Involvement of the cyclic AMP‐protein kinase a pathway in gap junctional communication in preimplantation mouse embryos

Abstract

In this study, we have examined the role of cAMP in gap junctional communication (GJC) in preimplantation mouse embryos. GJC was monitored by Lucifer Yellow (LY) injected into one blastomere of compacted embryos. The speed of GJC was defined as the time taken for the last blastomere of the embryo to become visibly fluorescent. The median time for 8‐cell embryos (140 sec) was similar to that for 16‐cell (135 sec). To determine whether cAMP and cAMP‐dependent protein kinase (PKA) are involved in the regulation of GJC, the effects of PKA inhibitor (H8) and cAMP analogues (Rp‐cAMP and 8‐Br‐cAMP) on dye transfer between blastomeres of compacted embryos were examined. Some of the embryos treated with either H8 or Rp‐cAMP failed to transfer LY to all blastomeres within 10 min. In contrast, 8‐Br‐cAMP speeded up fluorescent dye transfer. The median time to fill all blastomeres with LY was 140 sec in untreated controls and 90 sec in siblings treated with 8‐Br‐cAMP. Inhibition of PKA by H8 or Rp‐cAMP induced delay or arrest in embryo development after compaction, but the increase of intracellular cAMP showed no effect. These findings suggest that GJC in preimplantation mouse embryos is regulated by cAMP‐PKA pathway and transient interference by PKA inhibitors induces the developmental delay beyond compaction

Key words:

• cAMP‐protein kinase
• Gap junctional communication
• Lucifer Yellow
• Mouse embryos

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