BioProject

alpha2-adrenoceptors are essential presynaptic regulators of norepinephrine release from sympathetic nerves. More...

alpha2-adrenoceptors are essential presynaptic regulators of norepinephrine release from sympathetic nerves. Previous studies in mice with targeted deletions in the three alpha2-adrenoceptor genes have indicated that these receptors are essential for embryonic development. In the present study, we searched for the alpha2-adrenoceptor subtype(s) involved in placental development and its molecular mechanism using mice carrying targeted deletions in alpha2-adrenoceptor genes. Congenic alpha2B-adrenoceptor-deficient mice (Adra2b-/-) developed a defect in fetal and maternal vessel formation in the placenta labyrinth at embryonic day E10.5. This defect was accompanied by reduced endothelial cell proliferation and decreased ERK1/2 phosphorylation levels in Adra2b-/- as compared with Adra2b+/+ placenta. Microarray analysis of wild-type and mutant placentae (maternal genotype Adra2b+/-) revealed 179 genes which were significantly up- or downregulated >1.5-fold in alpha2B-deficient placenta. The type 1 receptor for vascular endothelial growth factor (Flt1), which is coexpressed with alpha2B-adrenoceptors in spongiotrophoblast and giant cells of the placenta, was found to be 2.3-fold upregulated in alpha2B-deficient placenta. Neutralization of Flt1 and its soluble splice variant sFlt1 by a specific antibody in vivo prevented the vascular defect in alpha2B-deficient placenta at E10.5. Thus, alpha2B-adrenoceptors are essential to suppress antiangiogenic (s)Flt1 in spongiotrophoblasts to control the coordinated formation of a vascular labyrinth of fetal and maternal blood vessels in the murine placenta during development. Keywords: Comparative expression profiling Overall design: Comparative transcriptome analysis was determined using the GeneChip Mouse Genome 430 2.0 Array (Affymetrix, Santa Clara, CA, USA). Six microarrays from three wild-type and three adra2b deficient mice were performed. Less...