PROTECTIVE EFFECT OF CATECHOLESTROGEN ON INJURY CAUSED BY CO-60-IRRADIATION IN MICE

When 10-week-old male BALB/c mice received whole-body irradiation with a sublethal 4-Gy single dose of Co-60 gamma-ray, the occurrence of le ucopenia caused by the irradiation was lessened to some extent by subc utaneous injection of 2-hydroxyestradiol (2-OHE(2)), one of catecholes trogens, given 3 h before and 3 h after the irradiation. Upon irradiat ion, the weight of the thymus was reduced, but the recovery of organ w eight was markedly accelerated by subcutaneous injection of 2-OHE(2). Light microscopic observation revealed that 2-OHE(2) prevents the redu ction by gamma-ray irradiation of cortical and medullary volumes of th e thymus. These results indicate that 2-OHE(2) is a potent radioprotec tor.