Identification and characterization of human placental opiate peptides, kappa receptors, and mediated responses; The in vitro and in vivo effects of short- & long-term opiate administration on placental kappa opiate receptors and their mediated responses; The role of human placenta as a functional barrier regulating fetal exposure to xenobiotics including medications; A non-human primate as an animal model for human pregnancy; Bioanalytical