Adenosine is a short-range signal molecule that surges in the mouse uterus immediately after blastocyst implantation (Blackburn et al. [1992] Dev. Dyn. 194:155-168). The present study has investigated patterns of uterine adenosine receptor expression during early post-implantation development. Strong expression of the A2b adenosine receptor was observed.
Utilizing northern blot analysis, in situ hybridization, and immunostaining, the source of expression was mapped to the primary and secondary decidua of the antimesometrial region, between days 4-8 of gestation. Distribution of the A2b receptor protein followed that of the corresponding transcript by about one gestational day and reflected the dynamics of antimesometrial tissue organization during implantation chamber development. Uterine adenosine surges to levels sufficient for A2b receptor engagement during a defined period (i.e., days 4-6) after blastocyst implantation. Decidual A2b receptor expression thus defines a transitory window of murine gestation that corresponds to a period of human gestation encompassing most spontaneous pregnancy losses. Because adenosine receptors are sensitive to metabolically stable adenosine analogues, their differential expression during implantation chamber development may hold therapeutic potential in the prevention of early pregnancy loss.