2,3,7,8-四氯二苯并对二噁英对大鼠卵巢颗粒细胞雌二醇和孕酮分泌的影响

为研究2,3,7,8-四氯二苯并对二噁英(TCDD)对体外原代培养大鼠卵巢颗粒细胞活力和雌二醇(Estradiol,E2)、孕酮(Progestone,P)分泌的影响,探索TCDD对卵巢颗粒细胞的毒性作用阈值和程度,对未成熟SD大鼠卵巢颗粒细胞进行了原代培养,并设2组体外染毒实验:终浓度分别为0.1、1、10、100nmol·L-1TCDD染毒24h和10nmol·L-1TCDD染毒1、3、6、18、24h.染毒结束后采用MTT法检测细胞活力,RIA法检测收集培养液中的E2和P含量.结果表明,1、10、100nmol·L-1TCDD可显著抑制大鼠卵巢颗粒细胞活力和E2、P的分泌,与阴性对照、0.1%DMSO组、0.1nmol·L-1TCDD组比较差异均有显著性(p<0.05);10nmol·L-1TCDD染毒6、18、24h可明显抑制细胞活力和E2、P的分泌,与对照组和短期染毒组(1h、3h)差异均有显著性(p<0.05).痕量的TCDD可显著降低大鼠卵巢颗粒细胞活力并抑制细胞E2和P分泌,对大鼠卵巢颗粒细胞的毒性作用阈值可能为1nmol·L-1或更低.TCDD的生殖毒性作用可能与直接对卵巢颗粒细胞的毒性作用和抑制甾体激素的生物合成以及分泌有关.

Effects of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin on Estradiol and Progestone Secretion of Ovarian Granulosa Cells in Rats in Vitro

In order to investigate the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD)on the secretion of estradiol(E2)and progestone(P),and the viability of ovarian granulosa cells in rats in vitro,ovarian granulosa cells were exposed to two conditions:(i)different concentrations(0.1,1.0,10,and 100nmol·L-1)of TCDD for 24 hours,and(ii)10nmol·L-1 of TCDD for different time periods(1,3,6,18,and 24h).Cell viability was assayed by the MTT method,and concentrations of progestone and estradiol were determined by the RIA method.Results showed that the viability of granulosa cells and the accumulation of estradiol and progestone in the media with exposure to 1,10,or 100nmol·L-1 TCDD were inhibited significantly(p<0.05)compared with negative control,0.1% DMSO,and 0.1nmol·L-1 TCDD;The secretion of estradiol and progestone and the viability of ovarian granulosa cells in rats were significantly(p<0.05)lower with a TCDD treatment for 6,18,or 24 hours than those from the control group and the short-term treatment groups(1 and 3h).This study demonstrates that trace-level TCDD may remarkably reduce cell viability and inhibit the secretion of estradiol and progestone of ovarian granulosa cells in rats,and the toxicity threshold of ovarian granulose cells may be 1nmol·L-1 TCDD or even lower.The results suggest that TCDD may be capable of mediating the activity of mammalian ovary through a direct inhibition of steroid secretion of ovarian granulosa cells.