Wójcik-Gładysz Anna, Romanowicz Katarzyna, Misztal Tomasz, Polkowska Jolanta, Barcikowski Bernard
Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland.
Anim Reprod Sci. 2005 Apr;86(3-4):221-35. doi: 10.1016/j.anireprosci.2004.08.004.
Phytoestrogens, plant derived estrogen like-compounds exert numerous effects on the reproductive functions of animals. The present study was designed to demonstrate if exogenous genistein infused during the breeding season into the third ventricle of the brain of ovariectomized ewes could affect the secretory activity of the GnRH/LH axis. Two-year-old ovariectomized ewes (n=8) were infused with vehicle (control, n=3) or genistein (10 microg/100 microl/h, n=5) into the third ventricle. The infusions were done from 10.00 to 14.00 h and blood samples collection was performed this day up to 20.00 h and next day from 8.00 to 10.00 h. The animals were slaughtered, thereafter. Immunoreactive (IR) GnRH neurons in the hypothalamus and LH cells in the adenohypophysis were localized by immunohistochemistry. Messenger RNA analyses were performed by nonisotope in situ hybridization using sense and anti-sense riboprobes produced from beta subunits of LH cDNA clones. Plasma LH concentrations were measured by radioimmunoassay. Immunohistochemical analysis revealed that genistein infusion affected the morphology of GnRH neurons evoking a visualization of long axons in the GnRH perikarya and visibly diminished IR GnRH stores in the median eminence. The number of IR LH cells and IR material stored in the adenohypophyses increased in genistein-infused animals, which was confirmed by statistical analysis (P<0.001). The in situ hybridization analyses showed in these ewes the increase of mRNA LHbeta hybridization signal. The changes in LH release in response to genistein infusion had a biphasic character: it decreased within 6 h after infusion and increased 24 h later. Mean concentration of LH and amplitude of pulses measured from the beginning of infusion up to end of the experiment were significantly higher (P<0.05) in genistein-infused ewes compared to vehicle-treatment. In conclusion, our data show that genistein, a phytoestrogen, may effectively modulate GnRH and LH secretion in OVX ewes by acting directly on the CNS. The biphasic character of the LH response is similar to that of estradiol during the breeding season in the ewes.
植物雌激素是一类源自植物的雌激素样化合物，对动物的生殖功能具有多种影响。本研究旨在证明在繁殖季节向去卵巢母羊的第三脑室注入外源性染料木黄酮是否会影响GnRH/LH轴的分泌活性。将两岁的去卵巢母羊（n = 8）分为两组，一组注入赋形剂（对照组，n = 3），另一组注入染料木黄酮（10微克/100微升/小时，n = 5）到第三脑室。输注时间为10:00至14:00，当天直至20:00以及次日8:00至10:00采集血样。之后宰杀动物。通过免疫组织化学定位下丘脑的免疫反应性（IR）GnRH神经元和腺垂体中的LH细胞。使用从LH cDNA克隆的β亚基产生的正义和反义核糖探针，通过非同位素原位杂交进行信使RNA分析。通过放射免疫测定法测量血浆LH浓度。免疫组织化学分析显示，注入染料木黄酮会影响GnRH神经元的形态，使GnRH核周体中出现长轴突的可视化，并且明显减少正中隆起中IR GnRH的储存量。注入染料木黄酮的动物腺垂体中IR LH细胞的数量和储存的IR物质增加，这通过统计分析得到证实（P<0.001）。原位杂交分析显示这些母羊中mRNA LHβ杂交信号增加。注入染料木黄酮后LH释放的变化具有双相性：注入后6小时内降低，24小时后升高。与赋形剂处理组相比，注入染料木黄酮的母羊从注入开始到实验结束测得的LH平均浓度和脉冲幅度显著更高（P<0.05）。总之，我们的数据表明，植物雌激素染料木黄酮可能通过直接作用于中枢神经系统有效地调节去卵巢母羊的GnRH和LH分泌。LH反应的双相性与母羊繁殖季节中雌二醇的反应相似。
