Early expression of D 3 dopamine receptors in murine embryonic development

Abstract

In order to determine whether the D 2 and D 3 dopamine receptors may have a role in prenatal development, we have studied the mRNA expression and distribution of these receptors during murine embryonic development. Using RT-PCR on RNA from embryos taken at progressive stages of development, we have shown that the D 3 receptor is expressed significantly earlier than the D 2 receptor, being detectable at day 9.5 post-conception (p.c.), compared with day 13.5 p.c. for the D 2 subtype. We have also examined the mRNA distribution of the two receptors by whole mount in situ hybridisation. In agreement with the PCR assays, the D 3 receptor was expressed earlier than the D 2 subtype. D 3 receptor transcripts were first detected at day 9.5 p.c. in the ventral aspect of the anterior neural tube, whereas D 2 receptor transcripts first appeared a day later. By day 10.5–11.5 p.c. both D 3 and D 2 receptor transcripts were present in the developing forebrain, and later also in the branchial arches and along the prospective vertebral column. The early appearance of the D 3 subtype in murine development and its predominance over the D 2 subtype suggest that the D 3 receptor may have a functional role in prenatal development.