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Abstract: The objective was to investigate the expression of bone morphogenetic protein (BMP) family members in the mouse uterus during the estrous cycle by real-time polymerase chain reaction (PCR) and immunohistochemistry. Uterine samples from Swiss ICR mice were collected and dissected free of surrounding tissue. One uterine horn was snap frozen in liquid nitrogen immediately after collection and stored at −80 °C for RNA extraction, and the other was fixed in 40 mg/ml paraformaldehyde at room temperature for immunolocalization of BMP2 protein. Real-time PCR analysis showed that the expression level of Bmp2 was significantly higher at proestrus than at estrus and metestrus (P<0.05). The relative abundance of Bmp4 exhibited significant fluctuations, but there were no statistically significant differences between the expression levels of Bmp2 and Bmp4 (P>0.05). The expression levels of Bmpr1a and Bmpr2 remained unchanged during estrous cycles. However, the level of Bmpr1b mRNA decreased significantly at estrus (P<0.05), increasing subsequently at metestrus. Furthermore, the level of Bmpr1b mRNA was significantly lower than those of Bmpr1a and Bmpr2 mRNA at the corresponding stages (P<0.05). All three receptor-regulated SMADs (R-SMADs) detected were differentially expressed in the mouse uterus and the expression levels of SMAD1 and SMAD5 were significantly higher than that of SMAD8 (P<0.05). In addition, the expression level of SMAD4 did not change substantially throughout the estrous cycle. Immunohistochemical experiments revealed that BMP2 protein was differentially expressed and localized mainly in the uterine luminal and glandular epithelial cells throughout the estrous cycle. In conclusion, our results provide information about the variation in the mRNA levels of Bmp2 and Bmp4 and related components of the BMP signaling pathway. The data provide quantitative and useful information about the roles of endometrial BMP proposed and demonstrated by others, such as the degradation and remodeling of the endometrium.

BMP2，BMP4及BMP信号通路相关成员在发情周期小鼠子宫中的表达

研究目的：研究骨形态发生蛋白（BMP）2，4及BMP信号通路相关成员在发情周期小鼠子宫中的表达模式。
创新要点：运用实时荧光定量聚合酶链式反应（PCR）系统地研究了Bmp2和Bmp4及其BMP信号通路相关成员在小鼠子宫中mRNA水平表达模式，同时运用免疫组化方法研究了BMP2蛋白在小鼠子宫中的定位模式。
研究方法：收集发情周期各个时期小鼠子宫，一侧子宫角贮存于液氮或−80 °C冰箱用于实时荧光定量PCR，另一侧子宫角用40 mg/ml 多聚甲醛固定用于BMP2蛋白免疫组化定位。
重要结论：实时荧光定量PCR结果表明，Bmp2的表达水平在发情前期显著高于发情期和发情后期（P<0.05），Bmp4的表达水平呈现显著波动，但Bmp2与Bmp4差异不显著（P>0.05）。Bmpr1a和Bmpr2的表达水平在整个发情周期无显著变化（P>0.05）。然而，Bmpr1b的mRNA水平在发情期显著下降（P<0.05），在发情后期上升。此外，Bmpr1b的mRNA水平显著低于相应时期Bmpr1a和Bmpr2的mRNA水平（P<0.05）。三种R-Smads差异地表达于小鼠子宫，并且Smad1和Smad5的表达水平显著高于Smad8（P<0.05）。此外，Smad4的表达水平在整个发情周期无显著变化。免疫组化结果显示，BMP2蛋白在整个发情周期差异表达，并主要定位于子宫腔上皮细胞和腺上皮细胞。我们的结果提供了BMP2和BMP4及其BMP信号通路相关成员mRNA水平表达变化信息，这些数据为论证BMP在子宫内膜中的作用如子宫内膜的退化与重塑提供量化和有用的信息。

关键词：骨形态发生蛋白；骨形态发生蛋白受体；SMAD蛋白；子宫；发情周期

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