumulation in t he retina was evaluated in vivo by means of acridine orange digital fluorog raphy. Histologic and electroretinographic (ERG) studies were carried out t o evaluate retinal damage. RESULTS. Treatment with 17 beta-estradiol significantly inhibited postische mic leukocyte accumulation; the maximum number of accumulating leukocytes w as reduced by 35.7% at 24 hours after reperfusion (P = 0.01). Histologic ex amination showed that administration of 17 beta-estradiol significantly red uced 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 reper fusion showed that recovery of the b-wave amplitude was significantly impro ved with treatment of 17 beta-estradiol (P = 0.023). CONCLUSIONS. The present study demonstrated the inhibitory effects of 17 be ta-estradiol on leukocyte accumulation and subsequent tissue injury during retinal ischemia-reperfusion injury.