Dose- and photoperiod-dependent effects of 17β-estradiol and the anti-estrogen ICI 182,780 on testicular structure, acceleration of spermatogenesis, and aromatase immunoexpression in immature bank voles

It has been known that administration of estrogens or deficiency of estrogens can affect development and/or maintenance of male gonadal functions. These hormones are able to control germ cell development, and especially spermatid production and epididymis sperm maturation. The aim of the present study was to show the effects of 17β-estradiol and a pure anti-estrogen, ICI 182,780, on the bank vole testis. Immature bank voles reared under either short or long light cycles were injected intraperitoneally with two doses of either 17β-estradiol (0.1 and 10 μg/g body weight, respectively) or pure anti-estrogen ICI 182,780 (10 and 100 μg/g body weight, respectively) both dissolved in 20 μl sesame oil. Control groups (from both photoperiods) received 20 μl sesame oil only. The injections were performed twice a week during 2 weeks. Exposure to the low dose of estradiol induced acceleration of the onset of spermatogenesis. This was particularly apparent in voles kept under short light cycle conditions. On the other hand, when males were treated with a high dose of estradiol or ICI 182,780, disruption of testicular structure and tubular atrophy were observed. Increased apoptosis of germ cells was evident. It is concluded that bank voles as seasonally breeding animals are a useful model for studying the role of estrogens in structure and function of the testis.