Short term pretreatment with medroxyprogesterone and testosterone may potentiate irradiation damage to spermatogenesis in rats.

Background: Hormonal treatments lasting 2-6 months inhibit spermatogenesis in men and have been proposed as germ cell protection against anticancer therapy. Because it is unthinkable to delay anticancer treatments, the authors investigated the protection afforded against irradiation of rats by 22 days of hormonal pretreatment.

Methods: Adult Sprague-Dawley rats were assigned to an untreated control group (C) or to one of 5 treatments: medroxyprogesterone acetate plus testosterone only (M), 3 or 5 gray of irradiation (R3 and R5), or hormonal treatment prior to 3 or 5 gray of irradiation (MR3 and MR5). Mating trials were conducted 1, 24, 45, 65, 86, and 109 days after treatment. At 122 days, genital organ weights, testis histology, and epididymal spermatozoa were evaluated.

Results: Irradiation reduced sperm production and had a clastogenic effect on postmeiotic germ cells. No protective effect of steroid treatment was observed. Moreover, testis weight, tubule diameter, the repopulating index, and the sperm head count decreased more in the MR5 group than in the R5 group. Mating tests showed decreases in positive vaginal smears and fertility at both 45 and 65 days, and an increase in resorption at 109 days.

Conclusions: These results indicate that hormonal pretreatment potentiates irradiation damage to germ cells, especially stem cells, as regards survival and genomic alterations, probably because of increased lipoperoxidation of late spermatids.