Department of Animal Physiology, Faculty of Biology and Biotechnology, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland.
Theriogenology. 2013 Jul 15;80(2):90-8. doi: 10.1016/j.theriogenology.2013.03.020. Epub 2013 Apr 21.
Estrogens are produced by porcine embryos during early pregnancy. It was found that the uterus of pigs might be a source of steroid hormones, including estrogens. However, the factors involved in the regulation of endometrial steroidogenesis remain unknown. We hypothesize that interleukin (IL) 1β and IL6, which are cytokines produced by porcine embryos and uterine cells, might be involved in the regulation of endometrial estrogen synthesis. Porcine endometrial explants were harvested from gravid (N = 15) and cyclic (N = 15) pigs on days 10 to 11, 12 to 13, and 15 to 16. Samples were analyzed to determine: (1) the expression of CYP19 mRNA and the presence of aromatase cytochrome P450 protein in the tissue; and (2) the release of endometrial estradiol-17β (E2) in response to IL1β and IL6 after 6 and 12 hours of in vitro incubation. The effects observed in pregnant gilts were compared with the effects in nonpregnant gilts on corresponding days of the estrous cycle. On days 15 to 16 of pregnancy the expression of CYP19 in the endometrium was markedly decreased when compared with other periods, and the quantity of endometrial P450 aromatase protein was higher on these days than on days 12 to 13. In nongravid pigs, the expression of CYP19 was lower on days 15 to 16 when compared with days 12 to 13 and the quantity of P450 aromatase protein did not differ during the studied days of the estrous cycle. Basal endometrial E2 release was higher in pregnant gilts when compared with cyclic gilts only on days 15 to 16. In gravid pigs IL1β and IL6 did not affect endometrial E2 release on days 10 to 11 and 12 to 13 of pregnancy (P > 0.05); however, increased E2 release was observed on days 15 to 16 (P < 0.05). In cyclic pigs neither IL1β, nor IL6 affected endometrial E2 release (P > 0.05). These results provide evidence that: (1) the endometrium possesses a potential for steroidogenesis and produces E2in vitro in gravid and nongravid pigs between days 10 to 16; and (2) IL1β and IL6 increase in vitro endometrial synthesis of E2 in pregnant pigs on days 15 to 16. Therefore, IL1β and IL6 might act as stimulators of endometrial E2 secretion in vitro during the time of decreased production of embryonic estrogens. This correlates with a rapid remodeling of the endometrial tissue and the beginning of hemotrophic nutrition of the embryos occurring on days 15 to 16 of pregnancy.
雌激素是猪胚胎在妊娠早期产生的。人们发现，猪的子宫可能是类固醇激素的来源，包括雌激素。然而，调节子宫内膜甾体生成的因素仍不清楚。我们假设白细胞介素（IL）1β和 IL6，这些细胞因子由猪胚胎和子宫细胞产生，可能参与调节子宫内膜雌激素的合成。在妊娠（N=15）和循环（N=15）猪的第 10-11、12-13 和 15-16 天，从妊娠和非妊娠猪中采集子宫内膜组织样本。分析样本以确定：（1）组织中 CYP19 mRNA 的表达和芳香化酶细胞色素 P450 蛋白的存在；（2）在体外孵育 6 和 12 小时后，子宫内膜雌二醇-17β（E2）对 IL1β 和 IL6 的释放。比较妊娠母猪的影响与发情周期相应天数非妊娠母猪的影响。在妊娠第 15-16 天，与其他时期相比，子宫内膜 CYP19 的表达明显降低，而这些天的子宫内膜 P450 芳香化酶蛋白数量高于第 12-13 天。在非妊娠猪中，与第 12-13 天相比，第 15-16 天 CYP19 的表达更低，研究发情周期的这些天，P450 芳香化酶蛋白的数量没有差异。与循环母猪相比，妊娠母猪仅在第 15-16 天的基础子宫内膜 E2 释放更高。在妊娠第 10-11 和 12-13 天，IL1β 和 IL6 对妊娠母猪的子宫内膜 E2 释放没有影响（P>0.05）；然而，在第 15-16 天观察到 E2 释放增加（P<0.05）。在循环猪中，IL1β 和 IL6 均不影响子宫内膜 E2 的释放（P>0.05）。这些结果表明：（1）子宫内膜具有甾体生成的潜力，并在妊娠和非妊娠猪的第 10-16 天在体外产生 E2；（2）在妊娠第 15-16 天，IL1β 和 IL6 增加了体外子宫内膜 E2 的合成。因此，IL1β 和 IL6 可能在胚胎雌激素产生减少的时期作为体外子宫内膜 E2 分泌的刺激物。这与妊娠第 15-16 天发生的子宫内膜组织快速重塑和胚胎开始血液营养相吻合。
