[Effects of prepubertal exposure to estradiol benzoate on testicular development and function of Sprague-Dawley rats].
Klíčová slova
Abstraktní
OBJECTIVE
To investigate the effects of prepubertal exposure to estradiol benzoate (EB) on the testicular development and function of SD rats.
METHODS
Fifty four 21-day-old male SD rats were randomly and equally divided into 2 experimental groups (AEa and AEb, n = 18 each) and one control group (AC, n = 18). The rats in the experimental groups were injected (s. c.) with EB dissolved in corn oil at a dose of 0.1 (AEa) and 100.0 microg/(kg x d) (AEb) respectively during prepuberty for 14 d [from postnatal day (PND) 22 to PND 35]. The rats in the control group received vehicle injections only. The testicular development of the rats was observed. The testes were harvested at the stages of late puberty (PND 50), sexual maturity (PND 64) and adulthood (PND 130) (n = 6 at each stage). The serum testosterone, the weights and histology of the testes, and the quality of sperms in the epididymal cauda were examined.
RESULTS
The testes of rats in group AEb descended at day 43.17 +/- 1.72, later than the rats in the AC group (27.00 +/- 0.89, P < 0.01). At the stage of late puberty, the AEb group had lower serum testosterone than the AC group (P < 0.05) and had less unilateral testes weights than the AC group (P < 0.01). Compared with the AC group, the histological alteration of the testes of rats in the AEb group included seminiferous tubules maldevelopment, decreased cell numbers of seminiferous epithelia, spermatogenesis blocking and Leydig cells aplasia. At the stage of sexual maturity, the AEb group had less unilateral testes weight than the AC group (P < 0.01) and maintained similar histological alterations of testes as at the stage of late puberty. At the stage of adulthood, no differences were observed among the three groups in the unilateral testes weights and the histological features of the testes (P > 0.05). However, the AEb group had significant lower density and motility of sperms and percentage of grade a+b sperms in the epididymal cauda than the AC group (P < 0.05).
CONCLUSIONS
Prepubertal exposure to low dose of EB does not affect the testicular development and function of SD rats, while high dose [100 microg/(kg x d) x 14 d] exposure has significant short (PND 50 and 64) and long-term (PND 130) toxic effects. The toxic effects are associated with the damage of Leydig and Sertoli cells.
