Germ cell apoptosis induced by progesterone in rats

Objectives:To document the effect of progesterone exposure with large dose and long term on spermatogenesis,especially on the germ cell apoptosis in rats.This study was also to evaluate the toxicity of progesterone in the reproductive system when administered with large doses and long term in men.Methods:Groups of adult male SD rats were administered with 37.5,75 and 150 mg/kg depot-medroxyprogesterone acetate(DMPA)per two-weeks for 12 or 18 weeks.At the end of treatment,each male rat was paired with one adult female SD rat to estimate the reproductive function.Serum testosterone concentration was analyzed in duplicate by radioimmunoassay(RIA).The pathological changes of testes,epididymis,and prostate were checked under light microscopic,epididymis was also used for sperm count,and fresh testis tissue was used for apoptosis assessment by flow cytometry.Results:After treatment with DMPA,weights of gonad,the ratio of testes/body,the ratio of epididymides/body,and the ratio of prostate/body decreased significantly(P<0.01).The level of serum testosterone,sperm count,sperm activity decreased significantly(P<0.01)while abnormality of sperm increased significantly(P<0.01).The embryonic number in uterus of pairing female rat decreased significantly after DMPA treatment.Compared with control,the number and the ratio of apoptotic germ cell increased dramatically(P<0.01)along with dose increase or treating prolongation of DMPA,which analyzed by flow cytometry.Conclusion:In summary,in addition to inhibition of pituitary gonadotrophin and subsequently deprivation of androgen,progesterone(DMPA)inhibits spermatogenesis by the induced germ cell apoptosis.The reproductive toxicity of DMPA administrated with large doses and long term is confirmed.