Clarification of the effects of diethylstilbestrol, an endocrine disruptors, on synaptic plasticity and its application as an detailed test

从妊娠第11 ~ 17天开始，ddY小鼠每天一次经口给予100 ng己烯雌酚（DES）溶于30 μl玉米油或单独给予玉米油。出生后6周（PNW），DES暴露组海马CA 1区长时程增强（LTP）增强。而DES暴露组在PNW 6时长时程抑郁（LTD）消失。LTP的增强与被动回避测试中的学习障碍有关。雌激素受体基因敲除小鼠的初步研究结果表明，雌激素受体α可能参与了DES对突触可塑性的影响。为了阐明这一可能性，今后有必要进行进一步的研究。蛋白质组学分析显示，DES产前暴露组至少有9种蛋白质水平发生了2倍以上的变化。其中3个可能是乳酸脱氢酶、乳酸脱氢酶2和微管蛋白α。然而，这些物质是否参与突触可塑性尚不清楚。未观察到产前DES暴露对雌性小鼠的影响。DES对突触可塑性影响的性别差异有待进一步研究，DES对LTP的影响与频率刺激条件有关，即50 Hz 30脉冲比20 Hz 100脉冲更能诱导LTP。产前DES暴露对LTP和LTD的影响在PNW 6时最为突出。离体实验表明DES对LTP的影响弱于17β-雌二醇，这种作用可能通过雌激素受体介导。总之，结合两个实验方案，对LTP的影响所造成的50 Hz 30脉冲和对LTD的影响所造成的1 Hz 900脉冲，可能是有用的验证具有雌激素活性的环境干扰剂，如DES的突触可塑性的影响。

Diethylstilbestrol(DES) 100 ng dissolved in 30 μl corn oil or corn oil alone was administered orally to ddY mice once a day from gestation day 11 to 17. When performed at post natal week(PNW) 6, long term potentiation(LTP) in the hippocampal CA1 was enhanced in DES exposure group. On the other hand, long term depression(LTD) was abolished at PNW6 in DES exposure group. Enhancement of LTP was related to the learning disability in the passive avoidance test. Preliminary data in estrogen receptor knock out mice showed the possibility that ERα might contribute to the DES-induced effects on the synaptic plasticity. To elucidate this possibility, further studies are necessary in the future. Proteome analysis revealed that the levels of at least 9 proteins were changed by more than 2 times in prenatal DES exposure group. Three of them were possibly lactate dehydrogenase, lactate dehydrogenase 2 and tubulin alpha. Nothing, however, is known about whether or not these substances are involved in the synaptic plasticity. No effect of prenatal DES exposure in female mice was observed. Further studies are needed to clarify the sexual differences in the effect of DES on the synaptic plasticity.The effect of prenatal exposure of DES on the LTP depended on condition of frequency stimulation, that is, stimulation with 50 Hz 30 pulses was more effective to induce LTP than that with 20 Hz 100 pulses. Effects of prenatal DES exposure on LTP and LTD were the most prominent at PNW6. In vitro experiment suggested that the effect of DES on LTP, which may be mediated through estrogen receptors, was weaker than 17β-estradiol. In conclusion, combination of two experimental protocols, effect on the LTP caused by 50 Hz 30 pulses and effect on the LTD caused by 1 Hz 900 pulses, might be useful for verifying effect on the synaptic plasticity of environmental disrupters possessing estrogenic activity such as DES.