NOVEL EXPRESSION OF FUNCTIONAL HUMAN CHORIONIC-GONADOTROPIN LUTEINIZING-HORMONE RECEPTOR GENE IN HUMAN UMBILICAL CORDS

Human umbilical cord contains two arteries and a vein surrounded by Wh arton's jelly with amnion covering the exterior surface. The cord bloo d and amniotic fluid contain human CG (hCG). Whether hCG can directly regulate cord functions is unknown. We now report that human umbilical cords contain a major 4.4-kilobase and minor 2.6- and 1.8-kilobase hC G/LH receptor messenger RNA transcripts. The cords also contain a 50-k ilodalton immunoreactive receptor protein which can bind hCG and LH, b ut not hFSH or hTSH. Rat testis used as a positive tissue control cont ained the same major and minor receptor transcripts and an 80-kilodalt on receptor protein which can bind [I-125]hCG. Rat liver used as a neg ative control contained neither receptor transcripts nor receptor prot ein. The smooth muscle and endothelial cells of umbilical arteries and vein, umbilical amnion, and cells in Wharton's jelly contain the rece ptor transcripts and receptor protein which can bind [I-125]hCG. The r eceptor expression was higher in umbilical vessels closer to the baby and decreased toward placenta, becoming barely detectable once the ves sels were inside the placental tissue. In vitro treatment of umbilical cords with highly purified hCG resulted in an increase of immunoreact ive cyclooxygenase-l, cyclooxygenase-2, prostacyclin synthase, and 6-k eto-prostaglandin F-1a, little change in thromboxane A(2) synthase and a decrease of prostaglandin E(2) and thromboxane B-2 as Compared to t he controls, indicating that the cord receptors are functional. In sum mary, these novel findings suggest that hCG present in cord blood and amniotic fluid may directly regulate the vascular tone and quite possi bly other functions of human umbilical cord