青春期前己烯雌酚暴露对大鼠性成熟后生精细胞凋亡的影响及其机制初探

目的:研究青春期前己烯雌酚(d iethylstilbestrol,DES)暴露对SD大鼠性成熟后睾丸生精细胞凋亡的影响并初步探讨其机制。方法:30只21日龄雄性SD大鼠,随机分为DES 0.01、0.1、1.0、10.0μg/(kg.d)4个实验组和1个对照组(编码为ADa、ADb、AD c、ADd和AC组,每组6只)。于青春期前出生后第22 d(postnatal day 22,PND22)至35 d(PND35)],实验组每日皮下注射相应剂量的DES,对照组仅注射溶媒。于大鼠性成熟后(PND 64)处死各组大鼠切取双侧睾丸,采用TUNEL法检测大鼠睾丸生精细胞凋亡,用免疫组化方法检测凋亡相关蛋白Bc l-2和Bax在生精细胞中的表达。结果:与对照组相比,ADa组大鼠性成熟后生精细胞凋亡无明显变化,ADb、AD c和ADd 3组生精细胞凋亡增加,且随DES暴露剂量增加而有增加趋势。AC、ADa组生精细胞Bax相对弱表达而Bc l-2强表达,伴随DES暴露剂量增加,Bax表达逐渐增强而Bc l-2表达逐渐减弱,ADd组Bax强表达而Bc l-2弱表达。结论:青春期前较大剂量DES暴露可使大鼠性成熟后睾丸生精细胞凋亡增加,且随DES暴露剂量增加而有加强趋势。凋亡相关蛋白Bax和Bc l-2参与青春期前DES暴露所致的生精细胞凋亡过程。

A Preliminary Study on the Effect of Prepubertal Exposure of Male Rats to Diethylstilbestrol on the Apoptosis of Spermatogenic Cells after Sexual Maturation and Its Mechanism

OBJECTIVE: To preliminarily study the effect of prepubertal exposure of male SD (Sprague-Dawley) rats to diethylstilbestrol (DES) on the apoptosis of spermatogenic cells after sexual maturation and its mechanism. METHODS: Thirty 21-day-old male SD rats were randomly divided into 4 experimental groups, DES 0.01, 0.1, 1.0 and 10.0 microg/(kg x d) and 1 control group. The experimental groups were injected (s.c.) with different doses of DES (dissolved in corn oil) during prepuberty from postnatal day (PND) 22 to PND 35] and the control group with medium only. The apoptosis and related proteins Bcl-2 and Bax expressions of testicular spermatogenic cells were studied with TUNEL and immunohistochemistry after the rats sexual maturation (at PND 64). RESULTS: Compared with the control group, the apoptosis of testicular spermatogenic cells in the DES 0.01 microg/kg group had no difference, but significantly increased in the DES 0.1, 1.0 and 10.0 microg/kg groups and the apoptosis increased with the increase of DES dose. In the control and DES 0.01 microg/kg groups, Bax protein expressed weakly but Bcl-2 protein strongly in spermatogenic cells. With the increase of DES exposure, Bax protein expression in spermatogenic cells increased but Bcl-2 protein expression decreased. CONCLUSION: Prepubertal exposure of SD rats to inappropriate dose of DES can make the apoptosis of spermatogenic cells increase after sexual maturation. Bax and Bcl-2 proteins participate in the apoptotic course caused by prepubertal DES exposure.