| 摘要: |
Pregnancy loss is a serious social-medical issue, with one important cause associated with aberrant embryo implantation during early pregnancy. However, whether and how the process of embryo implantation is affected by environmental factors such as stress induced sympathetic activation remained elusive. Here we report an unexpected, transient effect of β2-Adrenoceptor (β2-AR) activation (day4 postcoitus) in disrupting embryo spacing at implantation, leading to substantially increased mid-term pregnancy loss. The abnormal embryo spacing could be prevented by pretreatment of β2-AR antagonist or genetic ablation of β2-AR. Similar β2-AR activation at day5 postcoitus, when implantation sites have been established, did not affect embryo spacing or pregnancy outcome, indicating the adverse effect of β2-AR activation is limited to preimplantation period before embryo attachment. In vitro and in vivo studies demonstrated that the transient β2-AR activation abolished normal preimplantation uterine contractility, without adversely affecting blastocyst quality. The contractility inhibition is mediated by activation of cAMP-PKA pathway and accompanied with specific downregulation of lpa3, a gene previously found to be critical for uterine contraction and embryo spacing. These results indicated that normal uterine contraction mediated correct intrauterine embryo distribution is crucial for successful ongoing pregnancy. Abnormal β2-AR activation at early pregnancy provided a molecular clue in explaining how maternal stress at early stage could adversely affect pregnancy outcome.
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