来曲唑对高龄雌性SD大鼠子宫内膜容受性、血管内皮生长因子和内皮型一氧化氮合酶表达的影响

Effects of Letrozole on Endometrial Receptivity and Expression of Vascular Endothelial Growth Factor and Endothelial Nitric Oxide Synthase in Elderly Female SD Rats

目的:探讨来曲唑对高龄雌性SD大鼠子宫内膜容受性、血管内皮生长因子(VEGF)和内皮型一氧化氮合酶(eNOS)表达的影响。方法:将SD大鼠分为对照组、模型组、来曲唑低剂量组、来曲唑中剂量组和来曲唑高剂量组,每组12只。除对照组外,其他组均采用促性腺激素释放激素激动剂+尿促性腺激素+人绒毛膜促性腺激素构建超促排卵模型。建模成功后,来曲唑低剂量组、来曲唑中剂量组和来曲唑高剂量组大鼠分别按照0.13、0.26和0.52 mg/kg的剂量灌胃来曲唑,对照组、模型组大鼠灌胃等体积的0.9%氯化钠溶液,在妊娠第6日时,麻醉大鼠后解剖腹腔,观察子宫中胚泡的着床情况,记录大鼠胚胎着床率及平均着床胚泡数;采用苏木精-伊红染色检测大鼠子宫内膜病理变化;采用扫描电镜观察大鼠子宫内膜胞饮突表达;采用定量反转录聚合酶链反应检测子宫内膜中VEGF mRNA、eNOS mRNA表达;采用免疫组化法分析大鼠子宫内膜中VEGF、eNOS表达。结果:与对照组比较,模型组大鼠子宫内膜发育缓慢,子宫内膜变薄,血管较少,细胞核固缩,胞饮突数量减少,胚胎着床率、平均着床胚泡数、VEGF mRNA和eNOS mRNA水平及平均光密度值显著降低,差异均有统计学意义(P<0.05)。与模型组比较,来曲唑低剂量组、来曲唑中剂量组和来曲唑高剂量组大鼠子宫内膜增生,变厚,固有层疏松水肿,血管数量增多,胞饮突表达增加,胚胎着床率、平均着床胚泡数、VEGF mRNA和eNOS mRNA水平及平均光密度值显著升高,且呈剂量依赖性,差异均有统计学意义(P<0.05)。结论:来曲唑可提高子宫内膜容受性,使胚胎着床率及平均着床胚泡数升高,可能与促进VEGF、eNOS的表达升高有关。

OBJECTIVE: To probe into the effects of letrozole on the endometrial receptivity and expression of vascular endothelial growth factor(VEGF) and endothelial nitric oxide synthase(eNOS) in elderly female SD rats. METHODS: The SD rats were divided into control group, model group, letrozole low-dose(LE-L) group, letrozole medium-dose(LE-M) group, letrozole high-dose(LE-H) group, with 12 rats in each group. Except for the control group, the other groups were given gonadotropin releasing hormone agonist + urogonadotropin + human chorionic gonadotropin to construct ovarian hyperstimulation models. After successful modeling, rats in the LE-L group, LE-M group and LE-H group were gavaged with letrozole at the doses of 0.13 mg/kg, 0.26 mg/kg and 0.52 mg/kg, respectively, the control group and model group were gavaged with body volume of 0.9% sodium chloride solution. On the 6 th day of pregnancy, the rats were anesthetized and the abdominal cavity was dissected to observe the embryo implantation of blastocyst in uterus, the embryo implantation rate and the average number of implanted blastocyst were recorded;hematoxylin-eosin staining was used to detect pathological changes in the endometrium of rats;scanning electron microscopy was used to observe the expression of pinopode in the endometrium of rats;quantitative reverse transcription PCR was used to detect the expression of VEGF mRNA and eNOS mRNA in the endometrium;immunohistochemistry was used to analyze the expression of VEGF and eNOS in endometrium of rats. RESULTS: Compared with the control group, the endometrium of rats in the model group developed slowly, with thinner endometrium, less blood vessels, karyopyknosis, less number of pinopode, significantly lower embryo implantation rate, average number of implanted blastocyst, VEGF mRNA level, eNOS mRNA level and mean optical density values, with statistically significant differences(P<0.05). Compared with the model group, the endometrium of rats in the LE-L group, LE-M group and LE-H group were hyperplastic and thickened, with loose and edematous lamina propria, more blood vessels, increased expression of pinopode, significantly higher embryo implantation rate, average number of implanted blastocyst, VEGF mRNA level, eNOS mRNA level and mean optical density values, which presented a dose-dependent, with statistically significant differences(P<0.05). CONCLUSIONS: Letrozole can improve the endometrial receptivity, increase the embryo implantation rate and average number of implanted blastocyst, which may be related to the promotion of elevated expression of VEGF and eNOS.