Expression of dopamine and adrenergic receptors in mouse embryonic stem cells and preimplantation embryos

Using RT-PCR we examined expression of dopamine and adrenergic receptors in undifferentiated and spontaneously differentiating mouse embryonic stem (ES) cells. We also examined expression of dopamine receptor subtypes in mouse ovulated oocytes and preimplantation embryos. Comparing the expression of catecholamine receptors in undifferentiated mouse ES cells and in blastocysts (from which ES cells are derived), we found that transcripts of all five dopamine receptors were expressed in both cell types. In contrast, we detected eight adrenergic receptor subtypes in undifferentiated mouse ES cells, but only three subtypes were found in mouse blastocysts. In three adrenergic receptors (α1D, α2B, β1), we found higher expression in the spontaneously differentiating ES cells than in undifferentiated ES cells, and the α1B adrenoceptor was not even detectable in the undifferentiated cells. These results indicate that genes encoding all types of catecholamine receptors are transcribed in mouse ES cells, and some of them are differentially expressed during ES cell differentiation. We found several profiles of dopamine receptor mRNA expression during the preimplantation period. The DR3 transcript was present in all examined stages (oocytes, 4-cell embryos, 8- to 16-cell embryos, blastocysts). DR1 and DR4 transcripts were not found in oocytes, but we detected them in preimplantation embryos. The DR2 receptor transcript was found in all examined stages except for the 4-cell embryos, and the DR5 receptor transcript was found in all examined stages except for the 8- to 16-cell embryos. The expression profiles of dopamine receptor transcripts suggest different roles of some receptor subtypes in particular preimplantation developmental stages.