Estrogen suppression of surgically induced vascular intimal hyperplasia in rabbits

Since estrogen has been shown to reduce aortic medial hypertrophy in hypertensive rats, a naturally occurring estrogen compound, estradiol, was studied for its ability to suppress the intimal hyperplasia which follows vessel transection and anastomosis. Suture lines and adjacent abdominal aortas were examined by light and electron microscopy 1 month after surgery, in 23 rabbits. Test animals were given 200 microgram of Depoestradiol I.M. weekly, starting 3 days preoperatively. Control animals were similarly manipulated but received no estrogen. Control animals showed striking intimal thickening over the sutures, in contrast to the estrogen-treated group in which there was significantly less growth of corresponding tissue (p less than 0.01).