Differential G protein-coupled cannabinoid receptor signaling by anandamide directs blastocyst activation for implantation.
Mammalian fertility absolutely depends on synchronized development of the blastocyst to the stage when it is competent to implant, and the uterus to the stage when it is receptive to implantation. However, the molecular basis for the reciprocal interaction between the embryo and the uterus remains largely unexplored. One potentially important mechanism involves signaling between an evolutionarily conserved G protein-coupled protein cannabinoid receptor, CB1, that is expressed at high levels on the surface of the trophectoderm and anandamide (N-arachi-donoylethanolamine), an endocannabinoid ligand found to be produced at higher levels by the uterus before implantation and then down-regulated at the time of implantation. Using genetic, pharmacological, and physiological approaches, we show here that anandamide within a very narrow range regulates blastocyst function and implantation by differentially modulating mitogen-activated protein kinase signaling and Ca2+ channel activity via CB1 receptors. Anandamide at a low concentration (7 nM) induces extracellular regulated kinase phosphorylation and nuclear translocation in trophectoderm cells without influencing Ca2+ channels, and renders the blastocyst competent for implantation in the receptive uterus. In contrast, anandamide at a higher concentration (28 nM) inhibits Ca2+ channel activity and blastocyst competency for implantation without influencing mitogen-activated protein kinase signaling. Besides uncovering a potentially important regulatory mechanism for synchronizing blastocyst and uterine competency to implantation, this observation has high clinical relevance, because elevated levels of anandamide induce spontaneous pregnancy loss in women.
Wang
Haibin
H
Department of Pediatric, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Matsumoto
Hiromichi
H
Guo
Yong
Y
Paria
Bibhash C
BC
Roberts
Richard L
RL
Dey
Sudhansu K
SK
D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology*; D001755:Blastocyst / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology; D002454:Cell Differentiation; D002614:Chelating Agents / Q000494:pharmacology; D015536:Down-Regulation; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D010064:Embryo Implantation; D063388:Endocannabinoids; D004789:Enzyme Activation; D005298:Fertility; D019204:GTP-Binding Proteins / Q000378:metabolism; D005838:Genotype; D005982:Glutathione Transferase / Q000378:metabolism; D008024:Ligands; D020935:MAP Kinase Signaling System; D051379:Mice; D008817:Mice, Mutant Strains; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D053284:Polyunsaturated Alkamides; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism; D043882:Receptors, Cannabinoid / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D015854:Up-Regulation
D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D002614:Chelating Agents; D063388:Endocannabinoids; D008024:Ligands; D053284:Polyunsaturated Alkamides; D043884:Receptor, Cannabinoid, CB1; D043882:Receptors, Cannabinoid; D004533:Egtazic Acid; D005982:Glutathione Transferase; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D002118:Calcium; C078814:anandamide