Expression of adrenergic receptors in mouse preimplantation embryos and ovulated oocytes

Abstract

Epinephrine and norepinephrine can play an important role in basic developmental processes such as embryogenesis and morphogenesis, regulating cell proliferation, differentiation and migration. We showed that β-adrenergic receptors can mediate the effects of catecholamines on preimplantation embryos in our previous work. In the present study, we designed specific oligonucleotide primers which can distinguish among all members of the α-adrenergic receptor family, and showed (using RT-PCR) that the α2C-adrenergic receptor is transcribed in ovulated oocytes, 8- to 16-cell morulae and expanded blastocysts. We did not detect the α2C-adrenoceptor transcript in 4-cell embryos. Our immunohistochemical study showed the presence of α-2C-adrenoceptor protein in ovulated oocytes, 8- to 16- cell embryos and blastocysts, but the signal in 4-cell embryos was weak, and probably represents remaining protein of maternal origin. We did not detect any other α-adrenergic receptor in preimplantation embryos and oocytes. Exposure of mouse preimplantation embryos to the α2-adrenergic agonist UK 14 304 led to significant reduction of the embryo cell number, and the effect was dose dependent. Our results suggest that epinephrine and norepinephrine could affect the embryo development in the oviduct via adrenergic receptors directly and support the opinion that maternal stress can influence the embryo even in very early pregnancy.