Progestagens androgenic action on the bone of male castrated mice

It has been suggested that some progestagens could have an androgenic stimulatory effect on bone formation. The androgenic effects of progestagens were tested in vivo in the absence of androgens and estrogens in the castrated male mice, species extraordinary responsive to the withdrawal or administration of androgens. Three progestagens (norethisterone, uterogestan and medroxyprogesterone acetate were compared as to their androgenic activity. Tissues especially sensitive to androgens, the seminal vesicles and kidney of the mice fell significantly after castration and all three progestagens did not affect their weights. The present results confirm the well known fact that castration leads to osteopenia in mice. Uterogestan micronized progesterone and MPA have no effect on the bone density or mineral content of the tibia of tested mice. Only in the case of NETA we observed slight statistically significant (p < 0.05) increase in bone density. Progestagens do not appear to have the androgenic effect on the skeleton and NETA has been suggested as one of the exception. Our results indicate that only NETA at the dose which is used in hormonal therapy for prevention of osteoporosis has a slight protective effect against bone mineral loss in castrated mice.