Localization of dopamine and dopamine D2 receptor in the human placenta, fetal membranes and umbilical cords by immunohistochemistry

Abstract

During human pregnancy, the placenta is the major site to feed the fetus, many hormones are synthesized and maintain high concentrations in the maternal circulation. It has been reported that the human placenta could produce many neuropeptides, growth factors, and cytokines. Dopamine is one of these hormones. Dopamine exerts its effects through interactions with dopamine receptors. Dopamine receptors have been divided into two types: D1 and D_(2) receptor. Dopamine D1 or D_(2) receptor has been proved their presence in the human placenta, in fetal membranes by many authors, but research about localization of the dopamine is very few. The aim of this study was to determine the localization of Dopamine and Dopamine D_(2)receptors in the human placenta, fetal membranes and umbilical cords of normal pregnancy at term by immunohistochemistry analysis, using the immunohistochemical ABC methods with rabbit anti-dopamine polyclonal antibody AB122s and polyconal antibody rabbit anti-dopamine D_(2)receptor AB1558 as primary antibody. Immunoreactive was localized in the syncyotiotrophoblastic cells and trophoblastic cells and deciduas of menbrane. With one hundred fifty seven stains, the positive was 33.3% (14/42), 25% (5/20), 38.5% (3/8) for Dopamine , and 48% (24/26), 56% (14/25), 50% (6/12) for Dopamine D2 receptor in placenta, fetal membranes and umbilical cords. According to our results, Dopamine and Dopamine D_(2) receptors have a relationship with placenta. We propose the hypothesis that Dopamine is present in human placenta. This study is the first toshow the presence of Dopamine in human placenta, and Dopamine D_(2) receptor have also an activity on the placenta. Dopamine and Dopamine D_(2) receptor were not only showed in human placenta but also in the fetal membranes and umbilical cords. It is speculated that placenta may produce Dopamine, Dopamine D_(2)receptor. May be they play a more important role in the human placenta development and pregnancy maintenance, and also take part in regulating fetal development.