Evidence for the presence of dopamine D 1 receptor mRNA and binding sites in monkey amniotic epithelial cells

Abstract

In this study we examined the presence of dopamine D 1 receptors in monkey amniotic epithelial cells (MAEC) using RT-PCR and radioligand binding experiments. We found that MAEC express D 1 receptor mRNA that is having 99% homology with human dopamine D 1 receptors. Saturation binding studies using [ 3H]SCH-23390 showed a high affinity D1 site with K D and B max values of 0.82±0.12 nM and 20.77±4.22 fmol/mg protein, respectively. Competition experiments showed that selective D 1, but not D 2, antagonists are potent displacers of [ 3H]SCH 23390 binding with a rank order of potency that is consistent with the pharmacology of the dopaminergic D 1 site. These data provide, for the first time, compelling evidence that MAEC natively express D 1 mRNA and binding sites and suggest that it may be a potential primate cell model to study D 1 receptors and to explore new selective drugs active at these receptors.